Return of Caribou to Ungava 9780773576780

Table of contents :
Cover
Contents
Donors
Acknowledgments
List of Tables
List of Figures
Preface
Plates
1 Setting and Background
The Eruption of the George River Caribou Herd
Ungava
Boundaries of Vegetative Zones
Plant Species Composition of Vegetative Zones
Forest Fires
Mammalian Fauna
Those Other Animals
Native Inhabitants
2 Taxonomy, Ecotypes, Herds, and Morphology
Ecotypes
Migratory Herds
Morphology
3 The Return of Caribou to Ungava after the Last Ice Age
Postglacial Dispersal and Ecotypes
Recolonization
4 The Abundance and Distribution of Sedentary Caribou
Distribution
Population Dynamics Background
Population Dynamics of the Major Herds
Population Regulation and Management
5 Past Population Fluctuations
Postglacial Distribution of Ungava Caribou
Historical Distribution
Past Fluctuation of Numbers
At Home in the Wilderness: The Mushuau Innu and Caribou
6 Causal Factors in Historical Fluctuations
Early Explanations
A Recent Hypothesis: Increased Snow Cover
Shortage of Green Forage and Cold Springs
7 Forage and Range
Range Survey, 1988–89
Food Preferences
The Condition of Winter Pastures
The Condition of Summer Pastures
Activity and Energy Budgets
Range Trends
A Look Ahead
8 Body and Antler Growth
The Measurement of Growth and Body Size
Body Size
Fetal Growth
Birth Mass of Calves
Growth of Calves and Yearlings
Retarded Growth and Compensation
Adult Body Mass
Antler Size
Growth and Demography
9 Physical Condition
Antler and Calving Indexes
Antler Condition Index
Female Antler Casting
Chewing of Antlers
Calving Chronology
Nutrition and Antler Casting
Liver Weights
Fat Cycle
Energy Expenditure during Migration
Migration/Habitat Strategies and Fat Deposition
Fat Deposition Strategies
Trends in Condition Indices
10 Recruitment, Mortality, and Population Growth
Basic Indices
Pregnancy/Parous Rates
Calf Mortality Statistics
Adult Mortality
Population Growth
The Decline Phase, 1988–93
11 Limiting Factors
Starvation
Accidents
Hunting Mortality
Weather Factors
Disease and Parasite
Predation
Differential Mortality of Males and Females
12 The Use of Space
Aerial Surveys and Radio Monitoring
The Centre of Habitation
Range Expansion
Range Contraction
Range Predictability
Calving, Rutting, and Winter Distributions
Movement Routes
Releasing/Expansion Densities
The “Social Stimulus” Concept
Density-Dependent Changes in the Use of Space
13 Environmental Factors in Distribution and Movement
Basic Quantification Methods
Seasonal Changes in Mobility
Annual Dispersion and Fidelity in Distributions
Environmental Influences on Seasonal Distributions
14 Optimal Foraging and Predation Risk in the Winter and Growing Season
Distribution Strategy in Winter
Spacing Strategy in the Growing Season
Competitive Interference at High Densities
Global Warming and Optimal Foraging/Predation Risk
15 Spacing Theory of Calving and Migration
Migration Hypotheses
Nutrition Destination Hypothesis
Predation Displacement Hypothesis
The Location and Shifting of Calving Grounds
Females Shifted to Reduce Predation Risk
Snow Cover on Calving Grounds
Calving Grounds at Maximum Distance from Tree Line
Density Dependence of Calving Ground Location
Timing of Births
Synchrony of Births
Homing and Navigation
Experimental Evidence of True Navigation
Birth Site Fidelity
Homing of Yearlings
16 Population Regulation
Parturition Rates
Summer Calf Mortality
Winter Mortality of Calves
Adult Mortality
The Foraging Carrying Capacity
Winter Starvation
Range Fecundity and Calf Survival
Population Model
A Shortage of Summer Foods
Final Comments
Appendix: Summer Energy Budgets for Lactating Females
Bibliography
Index
A
B
C
D
E
F
G
H
I
J
L
M
N
O
P
R
S
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V
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Citation preview

The Return of Caribou to Ungava

McGILL-QUEEN’S NATIVE AND NORTHERN SERIES Bruce G. Trigger, Editor

 When the Whalers Were Up North Inuit Memories from the Eastern Arctic Dorothy Harley Eber 2 The Challenge of Arctic Shipping Science, Environmental Assessment, and Human Values Edited by David L. VanderZwaag and Cynthia Lamson 3 Lost Harvests Prairie Indian Reserve Farmers and Government Policy Sarah Carter 4 Native Liberty, Crown Sovereignty The Existing Aboriginal Right of Self-Government in Canada Bruce Clark 5 Unravelling the Franklin Mystery Inuit Testimony David C. Woodman 6 Otter Skins, Boston Ships, and China Goods The Maritime Fur Trade of the Northwest Coast, 785–84 James R. Gibson 7 From Wooden Ploughs to Welfare The Story of the Western Reserves Helen Buckley 8 In Business for Ourselves Northern Entrepreneurs Wanda A. Wuttunee 9 For an Amerindian Autohistory An Essay on the Foundations of a Social Ethic Georges E. Sioui 0 Strangers Among Us David Woodman  When the North Was Red Aboriginal Education in Soviet Siberia Dennis A. Bartels and Alice L. Bartels 2 From Talking Chiefs to a Native Corporate Elite The Birth of Class and Nationalism among Canadian Inuit Marybelle Mitchell

3 Cold Comfort My Love Affair with the Arctic Graham W. Rowley 4 The True Spirit and Original Intent of Treaty 7 Treaty 7 Elders and Tribal Council with Walter Hildebrandt, Dorothy First Rider, and Sarah Carter 5 This Distant and Unsurveyed Country A Woman’s Winter at Baffin Island, 857–858 W. Gillies Ross 6 Images of Justice Dorothy Harley Eber 7 Capturing Women The Manipulation of Cultural Imagery in Canada’s Prairie West Sarah A. Carter 8 Social and Environmental Impacts of the James Bay Hydroelectric Project Edited by James F. Hornig 9 Saqiyuq Stories from the Lives of Three Inuit Women Nancy Wachowich in collaboration with Apphia Agalakti Awa, Rhoda Kaukjak Katsak, and Sandra Pikujak Katsak 20 Justice in Paradise Bruce Clark 2 Aboriginal Rights and Self-Government The Canadian and Mexican Experience in North American Perspective Edited by Curtis Cook and Juan D. Lindau 22 Harvest of Souls The Jesuit Missions and Colonialism in North America, 632–650 Carole Blackburn 23 Bounty and Benevolence A History of Saskatchewan Treaties Arthur J. Ray, Jim Miller, and Frank Tough 24 The People of Denendeh Ethnohistory of the Indians of Canada’s Northwest Territories June Helm

25 The Marshall Decision and Native Rights Ken Coates 26 The Flying Tiger Women Shamans and Storytellers of the Amur Kira Van Deusen 27 Alone in Silence European Women in the Canadian North before 940 Barbara E. Kelcey 28 The Arctic Voyages of Martin Frobisher An Elizabethan Adventure Robert McGhee 29 Northern Experience and the Myths of Canadian Culture Renée Hulan 30 The White Man’s Gonna Getcha The Colonial Challenge to the Crees in Quebec Toby Morantz 3 The Heavens Are Changing Nineteenth-Century Protestant Missions and Tsimshian Christianity Susan Neylan 32 Arctic Migrants/Arctic Villagers The Transformation of Inuit Settlement in the Central Arctic David Damas 33 Arctic Justice On Trial for Murder – Pond Inlet, 923 Shelagh D. Grant 34 Eighteenth-Century Naturalists of Hudson Bay Stuart Houston, Tim Ball, and Mary Houston 35 The American Empire and the Fourth World Anthony J. Hall 36 Uqalurait An Oral History of Nunavut Compiled and edited by John Bennett and Susan Rowley 37 Living Rhythms Lessons in Aboriginal Economic Resilience and Vision Wanda Wuttunee

38 The Making of an Explorer George Hubert Wilkins and the Canadian Arctic Expedition, 93–96 Stuart E. Jenness 39 Chee Chee A Study of Aboriginal Suicide Alvin Evans 40 Strange Things Done Murder in Yukon History Ken S. Coates and William R. Morrison 4 Healing through Art Ritualized Space and Cree Identity Nadia Ferrara 42 Coyote and Raven Go Canoeing Coming Home to the Village Peter Cole 43 Something New in the Air The Story of First Peoples Television Broadcasting in Canada Lorna Roth 44 Listening to Old Woman Speak Natives and Alternatives in Canadian Literature Laura Smyth Groening 45 Robert and Francis Flaherty A Documentary Life, 883–922 Robert J. Christopher 46 Talking in Context Language and Identity in Kwakwaka’wakw Society Anne Marie Goodfellow 47 Tecumseh’s Bones Guy St-Denis 48 Constructing Colonial Discourse Captain Cook at Nootka Sound Noel Elizabeth Currie 49 The Hollow Tree Fighting Addiction with Traditional Healing Herb Nabigon 50 The Return of Caribou to Ungava A.T. Bergerud, Stuart Luttich, and Lodewijk Camps

Massing of the George River Herd. Photograph by Patrice Halley.

caribou

THE RETURN OF

TO UNGAVA

A.T. Bergerud, Stuart N. Luttich, and Lodewijk Camps

McGill-Queen’s University Press Montreal & Kingston | London | Ithaca

© McGill-Queen’s University Press 2008 ISBN 978-0-7735-3233-5 Legal deposit first quarter 2008 Bibliothèque nationale du Québec Printed in Canada on acid-free paper. McGill-Queen’s University Press acknowledges the support of the Canada Council for the Arts for our publishing program. We also acknowledge the financial support of the Government of Canada through the Book Publishing Industry Development Program ( BPIDP ) for our publishing activities

LIBRARY AND ARCHIVES CANADA CATALOGUING IN PUBLICATION

Bergerud, A. T. The return of caribou to Ungava / A.T. Bergerud, Stuart N. Luttich and Lodewijk Camps. (McGill-Queen’s native and northern series ; 50) Includes bibliographical references and index. ISBN 978-0-7735-3233-5 1. Caribou – Québec (Province) – George River Region. 2. Caribou – Newfoundland and Labrador – Labrador. I. Luttich, Stuart N. II. Camps, Lodewijk III. Title. IV. Series. QL737.U55B475 2007

599.65’809714111

C2007-901605-7

Set in 11/13.5 Minion Pro with Avenir Book design/typesetting by Garet Markvoort/zijn digital

This book is dedicated to the late Captain Harry Walters, the first director of the Newfoundland Wildlife Service, and to Douglas Pimlott, the first chief biologist, and to those dedicated wildlife officers who walked the hills with the senior author in earlier days: Michael Nolan, Samuel Kelly, Steven Hall, and William Anderson. Special recognition is extended to the late Wildlife Field Technician Robert (Bob) Baikie – one of many unsung heroes and a true “Labradorean,” whose unmatched hunting and camping savvy, relaxed personality, and intimate understanding of the “big land” converted all of the many often lengthy trips into the field under primitive and distantly isolated conditions, whether by canoe and boat, snow machine, or aircraft, irregardless of all the inclement weather conditions, mechanical difficulties, and otherwise encountered hardships, into both a rewarding success and pleasure to be long remembered. Without Bob much of the field data and observations during the late 1970s and throughout the 1980s would likely have never been gathered.

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Donors

We wish to thank the following donors whose contributions helped make publication of this book possible. Aurora Energy Resources Department of Environment and Conservation, Wildlife Division, Government of Newfoundland and Labrador Department of Environment and Natural Resources, Government of the Northwest Territories Department of Lands and Resources, Nunatsiavut Government Hunting, Fishing and Trapping Coordinating Committee (9th North-American Caribou Workshop) Iron Ore Company of Canada Ministère du développement durable, de l’Environnement et des Parcs, Gouvernement du Québec Naskapi Nation of Kawawachikamach Newfoundland and Labrador Outfitters Association New Millennium Capital Corp Safari Club International Voisey’s Bay Nickel Company Limited Yukon Department of Environment

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Contents

Donors ix Acknowledgments xv List of Tables xix List of Figures xxv Preface xxxv Plates xxxix  Setting and Background 3 The Eruption of the George River Caribou Herd 3 Ungava 4 Boundaries of Vegetative Zones 2 Plant Species Composition of Vegetative Zones 5 Forest Fires 7 Mammalian Fauna 2 Those Other Animals 27 Native Inhabitants 28 2 Taxonomy, Ecotypes, Herds, and Morphology Ecotypes 34 Migratory Herds 40 Morphology 4

3

3 The Return of Caribou to Ungava after the Last Ice Age Postglacial Dispersal and Ecotypes 54 Recolonization 64

54

xii | CO NTENT S

4 The Abundance and Distribution of Sedentary Caribou Distribution 76 Population Dynamics Background 8 Population Dynamics of the Major Herds 85 Population Regulation and Management 02 5 Past Population Fluctuations 06 Postglacial Distribution of Ungava Caribou Historical Distribution 09 Past Fluctuation of Numbers 3

74

06

At Home in the Wilderness: The Mushuau Innu and Caribou 23 by Stephen Loring, Arctic Studies Center, Smithsonian Institution 6 Causal Factors in Historical Fluctuations 35 Early Explanations 37 A Recent Hypothesis: Increased Snow Cover 43 Shortage of Green Forage and Cold Springs 46 7 Forage and Range 50 Range Survey, 988–89 5 Food Preferences 55 The Condition of Winter Pastures 60 The Condition of Summer Pastures 66 Activity and Energy Budgets 74 Range Trends 77 A Look Ahead 79 8 Body and Antler Growth 8 The Measurement of Growth and Body Size Body Size 83 Fetal Growth 87 Birth Mass of Calves 90 Growth of Calves and Yearlings 96 Retarded Growth and Compensation 97 Adult Body Mass 207 Antler Size 24 Growth and Demography 28 9 Physical Condition 222 Antler and Calving Indexes 223 Antler Condition Index 226

82

CO NTENT S |

Female Antler Casting 229 Chewing of Antlers 232 Calving Chronology 234 Nutrition and Antler Casting 239 Liver Weights 24 Fat Cycle 242 Energy Expenditure during Migration 25 Migration/Habitat Strategies and Fat Deposition Fat Deposition Strategies 257 Trends in Condition Indices 262 0 Recruitment, Mortality, and Population Growth Basic Indices 268 Pregnancy/Parous Rates 273 Calf Mortality Statistics 275 Adult Mortality 282 Population Growth 286 The Decline Phase, 988–93 287  Limiting Factors 292 Starvation 292 Accidents 295 Hunting Mortality 297 Weather Factors 298 Disease and Parasite 300 Predation 305 Differential Mortality of Males and Females

256

267

30

2 The Use of Space 38 Aerial Surveys and Radio Monitoring 39 The Centre of Habitation 32 Range Expansion 324 Range Contraction 33 Range Predictability 337 Calving, Rutting, and Winter Distributions 34 Movement Routes 34 Releasing/Expansion Densities 348 The “Social Stimulus” Concept 348 Density-Dependent Changes in the Use of Space 349 3 Environmental Factors in Distribution and Movement Basic Quantification Methods 353

353

xiii

xiv | CO NTENT S

Seasonal Changes in Mobility 358 Annual Dispersion and Fidelity in Distributions 375 Environmental Influences on Seasonal Distributions 38 4 Optimal Foraging and Predation Risk in the Winter and Growing Season 404 Distribution Strategy in Winter 404 Spacing Strategy in the Growing Season 43 Competitive Interference at High Densities 424 Global Warming and Optimal Foraging/Predation Risk 5 Spacing Theory of Calving and Migration 432 Migration Hypotheses 432 Nutrition Destination Hypothesis 434 Predation Displacement Hypothesis 437 The Location and Shifting of Calving Grounds 443 Females Shifted to Reduce Predation Risk 447 Snow Cover on Calving Grounds 450 Calving Grounds at Maximum Distance from Tree Line Density Dependence of Calving Ground Location 452 Timing of Births 456 Synchrony of Births 460 Homing and Navigation 462 Experimental Evidence of True Navigation 467 Birth Site Fidelity 469 Homing of Yearlings 476

427

45

6 Population Regulation 479 Parturition Rates 480 Summer Calf Mortality 484 Winter Mortality of Calves 488 Adult Mortality 49 The Foraging Carrying Capacity 494 Winter Starvation 494 Range Fecundity and Calf Survival 496 Population Model 498 A Shortage of Summer Foods 50 Final Comments 508 Appendix Summer Energy Budgets for Lactating Females Bibliography 539 Index 577

53

Acknowledgments

A preliminary version of this book was sent to several academic presses in May 2003; McGill-Queen’s was interested. In 2004 it was accepted for publication if I could raise money to publish a high-quality book with coloured photographs, maps, and figures. For the reminder of 2004 and most of 2005 I solicited funds unsuccessfully – the book was on the rocks and sinking. Then in late 2005 Paul Wilkinson came on board and thirty-five letters were written but there was still only 2,500 in pledges. Stas Olpiniski said there were funds left from the Kuujjuaq caribou conference. Anne Gunn said she would write her director Susan Fleck in the NWT. The bilge pumps started up. Jim Hancock and Rob Otto of Nfld. Wildlife sent a check for 0,000 dollars for one copy of the future book. The tide was in and she was moving. Rick Farnell found Yukon wildlife funds and we made land fall with a contract on 7 May 2006. I thank you all: Paul, Stas, Anne, Susan, Rob, Jim, and Rick for having faith in the book and saving it from Davy Jones locker. I thank Heather Butler, my partner for thirty years in research, for all the years of encouragement and stimulating discussions as we followed the caribou across North America from the Western Arctic herd to the Labrador. She is an incredibly keen observer, capable of sitting for hours. In 988, on the calving ground, after hours of watching she discovered that many of the females that had udders had not conceived in 987 and were still nursing their yearlings. She was there when we took the major risk of trying to do a range survey in 988 by fixed wing plane, landing in lakes too small, too rocky in a latitude-longitude grid pattern. I remember well sitting in the front seat, raising my legs time and again to assist the plane to lift above the trees as they filled the window. Pilot Dave Fletcher was

xvi | ACK N OW L E D G M ENT S

a professional and pulled it off. Don Miller was my partner on the first survey in 958 and still climbs Mt. Albert on the Gaspe to study that endangered herd. Dan Bergerud drafted all the figures for the book, which are unequalled. I can’t remember how many times he has drawn some of them. Annamarie Linders crunched all the data numbers that Stu and Lo and the radio-collared caribou sent in. I thank Elissa Poole for a heavy load of editing. I thank Bramwell Ryan, who took one look at Stu’s caribou map of 20 years of research and coined the inspirational phase The Loop of Life and Roberta Cooke for drafting the map. I thank Patrice Halley and Serge Couturier for sharing their caribou photographs. Serge is a true colleague, always sharing his data, putting the caribou first. I thank Eugene Mercer – who flew north in the early 970s counting the herd and did the first plant survey along the George in 975. Stephen Loring takes us back in time to the first hunters – the Innu – who followed the caribou north 7,000 years ago as the Laurentide ice sheet retreated and who were still on the land only 00 years ago when Cabot visited them. I want to thank Voisey Nickel and the Iron Ore Company of Canada for their financial contributions. I only wish Newfoundland Hydro could have been supportive – we asked many times. They have made a huge footprint on the landscape in southern Labrador that was shaped by the Laurentine ice sheet 9,000 years ago. Beautiful Michikamau Lake is gone – the jewel of the Labrador Plateau. The mighty Grand Falls of the Hamilton is silent, and even the names have been changed – erasing the past. Now they are going to change the course of rivers and flood large sections of western Labrador. I do not believe they have an ethical attitude toward the land. Their huge project may spell the end of the sedentary caribou. Please give the caribou a chance with wise decisions. Treat the land with respect: It is no one’s commercial enterprise. A .T. Bergerud Wildlife Field Technician Maria (Berger) Whitaker, whose sense of humor, knowledge, and personality served to further compliment Bob Baikie’s and whose selfless enthusiasm, interest, and cooperation helped create a most productive atmosphere in both the field, laboratory, and office, deserves special acknowledgment. And it is only fair to acknowledge and recognize the many others, including the late Warren Chaulk, the first wildlife field technician positioned in Labrador; Wildlife Field Technicians Alasdair Veitch and Frank Phillips; Abraham Kojak (Nain) whose Inuit heritage and experience conclusively proved the worth of constructing an igloo when gathering field data from the commercial late winter harvests on the barren lands of Northern Labrador, even after arriving at the camping site long after dark and having to construct the snow house in

ACK N OW L E D G M ENT S |

xvii

the glow of snow machine lights to find, peering out from the igloo the following morning, the gale force winds and drifting snow of another storm; Messrs. Joe, Henry, and Cheslie Jr Webb as well as the entire Webb family (Nain), for whose unsolicited friendship and assistance when working and residing in Northern Labrador for extended periods of time on field projects, I remain forever grateful; Wildlife Enforcement and Protection Officers Bill Barbour (Nain), Todd Kent (Labrador City), Wallace Lyall (Happy Valley), the late Joby Flowers (Hopedale) and Sandy Gordon (Kuujjuaq) (Quebec MLCP); and William (Bill) Anderson, Sr (Makkovik), and Douglas Blake (North West River); Brenda Sakauye, who volunteered assistance when working with the Naskapi-Montagnais Innu Association out of the Naskapi Davis Inlet Band Office; Johnny May – pilot and owner May’s Flying Service (Kuujjuaq) – whose piloting and cultural experiences in the central Labrador/Ungava Peninsula proved almost indispensable, if not life-saving; William (Willie) Emudluk (Kangiqsualujiuaq/Port George River), whose Inuit knowledge of the lower George River and western Torngat Mountain drainage, advice, and assistance expedited solutions to unexpected problems; Judy Rowell, the Labrador Inuit Association Environmental Coordinator, who helped arrange LIA cooperation in on-going field work; Wildlife Biologists Eugene Mercer, Steve Fergurson, Bill Dalton, and Brian Hearn, whose empathetic and intellectual interests and efforts only catalyzed encouragements and progress; John McGrath, former assistant deputy minister (NL Agriculture and Rural Development), without whose belief in the value of the work we were doing much of the money becoming available to do the work would never have been permitted; John (Przyborowski) Ski (Colchester CN), who volunteered personal use of his aircraft in performing summer field surveys; and all of the pilots for the air carriers, including Henry Blake, Dave Forgie, and Sean Tucker for Canadian Helicopters Ltd. (aka Sealand Helicopters Ltd.), Greg Baikie and the late John Innis for Universal Helicopters, and pilots for Air Labrador, Newfoundland Labrador Air Transport Ltd., and Labrador Airways Ltd, who were called upon to pilot aircraft through often severe and unforgiving weather conditions and across vast distances of an equally unforgiving rugged and uninhabited country. This is only a brief listing, and does not imply that the many others not mentioned were not instrumentally important; since, indeed, they all were. Stuart Luttich Working in Labrador has its challenges. Without the friendship of Bill Duffett and his willingness to share his knowledge and circle of friends, I would never have come to appreciate Labrador fully. The late Bob Baikie showed me true appreciation for Labrador’s wilderness. Annemarie Linders shared all Labrador

xviii | ACK N OW L E D G M ENT S

adventures with me (and still does). Our lives could not have taken a turn for the better if Tom Bergerud and Heather Butler had not accepted us as students. I am extremely grateful for their ongoing friendship and generous sharing of all they know about science and caribou. True wilderness became a part of me and for that I can thank Labrador. Lodewijk Camps

List of Tables

2. Transferrin allele frequencies of caribou in different regions (data Røed et al. 99) 32 2.2 Comparison of the size of record antlers of males between ecotypes 42 2.3 The location of damage on large male antlers compared between populations (from Butler 986) 45 2.4 Latitude, antler form, and dates at which 50% of the main beam length of large males was obtained (from Butler 986) 46 2.5 A comparison of the size of the antlers of large males of the George River herd in 978 (200,000 animals) and in 986/988 (600,000+) animals 48 2.6 Comparison of the size of caribou of the George River herd with animals measured in the Torngat Mountains (all males biased to large animals) and the sedentary Red Wine herd 50 3. A list of Rangifer fossils in eastern North America 57–8 3.2 The locations of dated caribou fossils in the Pleistocene in eastern North America compared between forest types existing at that time 59 3.3 The percentage of megafauna fossil sites in north-eastern North America (area from Missouri and Appalachian Mts. north to Canada) that also contained caribou fossils and the percentage of the megafauna sites in the lower 48 states that were in the Appalachian Mountains 62 4. The adult sex ratio, percent parous females, and adult female mortality rate 88 4.2 Mortality factors of radio-tagged females 89 4.3 Census estimates, recruitment, and hunting statistics from the Lac Joseph herd (western Labrador region) 9

xx | L I S T O F TA B L E S

4.4 The population estimates and recruitment of calves in late winter of the Red Wine and Mealy Mountain caribou herds 96 5. Abundance of caribou based on harvest (reported kill that year), unsuccessful hunts reported, and journals indicating the post had no kill that year. Journals searched where located in the HBC archives, Winnipeg (Luttich 983) 2 6. The change-over from summer hunting at Okak after the introduction of the musket in 785 39 6.2 Months that native peoples hunted caribou, 925–42 42 7. The phenology and utilization of birch (Betula glandulosa) in July 989–92 (lat. 56°49' N, long. 64°50' E) 56 7.2 The percentage of nitrogen in the forage and droppings of caribou in 989 59 7.3 The correlation matrix of range impacts compared between  regions (correlation coefficients and probabilities) 69 7.4 The matrix of correlation probabilities between variables measured in the range survey in 988 (range survey stations in grids below tree line on the upper right (italics) and above tree line on the lower left, n equals number of stations) 70 7.5 Comparison of the abundance of forage at two sites in 975 and 993 (based on the Blaun-Blanquet sampling method) 72 7.6 The percentage cover and phytomass of green forage at feeding sites and at random sites adjacent 73 7.7 The impacts of caribou compared between the monthly distributions of the satellite females in the growing season 74 7.8 The activity budgets of the George River caribou herd in June prior to insect emergence compared to other herds 75 8. The body size of the George River caribou in March 976 and April 980 84 8.2 The size difference between males and females as fetuses and new born calves 86 8.3 Comparison of fall and spring weights of cows and calf birth weights from various herds in the nearctic and the palearctic; grams of newborn produced at birth as a function of the mother’s metabolic size or grams per kilocalorie of maternal basal metabolic rate (BMR ) 9 8.4 Total body weight of calves and pregnant or parous females in April and June 92 8.5 Correlation coefficients compared between calf birth weight and condition indices of the females the previous growing season (Y₁) and in the spring prior to parturition (Y₂) 95 8.6 Comparison of the frequency and duration of nursing in June 978 and 988 96

L I S T O F TA B L E S |

xxi

8.7 The length of mandibles of females compared between cohorts and animals aged 0–70 months 202–3 8.8 The ratio of increase in spring weights for females for several herds in North America 204 8.9 Body and antler measurements of adult males from August to November by S. Luttich 22–3 8.0 The size of female antlers (≥ 34 months of age) for the George River herd 25 8. Comparison of calf and yearling weights by cohorts and pregnancy frequencies 220 9. Antler development in females and males as an index to condition (sample size in parentheses) 227 9.2 Comparison of the frequency of chewed and unchewed antlers on the skulls of females in April 980 with age, body weight, and antler size 232–4 9.3 The estimated mean calving dates based on calves/00 female classifications and the percentage of females with hard antlers (number of days classified) 235 9.4 Fat indices and body weights comparison between pregnant and nonpregnant females (≥ 34 months) before migration (March) and after migration (April) 244–5 9.5 Total fat content (FATP) of females on an ingesta-free weight basis using the formula FATP =[(ln kidney fat index of Riney 955)(3.73) - 3.29], from Huot and Goudreault (985) 246 9.6 Comparison of fat indices with prior environmental factors 255 9.7 A comparison of the ratio of change in fat and weight parameters between the Beverly and Kaminuriak herds between November–December and March–April (data from Dauphiné 976 and Thomas and Kiliaan 998) 26 0. Parturition and recruitment statistics for the 973 to 993 cohorts 270 0.2 Pregnancy rates based on autopsies in March and April 275 0.3 The mean age of females based on annulations counted from the incisors of females collected in March and April along the Labrador Coast (primarily from the commercial hunt conducted by residents of Nain) 277 0.4 The percentage of males classified from 973 to 993 279 0.5 Calculation of total caribou population in June 993 based on spring recruitment figures and adult mortality rates (λ = [ - M]/[ - R]) starting with a population estimate of 537,000 in June 984 285 . The causes of death of radio-collared females during the study, 984 to 992 293

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.2 The percentage of fat in the leg marrow of large males in the breeding season, after breeding in November/December, and in the next spring 295 .3 The incidence of parasitism in the George River herd 978–87 (data 978– 80 from Jean et al. (982), data in 983–84 and 987 from this study) 300 .4 Comparison of the weight and fat condition indexes between female caribou with high loads of warble larvae and liver flukes and those with low loads of both parasites 304 .5 Correlation matrix of indices of canid abundance, Ungava 974–92, correlation coefficients, probabilities, and sample sizes 307 .6 A comparison of the age of caribou killed by wolves over winter in the early 980s between males and females and compared to a random sample of the population drowned at Limestone Falls in September 984 309 .7 Observation of wolves killing caribou calves in 989 and 99 30 .8 The physical condition of females carrying male and female fetuses in the spring (April and May) 33 .9 Comparison of the fetal sex ratio between females of different ages and between years of good summer nutrition 980–83 and 993 (> 80% pregnant) and poor nutrition 985–92 (< 75% pregnant) 33 2. Minimum sizes of ranges (km² x ,000) used by the George River herd 324 2.2 Synchrony in the dominant activity of caribou during the growing season within aggregations compared with the group size 35 2.3 Comparison of social facilitation parameters in the 2-week post-calving period in 978 when the herd reached 300,000 animals and in 988 with a doubling of the herd to 600,000 animals 352 3. Kilometres travelled per day by satellite caribou June 986 to June 993 356–7 3.2 Annual cycle of acceleration and deceleration 986–87 to 992–93 (females with UHF radio transmitters) 359 3.3 The abundance of insect pests 988 to 99 366 3.4 Insect-related activity of active caribou (not lying) during different levels of harassment 369 3.5 Activity budgets and frequency of insect-related activity during attack of different numbers of oestrids 369 3.6 The winter pause based on UHF radio-collared females 374 3.7 The phenological dates associated with the May pause of females with UHF radio collars in seeking early greens 375 3.8 Total range size (,000s) in 6 years of satellite females when the population reached peak numbers (additional monthly distributions shown figs. 3.5 and 3.6) 379

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3.9 The spacing of individual caribou within groups of various size as affected by mosquito harassment, 988 385 3.0 Comparison of the direction caribou were travelling relative to wind direction from the ground observations July 988 to 99 when mosquitoes were active 39 4. Condition of females in April 980 compared to caribou that wintered on the tundra (Hebron) and returned from taiga (Nain) 4 4.2 Travel speeds (km/hour) of caribou active (not lying) in the pre-insect season in June between different size groups 44 4.3 The hours that caribou were active per day based on the Long-term Activity Index (LTA – 24-hour schedule, satellite collars) and field observations during daylight hours expanded to a 24-hour basis for comparison to the satellite schedule (June, July, August 988) 47 4.4 The activity budget of George River caribou at night compared to the abundance of mosquitoes and the temperature (6 July 990, 9 PM [200] to 5 AM [0500]) 420 4.5 Activity budgets of active caribou (not lying) during times of insect harassment 42 4.6 Use of space by caribou during the non-snow season 99–95 427 5. Characteristics of calving locations compared to other ranges 434 5.2 Mortality rates of young calves on the Beverly calving ground, 98–84 45 5.3 Range expansion of the Caribou House calving ground from 973–90 455 5.4 Comparison of distances between calving locations 47 6. Comparison of parameters affecting summer calf survival, 973–85 and 986–92 485 A Bite rate, bite size, and forage intake 523 2A Late spring and summer diets for George River females 525 3A Average dry matter intake of lactating George River caribou compared to Denali and Central Arctic herds in Alaska 526 4A Daily metabolizable energy intake and the average for George River females and three Alaskan herds 527 5A Mean daily expenditures and their proportion of total daily energy budget, 988–9 529 6A Daily summer scenarios for George River caribou, 988–9 53 7A Daily energy requirements for George River lactating caribou and other studies 532 8A Average daily fluctuations for George River lactating females 534 9A Average summer weight fluctuations for lactating and barren George River females 535

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List of Figures

I . The three major distributions of migratory caribou on the mainland of . .2 .3 .4 .5 .6 .7 .8 .9 .0 . .2 .3 .4 2. 2.2 2.3

North America xxxvi The vegetative zones of Ungava, published in 959 5 The locations of the native communities in Ungava 6 Physical relief map of Ungava 8 Annual temperatures and dates of freeze-up and spring break-up for Knob Lake, Schefferville 0 Dates of the start and end of the growing seasons  The median snow-depth isopeths in Ungava based on 20 winters 2 Snow depths at the beginning of each month at Schefferville 3 The pollen profile at Indian House Lake and Ublik Pond on the coast 20 Harvest statistics of wolverine and arctic fox 23 The caribou and wolf skins traded at Moravian Missions from Elton 942 25 The abundance of wolves based on aerial surveys and the harvest at Kuujjuaq and dates of rabies outbreaks 26 The range expansion of moose since 875 27 A cultural historical diagram of native peoples 29 The prehistory of native Indian bands in Ungava 30 The main distribution of the five different subspecies of caribou and the frequency distribution of the transferrin allele and mitochondria DNA clades 33 The two spacing ecotypes of caribou: spacing-out and spacing-away 35 Calving strategies of caribou to reduce predation risk 36

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2.4 The spring spacing-out of calving females of the Red Wine herd to lowland muskegs 36 2.5 The spacing-out of calving females of the Spatsizi herd in B.C. to alpine habitats 37 2.6 The spacing-out strategy of calving females of the Lake Nipigon herd to islands 38 2.7 The calving locations of the sedentary and migratory ecotypes in Ungava compared with the presence of open water at calving 39 2.8 The morphology of antlers of sedentary and migratory ecotypes 43 2.9 Antler length/body ratios compared with total lengths for various herds 43 2.0 The model proposed by Butler (986) for evolved differences in antler morphology of woodland and migratory ecotypes 44 2. The predicted and observed growth curves of antlers of sedentary and woodland caribou and migratory barren-ground caribou 47 2.2 Body size of male and female caribou compared to the length of the growing season 5 2.3 Travel speeds and long-term activity of UHF females when in the Torngats compared to animals not in the Torngats 52 3. The former distribution of caribou at 8,000 and 5,000 BP based on fossil locations 60 3.2 The last appearance dates of the megafauna compared to the first appearance dates of caribou in eastern North America 65 3.3 The retreat of the Wisconsinan ice sheet from 0,000 to 5,000 BP and the advance of plant biotypes 68 3.4 The proposed recolonization routes of sedentary and migratory caribou, 2,000 to 2,500 BP 70 4. (above) The mobility of 5 cows in the Red Wine herd; (below) The annual mobility cycle of four sedentary herds 75 4.2 The southern edge of the continuous distribution of caribou in Ungava 980–990s approximated the northern extent of moose densities > 0.0/km² 77 4.3 The line between the continuous distribution of caribou and the discontinuous distribution compared to moose densities 78 4.4 The recruitment of caribou in North America and adult mortality rates compared to wolf densities 79 4.5 The finite rate of increase for the sedentary herds compared to recruitment 83 4.6 The mean density of 27 sedentary herds in North America 84 4.7 Stabilizing recruitment for 9 sedentary herds compared to the stabilizing density (DS) 86 4.8 A summary of population trends and recruitment for the sedentary herds in Labrador 93

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4.9 The southern boundary of the George River herd compared to the distributions of the sedentary herds 98 5. Indian House Lake with the location of the historical tent rings, showing where the Innu waited for caribou moving west after the mosquito season 07 5.2 The length of hunting trips from Okak, 776 to 829 5 5.3 Reports of natives starving and/or moving locations because of food shortages 6 6. The relative abundance of the George River herd 800 to 993 compared to long-term climatic factors 36 6.2 Winter snowfall in Ungava compared to winter temperatures 45 7. The boundaries used in the regional analysis of range surveys in the summers of 988 and 989 53 7.2 The observed summer food habits documented 988 to 992 55 7.3 The percentage of lichens and shrubs for seven regions 58 7.4 The percentage of nitrogen in major summer forage species compared with that found in caribou feces in 989 60 7.5 (above) The percentage of the ground covered with lichens in 988; (below) The percentage of the lichen mat that had been disturbed by caribou grazing and trampling as recorded in 988 6 7.6 The distribution of caribou foraging and trampling impacts on six variables 63 7.7 The foraging and trampling impacts by regions 64 7.8 Three impacts of trampling: shattered lichens, broken twigs, and turf 65 7.9 Comparison of defoliated dead or broken twigs and ground covered with turf between the western tundra and the eastern tundra 67 7.0 The percentage of turf compared to the percentage of shrubs on the eastern tundra and the western tundra 68 7. The observed abundance of the ground covered with lichen fragments and shrub cover, moving from west to east 7 7.2 The dry matter intake during the growing season from 988 to 99 76 7.3 The annual growth of birch from 959 to 993 77 8. The mass of males and females for the George River herd compared with animals from the Nelchina and Kaminuriak herds 85 8.2 The growth in mass of fetuses from 25 to 200 days and at birth 88 8.3 The mass of Rangifer calves at birth compared to the fall and spring weight of females 90 8.4 (above) The mass of calves compared with the back fat of females; (below) The mass of calves at birth compared to warm temperatures in May and dates of spring break-up 94 8.5 The frequency histograms of April mandible lengths of 0- and 22month-old animals from early years, 974–8, and latter years, > 982 98

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8.6 8.7 8.8 8.9 8.0 8. 9. 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.0 9. 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 9.20 0. 0.2 0.3

The size of female mandibles by age, 973 to 993 99 The growth in mass of calves and yearlings based on mandible size 200 Compensatory growth mandible lengths 20 (above) The annual mass cycle for females; (below) The annual mass cycle for males 209 The length of the antlers of George River females by age 26 The length of the antlers of males by age 27 Calves per 00 females and the percentage of antlered females plotted against calving dates 225 The percentage of antlered females compared to snow cover in their herd areas 228 (above) The percentage of antlerless females as affected by the growth of birch; (below) Comparison of calving dates and antlerless condition the previous fall 230 Percentage of antlered females and years of early and late calving 23 Calving dates were later in 984–93 than in 975–80 236 The estimated dates of breeding and calving of satellite caribou 987 to 993 238 A comparison of calving dates to the growth of birch in the previous summer 239 The retention of hard antlers by George River females compared to annual calving dates 240 The weight of livers of females, 982 to 993 242 The mobilization sequence of femoral fat, kidney fat, and back fat 243 A comparison of back fat reserves and the age of females 247 A comparison of kidney fat reserves and the age of females 248 The annual yearly cycles of back fat, kidney fat, and metatarsal fat 249 The annual cycle of kidney and back fat reserves in males 25 A comparison of the back fat of females and migration distances in the spring 252 A comparison of the loss of back fat with migration distance and the age of the females 253 (above) A comparison of pregnancy rates and kidney fat reserves; (below) A comparison of pregnancy rates and body mass 258 Kidney fat, body mass, and pregnancy thresholds 259 A summary of fat reserves and mass as compared to migration distance 263 The decline of some condition indices in the interval 982 to 984 265 Calf recruitment to the herd, 973 to 993 274 The finite rate of increase and spring recruitment for  other migratory herds in North America 278 Survivorship curves for females harvested west of Nain, 975–93 283

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0.4 The growth of the George River herd from 945 to 988 and its decline after 988 286 0.5 The increase and then decline of the herd from 984 to 993 based on recruitment and mortality schedules 290 . The fat reserves in the marrow of leg bones from 980 to 992 294 .2 Harvest statistics, 957 to 992 297 .3 Comparison of infection loads of liver flukes, liver tapeworms, and warble larvae, 976 to 993 302 .4 Comparison of the abundance of liver flukes, liver tape warms, and warble larvae loads with female age 303 .5 The winter mortality rates of short yearlings following rabies outbreaks in wolves 308 .6 The proportions of males to females (the sex ratio) tallied by age classes 32 .7 A comparison of the age of maternal females and the sex of their fetuses 34 .8 The proportion of adult males and females by age classes that drowned at Limestone Falls in September 984 36 2. The centre of habitation of the George River herd 322 2.2 The range extensions of the George River herd, 973–94 325 2.3 Comparison of the calving, rutting, and winter distribution centres of the herd 326 2.4 The increase in total range of the George River herd as it increased compared to herds in Alaska 327 2.5 The proportion of the range above tree line as the total range expanded 328 2.6 A comparison of the distances between calving and rutting ranges and between rutting ranges and winter ranges as the herd grew in numbers 329 2.7 Herd growth and the rotation of rutting ranges around a stable calving centre 330 2.8 The size of calving and rutting ranges and winter ranges compared to the growth of the herd and snow depth 33 2.9 Lichen damage compared to longitude and to the trend of westward range expansion in the autumn 332 2.0 The correlation in the longitudes of the rutting and wintering locations 973–92 333 2. A comparison of snow depths and range occupations by caribou in winter, above and below tree line 334 2.2 The distributions of caribou in 8 winters compared to the abundance of lichens and long-term snow depth estimated in 988 334

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2.3 The winter distribution in 954–58 and a return to that area in 992–93 335 2.4 Travel distances and rates compared from 990–9 to 992–93 336 2.5 The travel routes of satellite females in the 980s 338 2.6 The travel routes of satellite females in the 990s 339 2.7 The distributions of VHF and UHF radio-collared females 340 2.8 A histogram of the number of lat. x long. grids occupied at calving, the rutting season, and winter 342 2.9 (above) The major directions of the leads in the lat. x long. grids in 988; (below) The observation of caribou and/or their fresh trails in the 970s before radio tracking 343 2.20 The major direction satellite females travelled in the lat. x long. grid matrix 345 2.2 The directions taken by the satellite animals as compared with the direction of eskers 347 2.22 The correlation coefficients between the monthly travel rates and the population estimates 350 3. The mean speed (km/day) that the satellite females travelled in spacing across the lat. x long. matrix 354 3.2 The annual mobility cycle of satellite females in seven years 355 3.3 The mobility of George River caribou in the Torngats and south of the Torngats compared to the mobility of the Porcupine herd in Alaska and the sedentary Red Wine herd 356 3.4 Mobility compared to plant cover 360 3.5 The daily maximum/minimum temperatures and the phenology of insects, 988–9 362 3.6 Travel speeds compared between years 988–95 with insect abundance and group size 363 3.7 Mobility rates compared to the biting of mosquitoes and the appearance of oestrids, 988–90 364 3.8 The activities of feeding and walking compared to evasive actions of caribou bothered by mosquitoes and oestrids, 988–89 365 3.9 Aggregation behaviour of caribou compared with no insects and mosquitoes and oestrids present 367 3.0 Mobility rates of caribou compared to the relief actions taken by caribou 368 3. A summary of the activity budgets of caribou and mobility compared to the abundance of insects 370 3.2 The decelerations of mobility in September with the cessation of oestrids 372 3.3 The deceleration of mobility in mid-winter as snow levels increased 373

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3.4 The deceleration of mobility in late May as females sought early greens 376 3.5 The monthly distributions June to November of the UHF radio-collared females 377 3.6 The monthly distributions December to May of the UHF radio-collared females 378 3.7 The herd dispersion and individual fidelity indices 380 3.8 The frequency of the eight basic azimuths that UHF females travelled in seven years 383 3.9 The calving area in June 993 384 3.20 A common route by Indian House Lake of the large groups in July and dispersal across tree line in August 387 3.2 The major routes of the August dispersal in 992 and 995 388 3.22 Variation in the abundance of mosquitoes with temperatures and wind speed 389 3.23 The wind directions at field camps compared to the direction caribou were moving 390 3.24 The movement of satellite females in August showing some synchronous turning 393 3.25 The emergence of mosquitoes, black flies, and oestrids in 988 and temperature and wind parameters 395 3.26 A comparison of the harassment of caribou and group size and mobility 398 3.27 The frequency of caribou turning, September to December 400 3.28 The Loop of Life. A summary of the major movements and environmental factors and the return each spring to Caribou House to calve 403 4. The options of optimal foraging vs predation risk 405 4.2 The monthly distribution of hunter return of tagged animals in the NWT above and below tree line 406 4.3 Physical condition in winter of animals in the Beverly herd, NWT 409 4.4 The mass of females in March/April and their position relative to tree line 40 4.5 The activity budgets of the George River animals in the growing season prior to the emergence of insects and when insects were present, 988–9 45 4.6 The daily energy budgets in the growing seasons, 988–9 46 4.7 The distribution of satellite females in 997 compared to tree line and the insect season 48 4.8 Daily energy budgets compared to insect presence or absence 49 4.9 A comparison of the time spent walking and feeding and travel speeds in the growing season in daylight hours 49

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5. Strategies used by sedentary and migratory ecotypes to reduce predation risk at calving 433 5.2 Spring segregation of males and females at calving and the impact on the quality of the diet 436 5.3 Spring migration of wolves following caribou in the NWT 439 5.4 The sex and age of George River caribou killed by wolves in migration, 982 440 5.5 The location of the calving ground of the Porcupine herd in relation to wolves, grizzly bears, and golden eagles 442 5.6 The annual calving distributions for the Lac Champdore, Caribou House, and Harp Lake calving grounds, 973 to 985 444 5.7 The change in the location of the Leaf River calving ground from 975 to 2000 (broken) 445 5.8 The composite Caribou House calving ground 973 to 995 (broken) and the annual snow cover at calving and the location of black bears seen at calving. The routes of returning satellite females is shown 446 5.9 The location of Caribou House calving ground in 977 on the height of land prior to the overgrazing of the tundra on the Labrador Peninsula 449 5.0 A comparison of the size of the Caribou House calving ground 973–93 and the distance to the George River 453 5. The percentage of turf created and shifting of calving areas 454 5.2 The dates of peak calving compared to the length of the growing season 457 5.3 The date satellite females left winter ranges, distance from Caribou House, and the speed of their travel 464 5.4 The correction azimuths of returning females to Caribou House as they entered the centre of habitation 465 5.5 The convergence orientation of females to Caribou House when they had remained mostly farther east in the winter 466 5.6 Experimental evidence of homing based on Newfoundland caribou released on Mt. Katahdin in Maine in 963 468 5.7 Philopatry of George River females to Caribou House between years 472 5.8 An example of females switching calving grounds 473 5.9 Maternal calving locations compared with those of their female progeny 474 5.20 Fidelity of females to their prior calving locations 475 6. Comparison of calf and adult female mortality rates and pregnancy rates with summer and winter densities 48 6.2 The summer mortality rates of calves compared with relevant parameters 486

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6.3 The mortality of calves in the summer compared to their weight at birth 487 6.4 The mortality of calves over winter compared with snow cover, the presence of rabies in wolves, and body size of short yearlings 490 6.5 The annual mortality of radio-tagged females compared with the percentage of females without antlers the previous fall 492 6.6 The annual mortality rates of females in three herds in North America compared to winter severity indexes 493 6.7 The density-dependent population model for the George River herd 500 A The flow of energy expenditure and intake model 54 2A Daily energy expenditure segregated into major losses 528 3A Target lactation and actual milk production 530

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Preface

A growing problem of our century is the extinction of animal species. This is especially relevant in the Arctic, with the rapid advance of global warming. The view is widely held that caribou numbers in North America are vastly reduced from the pristine abundance of former years. However, the story of caribou in North America is the story of constant change. In 940, Clarke’s estimate of barren-ground caribou in Canada was 2 million animals (Clarke 940); by 976 the total number of animals in the seven largest herds was listed at 636,000 (Calef 980). But 0 years later the same herds were .5 to .8 million strong (Williams and Heard 986; Bergerud 988b), a phenomenal increase of % per year: The caribou had returned! In 984 the largest herd in North America – and in the world – was the George River herd in Ungava, totalling over 600,000 animals (Messier et al. 988; Pavlov et al. 996). Natives there could not remember a period in their lifetimes when the animals had been so abundant. And yet when I conducted the first systematic census of this herd in 958, it had only 5,000 animals. Fluctuations in caribou numbers and distributions in Ungava and the Northwest Territories have a long history, though: The natives say, “Nobody knows the way of the caribou,” and they should know. Their fate has been intertwined with that of the caribou herds for centuries: Intercepting the caribou, however unpredictable its wanderings, has often been a condition for survival. This book discusses the abundance and distribution of the George River herd historically, from the time the Moravian missions arrived in Labrador at about 770 (Elton 942) until 994, including recent demography of the George River herd 974–94 and a census in 200 (Couturier et al. 2004). Stuart Luttich, who

xxxvi | PR EFACE NORTHWEST TERRITORIES 1954 RANGE 199

6

EXTENSIONS ?? EXTREME PENETRATIONS

GEORGE RIVER 1954/58 RANGE

ALASKA

EXTENSIONS

1953 RANGE EXTENSIONS

1989

EXT

REME PENETRATION

2005 1988–

Fig. I.1 The three major distributions of migratory caribou on mainland North America are in Alaska, the Northwest Territories, and Ungava. The George River herd in Ungava was nearly extinct in 1954 yet by 1988 it had expanded its range sevenfold, totalling over 700,000 animals, and was the largest herd in the world. Leopold and Darling 1953, Banfield 1954, Banfield and Tener 1958, Bergerud 1958, 1967

became the regional biologist in Labrador in 974, monitored the growth and distribution of the herd as it rapidly increased until the mid-980s, measuring annual recruitment of calves and gathering data on physical condition. I returned to Labrador for calving and range studies in 978 and 988. And Lodewijk Camps investigated summer activity and energy budgets 988–92, when it appeared the herd’s condition was declining. When I initially studied the herd in 958, the north was exceedingly wild and inviolate, with large portions of the Peninsula still unmapped. Even today, Ungava remains a largely untouched wilderness. You can fly from Churchill Falls on the Churchill River north to the tip of the Labrador Peninsula for 765 km without seeing a human transportation corridor or settlement. Or, for a real sense of “miles beyond measure,” you can leave the runway at Schefferville in central Ungava and wing north 000 km to Cape Wolstenholme without sight of human intrusion. Thus it was still possible in 974 to study the natural ecology of these animals in a vastness of space uncompromised by progress. The George River herd 974–93 ranged over an area of 750,000 km², the most extensive range of any one ungulate population in North America (fig. I .). We tracked these animals by placing VHF radios on some of the females (starting in 982), and following them by satellite tracking 986–93. The radios

PREFACE |

xxxvii

reported their new locations every 3–4 days, which allowed us to monitor their rates of travel, their 24-hour activity budgets, and the dates they changed directions. In order to get a better understanding of how caribou perceive their environment, we compared these parameters with possible stimuli from the extrinsic environment, including forage abundance, snow cover, predators, habitat and topography, and insect and animal populations. In addition, commencing in 974, Luttich measured calf survival each fall and spring to keep track of the demography as the herd grew. This is the story of the distribution and abundance of what was the largest herd in North America as we monitored it for 20 years. In the course of the study, we asked some of the following questions: Why, when herds increase in numbers, are there corresponding changes in their distributions? Is the George River herd unique, or could it be used as a model to explain fluctuations in population (and corresponding changes in distribution of other large herds in North America that, even as recent as the 950s, resulted in the starvation of some native peoples in the Northwest Territories)? Will the George River herd crash, and, if we understand the dynamics, can the pattern be managed? Can we determine the role of space in caribou habitat and migration strategies? Can we predict how caribou will fare with global warming? We hope our insights provide a way of ensuring a future for la foule (the throng), so that we don’t lose this bounty, as we did that of the Atlantic cod, for not having asked the right questions. It has been the highest privilege of my career to observe this herd grow from a mere 5,000 into the largest in the world, to know that each spring Luttich was there to record the return of the females to “Caribou House” above tree line in completion of another annual life cycle. What a marvel of this earth! I can still remember the day in 958 at Mistastin Lake when I talked with Chief Joe Riche of the Naskapi – the last of the inland caribou hunters. He imagined such a wonder, but I never did. A.T. Bergerud January 2007 Salt Spring Island, bc

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The George River herd’s river of life – from ocean to ocean, their epic trek – the most dramatic land-based journey in North America. Across the tree line and ever west, seeking new lichen pastures for breeding and sustenance in the winter. But as in the past always returning in the spring to their calving core – Caribou House – to give birth to a single calf on the bleak height of land, where the sky is near and rivers run east to the Atlantic and west to the Arctic. And here their offspring learn the ways of caribou and their map of space.

Plate 1 The forbidding Torngat Mountains. “He is now there together with the caribou. Chief of caribou. His house is called Caribou House. And so he is chief there in the white mountain. It is he who gives the caribou to the hunters” (Speck 1935, 83). Photograph by Patrice Halley.

Plate 2 The height of land on the Labrador Peninsula where the caribou calve, far removed from wolves denning at tree line. The location is selected to be inhospitable, precluding alternate prey for wolves. Photograph by Patrice Halley.

Plate 3 Indian House Lake, the centre of habitation and where for thousands of years the Innu waited for the migrating caribou in the fall. Photograph by L. Camps.

Plate 4 The George River flowing by the Pyramid Hills. The pollen profile of this location showed organic elements at 7,000 BP. The Laurentine Ice Sheet covered this area 8,000 BP (Short and Nichols 1977). Note the inukshuk in stone (man-of-rocks) to the left, which can be seen from the river. Photograph by Serge Couturier.

Plate 5 (above) The Taiga. “The Land of Little Sticks,” the winter lichen range of the herd. Photograph by A.T. Bergerud. Plate 6 (facing page, above) The tundra, which provides deciduous shrub for forage, openness for insect relief, and space that allows calving females to reduce predation risk by remaining away from denning wolves. Photograph by Stuart Luttich. Plate 7 (facing page, below) The ocean and shore where spring arrives early and summer lingers late. Here, there are on-shore breezes for insect relief, and greening birch and willow shrubs for summer growth and body condition for fall breeding. Photograph by Stuart Luttich.

Plate 8 Calving females dispersed across the Caribou House calving ground. You can only see the females, which are white, but not their calves, which are reclining on bare ground where their brown coat colour blends with the background. Calving grounds thus need to have areas of bare ground to reduce predation risk before the calves are able to travel. Photograph by Stuart Luttich.

Plate 9 Cows and yearlings on the calving ground. The female to the left is followed by a calf; the female with two black velvet knobs is probably not pregnant and shed her antlers earlier in April. The female to the right with hard antlers is likely expecting; pregnant females shed their antlers within days of giving birth. Photograph by A.T. Bergerud.

Plate 10 A young calf is following its mother a few hours after birth. Calves can show the “following response” within 30 minutes of birth and will imprint and follow the first large moving object they see after birth – be it mother or man. This is an adaptation that helps avoid predation among animals calving in the open. Photograph by Patrice Halley.

Plate 11 Females and their calves generally leave the calving ground within 1–2 weeks of calving. Wolves do not generally den on calving grounds because of the difficulty of securing food for their initially helpless pups. Also calving grounds are generally located where there is a scarcity of alternative prey. Photograph by Patrice Halley.

Plate 12 Although caribou are the strongest swimmers of the deer family, a common cause of mortality of calves in the spring is drowning when the rivers are in spring flood. Photograph by L. Camps.

Plate 13 By mid-June warble fly larvae from eggs deposited the prior August have migrated to the backs of the bulls. Note the larval lumps on the backs of the bulls. The larvae burrow through the skin and drop to the ground in June to pupate. The pupa stage lasts 3 to 8 weeks and the flies are on the wing in August, seeking caribou just as the mosquito season ends. Photograph by A.T. Bergerud.

Plate 14 On the Loop-of-Life trek, swimming rivers and lakes and approaching tree line as the mosquitoes cease, then heading west in search of greater forage and fall and winter lichen pastures and low snow. Photograph by Serge Couturier.

Plate 15 Caribou are noted for their swimming ability and are extremely buoyant in the winter pelage but sink lower in the water when their buoyant winter coats are molted and the summer new coat (black patches) grows. Note that the large bull in the centre of the picture in complete summer pelage is sinking lower in the water than the post-parturient females still in their white winter pelage. The molt sequence in the spring is bulls, then barren females, then parous females, meaning that the herds appear in a black-and-white checked pattern. Photograph by Patrice Halley.

Plate 16 (above) These bulls were bothered by parasitic insects (oestrids) that lay their eggs on the short fur of the summer coats. The animals had found some relief by going into the ocean when an on-shore breeze came up. By standing together the inside animals gain some relief through what is called the “dear neighbour” strategy – share your tormentors. Photograph by Stuart Luttich. Plate 17 (facing page, above) A large herd dispersing into forest cover to forage following a reduction in insect harassment. In the insect season the animals travel long distances without feeding and in July reach their lowest weights of the year. Photograph by Serge Couturier. Plate 18 (facing page, below) In July the caribou mass in large herds to escape mosquitoes. Their body heat causes heat convection currents that carry their CO 2, thus reducing mosquito detection. This herd will be dispersing to forage later in the evening when the mosquito harassment abates. Photograph by Annemarie Linders.

Plate 19 To avoid oestrid flies in August the animals stand on exposed hills and snowfields. Males have more warble larvae than females because they molt sooner and their shorter summer coats are more easily penetrated than the thick winter pelage of the females. Photo by Patrice Halley.

Plate 20 In September, after the oestrid and biting flies cease, the caribou slow their rate of travel and make maximum weight and condition gains in preparation for the rutting season. Photograph by Didier Le Henaff.

Plate 21 (above) Snow comes early in the north. During the pre-rut males often travel together, testing their antlers and seeking dominance in small groups. Because breeding takes place in large groups, animals moving together may not be familiar with each other and will judge opponents by the size of their antlers without fighting. Photograph by Patrice Halley. Plate 22 (facing page, above) Limestone Falls on the Caniapiscau River has claimed the lives of many caribou and is well known in traditional knowledge. Photograph by Stuart Luttich. Plate 23 (facing page, below) Two caribou that drowned in September 1984 after being swept over Limestone Falls, seen in the background. The high water was caused by heavy rain and the opening of the gates of the Caniapiscau reservoir. Photo by Stuart Luttich.

Plate 24 (facing page, above) Four bulls and a cow in the pre-rut period. Their velvet has been recently cast. Note the sharp bend in the main beam of the bulls and the absence of a rear point. Both of these beam formations are characteristic of the antlers of George River bulls. Also note that the bez tine on the bull behind the female comes off the main beam immediately above the brow tine and is characteristic of the migratory caribou ecotype. Photograph by Patrice Halley. Plate 25 (facing page, below) A bull and cow in the rutting season. The males in the George River herd have the widest spreading antlers in North America. Photograph by Serge Couturier. Plate 26 (above) In the pre-rut males constantly spar, learning the feel of their antlers and fitting themselves for competition with other males for access to females in heat. Photograph by Patrice Halley.

Plate 27 The actual breeding season takes place in mid to late October after the animals have switched to their winter lichen diet. This male is courting the female by showing her his large neck mane and walking behind her with a tongue movement called slurping. Females are in heat for only two days and most of the breeding takes place in less than two weeks. Photograph by Bill Duffett.

Plate 28 Locked antlers, a reminder of serious battles for dominance and the right to breed with the females. Photograph by Stuart Luttich.

Plate 29 (above) The animals are making an early winter movement, possibly looking for shallower snow where they can reduce predation risk. The animals walk single file with their heads down. This improves trekking by tramping down the snow cover but can be a disadvantage in wolf chases when trailing animals are often forced to leave the compact snow, which reduces their mobility. Photograph by Stuart Luttich. Plate 30 (facing page, above) When the lakes freeze the caribou use them for a highway to reach new food sources. When wolves are encountered, caribou run for the frozen lakes, where they have visibility and mobility advantages that they do not have in deep snow cover in the woods. Biologists find most wolf kills of caribou on these lakes simply because this is where most chases take place. Photograph by Serge Couturier. Plate 31 (facing page, below) The ease of travelling on early fall ice can have serious consequences. Photograph by Serge Couturier.

Plate 32 (above) Caribou trying to make shore by breaking ice. Global warming is already reducing ice cover in the NW T, which will be a major problem, reducing visibility and the safety of mobility and leading to increased drowning and wolf predation opportunities. Photograph by Serge Couturier. Plate 33 (facing page, above) Late winter – March and April – is the preferred season for winter travel and for the harvest of animals in the interior by the Innu and Inuit. Chief Joe Riche and the Davis Inlet Naskapi hunters are shown camped at Mistastin in April 1958. The Innu were at Mistastin lake 7,000 years ago at a time when the retracting ice sheet of the last Ice Age was only a few kilometres to the west. Were the caribou also already there? Photograph by A.T. Bergerud. Plate 34 (facing page, below) The Naskapi abandoned Indian House Lake in 1916 when the caribou failed to appear. After this they hunted the herds mostly by dog team in winter. By the 1970s skidoos had gradually replaced dog-team travel and the old way of long hunts and living in the country became part of the past. Photograph by A.T. Bergerud.

Plate 35 A winter aggregation on the move. Note the effect of large numbers in compacting the snow – an aid to flight from wolves. Photograph by Serge Couturier.

Plate 36 The females on the long trek back to Caribou House to give birth and send a fresh cohort on the Loop of Life. The trek will take the new generation to Indian House Lake or Lac Mistinibi in August and September, where in the past the Innu waited, trusting that the master of the deer in his mountain caribou house would again give his caribou to the hunters. Photograph by Serge Couturier.

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The Return of Caribou to Ungava

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CHAPTER ONE

Setting and Background

The Eruption of the George River Caribou Herd On 2 April 954, Frank Banfield and John Tener were on an aerial survey flying northeast from Knob Lake over the immense wilderness of Ungava when they located 36 caribou adjacent to the George, Whale, and Wheeler Rivers. They estimated 4,200 animals in the herd. It was the start of research and surveys. Other population estimates followed: 5,000 animals in 958; a sevenfold increase to 05,000 by 973; 76,000 by 976; 27,000 by 982; a major jump to 472,000 two years later in 984; and another increase to 700,000 animals by 988 – all occurring in the herd we named the George River herd (Bergerud 958). Messier et al. (988) estimated the annual growth rates (r) at 4% (955–84) or % for 970–85. It is likely that the herd increased at a greater rate in the later years – more, particularly, between 980–84 than in the 960–970s, because initial low numbers would have meant higher mortality rates, given a relatively heavy hunter harvest. This is a remarkable growth rate for a large mammal with a litter size of only one offspring. This herd had been of immense size only 70 years earlier yet was nearly extinct in the 940s and 950s: What could have initiated such an eruption, such an amazing comeback? The first systematic census of the herd in 958 showed a total population of 5,000 animals (Bergerud 958, 967). This population sustained an annual legal harvest of approximately ,000 animals. These were reliable harvest figures. Each summer 955–65 the Newfoundland wildlife officer William Anderson of Makkovik travelled the Labrador coast (Makkovik to Hebron) interviewing hunters in the seven major settlements (Hebron closed in 960). Anderson was a respected officer of the coast well known for his inland “country” skills and

4 | TH E R E T U R N O F C A R I BO U TO U N G AVA

integrity. The hunters of the coast spoke openly of their hunting adventures and the abundance of inland game. The total harvests for the coastal settlements each year averaged 885 animals 955–65 (see Bergerud 967, table 4). Animals were also harvested from the communities of George River and Knob Lake. The total coastal and inland harvests represented 6–7% of the herd. Yet most of the herds in North America have not increased with harvests of greater than 5% (Bergerud 980, 983). The difference was that the George River must have had high pregnancy rates given the abundance of forage. More importantly, the natural mortality of adult caribou and calves in the herd would have been low because their natural predators, wolf and wolverine, were nearly extinct in 958. Some older, inland hunters had never seen a wolf in their years on the land, although they remembered talk of wolves being common 50 years earlier (Bergerud 958). Without natural predators, the deaths of adults from factors other than hunting could have been as low as 5%, while calf additions to the herd could have been as high as 20% per year (Kelsall 968; Skoog 968; Bergerud 980). The relatively low calf percentages tabulated in the 950s by Newfoundland wildlife officers were not representative (see Bergerud 967, table 6). Research funds were extremely limited in those times (annual budgets of 20,000–30,000 dollars for all of Newfoundland and Labrador). We quantified the annual caribou calf increments by flying north in April from Goose Bay, saving funds by classifying only the most southern aggregations we encountered, and turning back when the sample reached 500 animals. Later we learned that these southern groups were biased to males. The equation for the growth of the herd in 958, then, is the finite-rate-ofincrease equation: λ = [.00 minus % annual mortality of adults (hunting + natural) divided by (.00 minus % annual recruitment of calves)], λ = ( - M)/( - R) (Hatter and W. Bergerud 99). The annual increase then could have been λ = ( - 0.065 + 0.05)/( - 0.20) = . (0.6%). This herd expansion had elements of the Lotka-Volterra theoretical equations of predator vs prey oscillations (Allee et al. 949): The predators had nearly vanished because of the scarcity of their prey and the prey had escaped this mortality limitation. The George River herd had turned the corner and was on its way back. Ungava Ungava is a vast land mass of one million square kilometres lying between Hudson Bay and James Bay and the Labrador coast. Northern Ungava is divided into two peninsulas, the Upper Ungava Peninsula, situated between Ungava Bay and Hudson Bay, and the Labrador Peninsula, situated between the eastern shore of Ungava Bay and the Atlantic Ocean. Even today Ungava is a vast wilderness, ranging from spruce forests to the south to a middle latitude belt of open boreal forest comprising lichen woodlands with extensive mats of reindeer lichens and,

Setting and Background | 5

SED

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Fig. 1.1 The vegetative zones of Ungava, published in 1959 by Professor Kenneth Hare of McGill University (Hare 1959). The northern limit of forest fires was based on our survey in 1988.

at the northern end, two major tundras (fig. .). We refer to the larger tundra area to the west as the Leaf River or Upper Ungava tundra; the smaller one to the east we call the George River or Labrador Peninsula tundra. Although the eastern tundra is only a quarter of the size of the western tundra, this small area has been a significant factor in the dynamics of the George River herd. Economic Development

In the 990s the residents of first nation settlements adjacent to the range of the George River herd numbered only approximately 25,000 inhabitants. Most of these settlements were coastal (fig. .2) and had no impact on interior caribou

6 | TH E R E T U R N O F C A R I BO U TO U N G AVA

IVUJIVIK (156)

AKULIVIK (354)

SALLUIT (880) KANGIQSUJUAQ (456)

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(2794)

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CHURCHILL FALLS (810)

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CAR TWRIGHT (674) PORT HOPE SIMPSON (604)

MARY’S HARBOUR (463)

NEMISCAU (316)

Fig. 1.2 The locations of the native communities in Ungava are mostly along the coastline of Ungava and the total population in the late 1990s was about 25,000 residents. The data for Quebec is from Dumas et al. 1995.

movements. However, since 94, a NATO air force base has been situated at Goose Bay and jet aircraft have practiced low-level flying over Ungava, both a worldly reminder and an intrusion upon native peoples who were attempting to return to a more traditional lifestyle. The base is now being phased out. The major economic developments in southern Ungava are the iron ore mines formerly located at Schefferville and now in operation at Labrador City and Wabush Lake. The Schefferville iron deposits were discovered in 949 and a 500 km railroad reached Schefferville in 954. Though the mine is now closed, the railroad still operates, primarily for natives who have relocated at Schefferville. Schefferville remains the jumping-off spot for points further north. Besides iron ore, the main resource that has been developed in central Ungava is hydroelectric power. The Churchill Falls, whose 75-m drop makes it one of the greatest falls in North America, were silenced in 969 (so awesome were these

Setting and Background | 7

falls that the Montagnais-Naskapi believed that to look at them meant death). Another loss was Michikamau Lake (203 km²), the crown jewel of the Labrador Plateau. Once the gateway to the George River, it is now drowned by the Smallwood Reservoir (6527 km²), tenth-largest lake in Canada (fig. .2). The dam gates on the Upper Caniapiscau River were closed in the early 980s to create the Caniapiscau Reservoir (3000 km²), entailing a 600-km penetration of the land base with a road from Hudson Bay. Finally, the La Grande or Fort George River was blocked in three stages (979, 982 and 984) with the creation of three reservoirs (fig. .2). More recently, Goose Bay was connected to the outside world by road extensions that stretch from Wabush Lake to Esker (on the Schefferville railroad) and then to Churchill Falls and on to Happy Valley, Goose Bay. Further developments are in progress in the vicinity of Nain, since large nickel deposits were discovered at Voisey Bay (62° W, 58°5' N) in the 990s. The mine was completed in 2005. This mine is in a high-use area of the George River herd. The offshore islands and coastal region provide the animals escape from mosquitoes in July, and the islands act as refuges when the surrounding waters are free of ice. The most recent road extends from the Red Bay on the Strait of Belle Isle to Cartwright. A connector road planned from Goose Bay to the Red Bay–Cartwright Road will bisect the range of the Mealy Mountain herd in Southern Labrador. These developments are mostly south of the ancestral range of the George River herd, but in recent years the herd has penetrated south of Schefferville and has also crossed the Caniapiscau Road. If we draw a line from Chisasibi (formerly the Hudson’s Bay trading post, Fort George) east to Schefferville and thence, as the crow flies, to Nain, there remains to the north of this line a continental area of 400,000 km² with neither all weather road nor interior settlement. Physiography

Ungava belongs to the Precambrian Shield, with bedrock mostly of Cambrian granite, gneisses, and related rocks. The Labrador/Quebec Provincial boundary generally follows the height of land, with rivers running east in Labrador, west in Quebec. The Churchill River (formerly the Hamilton River) flows from the Smallwood Reservoir into Lake Melville of the Atlantic Ocean. The Naskaupi and Canairiktok Rivers also flow from Labrador Plateau to the Atlantic Ocean (fig. .3). Major rivers that flow north to Ungava Bay (proceeding from east to west) are the George River, Tunulic River, Whale and Wheeler Rivers, and the Koksoak, with major tributaries the Caniapiscau and Du Gue Rivers. The Leaf River on the Upper Ungava Peninsula flows northeast, draining Lake Minto. The Payne River flows east from Payne Lake to Ungava Bay (fig. .3). On the east coast of Hudson Bay, the major rivers are the Great Whale River from Lac Bienville, the La Grande River (Fort George River on older maps) from Nichicun Lake, and the Eastman draining from the Otish Mountain region.

8 | TH E R E T U R N O F C A R I BO U TO U N G AVA

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Fig. 1.3

Physical relief map of Ungava (adapted from Hare 1959)

Hare (959) used aerial photographs to divide Ungava into three major physiographic divisions: () bedrock–controlled plateaus; (2) upland areas; and (3) drift covered belts. Each of the three regions cover about one third of the Peninsula. There are two sub-regions of the bedrock classification: the Western Plateau Belt bordered by Hudson Bay south to 52° N and north to the tip of the Ungava Peninsula; and the Eastern Plateau Belt stretching from Ungava Bay southeast to the Canairiktok River. These belts are covered with glacial till with an unbelievable supply of eskers, drumlins, and shallow lakes (fig. .3, adapted from Hare 959). The Western Plateau has an undulating relief (00–300 m), with joining and folded bedrock frequently visible. North-south beach ridges run 0–6 km inland from the former wash of the Tyrell Sea that flooded inland 7,000 BP. The Eastern Plateau (750–900 m elevation) is a vast, treeless rock plain, nearly all covered with drift, The uplands are divided into massifs (upland blocks) and Appalachian-type ridge and valley folding. Four massifs used by caribou, especially in winter when

Setting and Background | 9

windswept, are the Torngat Mountains on the Labrador Peninsula – which rise to more than 500 m with spectacular cliffs and fiords; the Red Wine Mountains northeast of Lake Melville (700–800 m elevation); the Mealy Mountains south of Lake Melville with steep cliffs and elevations to 000 m; and the Kaniapiskau Highlands (700–800 m) at the headwaters of the Caniapiscau River. The Labrador Trough, 25–80 km wide, displays typical ridge-valley relief and runs from Schefferville northeast to the Leaf River. Another major region is the drift– covered belts in south-central Ungava. These are till plains with strong grooving and drumlinization with extraordinarily well-developed eskers. The largest subdivision of this section is the Lake Plateau in the centre of Ungava, where lakes cover 5% of the surface area (see Hare 959, fig. 7, for details and locations). Climate/Weather

The climate is sub arctic with long, cold winters and cool summers. The mean January temperature at Schefferville in the centre of Ungava was –23.°C ± 0.6° (955–93), while mean temperature in July was 2.5°C ± 0.5°, with temperatures getting colder during these years. The correlation of mean January temperature on year was significant: r = 0.32, (n = 39, P = 0.05), which predicted a temperature in 995 four degrees colder than 955 (fig. .4). The mean annual temperature has also declined by one degree in the past 40 years (fig. .4). Studies of growth rings of spruce in central Ungava indicate that the warmest decades in this century occurred in the 930s and 940s (Enright 984; Payette and Gagnon 985). Our averages reflect the continental aspect of the climate, although maritime influences adjacent to the coast result in milder, moist winters and cooler, cloudy summers. Caribou of the George River herd frequent the coast of the Labrador in mid-summer to gain relief from insects. The growing season (temperature > 5.56°C) commences in central Ungava (approximately 55° N) about 3 May and in northern Ungava adjacent to the George and Leaf Rivers on about 0 June (fig. .5; Wilson 97). The 3 May isotherm is mostly a latitude response with the line paralleling 66° W. But the 0 June isotherm is bowed north in the centre, showing a 350-km advance in the interior but only 20 km on the coasts (fig. .5), where coastlines are held back by the cooling presence of sea ice (Tanner 944; Farmer 98). In the continental interior, the average day of ice break-up at Knob Lake near Schefferville was 3 June (955–93), with the latest date occurring 29 June 992 and the earliest break– up occurring 28 May 959 (fig. .4). The end of the growing season in central Ungava arrives about 20 October but comes about 0 days earlier across the Upper Ungava Peninsula and the Labrador Peninsula (fig. .5), adjacent to the cold Labrador Current. The mean date of ice forming at Knob Lake was 29 October (954–93, fig. .4); the earliest freeze was 3 October 955; and the latest was 6 November 977 (a spread of 44 days). The inland lakes and rivers always freeze before the coastal waters (Tanner 944).

15

10

TEMPERATURE (C)

5

JULY TEMPERATURE MEAN 12.5 ± 0.16° C

Y = 34.116  0.011X r = 0.121, P = 0.46

ANNUAL TEMPERATURE MEAN -5.0 ± 0.15° C

Y = 49.179  0.029X r = 0.335, P = 0.04

JANUARY TEMPERATURE MEAN -23.1 ± 0.61° C

Y = 184.814  0.105X r = 0.312, P = 0.05

ANNUAL SNOWFALL MEAN 382.5 ± 16.5 cm

Y = 4877.641 + 2.66X r = 0.287, P = 0.085

DATE ICE FORMS MEAN OCT 29 ± 1.87

Y = 175.348 + 0.064X r = 0.056, P = 0.076

DATE ICE LEAVES MEAN JUNE 12 ± 1.14

Y = 91.963 + 0.129X r = 0.212, P = 0.20

0

-5

-10

-15

-20

-25

DATE ICE LEAVES

DATE ICE FORMS

SNOWFALL (cm)

-30

525 450 375 300 225 20 NOV 10 NOV 30 OCT 20 OCT 10 OCT 30 SEPT 30 JUNE 20 JUNE 10 JUNE 30 MAY 20 MAY 10 MAY

1955

1960

1965

1970

1975

1980

1985

1990

1995

BIOLOGICAL YEARS (1 JUNE–31 MAY) Fig. 1.4 Annual temperatures and dates of freeze-up and spring break-up statistics for Knob Lake, Schefferville, gathered by the McGill Research Station at Schefferville and kindly provided to us

Setting and Background | 

10 JULY END OF GROWING SEASON

AU

G

START OF GROWING SEASON

51 62

UNE 30 J

82 LENGTH OF GROWING

G

AU

SEASON

562 ELEVATION (m)

72

E JUN 30 AUG 31 PT SE 10

1428

NE 20 JU

92

893

376

PT

72

247

838

102

630

102

0

50

0

112

31 M AY 30 S EPT

655

517

92 102

123 20 MAY

133

100 KILOMETRES

10

10 JUNE

20

SE

UG 20 A

51

82

20

LY

41

262

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51

10 SEPT

20

JU

62

10

31

734

599

50

100 MILES

AY 31 M

112

735

113 123

142 123 20 MAY

Fig. 1.5 The dates of the start and end of the growing seasons in Ungava and the total length of the growing seasons

Since caribou generally use frozen lakes as travel routes to reduce predation risk, such a wide spread in freezing dates could influence travel routes and rates. The interior of the Peninsula is subject to heavy snowfall and mean snowfalls were 466 cm (n = 27) at Goose Bay and 499 cm (n = 5) at Churchill Falls. Snowfall is considerably less along the coast, however, and Kuujjuaq averaged 262 cm for a 23-year period (fig. .6). McGill University operated a snow-depth course at Schefferville comprising 0 stations through different habitats measured three times a month for nearly 40 years (fig. .7). The greatest monthly falls generally occurred in December (mean 49.7 cm ± 4.63 cm), and January (mean 48.5 cm ± 4.63 cm), but the greatest depths accumulate in April, averaging 3.26 cm ± 5.23 cm (n = 20). The least reported depth during our study was 68.6 cm in April 985, while the greatest reported depth was 57. cm in April 979 (fig. .7). Snow

2 | TH E R E T U R N O F C A R I BO U TO U N G AVA

72.2 cm (30 inches)

UNGAVA BAY

27

15 18 49

27

53

D ME

IAN

20

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33

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9

30

42

53

42

63

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45

20

45

71

86

79

62

60

3

8

28

41

28

56

69

69

55

98

70

15

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56

63

60

67

45

67

59

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44

94

60 102

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80

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85

75

72 108

50

63

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65

66

83

S TER

78 71

52

75

102 85 77

77

80

85 MAXIMUM DEPTHS (cm) FROM RANGE SURVEY

15 24

101.6 cm (40 inches)

25

7 127 cm (50 inches)

84

72

87

36

119 92

0 0

50 100 KILOMETRES 50

83 inc 60

s he

2.4 15

cm

100 MILES

Fig. 1.6 The median snow-depth isopeths in Ungava based on 20 winters. The statistics at weather stations locations are mean depths for the end of March 1951 to 1990 (Jacobs et al. 1996). The grid of snow depths in central Ungava are the depths we recorded in 1988 by recording the gap in the branches of black spruce caused by wind/snow abrasions, a technique first documented by Hustich (1951) for Labrador.

generally remains on the ground in the last week of May; the mean depth in 20 years was 29.5 cm ± 4.7 cm. Boundaries of Vegetative Zones The first forest classification of Ungava was that of Halliday (937), who labelled nearly all the region from 52° N to Ungava Bay, as well as a transition zone between the northern coniferous forest and the tundra which was shown to commence north of the Leaf River. Other classifications followed: Hustich (949);

TOTAL BEGINNING OF MONTH SNOW DEPTH (cm)

800 700 600

MEAN

500 400 300

160 150 140 130 APRIL 1 120

MARCH

CUMULATIVE SNOW DEPTH (cm)

110

FEBRUARY

100

JANUARY 90

MARCH 1 FEBRUARY 1

80

DECEMBER

70

JANUARY 1

60 50

NOVEMBER

DECEMBER 1

40 30 20

OCTOBER

10

NOVEMBER 1

0

72–73

74–75

76–77

78–79

80–81

82–83

84–85

86–87

88–89

90–91

BEGINNING OF MONTH

Fig. 1.7 The snow depths recorded at the beginning of each month at Schefferville by students at the McGill Research Station. Depths are based on a 10-station course through a variety of habitats. The snow statistics recorded at the weather station located at the Schefferville airport, were, we felt, biased by snow-clearing operations.

4 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Hare (950, 959); Rousseau (952a); Harper (96); Rowe (972); and Ritchie (987). Common to all schemes was a shrub tundra biotype on the Upper Ungava Peninsula, generally north of the Leaf River (fig. .), and another tundra on the Labrador Peninsula east of the George River. The southern boundary of the tundra zone is the arctic tree line. In Ungava and the rest of Canada tree line is based on the presence of black spruce Picea mariana (Payette 983). In Ungava white spruce (Picea glauca) and larch (Larix laricina) reach almost the same latitudes (Ritchie 987). The broad zone between the tree line and closed canopy (closed crowns) has been called the Hudsonian life zone (Harper 96, after Merriam 898) and most recently the transition ecological province (Ritchie 987), although other authors have separated the region into two zones. Hare (950) recognized forest-tundra to the north and taiga to the south; a classification by Hustich (949) showed forest tundra north of 56° N and open boreal forest between 56° and 52° N. However, these early classifications failed to emphasise the northern extension of tree species to Ungava Bay. This central zone of scattered forests (“the land of little sticks”) is especially important to the George River herd after the insect season and during the period of gradual snow build in November/December. Hare’s (959) photo reconnaissance corrected this oversight, as did Rowe’s (972) forest region map of Canada. We have relied on these two classifications to demarcate the arctic tree line and the northern boundary of closed canopy forests (fig. .), and to separate the middle transition zone into forest-tundra and lichen woodland subdivisions. The arctic tree line is the most important landscape feature in the biology of caribou. As any observer who has flown in the North knows, the tree line is not an abrupt change from conifers to treeless plains dominated by shrubs. As you fly north across the ecotone the patches of spruce trees simply get further and further apart until even in the most favourable protected lowland niches they are replaced by shrubs and possibly Krummholz vegetation, where spruce has failed to grow above protective snow canopies. The tree line separates areas that differ in: snow characteristics; caribou foods (broad-leaf shrubs vs terrestrial lichens); wind (for insect relief); and visibility (for detecting predators). Payette (983) is the recognized authority on the tree line in Ungava, but we feel his configuration of the tree line is less relevant to caribou than that of Hare and Rowe. Payette’s tree line extends somewhat further north than the Hare/Rowe line and is more inclusive of Krumholz, but spruce trees that exceed snow cover in height have more impact on caribou biology than prostrate spruce. Furthermore, we wanted to emphasize the importance of an isolated tundra near Harp Lake that is shown as such on the Hare/Rowe maps. Rowe’s (972) tree line is also used by Kelsall (968) in discussing the movement of the herds west of Hudson Bay. A unique feature of the tree line adjacent to the George River is that it extends north and south (rather than east and west) in response to the cold Labrador

Setting and Background | 5

Current which flows south off the coast. In contrast, the tree line on the Upper Ungava Peninsula runs mostly east to west. West of Hudson Bay, the tree line has primarily an east-west distribution from the mouth of Nelson River on the southeast, northwest to the MacKenzie River Delta. The major herds west of Hudson Bay migrate at right angles to the tree line (Kelsall 968) and one might hypothesize that the response to travel north in spring migration is contingent upon some type of latitudinal gradient such as increased day length or retreating snow cover; or the caribou navigate following magnetic lines of force; or they are channelled north by tracking eskers. The major spring route first takes the George River herd east, parallel to the tree line of the Upper Ungava Peninsula and Ungava Bay, and not at right angles as it does in the Northwest Territories. The George herd spring route then turns south adjacent to Ungava Bay (after crossing the Koksoak River), intersecting the north-south tree line west of the George River (Vandal et al. 989). We have used the contrasting directions of the George River vs Leaf River tree lines in Ungava to evaluate environmental influences on shifting animals. South of the transition zone we also wanted to recognize a boundary that relates to the southern edge of the George River herd’s distribution. The line we chose was the northern border of the closed canopy region of conifers according to Rowe (972). This line runs approximately between sub-regions 3a and 3 to the north (the North Transition section and the Newfoundland-Labrador Section) and Rowe’s boreal forest sub-region b to the south (ChibougamauNatashquan), and roughly corresponds to Hare’s (959) interface between forest and lichen woodland (fig. .). The commencement of closed canopy marks the farthest south that the George River herd should reach. The increasing overhead tree cover even farther south would limit the development of lichen cryptograms that are required by the large winter aggregations of this herd. Plant Species Composition of Vegetative Zones The shrub tundra ecological region has a low arctic climate where the July mean temperature reaches 8–2°C (Ritchie 987). As the name implies, the flora is dominated by dwarf shrubs, and by far the most important of these for caribou is dwarf birch (Betula glandulosa). Other species heavily utilized are Vaccinium ulignosum and Arctostaphylos spp. Important willow species (Salix spp.) that are eaten range in height from Salix planifolia (–3 m) to Salix arctica in protected microclimates and Salix Uvi-ursi (less than 0 cm) on exposed uplands. Above tree line, reindeer lichens (Cladina spp.) as well as alpine lichens such as Cetraria nivalis dominate the cryptogram.. A major difference in the two tundras, Leaf River and George River, is that lichens are much more common on the Upper Ungava Leaf River tundra than on the George River tundra. Two major species north of the Koksoak River that can have mats 0–5 cm deep are Alectoria

6 | TH E R E T U R N O F C A R I BO U TO U N G AVA

ochroleuca and Cornicularia divergens. The lichen mat east of the George River, though diminished from caribou grazing, was already less extensive before the George River herd grew in numbers and summer trampling developed. Eugene Mercer (Newfoundland biologist) investigated the range in 976 and noted the scarcity of lichens (personal communication). Even in 988 we could recognize the former distributions of the trampled lichen mats by filament fragments that still delineated the extent of former mats. The major stands had been in sheltered locations in the Valley of the George River. Also note in figure . that recognizable tundra fires in the 930–940s, which occurred when the herd was nearly extinct, were much less common on the George River tundra than on the Leaf River tundra. Since lichens are fire fuel, especially in the absence of Krummholz vegetation, this difference in fire regimes supports the view of a natural scarcity of lichens in the east. The abundance of lichens away from the coast in northern Ungava should relate to wind exposure (see Bergerud 97a) and not precipitation (see Crête et al. 990b). Elevations in the eastern George River tundra average 000 m, whereas those north of the Leaf are generally 300 m (i.e., 700 m lower in elevation) and the landscape is less undulating and exposed to wind than it is east of the George River. The forest-tundra region (fig. .) has a sub arctic climate with July mean temperatures slightly above 0°C. Spruce is generally restricted to the lowlands and the uplands are dominated by shrub tundra, and a fire/climate combination can alter the alignments (Payette and Gagnon 985). Cladonia/Cladina mats are deeper with less exposure, and they are protected by deeper snow cover (Hustich 95; Crête et al. 990b). The shrub species that caribou depend on in the growing season – Betula, Salix, Vaccinium and Archostaphylos – are also widespread in this region, based on range studies we conducted in 988. The open spruce/Cladina association that Hustich (95) and Hare (959) termed lichen woodlands are located in central Ungava (fig. .). Lichen heights at Schefferville in the 940–960s had a mean maximum depth of 3 cm (Hustich 95; Fraser 956; Bergerud personal observation). The lichen heights, even in 988, after being grazed by the large George River herd, were commonly 4–9 cm. Crête et al. (990b) recorded phytomass up to 6,000 kg/ha, and Arseneault et al. (997) showed caribou had removed 2% of the lichens by 992 with supplies remaining of 2,800 kg/ha to 5,400 kg/ha. We noted in 988 that on sunny days one could actually map the presence of recent caribou grazing and trampling of lichens from the air, classifying the mat as to white, white/grey, and grey. Mats that had been recently disturbed were grey, with many podetia crushed or dislodged and lying horizontally such that they did not reflect light from their crowns. Even in heavily grazed habitats there were always rock cliff exclosures with which to check our colour classifications. These park-like forests of open spruce with their soft carpet of lichens have a reduced shrub flora due to substrate competition from climax lichens. Cladina

Setting and Background | 7

stellaris (formerly known as Cladonia alpestris), blueberry (Vaccinium angustifolium), and dwarf birch are the primary shrub competitors in mesic habitats. These beautiful woodlands are easy to travel if caribou leads are present in the moss but in summer these habitats can be unattractive for both man and caribou. Because the trees block wind currents, mosquitoes and flies – especially the tabanids – can make a day’s journey utter misery. From the air the closed canopy of boreal forest – with some additional deciduous elements of paper birch (Betula papyrifera) and aspen (Populus tremuloides), especially on fire succession slopes – presents a more uniform vista. This ecological region has a boreal climate with a four–five month growing season and is delimited by the isotherms of 600 and ,000 growing degree days (Ritchie 987). Davis (98) showed that the boundaries of the boreal forest coincide with the boundaries of the summer and winter arctic frontal systems. Models of climatic warming from increased CO ₂ concentrations predict a major northward extension of this region (review by Gates 993). The closed canopy results in a major reduction in the lichen and shrub layers – a plant association where large numbers of caribou can remain together. Forest Fires The major forage for wintering caribou of the George River herd is ground lichens, as elsewhere in North America (Parker 98; Gauthier et al. 989). Lichen succession following fires is a slow process, and it can take more than 50 years for the heavy mats of Cladina lichens, especially Cladina stellaris, to return (Hustich 95; Scotter 964; Bergerud 97a; Thomas et al. 996). Several caribou biologists have postulated that forest fires can result in caribou declines (Leopold and Darling 953; Scotter 965), a theory Skoog (968) and Bergerud (974a) dispute. Nonetheless, there is also concern – especially by native peoples – that lichen reduction in traditional hunting areas will shift distribution patterns; indeed Thomas et al. (996) has documented this sequence for the Beverly herd in the Northwest Territories. Forest fires have occurred in Ungava at least since deglaciation and the arrival of black spruce in central Ungava (about 5,000 BP). Spruce may not have reached the Hudson Bay coast until 4,000 BP (Richard 98). At Indian House Lake on the George River the maximal rate of burning at 3,000 BP (Samson 978) coincided with the period of optimum postglacial forests in Ungava. Carbon 4 dating of charcoal on well-drained sites near the Leaf River and Richmond Gulf indicated major burning periods at 600¹⁴Cyr and 650–450¹⁴Cyr (Payette and Gagnon 985). In 988 we had to give up our range studies west of Lac Bienville because dense clouds of smoke made low-level flying impossible; at that time 20,866 km² were ablaze near the La Grande River (Couturier and St. Martin 990).

8 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Hare (959) provided a forest cover map of all Ungava developed from the first set of aerial photographs that showed burned habitats accumulated to 948. The deforestation was greatest between 70°–76° W and 52°–56° N with 23 ± 4.5% of the habitat in this area recently burned (fig. .). The burns we recorded in 988 were not ground-truthed to measure how long they could still be recognized from the air, but the 92 burn shown in Hare’s aerial photographs (fig. .) was still evident in 988. Because of the frequency of fires around 950, we wanted to gauge what their natural frequency would have been prior to the construction of roads and railways that would have contributed to accidental ignitions. Payette and his students conducted a qualitative, intensive study of fire within a 54,000 km² in western Ungava between 55°–59° N and 76°–74° W (Payette et al. 989). Using fire scars, they mapped nearly all the burns between 920–84, even dating fires back to 894. The amount of burnt habitat peaked in 950–54 coincident with warm, dry summers (6% of the area burned). From 920–84, 23% of the lichen woodland near the Great Whale River and 4% of the lichen woodland farther north at Clear Water Lake burned, indicating natural fire rotation periods of 00–80 years. South of the Great Whale study area near the La Grande River, Couturier and St. Martin (990) used landsat photography to show that 6.4% of 26,526 km² had been burned since 972, an annual burn rate of 0.92% which yields a 09-year rotational interval. They reported a lichen phytomass (kg/ha) in pine/spruce forests of 7,873 kg/ha (n = 3), 29–39 years post-fire; 8,575 kg/ha 40–54 years post-fire (n = 6); and a reduced phytomass for sites burned ≥55 years 4,463 kg/ha (n = 4). These forests were extremely productive again only 30 years post burning. The recovery of lichen habitat for caribou based on a burning rate/year of 0.92% and a 30-year regeneration interval is 76% quantified kg/ha of terrestrial lichens for Ungava from a wide variety of lichen habitats currently used by caribou and showed phytomasses ranging from ,200–4,800 kg/ha (Crête et al. 990b). The most recent study of burning rates was that of Areseneault et al. (997), who measured lichen phytomass in 989 in 88,50 km² north of 55° N and west of 69° W in an area that appears to be the most heavily burned area in northern Ungava. They showed four successional stages: () 0–30 years, 9.7% of the area (530 kg/ha); (2) 3–50 years, 24.2% (2,700 kg/ha); (3) 5–90 years, 5.4% (4,400 kg/ ha); and (4) > 90%, 50.7% (8,00 kg/ha). They reported that lichen use by caribou in recent years was concentrated in stands > 50 years old, resulting in 5% lichen removal per year from those stands. The consensus is that the burning cycle in western Ungava is about 00 years in length (Payette 992) and should be viewed as a natural process controlled by the build up of forest fuel and weather conditions. A rotation period of 00–80 years is a common statistic in other northern coniferous areas of North America and Europe (Heinselman 973; Cwynar 977;

Setting and Background | 9

and Ferguson 983). Cogbill (985) notes a natural mean rotation period of about 00 years with a maximum stand age of 250 years for the eastern boreal forest. However, Payette et al. (985) have reported much older stands at the northern edge of the lichen woodlands in Quebec and argue that lichen woodlands can regenerate sexually in the absence of fire disturbance and do not degrade into tundra vegetation as suggested elsewhere. In 988 we conducted a range survey covering 400,000 km² (74°–64° W and 59°–54°30' N), flying between stations and recording the number of kilometres that our flight path crossed burned and non-burned habitat (Bergerud 996). The burned area for the central lichen woodland was 5.2%, almost identical to what Hare (959) showed on his map for the same region 40 years earlier (5%). Hence in both 948 and 988 past fires had been less common in central Ungava than in western Ungava (Hare 959; Payette et al. 989; Couturier and St. Martin 990). The northern limit of extensive, current-day fires in western Ungava is adjacent to the Koksoak River at 57°–58° N (Payette and Gagnon 985). This northern limit does not reach as far north in eastern Ungava, and was about 55° lat. based on the 948 and 988 surveys (fig. .). In the west all of the forest tundra biome is included in the burn, but in the east the fire zone stops at the border between lichen woodland and the forest-tundra biome (fig. .). Payette and Gagnon (985) used carbon 4 dating of charcoal to study deforestation caused by burning on the northern edge of the western forest tundra . They noted charcoal under several mats of lichens. They argued that deforestation began roughly 3,000 BP and the primary expansion of treeless vegetation at the expense of forest and Krummholz stands relates to forest fires in warm cycles and the failure of spruce to regenerate in colder cycles. We noted a much heavier lichen mat in the west than in the east (also Crête et al. 990b) and wonder if this might relate to the higher incidence of fire in the west since lichens are fire fuel. But Payette and Gagnon (985) note that lichen cover reduces shrub and Krummholz growth and should retard burning. They define a tree line according to an increase or decrease in the distribution of discrete spruce as an indicator of postfire regeneration success, the latter depending upon temperature extremes, as opposed to defining tree line as a forest zone that advances and retreats through climatic cycles. In general, deforestation in western Ungava has increased since a forest optimum 3,000 BP. Since fire adds instability to the tree line and is less frequent in the east than the west, the rates of deforestation should be less in the east. Our main camp 988–92 on the “running-out” of Indian House Lake has Indian tent rings that date back at least 2,000 BP (Samson 978). The site today has the most northern stand of spruce along the George River and probably provided firewood for native hunters thousands of years ago. Samson’s (978) pollen analysis at Indian House Lake (fig. .8) showed that conifer growth climaxed 3,000 BP and that

THOUSANDS OF YEAR S B P 0

0 20 40 60 80 0 20% 20 0 0 0

0 20 40 60 0 20 40 60

UBLIK POND 60 0

0

BOG

0 20 20

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UPLANDS

co p Iso odi ete um an Sp s no ha tin gn um um

ae

ce

40

Ly

pe ra

20 0 0

40 0

20

0 0

e

20 0 0

Cy

40

ea

0 20

Sa lix Gr am Eri inea cal e es

Ly co po diu ma nn

150

rac

0

us

2660 170

pe

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Aln

50

Cy

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ae

60% 0

Gr am ine

40 60% 0

lix

20 40

Sa

0 20

s

180 0

Aln u

250

a

40%

La rix Pin us Po pu B e lus tul a

200

tul

100

Be

ea

cm

Pin

0

Pic

20

a

510 150

Iso e Sp tes ha oti gn nu um m

Sa lix Gr am Eri ine ca ae Cy les pe rac ea e

Aln us

La rix Pin u Po s pu lus Be tul a

Pic e

0

us

ea

0

Pic

cm FIRES

3510 175

4090 250

0 0

20

0

50

100

150

3710 100

40

1 2

3

4

5 6

7

8 9

10

11

0 20 40 60 0 20 40 60

Setting and Background | 2

Fig. 1.8 (left) The pollen profiles at Indian House Lake (upper and middle figures) and at Ublik Pond. Ublik Pond is located between Okak Bay and Ublik Bay (elevation 122 m). The upper profile at Indian House Lake is an upland site commencing at 510 ± 150 years, level 3 commencing at 2,660 ± 170 years ago, level 2 commencing at 3,510 ± 175 years and ending at 4,090 ± 250 years. The graph to the upper left is an index to the frequency of charcoal (%) in the profile back to 4,090 BP and indicates an increase in forest vegetation and fires about 3,000 BP resulting from a warmer climate. The middle figure is from a bog at Indian House Lake and extends down in time to 3,710 ± 100 years. The Laurentide ice sheet had contracted to Indian House Lake about 7,000 BP based on the first organic material in a pollen profile at Pyramid Hills, adjacent east of the George River (Short and Nichols 1977). The Ublik profile on the Labrador coast is important since it indicated that the Laurentide Ice Sheet had retraced inland from the Labrador coast at 10,000 BP and that birch was available for caribou by 9,000 BP (pollen profiles adapted from Samson 1978 and Short and Nichols 1977).

there was no major vegetative change after 2,000 BP. Thus the forest tundra that the Naskapi saw as they waited for the caribou to swim Hutte Sauvage Lake so long ago is much the same as the one their descendants see today. Mammalian Fauna The number of mammalian species native to Ungava is slightly less than at similar latitudes west of Hudson Bay. Harper (96) listed 35 species resident in the Hudsonian Life zone and 22 species in the Arctic zone, north of tree line. All the important missing species are Arctic forms: musk ox (Ovibos moschatus), now introduced; Arctic ground squirrel (Spermophilus parryi); brown lemming (Lemmus sibiricus); tundra vole (Microtus oeconomus); and northern red-backed vole (Clethrionomys rutilus). According to MacPherson (965), four of the five species are thought to have survived the Wisconsinan glacial phase in Beringia but none of the numerous mammalian forms believed to have differentiated in Beringia succeeded in crossing into Ungava over Hudson Bay (MacPherson 965). The muskox survived in the periglacial refugium but never made the return trip to Ungava (Kurtén and Anderson 980). The possible existence of brown bears (Ursus arctos) in northern Labrador – especially along the north coast – is controversial. Elton (954) provided evidence from skins brought to Moravian mission stations and trading posts, as well as anecdotal accounts of bears different from black bears, but these, it was argued, were a brown phase of black bear (Harper 96). However, in 975 archaeologists Spiess and Cox (976) discovered the skull of a grizzly bear in an 8th-century Inuit sod hut at Okak. Furthermore, in 90, during one of his journeys into the Labrador interior, Williams Brooks Cabot found a unique Innu offering in a remote valley near Kamestastin. Cabot photographed (but left in place) a large

22 | TH E R E T U R N O F C A R I BO U TO U N G AVA

bear skull placed on a tall pole at the crest of a hill. (See page 32) Recently S. Loring and A. Spiess concluded that the photograph depicts a grizzly bear. Thus, grizzly bears may have persisted until 925–30, in line with the last recorded sighting in 925–26 (Elton 954). Black bears have replaced the grizzly bears on the Labrador tundra and are especially large and common along the northern coast. Their reproductive rate is excessively low (Veitch and Harrington 995). In only 3 of 22 cases were radiotagged females ≥5 years accompanied by cubs or yearlings. Veitch and Harrington believe that this, combined with native hunting and the loss of caribou as a food source during the extended caribou scarcity after 96, probably caused the extinction of grizzly bears; they postulate similar reasons for the extinction of wolverines in northern Labrador. There are five mammal species that could affect the dynamics of caribou, including four predators – wolf (Canis lupus); lynx (Lynx canadensis); bear (Ursus americanus); and wolverine (Gulo gulo) – as well as one ungulate, moose (Alces alces). We have never observed either a wolverine or lynx on the George River calving ground in the course of this 20-year study, but wolves do kill some calves, and bears are common just east of the George River calving ground along the Labrador coast from Okak Bay north. The absence of wolverines is an enigma. They apparently were common in the late 800s (Low 896; Bangs 92), but declined dramatically during the caribou low years in the 930–940s (fig. .9). Wolverines did reappear (963–64) in the fur return data and they were fairly common by 973–74, but by 980–8 they had disappeared again (fig. .9). Experienced trappers in Labrador interviewed by Pamela Northcott (Newfoundland biologist) recalled one trapped in 946; two in 950; and two seen in the Grand Lake area 978–80. Alaska biologist Patrick Valkenburg has recently completed an aerial survey for wolverine tracks in Ungava and reports that they are extinct (personal communication). The working hypothesis associates the decline of wolverines with the decline of the George River herd 920–50 (Harper 96; Northcott 990), as fig. .9 corroborates. The slight recovery in the 970s is also consistent with an increase in caribou. However, there were many more caribou in the 980s and the prodigious number of carcasses left around the countryside from the large legal harvest ought to have solved the food problem for wolverines. However, Ungava wolverines must have always been hard-pressed because of the absence of arctic ground squirrels. In Ontario wolverines were rare 966–67 to 974–76 but increased 976–77 to 983–84 with a mean annual harvest of 4, despite the lack of a corresponding increase in caribou as either prey or carrion. The Labrador wolf (Canis lupus labradorius) inhabits all Ungava Peninsula (Peterson 966; Banfield 974) and is the major predator of caribou. This subspecies never appears to have been common. Low (897), in all his travels exploring the interior, had never seen or heard a wolf. Similarly, Harper (96), when speaking of the past, said wolves had not been encountered anywhere, even when there

Setting and Background | 23

WOLVERINES HARVESTED

30

20

WOLVERINE 10

0

ARCTIC FOX HARVESTED (× 1000)

35 30 25

ARCTIC FOX

20 15 10 5 0 1919–20

29–30

39–40

49–50

59–60

69–70

1979–80

YEARS

Fig. 1.9 The harvest statistics of wolverine and arctic fox from northern Quebec, 1919–20 to 1983–84. The wolverine harvest statistics indicate that the wolverine disappeared from Ungava in the mid-1940s, at the time the George River herd was nearly extinct. The arctic fox graph depicts the 3- to 4-year cycle of arctic foxes that continues to this day and was first documented by Charles Elton (1942), the father of ecology, from fur records that went back to 1834 (Elton 1927).

were great herds of barren ground caribou. Historical fur returns tabulated by Elton (942) showed about equal harvests of wolves and wolverines, even though wolverines generally exist at low densities when away from mountain habitats. The Davis Inlet people (Naskapi) who lived in the interior until the early 900s and hunted west to 72° W harvested only 8 wolverines and 78 wolves in 0 years (88–90) when the George was high in numbers (Elton 942). In the years after the herd declined – hunters with dog teams spent weeks searching for caribou during that period – the wolverine disappeared (fig. .9).

24 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Wolves hung on but were extremely scarce. Wildlife Officer William Anderson of Makkovik recorded the following observations from interviews with these hunters (comments are organized by place names) in the 950s (Bergerud 958): Postville: “None seen since 923.” Postville: “None at all.” Makkovik: “No wolves since he has been going inland (last 2 years).” Makkovik: “Have seen the track of one wolf in 0 years.” Makkovik: “Four wolves in 946 (Snegamook L.), the only ones in 26 years.” Makkovik: “They used to be so plentiful, now there is none.” Makkovik: “They tell me about 50 years ago were very plentiful in these parts but now none.” Hopedale: “Abundant when a boy, none for 20 years.” Davis Inlet: “Saw seven at Mistastin eight years ago, three in 955.” Davis Inlet: “None for 5 years, plentiful 45 years ago.” Nain: “Saw four at Kingurutik R. in 924, tracks of two three years ago.” Nain: “Saw five at North River in 952; some at Nutak until 952.” Nain: “Fifty years ago there were plenty; have never seen any.” Nain: “None in the past 2 years.” This great scarcity of wolves – one that lasted for decades – came about after the George River herd declined drastically at the beginning of the 20th century (fig. .0). The wolves that survived the lean years must have scavenged along the sea coast (Andriashek et al. 985) and ranged through the central interior south of 55° N. They could hunt sedentary caribou (chapter 4): In April 963 Des Meules and Brassard (964) counted large numbers of caribou between Schefferville and Opiscotiche Lake (68° W, 53° N), south of the range of the George River herd. These caribou had antlers that were similar to those of sedentary Lac Bienville and Caniapiscau phenotypes (see photographs in Hayeur 979). The low numbers of wolves in Ungava is due to the recurring outbreaks of rabies that are pandemic in the Arctic where arctic foxes range (MacInnes 987). Rabies outbreaks occurred in the canids in northern Ungava in this study in 976, 980–82, 986–88, and 992+. The outbreaks were cyclic and no cases were reported in the intervening years (fig. .). Before the 980–82 outbreak, the harvest of wolves at Kuujjuaq and Nain was > 50 per year; in 982–83, after the outbreak, the harvest was 30. We observed seven wolves or their kills per survey in three surveys 979–80, but none in six surveys 98–83 (fig. .). Rabies in arctic foxes in Ungava, which provides one of the longest records of a disease in wild canid populations, was documented a posteriori by historical infections of arctic sled dogs (Elton 942; Plummer 947; MacInnes 987). Elton

Setting and Background | 25

WOLVES HARVESTED PER WOLVERINE

3.5

CARIBOU HIGH

3.0 2.5 2.0 1.5 1.0 0.5 0

CARIBOU HIGH WOLVES

CARIBOU LOW CARIBOU

TOTAL WOLVES

120

15

100 80

10

60 40

5

20 0

0 1834– 1844– 1854– 1864– 1874– 1884– 1894– 1904– 1914– 1843 1853 1863 1873 1883 1893 1903 1913 1923

CARIBOU HARVESTED (× 1000)

140

CARIBOU LOW

Fig. 1.10 The caribou and wolf skins traded at Moravian Missions reported by Elton (1942) in table 11.1, 375. He also listed the wolverine skins traded. It is hypothesized that past high populations of the George River herd existed at or just prior to a period where wolves were common (a high ratio of wolves to wolverines) and when there was a relatively low harvest of caribou adjacent to the Labrador coast (i.e., the herd was large and used the western winter ranges more frequently as did the high population in the 1980s).

(93, 942) summarized what was known of the “arctic dog disease” or “sled dog disease” in Ungava with records starting in 805. His most complete data – tabulated from 858 to 904 – documented 0 outbreaks or major infections every 4.6 years, an interval nearly identical with our four outbreaks in 9 years (fig. .) and the cycle length of arctic foxes in Ungava. MacInnes (987) has stated that there was no evidence to link the four-year arctic fox cycle to rabies, but if the disease is as lethal to foxes as it is to sled dogs and wolves, one cannot help but wonder (fig. .9). It was in Ungava that Charles Elton first documented the pulse of life of small northern herbivores and their furbearer predators: 3–4 year cycles in lemmings,

WOLVES AND KILLS SEEN PER TRIP

26 | TH E R E T U R N O F C A R I BO U TO U N G AVA 8

2

3

6 4

2

3

3

NUMBER OF FIELD TRIPS (≥ 7 DAYS)

1

2

3

4

2

2

2 3

0

3

2

2

1

NONE SEEN

150 NUMBER OF WOLVES HARVESTED AT KUUJJUAQ

2

2

2

r = 0.675 P < 0.05 n = 14

NO HARVEST DATA

100

CONFIRMED CASES

50

0

RABIES 73–74

1 75–76

11

NO CASES 77–78

79–80

16

NO CASES 81–82

83–84

85–86

NO CASES 87–88

89–90

13 91–92

Fig. 1.11 (above) The number of wolves and/or their kills seen per helicopter trip (each trip ≥7 days) while monitoring the George River herd during the study. Wolves were extremely scarce after the rabies outbreak 1980–82; (below) The number of wolves reported harvested at Kuujjuaq and the number of positive cases of rabies of northern canids confirmed by analysis reports from research laboratories to the Newfoundland Wildlife Division. The lack of positive cases in 1975–76 is because we were not aware of the problem and didn’t solicit information and encourage fresh skulls to be shipped to southern laboratories.

voles, and their chief predator, arctic fox; 9–0 year cycles in snowshoe hares and their primary predator, the lynx; 3–4 year cycles in red foxes who preyed primarily on mice; and 9–0 year cycles for red foxes further south who relied on hares. These cycles continue today (fig. .9), a reflection of the uncompromised integrity of the boreal and arctic ecosystems in the 990s. Moose arrived in Ungava well after the Little Ice Age ended (Peterson 955), and they have steadily pushed east and north since 875 (fig. .2). Ungava was the last place they reached in their post Little Ice Age dispersal, further evidence of the region’s cold climatic conditions. Keith (983) and Fuller (989) have both provided convincing evidence that the abundance of wolves can be predicted by the biomass of ungulates, most importantly moose. In Fuller’s body size conversion, one moose is equal to three caribou in determining wolf numbers. If the moose plus caribou biomass is sufficient to support > 7 wolves/,000 km², caribou populations may go extinct or persist only in low-risk refuges. The moose biomass is the wolves’ primary resource, but

Setting and Background | 27 NORTHERN LIMIT MOOSE

TREE LINE MOOSE EXPANSION OLDER EXTENSIONS

55°

NEWER EXTENSIONS

33

1895

NORTHERN LIMIT SEDENTARY TYPE

18

75

84

19

1973 66 19

75 7 19 196

1972

19

55°

7 –8

8 198

EE

TR

LIN

0 199

E

CALVING GROUNDS

8 –6

1961 IN I L. MISTASS 33 19

,19

50

196 6 18 95

?

1875

DISTRIBUTION PRIOR TO 1875 0 0

200

400 KILOMETRES 200

400 MILES

Fig. 1.12 The range expansion of moose into Ungava since 1875. Moose are now as far north as the tree line. Information from a variety of sources, including Peterson (1955) and Mercer and Kitchen (1968). (Sedentary type relates to woodland caribou)

because caribou are more easily killed, the wolves frequently switch over to caribou (Bergerud 985; Bergerud and Elliott 986). Those Other Animals Tabanid flies (Hybomitra spp. and Chrysops spp.), mosquitoes (Aedes spp.), and blackflies (Simulium spp.) are at times abundant and alter summer movement patterns, impacting caribou energy budgets (Camps and Linders 989). We have also noted that the caribou in Ungava appear to be unable to distinguish the landings of tabanids from warble flies and thus show severe anti-fly shaking and running behaviour to both. Another limitation is the relatively small size of the tundra of the George River herd (47,000 km², Torngats excluded), which leaves insufficient space to avoid areas where warble fly (Hypoderma [edemagena] tarandi) larvae pupate. In Norway the incidence of warble fly infections

28 | TH E R E T U R N O F C A R I BO U TO U N G AVA

dropped for herds that could make long post-calving migrations to distant areas. Similarly, west of Hudson Bay the mid-summer migration takes caribou away from calving areas where warble larva have been dropped by the post parturient females (Kelsall 968, 975). George River caribou return over the same area where oestrid larvae have pupated during their summer movements. George River animals do have one advantage over more northern herds, however, in that even in mid-summer there is still a distinct daylight–dark cycle. Since all flies are basically diurnal, sundown – when the caribou need only respond to mosquitoes – brings relief. We measured the abundance of biting and parasitic insects above tree line and their effect on behaviour in four summers 988–92 and made further notes in the two following years. Early travellers of the Interior of Ungava speak of the hordes of swarming insects encountered in these relatively southern latitudes. We found, however, that the abundance of these insects varied greatly between summers, with few mosquitoes and black flies in 989 and 99, for instance, but huge clouds in 988. One observation stands out: June 989 was extremely hot when the mosquito population in mid-June was emerging and water levels were low. During the third week of June the temperatures reached > 30°C, and on 24 June we recorded 36°C. Subsequent to that extreme temperature, mosquitoes virtually disappeared for the remainder of the summer. Native Inhabitants Native peoples moved north into Ungava 8,000–7,000 BP, 2,000 years after deglaciation. Anthropology research in this region has produced considerable disagreement among authorities. We have found Jordan’s (975) summary interpretation of this postglacial dispersal of native peoples useful, as well as Fitzhugh and Lamb’s (985) graphic analysis of the distribution of Indians and Inuit that includes changes in vegetation and climate (fig. .3). People of the Maritime Archaic Tradition (Algonkian origin) reached south-eastern Ungava by 8,000 BP (McGhee and Tuck 975), 2,000 years post deglaciation. The same people reached Groswater Bay by 7,500 BP (Jordan 975), Nain by 7,065 BP and Okak by 5,500– 6,000 BP (Cox 977). Their livelihood was centred upon marine life rather than inland hunting (Spiess 993), but by 4,000–3,000 BP a nomadic inland culture based on hunting caribou had developed (Jordan 978). About 3,800 BP PalaeoEskimo culture moved south as far as Davis Inlet; during a cooling trend 2,500– 2,200 BP a Dorset culture went further south to Groswater Bay (Jordan 975; Fitzhugh 978). These Dorset cultures replaced the Thule culture farther north about 400 ad (Fitzhugh 980), and their descendants remain in Ungava north of 56° N. Prior to European influence, the Cree, Montagnais and Naskapi travelled the interior in pursuit of the caribou in winter; fished, harvested seeds and gathered berries in summer. Figure .4 shows the home ranges of 25 kin-based

Setting and Background | 29

BP

HAMILTON INLET

SOUTH LABRADOR

NWR

NORTH COAST

GROS. BAY

NAIN-OKAK

HEBRON TORNGAT

0

LABRADOR

MONT. / NASKAPI

1000

ESKIMO / INUIT THULE

PT. REVENGE

LATE DORSET

MIDDLE DORSET 2000

DORSET

EARLY DORSET GROSWATER

GROSWATER 3000

UCE

R K SP

C BLA 4000

N OPE

PRE-DORSET

EST

FOR

DRA TUN

SAUNDERS PREDORSET

NULLIAK LATE M.A.

LATE REST

5000 6000

IR

FIR-B

8000

RA

ND

EARLY

?

O

ILL

H-W

C BIR

U WT

TU CE PRU

S

CH-

-BIR

ER ALD

MIDDLE MARITIME ARCHAIC

7000

RA

ND

E FO

C PRU CH-S

PREDORSET

ICE

9000

Fig. 1.13 A cultural historical diagram of the native peoples in Labrador, adapted from Fitzhugh and Lamb (1981). In 1981 it was still debated if the coast was free of ice at 10,000 BP. It is now recognized that the entire Labrador coast was free of the ice sheet at that time (Faunmap 1994).

hunting bands that ranged all of Ungava except the Upper Ungava Peninsula north of the Leaf River where there were no forests for their fires (Speck 935). With the advent of the fur trade in the 7th century came the need to maintain trap lines, and natives became more localized along the coast (although some of the Naskapi remained mostly with the caribou until the migration failed in 96). The Naskapi still made long inland trips until the mid-950s when some moved

30 | TH E R E T U R N O F C A R I BO U TO U N G AVA

INUIT

HUDSON UNGAVA

BAY

ATLANTIC

BAY

OCEAN

WHITE WHALE RIVER BAND

BARREN GROUND BAND

UNGAVA BAND

PETISIKAPAU BAND

BIG RIVER BAND

D

ND

N BA

BA

O AR

MINGAN BAND

ST. AUGUSTIN BAND

U SQ

LAKE ST. JOHN BAND

AN KW

WASIVANIPI BAND

BERSIMIS BAND

MU

MISTASSINI BAND

MOISE BAND

E

Y OR

T AC EF OS AND B

MO

RUPERT HOUSE BAND

NICHIKUN BAND

UERIT ARG ST. M BAND

EASTMAIN BAND

MICHI- NORTHWEST RIVER KAMAU BAND BAND

H TAS NA

BAY

AU ISK AP NI AND B

KA

JAMES

DAVIS INLET BAND

SHELTER BAY BAND

GODBOUT BAND

N.F.L.D.

GULF OF ST. LAWRENCE

Fig. 1.14 1935)

Prehistory distribution of native Indian bands in Ungava (adapted from Speck

to Schefferville (the Davis Inlet band remained mostly on the coast), but snowmobiles replaced dog teams in the 960s, making it possible to search for caribou from the settlement base, and the nomadic life style came to an end. In the 990s, there were approximately 7,000 Cree, ,500 Naskapi, 700 Montagnais and 9,500 Inuit living in permanent communities either on the sea coasts of the Ungava or at Schefferville (fig. .2). The non-native population is located at the mining communities of Wasbush Lake, Labrador City, and Fremont, and the military base at Goose Bay. Caribou is still the primary wild food for the natives, however, and hunting as a way of life remains deeply rooted in the culture.

C H A P T E R T WO

Taxonomy, Ecotypes, Herds, and Morphology

The caribou of Ungava are classified as woodland caribou Rangifer tarandus caribou) based on skull measurements (Banfield 96). Prior to this classification mammalogists recognized a northern form (Rangifer arcticus Caboti) and a southern species (Rangifer caribou caribou) (Seton 927; Anderson 938; Harper 96). The northern form made extensive migrations and lived in the summer largely above tree line; its behaviour was similar to the barren-ground caribou in the Northwest Territories. The southern species made short migrations and lived for the most part below tree line. Our next chapter discusses the postglacial dispersion of the ancestors of the present-day forms into Ungava from a refugium south of the Laurentide ice sheet and the separation of the present-day northern and southern ecotypes about 0,000 BP. The common origin proposed by Banfield during the Pleistocene is consistent with the frequencies of the transferrin alleles in the blood serum of caribou (Røed et al. 99). Especially significant was the genetic marker Alleles₁,₂,₃ (table 2.) – present in the stocks originally classified by Banfield as woodland caribou but nearly absent in the barren-ground stocks west of Hudson Bay and Baffin Island (table 2.). Recently Flagstad and Røed (2003) and Røed (2005) have argued that the North American woodland caribou originated as a separate subspecies from a single refugium south of the continental ice sheet based on mitochondrial DNA sequences. It should be noted that the marker allele (Tf) for woodland caribou was not found in caribou now classified as R. tarandus caribou (woodland) in Alberta adjacent to the Rocky Mountains; the westernmost population with this marker was in northern Saskatchewan (Røed 2005), consistent with dispersal from the Appalachian Refugium discussed in chapter 3 (see fig. 3.4).

32 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 2.1 Transferrin allele frequencies of caribou in different regions (data Røed et al. 1991)

Allele

A₁+₂+₃ C₂ E₁ G₂ H₂ I L₂ No. of Alleles

Quebec/Labrador Nfld. Quebec Ontario Manitoba NW T George Leaf Brunette Gaspe Slate Sasag. Baffin Beverly River River Island Pen. Islands Lake Island Lake n=131 n=22 n=12 n=13 n=16 n=13 n=117 n=95

0.331 0.118 0.015 0.305 0.103 0.015 15

0.409 0.023 0.023 0.318 0.068 0.023

1.000

10

2

0.346 0.577

0.606 0.214

0.429 0.000

0.127 0.043

0.038 0.038

9

0.077 7

4

0.000 0.026 0.026 0.030 0.128 0.094 0.052 14

0.001 0.068 0.111 0.116 0.153 0.121 0.011 21

Genetic Identities

George Leaf R Brunette Gaspe Slate Is Sasag. L. Baffin Beverly

0.926 0.533 0.341 0.806 0.583 0.149 0.543

0.728 0.086 0.766 0.475 0.080 0.413

0.011 0.771 0.465 0.000 0.018

0.539 0.667 0.042 0.223

0.797 0.056 0.276

0.216 0.268

0.316

Additionally, using mtDNA from herds ranging from Alaska to Newfoundland, Dueck (998) proposed two mtDNA clades that were isolated 49,000 years ago by the Wisconsinan glaciations: the northern clade from the Beringia refugium in Alaska, the Yukon, and Banks Island; and the southern clade from the periglacial refugium south of the ice that extended to 40° N. Relative to the George River herd, Dueck indicated that the southern clade represented 78% of the mtDNA and the northern clade 22% (fig. 2.). Dueck’s data also showed that the animals living on Baffin Island, those on Southhampton Island, and the Kaminuriak herd west of Hudson Bay had only the northern haplotypes profile. This suggests that the 22% northern clade in the George did not reach Ungava south across Hudson Strait nor across Hudson Bay via stepping stones South Hampton, Coast, and Mansel Islands. A possible contact belt between the northern and southern clades may have been in the vicinity of Hudson Bay but south of 60o (the Cape Churchill herd) (fig. 2.). Confusion remains as to whether the animals living along the southwestern shores of Hudson Bay should be classified as barren-ground or woodland (Banfield 954; traditional knowledge quoted in COSEWIC 2002).

Taxonomy, Ecotypes, Herds, and Morphology | 33

GREENLAND

ALASKA

YUKON NORTHWEST TERRITORIES BRITISH COLUMBIA

MANITOBA

LABRADOR

QUEBEC % TF ALLELES

R.t. GRANTI

NORTHERN mtDNA CLADE

R.t. GROENLANDICUS

SOUTHERN mtDNA CLADE

R.t. PEARYI R.t. CARIBOU R.t. TARANDUS

Fig. 2.1 The main distribution of the five different subspecies of caribou in North America. Superimposed on these current taxonomic distributions are two different genetic analyses of various caribou herds. (a) The circles shown in black are the frequency distribution of the pooled transferrin allele Tf A-3, Tf A-2, and Tf A-1 sampled at 12 herds (Røed et al. 1991) (b) The second analysis depicts for 22 herds the proportion of the northern mitochondria DNA clade (white) (from the refugium in Alaska and the Yukon) and the southern mitochondria DNA clade (red), from the Appalachian refugium (map in COSEWIC 2002: 6, mitochondria data based on Dueck 1998, see also Boulet et al. 2005).

It has been recognized – at least since the Calgary Conference on the behaviour of ungulates (Geist and Walthers 970) – that ungulates living in the open, be it Africa or North America, are more gregarious than forest-dwelling races and make longer migrations. Bergerud proposed at that conference that the gregarious behaviour of open-dwelling caribou was an antipredator strategy to reduce predation risk. He also hypothesized that during the spring migration females living in the open moved to areas where their calves had an increased chance of survival. He noted that wolves were more common on winter ranges than on calving grounds on the tundra (Bergerud 974b).

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Caboti and caribou (formerly recognized by early mammalogists as two separate species) are ecotypes that display different aggregation and migration strategies. These behavioural differences are mediated by the environment and should not be confused with taxonomic or preglacial distributions. These two ecotypes have been described as distinct by genetic studies, with each type represented as a meta-population (Courtois et al. 2003). However, the evidence is not conclusive at this junction. Ecotypes Cows have two distinct distribution patterns for reducing predation risk. In the first, the cows can be widely dispersed in the spring (spaced-out), thereby increasing the searching time for wolves and bears. In the second, the cows can show displacement and space-away from the distribution of predators (fig. 2.2). This second strategy occurs in the large Arctic caribou herds in North America, such as the Bathurst and Porcupine herds in the Northwest Territories and Alaska (Bergerud and Page 987; Bergerud 996; Heard et al. 996). The caribou that space-out are the sedentary ecotype; the animals that space-away and migrate to calving grounds on the tundra are the migratory ecotype (Bergerud and Page 987; Adams et al. 995a, b; Bergman et al. 2000; Schaefer et al. 2000). These two different antipredator strategies at calving are the basic selection units that resulted in the two different suites of distribution behaviour. Wolves generally den along tree line (Kuyt 972; Fleck and Gunn 982; Heard and Williams 992). Caribou that have extensive space available north of tree line can space-away from tree line and aggregate at areas with the fewest predators and the least alternative prey to attract predators. These areas develop into calving grounds (fig. 2.3; Bergerud 996, 2000). The caribou leave these calving grounds after calving, thereby making it unattractive for predators with altricial young to den nearby. Caribou that live south of tree line disperse and remain sedentary at calving, inhabiting islands and lakeshores where they can use water to escape wolf predation; calving on large muskegs; or scattering high in alpine areas (fig. 2.2) (Bergerud et al. 984; Brown et al. 986; Bergerud 996, 2000). These calving females are more widely dispersed at calving than in any other season (figs. 2.4–2.6), thereby increasing the searching time for predators, especially if they have selected habitats less frequently used by alternative prey such as moose. We propose that the northern limit of the sedentary, dispersed ecotype in nonmountainous habitat is the availability of open water in small ponds that can be used for escape when predators are encountered. Radio-tracking studies of sedentary caribou that live in these areas indicate that such animals invariably calve on islands or in wet areas. This behaviour applies to woodland caribou in Alberta (Edmonds 988; James et al. 2004); Manitoba (Simkin 965; Shoesmith

TREE LINE TRUE MIGRATION

TREE LINE

SPRING

WINTER

SPRING

WINTER

km² / FEMALE

CALVING

RUT

RUT

CALVING

W

S

S

F

SEDENTARY ( DISPERSED )

W

S

S

F

MIGRATORY ( AGGREGATED )

Fig. 2.2 Caribou have evolved two major antipredator spacing strategies to reduce the predation risk for their newborn calves. The sedentary ecotype is concentrated in the winter on ranges below tree line with low snow cover. In the spring these females migrate to relative safe sites dispersed from other females and alternative prey – they space-out. The range of these herds is more dispersed in the spring than at any other season. The migratory ecotype generally winters below tree line, also on lichen pastures, often with the males segregated from the females and young. In the spring these females migrate to calving grounds north of tree line where the lakes are still frozen – they space away from tree line where there are more predators and alternative prey. These females are maximally massed at calving on habitats as far as possible from tree line, consistent with remaining where there is still some habitat without snow so that their brown neonates will remain cryptic, generally where snow cover is < 75%.

TREE LINE DATE OF LARGE LAKE OPEN WATER NORTHERN BOUNDARY OF 505 DISPERSED CALVING LOCATIONS NORTHERN BOUNDARY OF BOREAL ECOTYPE (EDMONDS 1991) TR

CARIBOU CALVING ON ISLANDS EE

CARIBOU GROUNDS IN TUNDRA

E L IN

15 PENN ISLAND

EE TR

L

UNE 15 J

IN E

NE JU

HARP LAKE

AY 15 M

1 JU

1 JU NE

15 M

NE

AY

FORMERLY 0

200

0

400 KILOMETRES 200

400 MILES

1 MAY

1 MAY 20 APR–7 MAY

29 APR–3 MAY

30–31 MAY 1983 28–30 MAY 1982

CALVING

MIGRATION

MIGRATION

CALVING

MIGRATION

1.4 1.2

CALVING 23–24 APR–4 MAY

1.6

1.0 0.8 0.6 0.4

MIGRATION

SQUARE KILOMETRES PER CARIBOU

2.0 1.8

29–30 MAY 1984

CALVING

AGGREGATE DUE TO DEEP SNOW

28–30 MAY 1982

0.2

0 MA MJ J A S O N D J F MA MJ J A S O N D J F MA MJ J A S O N D J F MA MJ J

1982

1983

1984

1985

50 KILOMETRES

100

WINTER CALVING B.C.

0

30 km

1982–83

1983–84

C 9

AREA OF DISPERSION (× 1,000 km²)

C = CALVING 8 1982–83

7

1983–84

C

6 5 4 3 2 1 0

D

J

F

M

A

M

J

J

A

S

O

N

MONTHS

Fig. 2.3 (facing page, above) Calving strategies of caribou. The sedentary ecotype generally calves as far north in Canada as the availability of open water at calving. Some females at the southern end of this distribution use islands and shorelines to reduce predation risk at calving. On the northern edge of their distribution the animals commonly calve on large muskegs where there is some open water in small ponds by 1 June, although the larger lakes may not be free of ice until later in June. The migratory ecotype spaces-away to calving grounds north of tree line. Fig. 2.4 (facing page, below) The females of the sedentary Red Wine herd in Labrador space-out in the spring and move to lowland muskeg to reduce risk at calving (data from Brown 1986). Fig. 2.5 (above) Females of the sedentary Spatsizi herd in the mountains of British Columbia space-out in the spring to high alpine habitats to reduce predation risk (data from Hatler 1986).

38 | TH E R E T U R N O F C A R I BO U TO U N G AVA ARMSTRONG AIRPORT RAILROAD

C

LAKE NIPIGON

C C GREAT LAKES

C C C

C C C

0

5

0

C

10 KILOMETRES 5

10 MILES

C

C

C C

C

CALVES PRESENT WINTER CALVING DISTRIBUTION MOOSE PRESENT

and Storey 977; Darby and Pruitt 984); Ontario (Bergerud 985; Cumming and Beange 987; Bergerud et al. 990); and in Quebec and Labrador (Brown and Theberge 985; Brown et al. 986; Hearn and Luttich 987). The calving locations of the dispersed ecotype in Ungava, documented through radio-telemetry, applies to animals living near Lac Bienville, Lac Caniapiscau, Lac Joseph, the Red Wine Mountains, and the Mealy Mountains (Brown et al. 986 and Hearn and Luttich 987). An east-west plot of 505 of these June locations showed that they paralleled the isohydric line of spring break-up of large water bodies (fig. 2.7). Further, the northern range limit of sedentary (woodland) caribou in North America follows the line of spring break-up of 5 June (figs 2.3 and 2.7). The caribou that space-out to calving grounds have only frozen lakes at calving and are not able to use water escape as an antipredator strategy. These ice-free dates shown in figure 2.3 and 2.7 apply to the large bodies of water – the smaller ponds and muskegs have open water one to three weeks earlier. In Ungava the Harp Lake calving ground was on a high plateau with lakes frozen at calving, whereas animals in the Red Wine herd only 30 km further south migrate from a winter range plateau to calve in the lowlands where there is open water  June (fig. 2.7).

DATE LAKES OPEN 1 JULY 15 JUNE MEAN TEMP 0°

MEAN TEMP 0° C MAY 1 C1

JUN E

MEAN TEMP 0° C JUNE 1 TREE LINE

LEAF RIVER CALVING GROUND 1991

UNGAVA BAY

UPPER UNGAVA TUNDRA

LY 1 JU

SETTLEMENT

MEAN TEMP 0° C 1 JUNE

HIGH DENSITY 1991 HIGH DENSITY 1984 & 1986 JUNE LOCATIONS OF SEDENTARY CARIBOU

1986

LABRADOR PENINSULA TUNDRA

1984

GEORGE RIVER CALVING GROUND

0

I NE

50

0

100 KILOMETRES 50

100 MILES

INE: RANGIFER ARCTICUS CIES L RANGIFER CARIBOU

LAC BIENVILLE HERD

HARP LAKE CALVING

15 J U

SPE MER FOR

NE

15

JU NE

L TREE

1 JULY

McPHADYEN HERD

CANIAPISCAU HERD

MEALY MT. HERD RED WINE HERD LAC JOSEPH HERD

MEAN

CLOSED CANOPY

TEMP 0

WHITE BEAR LAKE HERD EXTINCT

DOMINION / ST. AUGUSTIN

° C 1 MA Y

CLOSED CANOPY

Fig. 2.6 (facing page) The females of the sedentary Lake Nipigon herd in Ontario move to the islands in Lake Nipigon to space-out in the spring, therefore reducing predation risk by using water as a barrier to the movement of wolves (Bergerud et al. 1990). The larger islands in Lake Nipigon supported moose, hence wolves and caribou didn’t calve on these islands. Islands that supported caribou could be detected simply by visiting sand beaches and searching for tracks, since an additional tactic of these females, even on small islands, was to remain near the shore to further enhance their opportunities to escape to water safety. Fig. 2.7 (above) The distribution in Ungava of radio-collared caribou (mostly females) from several sedentary herds in June and the locations of the calving grounds of the three migratory herds in Ungava. Note the 15 June line of open water in large lakes, which is the northern boundary of calving for the sedentary herds and the former boundary between the earlier species classification of R. arcticus and R. caribou (Anderson 1938). The sedentary animals were once distributed across central Ungava in a continuous distribution. The animals are gone from the Hudson Bay coast and the Labrador coast, probably due to hunting, which became more effective in the 1960s with the advent of the skidoo. The large water impoundments developed for hydro-electrical power that affected the spacing-out options of females at calving are shown in blue. We can expect with global warming that these large impoundments will be free of ice earlier in June and provide water escapes for calving females and calves.

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An alternative hypothesis to our theory that females of the sedentary ecotype calve as far north as open water is available at calving is that preparturient females select areas of early phenology and green-up for calving, regardless of predator abundance. Such females should then be spaced in a west-east distribution parallel to the tree line. However, in Ungava this relationship does not coincide with observations of the caribou distribution. The tree line extends to 58° N south of Ungava Bay but the most northern calving of dispersed females is at 55°30' N near Lac Bienville (fig. 2.7). However, nothing new is discovered: Low recognized as early as 898 that both migratory and sedentary types existed in Ungava and that their ranges could overlap. Captain Cartwright – observing caribou on the offshore islands in southern Labrador – noted 4 August 779 that “When pursued in the summertime they [caribou] make for the nearest water, in which no land animal has the least chance with them” (Townsend 9, 279). The June locations of these dispersed caribou (n = 505) was consistent with the boundary between Caboti and caribou proposed by Anderson in 938 and listed by Harper in 96 (fig. 2.7). The distance between the northern edge of these dispersed calving females and the calving ground of the Leaf River migratory ecotype is 500 km, and in eastern Ungava the distance between the calving of the sedentary Red Wine herd and the migratory George River calving ground is about 300 km. The distance between the Red Wine calving locations and the former calving ground of migratory caribou at Harp Lake is 50 km. This zone between the calving of the sedentary herds and the migratory herds (50 to 500 km) is unsuitable for calving caribou for three reasons: () there is lack of open water about  June; (2) there are no mountains sufficiently rugged to allow the dispersed hiding strategy as in western Canada (Bergerud et al. 984; Seip 992); and (3) there is no extensive tundra where the animals might use the calvingground strategy of aggregating, swarming, and group watchfulness to minimize predation losses (Bergerud 974b). Migratory Herds Three migratory herds in Ungava are (or were) located in each of the three separate tundras of Ungava: the Leaf River herd using the tundra on the tip of the Peninsula north of the Leaf River (235,46 km²); the George River herd using the eastern tip of the Labrador Peninsula east of the George River (54,000 km²); and the Harp Lake herd (extinct in the 980s) utilizing a small tundra area (4,000 km²) adjacent to Harp Lake in Labrador (fig. 2.7). In the early 970s calving grounds were located on each discrete tundra and these three migratory herds were recognized and named for their prospective calving areas, as has been the custom since Don Thomas named the Northwest Territory migratory herds based on calving locations (Thomas 969). We have named the calving ground of the George River herd “Caribou House” in honour of Naskapi mythological beliefs that this is where the god, or Chief, of all the caribou lived.

Taxonomy, Ecotypes, Herds, and Morphology | 4

Two of the migratory herds showed remarkable growth during this study. The Leaf River herd had about 56,000 animals in June 975 and increased to over 276,000 animals by 99 and to 628,000 total animals by 200 (Couturier et al. 2004; Boulet et al. 2005). The George River herd increased from 5,000 animals in 958 to 600,000 (λ = .5) by 984 (Bergerud 967; Goudreault et al. 985; Messier et al. 988). Stephen Wetmore located the calving ground of the third migratory herd, Harp Lake, at 52° N, 62° W in 973 (Wetmore 974). There were 73 animals on the ground in June 975. By 979, only three females and their calves could be located there. Historically the Inuit of Hopedale knew of this calving concentration (Brice-Bennett 977, Map 46), and we believe it was eliminated by over-hunting. In the 950s and 960s there were considerable numbers of caribou 60 km inland from Makkovik and Postville in the winter. Hunters reported seeing 25 caribou at six locations in 955; 407 in 956; 403 in 957; and 407 in 958, observed at nine locations. These animals would neither have been the sedentary Red Wine herd (see maps in Brown 986) nor animals from the Mealy Mountains, since this herd did not cross Lake Melville in any numbers in these years (Bergerud 967). Hunters at Makkovik and Postville reported that wintering caribou became scarce behind their settlements after 968. This decline occurred simultaneously with the advent of skidoo hunting in the late 960s and 970s and the northward extension of moose (Mercer and Kitchen 968; Pilgrim 976; Phillips 983; Chubbs and Schaeffer 997). Pilgrim (98a) noted heavy harvests in 978 (00–50 females) and 979 (500). Wolves and bears would have increased with the increase in moose, reducing calf survival. We believe the Harp Lake herd went extinct because of over-hunting that was possibly augmented by increased natural mortality, and that these factors were the cause of the extinction of the sedentary herd that once lived near White Bear Lake (fig. 2.7). Morphology Why did early taxonomists using morphology rather than behaviour measurements divide the Ungava animals into two species – Caboti summering north of tree line and caribou residing south of the tundra areas? The antlers in the 970s of the George River herd (then classified Caboti) were much more massive than those of caribou (table 2.2), and in fact have the greatest spread of any caribou subspecies in North America (table 2.2; see also photo in Harper 96, plate 7). To carry such large antlers, the skulls of Caboti were the largest of any of the woodland subspecies measured by Banfield (96). The antlers of the George River males are also distinctive for the common absence of the rear tine (Banfield 96) and for the sharp angle in the backward sweep of the main beam. Generally, the brow and bez tines are set low on the main beam, perhaps to balance the weight of the backward sweep of the main beams. Sedentary caribou in Ungava and elsewhere have shorter beams, with reduced spread and a higher proportion of

42 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 2.2

Comparison of the size of record antlers of males between ecotypes

Measurements

Length of: Main Beam (cm) Inside Spread Circumference Length of Brow Width of Brow Total Points Total

Sedentary/Dispersed Mountain Woodland

1263.3 ± 18.6 1038.0 ± 12.8 1001.6 ± 26.1 837.9 ± 20.0 172.7 ± 2.2 145.4 ± 2.4 425.7 ± 8.3 406.6 ± 10.7 226.1 ± 8.7 315.8 ± 18.2 18.9 ± 0.6 17.0 ± 0.5 3108.3 2760.8

Alaska

Migratory/Aggregated Northwest George Territories River

1366.8 ± 18.0 1284.0 ± 12.3 1346.6 ± 17.0 1094.0 ± 20.4 904.2 ± 19.0 1192.8 ± 17.7 171.7 ± 3.0 136.2 ± 2.2 142.8 ± 2.0 469.3 ± 10.2 400.6 ± 9.7 426.4 ± 9.6 276.0 ± 9.3 260.6 ± 9.0 280.4 ± 10.4 20.6 ± 0.5 17.9 ± 0.5 19.9 ± 0.5 3398.4 3003.5 3408.9

¹ Measurements were taken from the 50 largest antlers in each group from the book Records of North American Big Game 993, published by the Boone and Crockett Club. ² Circumference, length, and width based on the mean of the right and left antlers. ³ Total points is the sum of the right and left antlers.

the mass in the brow and the bez, with these two points generally spaced further apart along the main beams (fig. 2.8, from Butler 986). Additionally the ratio of total length of antlers to total body length is greater for migratory caribou than for sedentary forest ecotypes and is not a function of body size (fig. 2.9, from Butler 986). Body size per se is not a satisfactory explanation for the differences in antler morphology of sedentary vs migratory ecotypes. Sedentary and migratory animals also differ in the shape of the main beam in cross section (Jacobi 93; Banfield 96). The main beams of migratory males are generally round or slightly oval and smooth in contour. Woodland or sedentary males often exhibit vertical ridges along the posterior and sometimes anterior edges of the main beam that enhance the compressed shape of oval beams, creating a diamond-shaped cross section in round beams. Butler (986) provided a comprehensive display-weapon hypothesis to explain the differences in antler evolution based on all the antler statistics available in the literature at that time (8 populations shown, fig. 2.9). She argued that antler size and point placement were a function of intrasexual selection (offensive/defensive tactics) during breeding and were not adequately explained by nutritional factors. In her model (fig. 2.0), aggregation size determines male encounter distances and male familiarization, which in turn affects visual assessment of potential competitors and the display value of antlers in intrasexual selection. Migratory animals fight more on their tops, whereas sedentary males contact more at their bez and brows (table 2.3) and occasionally lock antlers, which is less common in migratory animals. Animals that rut while migrating in large aggregations are predicted to have large antlers with more mass on the tops than do caribou that

TOP REAR BEZ

BROW

BURR

BURR

MIGRATORY

SEDENTARY

RATIO ANTLER LENGTH / BODY LENGTH

Fig. 2.8 A comparison of the general morphology of the antlers of the migratory ecotype (left) and the sedentary ecotype (right) from Butler (1986: fig. 11.2, 436). Antlers were drawn to scale from measured and photographed cast antler sets of large males from the migratory Delta herd in Alaska and the sedentary caribou on Brunette Island, Newfoundland.

0.7 GEORGE RIVER

0.6

8

19 10

13 15

5

0.5

14

17

18

12

4

11 7

0.4

GEORGE RIVER

0.3 0.2

16

17

22 21

3

23

9

2

3 20

10

16

8

13 15 14

4

2

12

9

7 24

0.1

1 11

MIGRATORY SEDENTARY REINDEER HIGH ARCTIC

6

3

1

0.0 160

170

180

190

200

210

220

230

240

250

TOTAL LENGTH (cm) Fig. 2.9 Antler length/body ratios compared with total length. The migratory ecotype has larger antlers in comparison to body size than the sedentary ecotype (adapted from Butler 1986, fig. 11.12, 490). Butler used the nomenclature of barren-ground and woodland rather than migratory and sedentary in her thesis. The names of the herds can be found in Butler (1986, 490).

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AGGREGATION SIZE

POPULATION SIZE

SEX RATIO

FEMALE AVAILABILITY

FIGHT EFFORT

MALE ENCOUNTER RATE

FIGHT FREQUENCY

OFFENSIVE-DEFENSIVE TACTICS

MALE ENCOUNTER DISTANCE

MALE FAMILIARITY

VISUAL ASSESSMENT

DISPLAY VALUE

HOLDS USED

DISTRIBUTION AND SIZE OF POINTS

ANTLER LENGTH AND BEZ PLACEMENT

Fig. 2.10 The model proposed by Butler (1986) for the evolved differences in antler morphology between woodland (sedentary) and barren-ground (migratory) ecotypes (Butler 1986, fig. 11.3, 438).

breed in small rutting companies where there is greater familiarity with other males, such as the Red Wine herd (Brown 986; Butler 986). Butler also discussed at length an alternative hypothesis to her displayweapons model that would explain the typical differences in antler mass and shape between migratory and sedentary caribou as a function of the temporal patterning of nutrient procurement by male cervids. In this alternative, cervids with the antler mass weighted proximally and having relatively short antlers are a product of environments with an early nutrient flush, in which nutrients become much less available during the middle and later stages of antler growth. Any differences in fighting may then be a function, rather than a cause, of weapon shape. The display-weapons hypothesis has a genetic basis, whereas the nutrient hypothesis is explained by phenotypic responses to the environment. To test the nutrient hypothesis, Butler measured the length of antlers collected at different locations in North America and estimated the growth rates of several popula-

Taxonomy, Ecotypes, Herds, and Morphology | 45

Table 2.3 The location of damage on large male antlers compared between populations (from Butler 1986) Ecotype and Location

No. of Antlers

Rear

Distribution of Breaks and Chips (%) Brows Bezes Tops Others

Sedentary/Woodland Slate Is. Ontario Brunette Is. Nfld.

18 22

9 (3)¹ (0)

12 (4) 22 (9)

50 (17) 48 (19)

23 (8) 28 (11)

6 (2) 2 (1)

Montane/Mountain Level Mountain, BC

29

(0)

6 (1)

25 (4)

69 (11)

(0)

Migratory/Barren Ground Delta, Alaska George River

12 26

3 (1) 3 (2)

19 (6) 18 (12)

29 (9) 35 (24)

48 (15) 44 (30)

(0) (0)

¹ The number of chips and breaks

tions in the field in order to compare growth patterns with plant phenology and plant quality. The observed growth rates were the reverse of that predicted from the nutrient model (table 2.4; fig. 2.). Butler tested her hypothesis of antler morphology based on intrasexual selection rather than nutrition by looking at the antler development of Peary caribou. Peary caribou live on the Arctic Islands in an environment of delayed spring phenology, a short growing season, and sparse vegetation. Additionally, these animals live in small groups and breed in small aggregations. The display-weapons hypothesis predicts that mature Peary males should not have undergone selection for increased distal mass and lengthening of the antlers. Instead these animals should have antlers similar to woodland sedentary caribou, with short, stout beams, proximally-oriented mass, and high bezes. Biologist Frank Miller collected antlers of Peary caribou in the High Arctic and provided Butler with measurements and photographs. These antlers were more similar to boreal sedentary caribou than to the migratory herds in the Northwest Territories (Butler 986). Also, Miller reported finding several sets of locked antlers – a characteristic of woodland caribou – implying that major antler contact between antagonists occurred on the low mass of the brows and bezes. Butler (986, 472) ended her discussion with the statement: “Another high Arctic population still stands to serve as disproof of the display-weapons hypothesis. Svalbard reindeer (R.t. platyrhynchus) breed in small rutting groups like woodland caribou (T. Skogland and N. Tyler, personal communication 985). If these caribou have long, thin beams, heavy tops and weakly-tined bezes set close to the brows (typical, barrenground antlers), they will cast strong doubt on the display weapon hypothesis.” Two years later Tyler (987) published his Svalbard Ph.D study and the large male

46 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 2.4 Latitude, antler form, and dates at which 50% of the main beam length of large males was obtained (from Butler 1986) Ecotype and Herd Name

Degrees Latitude

Antler Form¹

Growing Season

Dates Measured

% Antler Beam Length Grown

Estimate 50% Date

Sedentary/Woodland Brunette Is.

47

SHP

5 May

15–21 June

50 (8)

18 June

Sedentary/Montane Ecotype Spatsizi, BC

58

THD

25 May

8–14 June 15–21 June

41 (3) 57 (15)

– 15 June

Migratory Ecotype Western Arctic Fortymile Delta

67 64 64

tld tld tld

15 May 10 May 15 May

58

tld

5 June

52 (31) 55 (7) 34 (12) 55 (8) 49 (2)

8 June 25 May

George River

5–13 June 27 May 17 May 26 May 7–8 June

24 May 8 June

¹ Main beams: S = short, T = tall; bez placement: H = high, L = low; Mass placement: P = proximal, D = Distal

antler he shows (plate 3/C ) appears to be a dead-ringer for a woodland/sedentary antler. Antlers we collected from the George River herd during this study also represent a disproof of the nutrient hypothesis and suggest some genetic inflexibility. In the 970s the George River herd was 200,000 animals, and the summer range was not overgrazed; the herd was producing world-class antler trophies (Boone and Crockett 993). Antlers that we collected in 978 had long heavy beams with distal mass (table 2.5). Ten years later, when the herd reached 600,000+ animals, the summer range, especially the mid-summer deciduous shrubs, was overgrazed, whereas the early May/June grasses and sedges seemed far less impacted. The antlers in 988 were greatly reduced in mass but the bone losses appeared proportional between early proximal growth (brows and bezes etc) and later growth (beam length and tops in the summer, table 2.5). These findings supported Butler’s model of genetic programming and are not consistent with the summer-nutrition theory. In addition to the three migratory herds and the sedentary herds south of 55° N that we have mentioned, another herd lives in the Torngat Mountains north of the George River calving ground. To clarify this herd’s status as either sedentary or migratory we first had to discuss the hypotheses of antler morphology which relate to the migratory and sedentary ecotypes. Animals in this herd

Taxonomy, Ecotypes, Herds, and Morphology | 47

(A)

BARREN-GROUND 2

MAIN BEAM GROWTH PER DAY (cm)

Fig. 2.11 Predicted and observed growth curves of antlers of sedentary woodland caribou and migratory barrenground caribou from Butler (1986, 465). (a) This curve is a prediction of the growth of the antler main beam based on the nutrition hypothesis. (b) This growth curve was constructed from the dates by which 50% of the total length of antlers had been achieved and was based on the maximum growth-rates of antlers from the barrenground Delta herd (migratory) and the woodland Brunette Island herd (sedentary) (data from Butler 1986, fig. 11.5, 465).

PREDICTED

3

WOODLAND

1

0

(B)

OBSERVED

3

BARREN-GROUND WOODLAND 2

1

0

APRIL

MAY

JUNE

JULY

TIME

are of special interest because their dispersed behaviour is similar to sedentary caribou living south of 55° N, but their antler morphology is similar to that of the George River herd. Additionally, the environment these animals reside in is much harsher than that faced by either George River or southern sedentary animals. In this mountainous region north of the Koroc River, the large aggregations of the George River herd seldom trek (however they were common there in June 993) (Couturier et al. 996). Bélanger and Le Henaff (985) felt that these Torngat animals qualified as a separate herd from the George River, and estimated this “Koroc herd” at 5,000 animals in 985. However, their distinction of a separate herd may not be valid. Winter concentrations of these northern animals were located at 65° N, 59° W in January and February 974, 975, 977, and 978; and in April 976 and 980, in the interval when the George River herd was increasing its range west and passing Kuujjuaq in its expansion. However, as the George River herd increased and its wintering locations shifted northwest, it could as well have included these distributions – there were no radio-collared

48 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 2.5 A comparison of the size of the antlers of large males of the George River herd in 1978 (200,000 animals) and in 1986/1988 (600,000+) animals Antler Components

1978 or Earlier

Total Weight (kgs) 3.78 ± 0.30 (8) Total Length along Contour (cm) 124.1 ± 4.56 (15) Size of Brow Width x Length (cm) 957.3 ± 50.88 (9) Size of Bez Width x Length (cm) 1142.2 ± 97.80 (13) Diameter between Brow and Bez (cm) 16.1 ± 0.53 (16) Pedicel Size Width x Length (cm) 20.9 ± 1.48 (12) Points Brow Plus Bez 11.0 ± 1.19 (15) Points on Tops 6.7 ± 0.62 (15) Beam Length below Rear Points (%) 29.9 ± 0.83 (10)

1986 1988

% Difference

t Probability Value Difference

2.44 ± 0.13 (10)

-35

3.72

0.004

114.8 ± 3.18 (27)

-8

1.57

0.12

931.5 ± 110.60 (16)

-3

ns

905.58 ± 60.84 (29) -21

ns

2.05

< 0.05

12.8 ± 0.34 (22)

-21

5.24

< 0.001

17.0 ± 1.51 (10)

-19

1.84

0.11

7.4 ± 0.74 (22) 5.0 ± 0.33 (22)

-33 -25

ns 2.43

ns 0.07

32.9 ± 1.59 (11)

+10

ns

ns

All the antlers were measured by A.T. Bergerud and/or H.E. Butler

caribou in those years. In addition, caribou were in these mountains in October 983 (Bélanger and Le Henaff 985) and have been located at these high latitudes on several occasions by Luttich, who also located a calving concentration north of Saglek Fiord in 984 and 985 (although the animals calved elsewhere in 986 and 987). Historically there have also been consistent sightings of caribou in the Torngat Mountains, especially in the summer, even when the population of caribou in Labrador was low in the 940s and 950s (Harper 96). A winter census in 958 estimated 425 caribou wintering west of Okak Bay where animals tagged in the Torngats have wintered (Bergerud 958, 967). Hudson Bay trading records show residents of the former Burwell settlement successfully harvesting animals in the 920s and 930s (Luttich 983). Even earlier, Elton (942) talked about calving caribou south of Cape Chidley. The type specimen for Rangifer arcticus Caboti was based on an antler collected at Nachvak Fiord in the Torngats 24 March 94 (Allen 94). The antler had the long kinked beam and high mass of the type of George River animals. To test the discrete herd hypothesis, Luttich placed radio collars on four calving cows north of Saglek in June 986. Three of these females were found with the George River herd in the following rutting and winter season, but two continued

Taxonomy, Ecotypes, Herds, and Morphology | 49

to calve north of Saglek while the other two calved with George River animals at Caribou House. To further clarify distributions and fidelity, Luttich and Schaefer placed six satellite collars on females believed to be Torngat animals based on their northern calving locations 988–97 (Schaefer and Luttich 998). The six females were observed for an average of 2.6 years and all the sightings in June except one were in the Torngats. However, as with the VHF radio monitoring, several of the females moved outside the Torngats in the rutting and winter seasons (Schaefer and Luttich 998). Several of these females’ calves dispersed, but unlike sedentary animals in central Ungava, they did not show philopatry to previous calving locations; variable snow cover may have been a problem (see Brown et al. 986). If the animals in the Torngat Mountains represent a discrete gene pool, one would expect them to have evolved a unique morphology to adapt to the harsh Torngat environment. For example, the caribou in the Red Wine herd 30 km south of the George River herd are considerably larger in size than George animals (table 2.6; Brown 986), and have antlers of the sedentary ecotype. The body size of caribou decreases with latitude (Geist 998) and is positively correlated with the length of the growing season (fig. 2.2). For example, the Red Wine herd resides where the growing season is 20 days longer than the George River and females are perhaps 5 cm greater in total length than George females. The growing season in the Torngat Mountains is brief, 4–72 days (fig. .5), whereas the season for the George River herd is approximately 82–04 days. The predicted total length of Torngat animals if genetically discrete should be smaller than George animals: 80 cm for males and 63 cm for females (fig. 2.2). However, extensive measurements of animals believed to be Torngat stock showed no statistical differences in the body sizes of either males or females (table 2.6). Additionally, the animals in the Torngats have reduced activity and mobility compared to George animals (Bergerud 2000; Schaefer et al. 2000), and they rutted in small aggregations. According to the weapons-display hypothesis (fig. 2.0) Torngat males if genetically separated should display antler lengths and beam spreads smaller than George males. To the contrary, antler sizes of Torngat and George River animals were similar in size. Both have the characteristic, long, rounded beams with the unique inverted J or question-mark sweep; low placement of brow and bez tines; and frequently the absence or reduction of the rear tine. These features identify the unique antler morphology of Caboti (Banfield 96; see also plates of large males, plates 20, 24, 25). Three world-class trophies killed at Abloviak Fiord (65° W, 59°5' N) had antlers of the same form and mass as George males (Boone and Crocket 993). These data do not support a hypothesis of long-term genetic isolation of Torngat animals from George River stock. What remains is that when animals move into the mountains they commonly reduce travel rates and aggregating tendencies and also show considerable affinity for remaining in this rugged alpine habitat for long periods of time. The

50 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 2.6 Comparison of the size of caribou of the George River herd with animals measured in the Torngat Mountains (all males biased to large animals) and the sedentary Red Wine herd Sex and Measurements (cm)

Adult Males Shoulder Height (withers) Shoulder Height (shoulder) Head Length Head Width Total Length (contour) Total Length (straight) Weight (kg) Mandible Length (mm) Widest Spread (inside) Widest Spread (outside) Longest Brow Widest Brow Total Points Brows Total Points Bezes Total Points Main Beams Adult Females (March/April) March Weight (kg) Shoulder Height (withers) Shoulder Height (shoulder) Head Length Head Width Total Length (contour) Total Length (straight) Heart Girth (over hump)

Red Wine Herd

George River

133.3 ± 2.87 (6) 124.3 ± 5.10 (6) 44.4 ± 0.96 (4) 20.3 ± 0.78 (4) 229.2 ± 3.96 (6)

126.9 ± 1.12 (10) 121.4 ± 1.56 (8) 44.0 ± 0.96 (17) 17.4 ± 0.27 (17) 208.3 ± 6.84 (3) 192.7 ± 5.78 (3) 159.0 ± 8.89 (4) 317.1 ± 393 (9) 93.0 ± 4.99 (10) 107.0 ± 8.09 (5) 33.5 ± 2.26 (16) 31.3 ± 1.61 (15) 8.7 ± 0.90 (9) 11.2 ± 2.14 (10) 11.8 ± 1.02 (10)

127.0 ± 0.41 (13) 119.9 ± 1.95 (12) 42.6 ± 0.36 (14) 18.3 ± 0.31 (14) 207.6 ± 2.44 (11) 190.6 ± 190 (11) 158.9 ± 7.92 (8) 319.0 ± 8.38 (11) 95.0 ± 5.85 (11) 108.2 ± 5.52 (11) 33.3 ± 2.60 (8) 30.3 ± 2.52 (8) 6.2 ± 1.17 (11) 10.5 ± 1.40 (11) 8.3 ± 0.36 (14)

97.3 ± 1.06 (91) 113.2 ± 0.67 (53) 108.3 ± 0.67 (53) 39.2 ± 0.44 (60) 14.8 ± 0.15 (60) 190.0 ± 1.14 (50) 174.0 ± 0.92 (50) 115.4 ± 0.21 (69)

109.7 ± 2.20 (5) 113.6 ± 0.55 (7) 106.0 ± 0.61 (7) 35.7 ± 2.12 (7) 16.1 ± 0.79 (7) 185.9 ± 1.99 (5) 173.7 ± 3.61 (6)

156.3 ± 6.58 53.3 (1) large M 39.1 (1) large M 35.6 (1) large M 6 (1) large M 11 (1) large M 14 (1) large M 124.6 ± 2.89 (26) 122.0 ± 0.90 (26) 114.9 ± 1.12 (26) 40.7 ± 0.74 (26) 17.3 ± 0.26 (26) 196.9 ± 2.15 (26) 128.0 ± 1.57 (26)

Torngat Animals

The Red Wine animals were measured by W.K. Brown (986) and all the Torngat and George River antlers by S. Luttich

advantages of this strategy could include greater insect relief, less forage competition, and reduced energy expenditures in travelling. The animals in the Torngat did have reduced activity and mobility (fig. 2.3), but when these animals left the Torngats they immediately increased their pace to accommodate the large George River aggregations they joined. Furthermore, when they returned to the more diverse mountains, they had reduced mobility and aggregating and there were pulses in their activity not explained by the reduced travelling rates (fig. 2.3). These responses would then be adaptive to more local conditions, such as a shorter growing season and more patchy snow conditions in the mountains. In Alaska two caribou herds that live in the Alaska

230 RED WINE

220

MEALY MOUNTAINS

210

GEORGE RIVER MEALY MT.

( ) MALES

200

82640 518.84  X r2 = 0.779

TOTAL LENGTH (cm)

Y=

n = 22

RED WINE

190

GEORGE RIVER

( ) FEMALES

180

Y=

72949.13 506.16  X

r2 = 0.784 n = 24 170

160

150

140 0

20

40

60

80

100

120

140

160

180

200

LENGTH OF GROWING SEASON (DAYS)

Fig. 2.12 The body size of caribou increases in correspondence with the length of the growing season. There is also a significant relationship between total body length and the starting date of the growing season: where Y = the total mean body length (cm) of males plus females divided by 2, and X = the Julian date of the start of the growing season (Y = 5.798Xe-0.01X , r 2 = 0.949, n= 18 populations)

ACTIVE HOURS PER DAY km TRAVELLED/DAY

2 INCREASED ACTIVITY NOT EXPLAINED BY MOBILITY SPEEDS

1

ACTIVE HOURS PER DAY

0 8

GEORGE RIVER CARIBOU (1986–92)

7

TORNGAT MOUNTAIN CARIBOU (1988–92)

6 5 4 3 2 1

KILOMETRES TRAVELED PER DAY

0 25 SEPTEMBER PAUSE

20 15

BREEDING PAUSE MAY PAUSE

JUNE PAUSE WINTER PAUSE

10 5 0

J

J

A

S

O

N D DATE

J

F

M

A

M

Fig. 2.13 A comparison of travel speeds and the long-term activity index of UHF satellite females when in the Torngat Mountains compared with those of satellite females monitored south of the Torngat Mountains. The radio telemetry methods are described in Schaefer and Luttich (1998).

Taxonomy, Ecotypes, Herds, and Morphology | 53

central mountain range – the Delta and Denali – have both rugged mountain topography and flat plateaus within their ranges and both dispersed and aggregated calving have been documented for both herds (Adams et al. 995a; Davis et al. 986). At one time, the Delta herd was separated into two separate herds (the Delta and Yanert herds), but radio tracking, similar to what we have done in the Torngats, showed an exchange of animals and the Yanert distinction was dropped. Such calving variability is not sufficient evidence of a distinct gene pool. In the absence of more sophisticated confirmation of genetic discreteness, these animals would still qualify as a discrete population in a management sense if there were changes in population size resulting from local recruitment and mortality schedules. These comparisons have not been made. Finally, we would agree that Banfield (96) was correct in combining the skull measurements from eastern North America into a single subspecies, R.t.caribou, that resulted from their progenitors being isolated for millenniums from other Pleistocene populations in their periglacial refugium south of the ice sheet (chapter 3). These animals then invaded the habitat in Ungava left vacant by the demise of the ice sheet. Still, Anderson (938) and Harper (96) were also correct: The caribou of north and south Ungava are distinct morphologically in antler configuration and body size. Each group has developed physical attributes that correspond to the two contrasting environments, coniferous forests and tundra. Sedentary animals are larger but have smaller antlers than migratory animals; they can probably cope with deeper snows. The lighter body colour and more visible antlers of the migratory type facilitate aggregating and breeding behaviour. There were two distinct habitat options available for colonizing Ungava, boreal forest and arctic tundra, and this resulted in two distinct ecotypes, each the result of different selection pressures within their respective environs.

CHAPTER THREE

The Return of Caribou to Ungava after the Last Ice Age

Postglacial Dispersal and Ecotypes The earliest records of Rangifer are based on fossils about .3 to .8 million years old recovered from Fort Selkirk, Yukon, and from the Cape Deceit fauna in Alaska (Guthrie and Matthews 97; Harington 999a). The consensus is that caribou evolved in northwestern North America (Eastern Beringia) and then spread to Asia during glaciations when land connections to Asia existed (Banfield 96; Harington 978; Kurtén and Anderson 980). Hence caribou have persisted through the Nebraskan, Kansan, Illinoian, and Wisconsinan glaciations and the Aftonian, Yarmouthian, and Sangamonian interglacials, when dozens of other mammal species went extinct. Kurtén and Anderson (980) list 87 species that went extinct in the Pleistocene and 229 that survived to the present in North America. The major adaptation of caribou for withstanding Pleistocene climatic extremes would have been its catholic food habits, ranging from primitive lichens and bryophytes to the more advanced deciduous spermatophytes. They also had the physiological and morphological adaptations for withstanding temperature extremes ranging from -60°C in the polar deserts of the High Arctic to 33°C (44°C in the sun), a temperature we recorded while watching George River caribou at the Tunulic River 23 June 989. During the last Sangamonian interglacial, caribou would have ranged across northern North America and Greenland. Fossils have been recovered from Sixtymile Basin, Yukon, 45,420 bp and Noatak Basin, Alaska, 52,500 bp (Harington 978, 999a, 2003); Greenland, 40,000 bp (Meldgaard 99); Toronto, Ontario, 46,000 bp (Hay 923; Harington 978); the Riviere du Loup, Quebec, 40,630 bp

The Return of Caribou to Ungava after the Last Ice Age | 55

(Harington 999b); and the Medicine Hat Fauna, Alberta, 00,000 bp (Churcher 984). Caribou never ranged as far south as New Mexico in the Pleistocene. The Burnet Cave specimen (N.M.) judged to be caribou by Banfield (96) and still quoted as caribou (see Courtois et al. 2003) was the Mountain Deer (Navahoceros fricki) (Kurtén 975). During the last ice age, the Laurentide Ice Sheet commenced forming in the centre of the current range of the George River herd in central Ungava about 70,000 years ago (Flint 97; Hays et al. 976) and expanded in all directions until it joined the Foxe-Baffin sector to the north, the Hudson Bay sheet to the west, and extended south over the Great Lakes region by 8,000 bp (Prest and Vincent, plate , 987). The maximum extent of the ice sheet along the Labrador coast 20,000–8,000 bp is still the subject of research. Some of the older glacial maps show the entire coast covered with ice (Prest 970; Fremlin 974). More recent research has indicated that there were nunataks in the Torngat Mountains during the Wisconsinan glaciation (Ives et al. 976; Ives 978; Clark et al. 989) and a coastal refugium (Prest and Vincent 987; review Pielou 99). Also a portion of the continental shelf (the Cartwright Saddle) was unglaciated to an age of 2,000 bp (Vilks and Mudie 978). There was also a nunatak in the Shickshock Mountains (Pielou 99), and a caribou fossil was found nearby at the Rivière du Loup aged 40,640 bp (Harington 999b). The eastward extent of the Laurentide ice sheet at 0,000 bp was debated (review Ives 978). Clark and Fitzhugh (990) believe the ice did not recede from the Hopedale section of the Labrador coast until 7,600 ± 200 years bp and from Nain until 8,500 ± 200 years bp, whereas earlier workers (Ives 978) felt that the ice had retracted well inland by 0,000 bp. The Faunmap (994) is the encyclopaedia of the mammalian fossil record for the lower 48 states (40,000 to 500 bp) and involved three compilers and 4 palaeobiologist collaborators. Their maps of the retreat of the Laurentide Ice Sheet show the Labrador coast covered at 8,000 bp ; however, nunataks may have persisted. By 0,000 bp the coast was free of ice. The pollen diagram of Short and Nichols (977) at Ublik Pond in the Torngats shows that following an initial vegetative phase of Gramineae and Cyperaceae, dwarf birch increased markedly at 9,000 bp (fig. .8). There is no evidence to date that caribou persisted during the Wisconsinan maximum on nunataks or any coastal refugia, although implied by Fitzhugh (979). People of the Maritime Archaic culture were as far north as Nain at 7,000 bp and were inland and hunting caribou (see Loring, page 34, this volume). The climate on the Torngat nunatak was harsh (Johnson 969; Clark et al. 989) and, at most, consisted of grasses and herbs. No plant species have been suggested as having originated from possible refugia, unlike findings from nunataks in western Canada (Pielou 99). Furthermore, Harington (999b) has reported 32 radiocarbon dates from the Quaternary vertebrates from Quebec, including marine mammals and terrestrial fauna from two caves on the Gaspé Penin-

56 | TH E R E T U R N O F C A R I BO U TO U N G AVA

sula. The dates of all these fossils postdate the Wisconsinan maximum at 8,000 BP except the Rivière-du-Loup caribou (40,640 bp) which was found between moraines (Harington 999a) and at the southern edge of the ice based on the glacial map at 40,000 bp shown in Delcourt and Delcourt (98). We believe the only viable refugium for the Ungava caribou during the Wisconsinan about 8,000 BP was south of the ice sheet (Banfield 96; Kurtén and Anderson 980; Harington 978; Churcher et al. 989). Caribou are now considered a subarctic/arctic species and many workers have concluded that the caribou fossils found south of the ice were the barren-ground race (see Storck 2004), assumed to have occupied the tundra strip immediately south of the Laurentine Ice Sheet. Banfield (96, 34) said, “We may conclude that at the height of the Wisconsin glaciations reindeer were distributed in a tundra belt across the south of the ice sheet.” He also noted they might frequent taiga habitats in the winter. Ever since European contact, explorers and biologists have remarked upon the spring migration of caribou to the arctic tundra to calve and their return journey in the fall to forage on lichens in the taiga. However, contrary to the view that caribou were common in the tundra zone south of the ice, all seven caribou of the fossils aged > 20,500 to 6,500 BP were found in situ in caves in the Appalachian Mountains several hundred kilometres south of the ice sheet (tables 3., 3.2). Older fossils were also found in these mountains, one aged 27,900 bp in New Bern, North Carolina, and three at New Trout Cave, West Virginia, aged 28,250–7,060 bp. The oldest fossil (> 36,830 bp) was not found in situ but on an ocean beach (table 3.). Based on the fossils in three caves in Sullivan County, Tennessee, the caribou were in this area for at least 20,000 years. One fossil dated at Baker Bluff Cave was 9,00 years old and another fossil in that cave indicated the caribou had died only 555 years ago. Nearby Beartown Cave yielded a fossil 20,000 years of age (Guilday et al. 975; Faunmap 994). Guilday et al. (975, ) stated that “caribou ranged far to the south of the continental glacial margin in North America during at least Wisconsinan times,” adding that “the likelihood of vertebrate fossils of any type from the higher altitudes of the Great Smokies is remote due to the lack of caves or bog sites.” Yet seven of the fossils were located in the mountains adjacent to alpine tundra habitats (fig. 3.; table 3.2). These same authors noted that fossils had yet to be found in caves at low elevations. Of the 42 dated caribou fossils from 2 locations dated 20,500 to 8,500 bp that were south of the ice sheet, at most only one animal may have died near the tundra strip juxtaposition to the ice sheet; most locations were 300–800 km south of the tundra zone in that period (fig. 3.). The tundra zone is based on maps in Delcourt and Delcourt (98) and pollen and sediment cores reviewed in Ritchie (987). Undoubtedly there are biases in terms of where palaeobotanists and palaeobiologists searched for pollen and fossils; however, as of 980, researchers had reported the fossil remains of 2 muskox Ovibos moschatus fossils south of

The Return of Caribou to Ungava after the Last Ice Age | 57

Table 3.1

A list of Rangifer fossils in eastern North America

Faunmap No

Age of Fossil (number)

Locality

References

Postglacial Postglacial Postglacial Post Pleistocene Post Wisconsin Post Wisconsin Late Wisconsin Late Wisconsin Late Wisconsin Late Wisconsin Late Glacial Late Glacial Late Glacial Wisconsin Early Holocene Early Holocene Late Pleistocene Late Pleistocene Late Pleistocene Late Pleistocene Late Pleistocene Paleo-Indian Paleo-Indian Late Holocene Late Holocene Late Holocene

La Redemption, Quebec Mansfield, Richland Co., Ohio Ossining, Westchester Co., NY Trenton, Mercer Co., New Jersey Muscatine, Muscatine Co., Wis. Castalia Marsh, Erie Co., Ohio Crosby, Crow Wing Co., Minn. Wauwatosa, Milwaukee, Co. Wis. Minden City, Sanilac Co., Mich. Zelienka, Wauwatosa Co., Wis. Humber River, Toronto, Ontario Osstburg, Lake Michigan, Wis. Flanders Site, Oakland Co, Mich. Avon, Polk Co., Iowa Harmann’s Cave, Monroe Co., Pa. Prairie Creek, Davis Co., In. Correctionville, Woodbury Co., Ia. Bass Lake, Starke Co., Indiana Delta, Eaton Co., Michigan New Haven, Connecticut Woodbury, Washington Co., Vt. Shoop Site, Pennsylvania Belmont, Nova Scotia Indian Point, Isle Royale, Mich. McKinstry, Koochiching Co., Minn. White Oaks Mound, Itasca Co., Minn.

Harington 1980 Guilday 1966 Hay 1923* Hay 1923* Hay 1924* Guilday 1966 Hay 1924* West 1978 Burt 1942 Long 1986* Coleman 1933* West 1978 Holman et al. 1986 Hay 1924* Hay 1923* Churcher et al. 1989 Hay 1924* Richards 1984* Holman et al. 1986 Hay 1923* Hay 1923* Hyland et al. 1990 Davis 1991 Cleland 1968* Lukens 1963* Lukens 1963*

Juntunen, Michigan Duxbury, Plymouth Co., Mass. NW of Ivujivik, Quebec Rattlers Bight, Hamilton Inlet, Lab. Port aux Choix, Newfoundland Schenectedy Co., NY Auger Site, Simcoe Co., Ontario St. Elzear de Bonaventure, Que. Nulliak, Labrador Genessee Co., Michigan l’Anse Amour, Labrador Cummins, Thunder Bay, Ontario Holcombe Site, Macomb Co., Mi. Steep Rock, Atikokan, Ontario Lapee Co., Michigan Udora, Ontario

Faunmap 1994 Guilday 1968 Harington 2003 Spiess 1993 Tuck 1976 Fisher/Ostrom 1952* Savage 1981* LaSalle 1984 Fitzhugh 1979 Crane 1956* McGhee/Tuck 1975 Jackson 1989 Cleland 1965 Jackson 1989 Mikula 1964* Storck & Spiess 1994

2187 2237 2188 2049

995 2363 2130

Aged Fossils 111 1,125–630 (4) 814 ~2,000 2,520 3,800 4,000–3,500 4,500 4,950 5,000 5,000 5,870 7,530¹ 8,500 2191 9,200 9,940 10,000–6,000 10,500

58 | TH E R E T U R N O F C A R I BO U TO U N G AVA Faunmap No

Age of Fossil (number)

Locality

2137

12,530–10,580

Duchess Quarry, Orange Co., NY

2192 2190

10,600 11,050–9,550 (3) 10,680 10,750 10,800

2125

11,000

808 2235 2178 336 2273 71

11,080–3,722 (3) 11,185–1,350 (8) 11,700 11,300 11,390–250 (21) 11,820 12,000–11,000 12,000–11,000 12,420

548 972 2133 2205 65

32 2136 2252

12,050 13,460 14,315 14,545–13,220 (6) 14,650–6,090 (2) 18,610 19,100–555 (4) 19,700 27,900 28,250–17,060 (3) > 36,830

References

Funk et al. 1969, 1970* Debert, Nova Scotia MacDonald 1968² Spiess et al. 1985 Whipple Creek Cheshire Co., NY Bull Brook, Ipswich Co., Mass. Grimes et al. 1984* Sandy Ridge, Udora Co., Ontario Storck & Spiess 1994 LaFleche Cave, Gatineau, Quebec P. Youngman (unpubl) Hollidaysburg Fissure, Pa. Fonda/Czebieniak 1986 Bootlegger Sink, York Co., Pa. Guilday et al. 1966 Kolarik, Starke Co., Indiana Ellis 1982* Sheriden Pit, Wyandotte Co., Ohio Hansen 1992 New Paris Cave, Bedford Co., Penn. Guilday et al. 1964* Steadman 1988* Hiscock, Genessee Co., NY Bell Cave, Colbert Co., Alabama Churcher et al. 1989 Little Egg Inlet, New Jersey Roberts 1990 Beach Haven, New Jersey Roberts 1990 Brayton, Audubon Co., Iowa Semken and Falk 1987 Eggleston Fissure, Virginia Corgan 1976* Saltville, Smyth Co., Virginia Ray et al. 1967³* Yarborough Cave, Bartow Co., Ga. Martin/Sneed 1989 Christensen Bog, Hancock Co., In. Graham et al. 1983 Darty Cave, Scott Co., Virginia Eshelman/Grady 1986* Yarborough Cave, Bartow Co., Ga. Martin & Sneed 1989 Baker Bluff Cave, Sullivan Co., Tenn. Guilday et al. 1978 Guy Wilson Cave, Sullivan Co., Tenn. Guilday et al. 1975 Guilday et al. 1975 New Bern, Craven Co., NC New Trout Cave, Pendleton Co., W. Vig. Grady & Garton 1982 McDonald et al. Virginia/NC Border/Beach 1996⁴

* References never seen by author; a number of references only from Faunmap (994). ¹ The Faunmap data base shows no caribou fossils in the eastern United States for the early Holocene (0,000–8,000 BP) or the Middle Holocene (8,000–4,000 BP). The most complete set of fossils (2) was from Hiscock, New York, but they spanned two different periods: ,390 to 8,20 BP (4) and 950 to 250 (7). Caribou spread into Canada ,000 to 0,000 BP (see fig. 3.4) and the population south of the border must have become rare for no fossils were reported in 44 sites in the range they occupied. Fossils again appeared in the Late Holocene (4,000–500 BP) in Minn., Mich., Ma., NY, and In. (Faunmap 994). ² A caribou fossil has not been found at Debert, caribou based on Indian presence. ³ Saltville also researched by other authors, and had a very wide range of megafauna species. ⁴ Fossils on beaches and not in situ and thus no support for McDonald’s et al. (996) claim that caribou were in the lowlands during glacial times and not restricted to the Appalachians.

The Return of Caribou to Ungava after the Last Ice Age | 59

Table 3.2 The locations of dated caribou fossils in the Pleistocene in eastern North America compared between forest types existing at that time Time Period and Forest Type

20,500 to 16,500 BP Appalachian Mts. Tundra Open Spruce (Taiga) Spruce and Jack Pine Jack Pine and Spruce Mixed Conifer and Hardwood Total 16,500 to 12,500 BP Appalachian Mts. Tundra Open Spruce (Taiga) Spruce and Jack Pine Jack Pine and Spruce Mixed Conifer and Hardwood Total 12,500 to 8,500 BP Appalachian Mts Tundra Open Spruce (Taiga) Spruce and Jack Pine Jack Pine and Spruce Mixed Conifer and Hardwood Total

Size of Area (1,000s km²)¹

Number of Fossil Locations Observed (No. of Ages) Expected

150k 340k 105k 530k 560k 55k

5 (7) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0)

0.43 0.98 0.30 1.52 1.61 0.16

1740k

5 (7)

5.00

150k 340k 565k 900k 345k 110k

3 (3) 0 (0) 2 (6) 0 (0) 0 (0) 0 (0)

0.31 0.70 1.17 1.87 0.72 0.23

2410k

5 (9)

5.00

150k 110k 265k 415k 330k 425k

4 (6) 1 (1) 4 (5) 2 (4) 5 (16) 5 (10)

1.86 1.36 3.28 5.14 4.09 5.27

1695k

21 (42)

21.00

¹ The distributions and areas of the forest types based on Delcourt and Delcourt (98), figures 5, 6, and 7, and include the region from the Atlantic Coast west to 98 degrees west longitude, north to the Laurentide Ice Sheet and Gaspé and south to the southern boundary of the Mixed Conifer and Northern Hardwood type. The Appalachian Mountains encompasses the area classified as Oak-Chestnut at 5,000 and 200 BP in Delcourt and Delcourt (98), figures 8 and 9. The area of the Appalachians subtracted from the other forest types located there at 8,000, 4,000, and 0,000 yrs.

the ice (Kurtén and Anderson 980), and presumably these fossils were located in former tundra habitats (Latin nomenclature follows Faunmap 994). To further test the hypothesis that caribou may have been rare in periglacial tundra 20,000 to 2,500 bp, we calculated recolonization travel rates as the ice retreated on the premise the colonizers originated just south of the ice sheet. We measured the distance from the edge of the ice 8,000 and 4,000 bp to

ICE SHEET

ICE SHEET

TUNDRA 14.5 28.2 to 17.1

JACK PINE SPRUCE

SPRUCE JACK PINE

JACK PINE SPRUCE

SPRUCE JACK PINE

13.4

20.0

OPEN SPRUCE

14.6

18.6

26.4 to 11.8

18,000 YR BP

n ICE SHEET

MIX

ED C

14,000 YR BP

n = 12

18.6

SPRUCE JACK PINE

14.3

n = 27

CARIBOU FOSSIL FOSSIL AT 18,600 BP NUMBER OF POLLEN SITES SPRUCE JACK PINE

OPEN SPRUCE

MIXED CONIFER HARDWOOD

JACK PINE SPRUCE

ONIF ER HARDWOOD

MIXED HARDWOOD

12.0

10,000 YR BP

n = 77

H

AVA N

10.6

OAK S

OPEN SPRUCE

OAK HICKORY SOUTHERN PINE

12.5

NA

OAK HICKORY

OAK CHESTNUT

GRASSLAND

SOUTHERN PINE

5,000 YR BP

n = 78

Fig. 3.1 These former distributions of caribou at 18,000 to 5,000 BP are based on fossil locations in various forest biotypes existing at that time (forest types from Delcourt and Delcourt 1981). Note that caribou were inhabiting the northern hardwoods/conifer community at 5,000 BP and white-tail deer were also present (Faunmap 1994). During the contemporary period deer have passed a fatal brain worm disease to caribou (Bergerud and Mercer 1989).

The Return of Caribou to Ungava after the Last Ice Age | 6

dated fossil sites generally located 2,000 to 0,000 bp, and calculated the possible rate of range extensions per year (m/yr). These theoretical advances were extremely low, averaging 38.8 ± 0.7 m/yr (n = ) from the ice’s edge at 8,000 bp and 54.6 m/yr measured from the ice 4,000 bp (n = 7). These rates of advance would not have kept the caribou abreast of the retreating tundra and ice sheet. The retreat of the ice sheet north was: from about 8,000 to 4,000 bp, 300 to 400 m/yr, 4,000 to 2,000 bp, 50 m/yr, and 2,000 to 0,000 bp, 200 m/yr. Also, the theoretical rates of colonization were less than the known minimum range extensions 0,000 to 5,000 bp measured between known fossil sites that generally averaged 200–400 m/yr, similar to the rate of retreat of the ice and the advance of higher plants such as spruce (Ritchie and MacDonald 986). If we assume that the caribou were not inhabiting the tundra initially but rather started their recolonization north from the mid-Appalachian mountains after the Pleistocene megafauna became rare and disappeared about 3,000–0,000 bp, then the rate of range extension necessary for reaching the ranges occupied ,000–0,000 bp in southern Ontario (fig. 3.) would have been 200–300 m/yr, similar to the rates of ice amelioration, plant recolonization and caribou dispersal north from 0,000 to 5,000 bp. We hypothesize that the tundra mosaic south of the ice and the adjoining taiga were seldom occupied by caribou during the Wisconsinan maximum. The tundra strip was narrow, only 60–00 km wide (Delcourt and Delcourt 98), and insufficient to space-away from the many Pleistocene herbivores and their predators. There were mammoths (Mammuthus spp.), mastodons (Mammut americanum), stag-elk (Cervalces scotti) and Harlan’s muskox (Bootherium bombifrons) in abundance in the forested lowlands north and east of the Appalachian mountains (table 3.3). The mastodon was one of the most abundant mammals of the Rancholabrean Land Mammal Age and it inhabited open spruce forest just south of the tundra and was especially abundant in the level terrain south of the Great Lakes. Predators were also abundant then. There were dire and timber wolves (Canis dirus) and (C. lupus); four species of bears; six species of cats; and others. In Eastern Beringia during the Pleistocene, Guthrie (968) estimated one wolf per 30 ungulates and one lion per 250 ungulates. But many of the large prey species adapted to the Mammoth Steppe in his calculations were rare in the forests of eastern North America about 8,000 bp. Abundant mammoths and mastodons were massive and predators likely selected the smaller young and feeble old (Kurtén and Anderson 980; Harington personal communication); the relatively small-bodied caribou may have faced heavy predation pressures when on the lowlands and the tundra belt. On the tundra there was the added problem of the less vulnerable muskox (Ovibos moschatus), which probably attracted predators to the open habitats. We believe that the main concentration of caribou prior to 3,000 bp was in the Appalachians and that they used a montane strategy of altitude migrations

62 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 3.3 The percentage of megafauna fossil sites in north-eastern North America (area from Missouri and Appalachian Mts. north to Canada) that also contained caribou fossils and the percentage of the megafauna sites in the lower 48 states that were in the Appalachian Mountains¹ Megafauna Species Fossil Sites

% Sites in NE That Also Had Caribou

% Mega Sites (Lower 48 states) in Appalachian Mts.²

Harlan’s Muskox (Bootherium bombifrons)

3.4 (59)

2.9 (102)³

Stag Moose (Cervalces scotti)

11.7 (34)

5.7 (35)

American Mastodon (Mammut americanum)

3.5 (145)

3.4 (206)

Jefferson’s + Wooly Mammoth (Mammuthus jeffersonii + Mammuthus primigenius)

2.5 (80)

1.2 (82)

Long-nosed Peccary (Mylohyus spp.)

10.0 (20)

26.0 (46)

Flat-headed Peccary (Platygonus compressus)

13.8 (29)

11.7 (60)

Tapirs (Tapius spp.)

22.2 (18)

19.6 (56)

¹ All frequencies based on data in the Faunmap (994); nomenclature in this chapter and table based on Faunmap (994). ² Tallies from the All Time Periods Maps in (Faunmap 994). ³ For caribou the percentage is 32, at 25 sites, but only eastern NA .

to avoid mammalian diversity at lower elevations (tables 3.–3.3). Also they may have been rare, hiding spaced-out in mountains as present montane females do at calving (Bergerud et al. 984; Hatler 986; Edmonds 988). We believe it was this strategy that permitted them to persist and reoccupy the Ungava tundra, whereas the tundra muskox in eastern North America – which was more obligatory to tundra – did not return to Ungava. Of faunal remains in five of the Appalachian caves that yielded caribou bones, three were associated with peccary, two with remains of Jefferson’s ground sloth (Megalonyx jeffersonii), two with tapirs (Tapirus spp.), and one with mammoth bones. None were associated with remains of the mastodon, the woodland muskox, the stag-elk, or the fugitive deer (Sangamona fugitiva). Mastodons were abundant south of the ice; fossils have been located at several hundred sites (Kurtén and Anderson 980), especially in the coniferous forest belt between the mountains and the tundra and along the Atlantic Coast and continental shelf. The conifers that existed then between the tundra and the Appalachians are

The Return of Caribou to Ungava after the Last Ice Age | 63

the same species that comprise winter habitat of extant North American caribou. The mastodon apparently depended on these early boreal forests, and one hypothesis for its demise was the rapid restriction of this biotope along the ice margin from ,000–9,000 bp (Whitehead et al. 982). The last radiocarbondated sabertooth (Smilodon fatalis) was dated 9,40 bp ± 55 years and was found at the First American Bank Site, Tennessee (Guilday et al. 978), a site in the lowland only 25 km from the Appalachians. The fissure also contained mastodon, horse (Equus spp.), and giant sloth remains but no caribou, even though caribou were still present nearby (Baker Bluff Cave, Sullivan Co., Tennessee, 0,560 bp ± 200 years), inhabiting the last remaining spruce biotope in the mountains (fig. 3.; Guliday et al. 975, 978). Caribou, being high in the mountains, displaced themselves from many lowland alternative prey, but in these mountains they shared the prey base with peccaries (table 3.3). Kurtén and Anderson (980) consider the peccaries the most abundant middle-sized mammal in the Pleistocene. The flat-headed peccary (Platygonus compresus) comprised 90% of the large mammal faunal fossils found in caves in the Appalachians. This peccary lived in small organized herds and commonly frequented caves (Kurtén and Anderson 980). Additional remains could also have been carried to caves by predators. These pigs were smaller than caribou (shoulder height 76 cm), and because of size and conspicuousness could have diverted predation from caribou. The long-nosed peccary (Mylohyus spp.) was also common in the Appalachian Mountains, as were tapirs (table 3.3). The finding that caribou were in the Appalachians and not in the tundra/ taiga and that they were commonly associated with austral faunal elements (see Churcher et al. 989) is consistent with the herculean study of the fossil mammal fauna of the Late Quaternary at 2,945 sites in the United States (Faunmap 994) and the 20-author publication in Science (Graham et al. 996). These investigators supported the Gleasonian community model – which assumes that species respond to environmental change in accordance with individual tolerances with varying rates of range shift – rather than the Clementsian model, which stresses competitive interactions. These authors concluded that “modern community patterns emerged only in the last few thousand years and many late Pleistocene communities do not have modern analogs” (ibid., 60). Consistent with our Appalachian Refuge model, only one caribou fossil locality is known from the entire region between these mountains and the ice maximum 8,000–4,000 bp and that is in Christensen Bog, Hancock Co., Indiana (4,800 to 2,060 bp, table 3.). Coincident with the extinctions of the mastodon (about 0,000 bp), the dire wolf, and the sabertooth (9,500 bp), caribou remains have been found at more than 23 locations from Minnesota to New Hampshire (fig. 3.; tables 3., 3.2). A portion of this apparent increase resulted from expanded searching on the part of archaeologists for the remains of PalaeoIndians – big game hunters who moved into the area south of the Great Lakes

64 | TH E R E T U R N O F C A R I BO U TO U N G AVA

about 0,500 bp (Wright 987) and must have relied on caribou when the mastodons became extinct. Still, a number of the caribou fossils have been found in sites not associated with early hunters. Caribou in the Appalachians would have shared a common gene pool having similar antler morphology. We know of remains of fossil antlers from  different faunal locations of animals south of the ice in the literature. Antlers from seven were classified by palaeobiologists as woodland caribou, based on oval or compressed cross sections, and we noted high bez tines in the photographs of antlers from three other locations. If these antlers also had well-developed tops, they would resemble present-day montane antlers (see Butler 986 for antler terminology). Unfortunately most fossil antlers consist of only the base sections, the brows, and bezes. The th antler (Jackson 989) appears to have the montane shape described by Butler (986) of a high bez tine dividing about 0 centimetres above the brow and palmate terminal points. This antler form in Butler’s terminology is THD : main beams, tall (T), bez placement, high (H), mass placement, distal (D). This form is neither the present shape of the sedentary woodland caribou (R. t. caribou) in Ungava (SHP – short/high/proximate) nor the George River herd (R.t.Caboti, TLD – tall/low/distal, fig. 2.8). It would appear that the current shapes in Ungava may have evolved since the Pleistocene during recolonization and/or in situ in Ungava. However, we do not know the antler morphology of Christensen Bog caribou. Still, it appears that Banfield (96) made the right choice in using conservative skull measurements to combine all the present-day caribou in Ungava as one subspecies regardless of variations in antler form. Recolonization At the Wisconsinan maximum we postulate a common gene pool of caribou that was concentrated in the Appalachians. These were rare compared to several of the species of Pleistocene megafauna that went extinct (fig. 3.2). From this Appalachian refuge, we wish to trace the spread of this gene pool north and examine how the stock separated into two ecotypes (fig. 2.7) that developed different lifestyles and antler morphology – the sedentary and migratory ecotypes (figs. 2.7, 2.8) that now occupy Ungava (Bergerud 996). Tracing the colonization routes is difficult since the acid soils of the Canadian Shield commonly obliterate bones. However, Indian cultures also advanced north and east as the ice retreated, and their hunting/scraping tools provide clues to their food supply. With the mastodon extinct about 0,000 bp, the food supply of the Palaeo-Indians (flute point people), ,500–0,200 bp, was primarily caribou and possibly fish; of the Early-Middle Archaic culture, 0,000–7,000 bp, caribou; of the Maritime Archaic natives, 6,000–3,500 bp, marine mammals and some caribou; of the Shield Archaic culture, 7,500(?)–3,000 bp, fish and caribou; and of the Eastern Plano linkage, 9,000–? bp, caribou (McGhee and Tuck

The Return of Caribou to Ungava after the Last Ice Age | 65

30 MEGAFAUNA LAST APPEARANCE DATE

NUMBER OF FOSSIL LOCATIONS

CARIBOU FIRST APPEARANCE DATE 25

A

CARIBOU IN APPALACHIAN MOUNTAINS

20

15

10

CARIBOU MOVING NORTH IN CANADA

5

0

A A A A

A 22

20

A A 18

16

14

12

10

8

6

4

2

YEARS BEFORE PRESENT ( × 1,000 )

Fig. 3.2 A frequency array of last appearance dates of the megafauna species in the various fossil beds in North America, compared to the first appearance date of caribou in eastern North America from table 3.1. The dates of last appearance of the megafauna are from Kurtén and Anderson (1980, table 19.6) and includes 45 species with 10 species listed from more than one location. Excluded from the fig. are six last appearance dates: 37,000 to 30,000 BP. Caribou fossils dating to before the extinction of the megafauna (i.e., prior to 14,000 BP ) were found primarily in caves in the Appalachian Mountains.

975; Jordan 975; Samson 978; Fitzhugh 979; Fitzhugh and Lamb 98; Spiess 993; and review Wright 987, 995). The spread of these groups northward as the ice retreated and plant life returned should parallel the spread of caribou. At the present time the migratory ecotype in Ungava (the George River and Leaf River herds) migrate to calving grounds on the Ungava tundra and winter in lichen woodlands (taiga). The sedentary ecotype lives south of the migratory herds in the boreal forests north to the limit of open water at calving at about  June (fig. 2.7; Bergerud 996). Both calving distributions are considered adaptations to reduce predation on neonates (Bergerud and Page 987; Bergerud 988b; Bergerud 996). The different antler morphology of the ecotypes is hypothesized

66 | TH E R E T U R N O F C A R I BO U TO U N G AVA

to relate to different aggregation and mobility parameters of the two ecotypes (figs. 2.7, 2.0; Butler 986). This dimorphism should have arisen from the montane form during the last 8,000 years. Caribou that colonized southern Ungava with open water available as escape habitat at calving should result in the sedentary ecotype. Animals north of open water at parturition that displaced to calving grounds to reduce risk would become the migratory ecotype (fig. 2.2). We examined the recolonization distributions of caribou to see if the two ecotypes, sedentary and migratory, were sufficiently discrete and habitat-specific to result in two subspecies, R.t.caribou and R.t.Caboti, formerly considered separate species Rangifer caribou caribou and R. arcticus Caboti (Anderson 938). Indicator plant species and pollen-core samples were used to distinguish the two divergent winter and calving habitats of sedentary and migratory ecotypes, 8,000–4,000 bp, notably boreal forest and open water escape habitat (the sedentary ecotype) vs taiga and shrub tundra and bodies of frozen water (migratory). We also used the forest-cover maps available for the United States 8,000 bp to present (Delcourt and Delcourt 98) and for Canada ,000–3,500 bp (McAndrews et al. 987). The distribution of balsam (Abies balsamea) nearly matches the distribution in 840 of woodland caribou in the boreal forest of North America; its northern limit coincides with the northern limit of woodland caribou, which in turn is coextensive with the presence of open water at approximately  June (compare Ritchie 987: fig. .3; and see Bergerud 996, 2000: fig. 3-). Jack pine (Pinus banksiana) is generally an indicator of habitats that have open water at calving. Both species are routinely segregated in pollen-core samples by palaeobotanists. Taiga habitat with frozen lakes at calving can be recognized in pollen cores by the predominance of spruce and dwarf birch (Betula glandulosa); herb tundra is recognized by the dominance of the Cyperaceae and Gramineae; and shrub tundra by these two plant groups plus birch and sometime alder (Alnus crispa) (Ritchie 987). From 8,000–4,000 bp the ice sheet retreated from the flat landscapes south of the present-day Great Lakes and a large area of open spruce developed of about 70,000 km² adjacent to 90,000 km² of tundra (fig. 3.). This would appear to be an ideal mix of summer and winter habitats, similar to that used by migratory herds currently (Bergerud 996, table 3, 00). However, only six radiocarbondated fossils are known for this period in this region (Christensen Bog, Hancock Co., Indiana – as noted previously, Faunmap 994). At 4,000 bp the caribou could still have been mostly in the Appalachian Mountains, while mastodon, stag-elk, muskox, and their predators still dominated the lowlands. By 0,000 bp caribou fossils were more common in lowlands south of the Great Lakes. Churcher et al. (989) showed 0 locations in Illinois, Indiana, and Ohio where fossils probably date from the late Pleistocene–early Holocene, but we plotted only one (fig. 3.) since the remaining nine locations were without dates. By 0,000 bp the megafauna were nearly extinct (fig. 3.2) and Jack pine had replaced spruce as the dominant conifer south of the Great Lakes (fig. 3.). By

The Return of Caribou to Ungava after the Last Ice Age | 67

8,000 bp Pinus strobes arrived (Heide 984). By then this former taiga area would have had open water at calving (water-escape habitat), and colonizing animals would have adopted the sedentary mode of spacing-out at calving (Bergerud 985; Bergerud et al. 990), rather than migrating across frozen landscapes and aggregating on the tundra at common calving locations. Another possible recolonization route north at 3,000–2,000 bp was the continental shelf that was exposed as deglaciation occurred in Nova Scotia and New Brunswick (see Pielou: fig. 0., 22). Animals could possibly have travelled from Cape Cod along Georges Bank, then the Browns Bank to reach Nova Scotia. Mastodons and mammoths did reach the Georges Bank, and the sediments from which their teeth have been dredged ranged in age from ,465 bp on the north to 8,30 bp on the south (Whitmore et al. 967). Other species identified from the shelf include the horse, tapir, woodland muskox, and stag-elk. Caribou fossils aged 0,680 bp ± 400 years were reported from the shelf, but only further south, off New Jersey (Roberts 990). They speculated that these fossils were from glacial outwash from farther inland. Further mastodon fossils in Nova Scotia are now considered to date from a cooler phase of the Sangamonian interglaciation and not from the Middle or Late Wisconsinan age deposits (Harington et al. 993). Even when the Georges Bank and Browns Bank were exposed, the Fundian Channel between the banks was at least 00 m deep and 30 km wide and would have represented a considerable barrier (Harington et al. 993). Caribou in recent times have commonly moved long distances between Arctic Islands on sea ice (Miller et al. 977). Alternatively, caribou may have avoided the homogeneous continental shelf plain with its megafauna and lack of escape terrain. We suggest caribou did not use this route in recolonizing Ungava, avoiding alternative prey and their predators. About 0,000 bp many caribou, according to remains with radiocarbon dates (fossils included in fig. 3. from 2,500–8,500 bp) died in forest habitats dominated by Jack pine or in mixed conifer/northern hardwoods (fig. 3.; table 3.2). Open water would have been available at calving as escape cover in these biotopes. Additional locations were in a spruce–jack pine association that McAndrews et al. (987) described as boreal (fig. 3.3). Smaller lakes and muskeg ponds were likely at hand for escape. These habitats should favour the sedentary ecotype with their short, limited migrations. Four fossils from just north of Lake Ontario (dated 0,500, 0,500–,000, ,300 and 2,000 bp) plot out in the jack pine/spruce biotope on Delcourt’s and Delcourt’s (98) map, but are just on the southern edge of lichen woodland at 0,600 bp in Robert’s and McAndrew’s (987) map (plate 3) of southern Ontario. These animals could have had a calving ground on the tundra north of the Champlain Sea. In the period about 2,000–9,800 bp the Atlantic Ocean extended up the Saint Lawrence River and a tundra area extended adjacent to these lowlands. Storck and Spiess (994) reported an arctic fox (Alopex lagopus) at the Udora site dated about 0,500 bp. They also report considerable disagreement in the palaeo-

Fig. 3.3 The retreat of the Wisconsinan ice sheet from 10,000 to 5,000 BP and the advance of plant biotypes (McAndrews et al. 1987). In recent millenniums migratory caribou have inhabited the arctic tundra and the lichen woodland taiga while the eastern sedentary caribou have occupied the spruce/jack pine forests of the boreal forest as well as the lichen woodland.

The Return of Caribou to Ungava after the Last Ice Age | 69

botanical literature concerning the dominant plants present in the region at that time, leaving open the question of the ecotype of these animals. The lake country of the Canadian Shield was only 70 km north of these four fossil locations; by 0,000 bp caribou in this area would be calving on lakeshores and islands, since the tundra had shifted 350 km farther north (figs. 3., 3.3). If animals in this region had wanted to calve on tundra they would have needed to advance 700 m/ yr to keep abreast, which is unlikely. One fossil from Steep Rock Lake, Atikokan, Ontario, west of Lake Superior, yielded a radiocarbon date of 9,900 bp ± 20 years (fig. 3.4, Jackson 989). One vegetative map indicated tundra available there; another only lichen woodland (figs. 3., 3.3). Pollen cores reviewed by Ritchie (987) indicated tundra 3,000– 2,000 bp followed by spruce. Pine appeared about 9,500 bp. There was no real opportunity for a migratory ecotype life style, nor for sedentary calving caribou to colonize fast enough to overtake the receding tundra. Also, glacial lakes Agassiz and Barlow-Ojibway replaced the tundra south of the ice and blocked caribou following the tundra northward. Animals in this area would have been able to shift northward to the west end of Lake Ojibway by 8,000 bp. By then caribou would have calved on the shores and islands of lakes that were free of ice in late May. A Shield Archaic cultural site was uncovered at Wapekeka, Big Trout Lake, 560 km north of Steep Rock, Ontario, dated 7,080 bp (Wright 995); if caribou had reached there from Steep Rock the travel rate was a reasonable: < 200 m/yr (fig. 3.4). In general, the spruce/pine/fir boreal forest advanced with climate warming from ,000–5,000 bp at rates 200–500 m/yr, based on the forest maps shown in figure 3.3 (McAndrews et al. 987): ,000 to 0,000 bp – 500 m/yr 0,000 to 9,000 bp – 200 m/yr 9,000 to 7,000 bp – 220 m/yr 7,000 to 5,000 bp – 250 m/yr These rates of retreat are too high for sedentary caribou that display lifetime philopatry to prior calving locations to track the tundra north. For example, the range extension of caribou between the Great Lakes Huron, Erie, and Ontario at ,000 bp probably reached Lake Mistassini by 6,000 bp (fig. 3.4) based on the eastern advance of the Shield Archaic culture (see Wright 987, Plate 6). To do so the animals would have expanded north-eastward from Lake Ontario at a rate of 60 m/yr (800 km/5,000 yr) – falling behind the retreating tundra. Even if these caribou calved on the two large tundra islands in Lake Ojibway (fig. 3.3) their mobility and aggregating behaviour would still not have been of the migratory type based on Butler’s (986) antler morphology model (fig. 2.0). However, this slower rate of advance for the sedentary ecotype does not apply to migra-

ICE SHEET 8 BP ICE SHEET 8 BP 2.5

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LAKE AGASSIZ 10 BP

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MISTASSINI

7?

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M M

ICE SHEET 10 BP 6.5

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L. ABITIBI S

S

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11.0 10.7 11.0

IA RE N M FU OU GE NTA IN

28,17

13–12

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20,13

LA PA P A

CARIBOU FOSSIL 12 000 YR BP

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DISPERSAL

M

MIGRATORY

S

SEDENTARY DISPERSAL 13–11 BP MIGRATORY-NORTH SEDENTARY-SOUTH

12

0 0

200 KILOMETRES 200 MILES

Fig. 3.4 The proposed recolonization routes of sedentary (S) and migratory ecotypes (M) from the Appalachian Refuge, 12,000 to 2,500 BP. Note the most likely introgression route of the northern mitochondria clade, at possibly 8,000 BP, is southeast between Lake Agassiz and the western shore of Hudson Bay. At 8,000 BP ice still covered southern Baffin Island and the west shore of Hudson Bay, blocking colonization. This northern clade represents 22% of the genetic profile of the George River stock while the southern clade, from the Appalachian refuge, accounts for the remaining 88% (fig. 2.1).

The Return of Caribou to Ungava after the Last Ice Age | 7

tory caribou that can shift their calving ground hundreds of kilometres between decades (Kelsall 968; Gunn 2000a). The largest number of Pleistocene/Holocene caribou fossils from the periglacial refugium were from the Hiscock site in Genessee County in western New York (2 fossils dated between ,390–250 bp, broken series between 8,000–,000 bp, Faunmap 994). Several of the fossils are antler segments and all have high bez tines with some palmation (photographs provided by Richard Laub and Arthur Spiess). These antlers are thus the sedentary woodland type (Butler 986). These results support our conclusion based on rates of range extension of caribou and vegetation in the Lake Ontario/Erie region that a migratory ecotype was not present there prior to ,000 bp (fig. 3.4). A second large taiga/tundra complex of 300,000 km² developed about ,000 bp in New England and Maritime Canada as the ice sheet retreated (fig. 3., 3.3). Here the tundra north of the Champlain Sea would have been ideal calving habitat (fig. 3.). Animals could cross the sea on the ice in April/May and have a summer water barrier to hinder predators. Caribou on the mainland of the Arctic Coast in the Northwest Territories in the 800s used to migrate across the Dolphine/Union Strait 30–40 km to calve on Victoria Island (Banfield 954) and have recently again taken up these migrations. Even if predators were scarce in this taiga the southeastern slopes northwest of the sea would have reduced snow loads and provided a high-quality green-food gradient from May to July. Even today tundra and taiga exist in the Shickshock Mountains on the Gaspé and at Mount Katahdin, Maine, and by 9,000 bp pine and balsam fir were invading this large taiga/tundra complex (Ritchie 987). Possibly 3,000 years had been available for caribou to adopt the migratory strategy of moving between tundra for calving and taiga for winter lichens. By 0,000 bp these maritime animals could have reached Labrador via Anticosti Island across sea ice, and by 9,000 bp a tundra corridor existed eastward along the north shore of the Gulf of St Lawrence (figs. 3.3, 3.4). A large migratory population in this region is suggested by the fossil locations of caribou at Whipple Creek, New Hampshire, about 0,680 bp ± 400 years and Bull Brook, Massachusetts, 0,680 bp ± 400 years (Grimes et al. 984). These fossils were on the southern edge of this taiga zone (fig. 3.). Palaeo-Indians were on site at both southern localities and would have been hunting caribou (Storck and Spiess 994). At the north end of this taiga and at the Nova Scotian isthmus there were more Palaeo-Indians at Debert dated 0,600 bp (MacDonald 968); this narrow land neck would be an ideal location to intercept animals migrating from Nova Scotia to the St Lawrence tundra. Fluted points and hide-scraping tools indicate a dependence on caribou. Further fluted points from this period have been located at seven additional locations between the coast and the St Lawrence (dated ,500–0,200 bp, Wright 987). Caribou would have invaded this area, followed by Indians, after the extinction of the mastodon farther south (see plate 5, Wright 987). We postulate that this region is the ancestral home of the

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migratory ecotype that became the George River herd. From this location they were able to recolonize Labrador, reaching the north coast of Labrador (≥56° N) moving through open shrub tundra the entire distance (figs. 3.3, 3.4) – hence maintaining the migratory and aggregating behaviour needed to develop the TLD antler morphology predicted in Butler’s (986) display-weapons hypothesis. The Early and Middle Archaic culture moved along the North Shore of the St Lawrence and north along the Labrador coast to Hopedale between about 9,500– 7,000 bp (Wright 987). McGee and Tuck (975) believe these people depended on sea life in the open-water season and hunted caribou in the winter. At the l’Anse Amour cultural site a caribou bone was dated 7,530 bp ± 40 years. Farther along the coast another fossil was found at the Fowler site, Belle Island, 6,800–6,300 bp (McGee and Tuck 975). The colonization rate to reach L’Anse Amour via Anticosti Island leaving Gaspeé at 0,000 bp is 250 m/yr (62/2,470). If the animals came along the North Shore past the ice barrier that disappeared about 9,000 bp, the rate was 425 m/yr (630/,470). These movements would have occurred in shrub tundra (fig. 3.3, Ritchie 987). In southern Labrador, a Betula tundra dominated between 2,000–7,000 bp, with (Picea/Abies) invading 6,000 bp (Lamb 980). The animals dispersing along the shores of the Gulf of St Lawrence would have turned north from the Gulf, moving northeast east of the remaining ice sheet, still in shrub tundra (fig. 3.4). If the animals continued at these rates, they could have reached the herb community on the highlands west of Hopedale by 7,500 bp, reaching the George River by 6,500 bp, when birch appeared at the Pyramid Hills (Short and Nichols 977). This colonization route along the North Shore of the St Lawrence was possibly used by other arctic-adapted mammals to recolonize Ungava (Harington personal communication). The Saint Elzear and La Re-Demption caves on the Gaspé contained fossils of arctic hare (Lepus arcticus), arctic fox, Ungava lemming (Dicrostonyx hudsonius), and barren-ground grizzly (Ursus arctos). These species were all able to recolonize Ungava, although the grizzly became extinct in recent times. These mammals are less mobile than caribou; that they reached Ungava suggests that the recolonization route via Anticosti Island was not essential for caribou. The last area to be colonized in northern Ungava by the migratory ecotype was the Ungava Peninsula north of the Leaf River where herb tundra still dominated at 5,000 bp. Picea mariana greatly increased on this northern tundra between 4,500–3,000 bp to a maximum of 60%, after which it decreased and birch and sedges increased to the present day (Richard 98, Ritchie 987). Pielou (99) believes the hypsithermal that occurred (in the early Holocene) reached its climatic optimum in the vicinity of the Leaf River 4,000 bp ; caribou would have been there then (fig. 3.4). In all their recolonization routes from the Maritimes 0,000–7,000 bp, they followed shrub tundra (where Betula glandulosa persisted

The Return of Caribou to Ungava after the Last Ice Age | 73

as global warming was delayed by the Labrador current). We believe that dwarf birch paced their recolonization and that they had sufficient time to develop their migratory, tundra-calving-ground strategy by the time they reached the Labrador tundra that is now their centre of habitation. The sedentary ecotype probably began its divergence from the migratory ecotype at least by ,000–0,000 bp near the end of the Pleistocene in the vicinity of Lake Huron and Lake Ontario (fig. 3.4) – possibly earlier as the Hiscock antlers suggest. This ecotype should have reached Lake Mistassini by 6,000 bp and then continued eastward. Wright (987) noted that Shield Archaic Indians in the Caniapiscau country east of Mistassini had small temporary camp sites. This would be the expected sequence if these natives were hunting the dispersed sedentary ecotype. These natives reached Hamilton Inlet moving east by 4,000 bp (Wright 987; 995), the date the sedentary type should have completed its colonization of Ungava north to 54° N and east to the coast. The caribou fossil found at the Rattlers Bight site, Hamilton Inlet (3,800 bp, table 3.) may represent the sedentary ecotype since the migratory George River herd was too far north for local hunters to reach. Samson (978) reported Rattlers Bight artefacts at Indian House Lake some 5,000–4,000 years after the migratory herd had returned to the north coast, but these hunters could have come from Okak (farther north along the coast than Hamilton Inlet). We believe the two ecotypes have been relatively isolated for the past ,000– 0,000 years. The sedentary caribou could not advance fast enough to avail themselves of the tundra and evolved their habitat option to use water as their primary escape habitat. These animals developed the SHP morphology because they bred in small, relatively stationary groups where sexual selection between males often resulted in serious dominance battles (Butler 986). The migratory type was able to colonize northern Ungava using the tundra as its highway north because of the slower advance of the boreal forest in coastal Labrador. Their antlers emphasized height and spread (TLD) since sexual selection in large migrating aggregations of animals not familiar with each other depends more on show and intimidation than serious, prolonged fighting (fig. 2.0 from Butler 986). The subspecies have remained largely discrete to this day (Anderson 938) because of their philopatry to calving areas (fig. 2.7). In a climatic warming period the tree line would advance and the migratory ecotype would move its calving ground farther north to space away from wolves and alternative prey (Bergerud and Page 987). The sedentary ecotype would also move farther north following the open water ecotone at calving, thus maintaining space between strategies. We might draw a parallel with the prehistoric movements of the native peoples along the Labrador coast: Inuit and Innu shifted north and south in response to warming and cooling cycles (fig. .3). Global warming had not arrived in Ungava during this study (fig. .4), but if it does – as it already has in Alaska, the Yukon, and Banks Island – we may be able to test the predictions of this hypothesis.

CHAPTER FOUR

The Abundance and Distribution of Sedentary Caribou

In this chapter we discuss the abundance, past and present, and distribution of the caribou in southern Ungava (south of 55° N). The females in these latitudes, in contrast to animals farther north, (the migratory Leaf River and George River herds) do not migrate to common calving grounds but rather disperse at calving (space-out) from other females, seeking birth sites of low predation risk (Bergerud and Page 987). These animals are called the sedentary ecotype (Bergerud 988b), and in contrast to the migratory ecotype, they are most aggregated on winter ranges and least aggregated at calving (fig. 2.2). These herds live in a growing season zone where open water is available at calving. We believe they use open water to reduce predation risk (Bergerud 985; Bergerud et al. 990). In three of the herds’ ranges, large hydro impoundments have been constructed since 969 (fig. 2.7), which would generally be ice-covered when the herds calve about  June (fig. 2.7). Formerly many of these landscapes would have contained small ponds and muskegs that provided protective standing water earlier in June. An analysis of the dynamics of the herds’ distributions should give us a better understanding of the various behavioural options of the George River herd in both forested and water environments. In the spring, the cows of the sedentary ecotype migrate from their winter ranges to their birthing sites rapidly, exceeding 0 km/day (fig. 4.). This spacingout results in the maximum dispersion of the animals in the annual movement cycle (figs. 2.2, 2.4). Such dispersion makes it impossible to recognize distinct herds; rather, there is a general distribution of dispersed animals across central Ungava (fig. 2.7). Segments of this continuous distribution are labelled “herds” for research and management purposes and workers have emphasized the lack of exchange between them (Brown 986; St. Martin 987). It is true that the animals

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MAR

APR

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OCT NOV DEC

Fig. 4.1 (above) The mobility of 5 cow caribou tagged in the Red Wine herd in 1982. There was considerable movement just prior to calving in late May; (below) The annual mobility of caribou in four sedentary herds in Ungava: Lac Bienville, Caniapiscau, Lac Joseph, and Red Wine Mountains (summarized by Brown et al. 1986) Note the major movement in all the herds occurs just prior to calving and moving to low-risk habitats.

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in these distribution aggregate in the winter on lichen pastures in areas of low snowfall (the Red Wine Mountains, the Mealy Mountains, and the Kaniapiskau Highlands), but in reality there are no herd affinities. Females show phiolpatry between years to their successful parturition sites (Brown et al. 986) and in the fall they aggregate nearby on upland winter ranges of low snow depths. The philopatry to prior calving areas leads to the lack of exchange between winter aggregations. The most constant feature in the landscape of these dispersing caribou is the critical one of calving sites with low predation risk, mirroring the traditional use of calving grounds by the migratory ecotype (Skoog 968). Distribution Southern Limit

At the end of the last cooling cycle in North America (the Little Ice Age) at about 860 (see Payette et al. 985; Crête and Payette 990), the caribou in Ungava, Quebec, were distributed south to the Gulf of St Lawrence and the Great Lakes (Banfield 96). In 2003 the range still extended nearly to the Gulf of St Lawrence north of 50° N (Courtois et al. 2003), but in central Ungava only relic herds remain south of Lake Mistassini (fig. 4.2; Bélanger and Le Henaff 985). In the 990s these included: the Val d’Or herd (48° N, 78° W); the Gaspésie Park herd (47° N, 66° W); the introduced Grands Jardins Park herd (47° N, 7° W); and the La Sarre herd (49° N, 79° W) (Rivard 978; Bélanger and Le Henaff 985; St. Martin 989; Crête et al. 990; Crête and Desrosiers 995; Courtois et al. 2003). The total animals in these four herds probably numbered less than 250 in the 990s. The Gaspésie Park herd is possibly the largest of the four and numbered about 40 animals in 2003 (Courtois et al. 2003). The southern line of continuous caribou distribution corresponds with the northern limit of high moose (Alces alces) densities (> 0.0/km²) and white-tailed deer (Odocoileus virginianus) in Ontario and Quebec (figs. 4.2, 4.3). The continuous distribution of caribou in Quebec 972–73 extended across the province at approximately 50° N, based on extensive surveys by Brassard and Bouchard (968), Brassard (972), and Pichette and Beauchemin (973). This limit was still valid in 2003 (fig. 4.3, Courtois et al. 2003). When moose numbers exceed > 0.0/km², the predicted density of wolves is ≥7/000 km² (Fuller 989). Expanded wolf predation results in negative demography where mortality and recruitment are not sufficient to maintain numbers and a continuous distribution (R < M) as shown in figure 4.4. Thomas (995) also proposed that when moose are common wolf densities of more than 5–8/,000 km² will hold caribou populations at low levels for long periods. The southern limit of continuous caribou in Ontario has been advancing north as logging progresses. In fact, the goal of the Ministry of Natural Resources in Ontario in the 980s was to increase densities of moose beyond 0.0/km² in northwestern

The Abundance and Distribution of Sedentary Caribou | 77

0.02

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QUEBEC

Fig. 4.2 The southern edge of the continuous distribution of caribou in Ungava in the 1980–1990s approximated the northern extent of habitats supporting moose densities > 0.10/km². Caribou living south of the line where moose densities exceed 0.10/km² persist only as relic herds in habitats with reduced predation risk (southern continuous limit of caribou based on Courtois et al. 2003).

Ontario (Bergerud et al., presented at th North American Conference, April 2006). The projected year 200 mean target for seven wildlife management units that still have a continuous distribution of caribou was 0.26 ± 0.50 moose per km2 (extremes 0.0–0.39 moose/km²). Unfortunately, their management concerns are primarily directed at moose, not caribou, even in wildlife management units north of 5° N that have little commercial timber. Schaefer (2003) has documented that the range recession of caribou in Ontario correlates with the extension of the forest industry and he suggests anthropogenic agents for the decline. Timber removal of balsam fir forests results in secondary succession of deciduous species that in turn results in the expansion of moose populations > 0.0 animals per km². Schaefer’s comments should not be construed to mean that the demise of caribou occurred because of inadequate food supplies or that animals

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2001

Fig. 4.3 The line between the continuous distribution of caribou (north of the line) in Ontario and the discontinuous distribution (relic herds) to the south. This interface is located between Wildlife Management Units that have less than 0.10 moose/km² to the north of the line and more than 0.10 moose/km² to the south (Bergerud 1989). This continuous/discontinuous interface was first published by Darby et al. in 1988 and was further substantiated by Armstrong in 1998 and Racey and Armstrong in 2000. Since 1985 the moose have been increasing north of the continuous line. By 2001 the moose densities in the eight Ontario Wildlife Management Units north of the line had increased from the mean in 1985 of 0.044 ± 0.011 moose/km² to 0.075 ± 0.013 moose/km². Three districts north of the line that in 1985 had moose densities of only 0.07–0.08/km² had increased by 2001 to a mean of 0.11 moose/km², too many for the persistence of the continuous distribution of caribou.

MORTALITY, n = 18 RECRUITMENT, n = 25

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PERCENT RECRUITMENT ( ) OR MORTALITY ( )

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WOLVES PER 1000 km ² Fig. 4.4 The recruitment of caribou in North America and adult mortality rates compared to wolf densities. The recruitment and mortality parameters of Northern American herds were about in balance when wolf densities reached 6.5 wolves/1,000 km². This graph was first published in 1986 (Bergerud and Elliott 1986) and included all the herds in North American in which recruitment, mortality, and wolf numbers could be compared at that time. The significance of a density greater than 0.10 moose/km² (figs. 4.2 and 4.3) is that this biomass of moose can support a wolf population > 6.5 wolves/1,000 km² based on wolf abundance equations regressed on ungulate biomass statistics (Fuller 1989, Dale et al. 1994). Thus one can predict that caribou will decline by censusing moose and finding that their numbers exceed 0.10/km². Moose densities are now expanding north with global warming and exceeding 0.10/km², which will result in further fragmentation of the continuous distribution of sedentary caribou and the extinction of caribou on the southern edge of their current continuous distribution as in Ontario and Quebec (figs. 4.2 and 4.3) (Bergerud et al. 2007). Note: The above hypothesis has recently withstood the test of disproof (Haskell and Ballard 2007) and Lessard (2005) has also modeled the cariboumoose-wolf system and found that 8 wolves per 1,000 km² would cause caribou to decline.

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deserted logged ranges due to disturbance. Sedentary caribou remain faithful to their calving locations despite human activity (see Brown et al. 986). Furthermore, the invasion of white-tailed deer into southern Ungava means that caribou can contract Parelaphostronglylus tenuis, a fatal disease (Anderson 972), and there is some historical evidence that caribou declined with the arrival of deer in southern Ungava (Low 898). Add to this unfavourable equation an expanding road network that facilitates illegal hunting, and the demise of the caribou in southern latitudes was assured. A range extension south cannot occur until there is a climatic cooling cycle and moose and deer numbers decline on their northern ranges. Northern Limit

The northern limit of calving for this ecotype coincides with the presence of open water and adjoining large muskegs at calving (fig. 2.7). All authors who have studied the calving locations of these caribou have commented on the preference of females for muskeg-wet habitats (Paré and Huot 985; Brown et al. 986; St. Martin 987; Le Henaff and Hayeur 983; James et al. 2004). Such large muskegs also permit the animals to be partially segregated from moose on more upland sites, and from wolves, which are more closely associated with moose abundance in these two ungulate systems (Cumming et al. 996; James et al. 2004). Speaking of calves born in late May and early June, a native Hopedale hunter (quoted in Brice-Bennett 977, 6) tells the same story: “Around the mossy places. Good feeding grounds, good hiding places, and just about always near a lake. And you know what the reasoning is for near a lake, because there’s lots of wolves around. When the wolves are around, the only chance these little ones get to have a rest is they head for water. They go in about two or three feet of water and stand there with the old one. And the wolf, he can’t do nothing because the wolf’s legs are shorter than the deer.” As shown in figure 2.7, the calving distribution is broken by the Smallwood Reservoir. The mean date that ice left Knob Lake at Schefferville (80 km west of the Reservoir) in 37 years was 2 June, with extremes occurring 8 May 959 and 29 June 992 (fig. .4). The ice in Lac Caniapiscau broke up about 20 June in 98–83 (Huot and Paré 986). Because the Smallwood Reservoir lies close to the 5 June isohydric line for open water (figs. 2.3, 2.7), it cannot provide water escape for caribou from wolves at calving time.. In 958 Bergerud was told that scattered caribou calved west and northwest of Michikamau Lake (now the Smallwood Reservoir), and Folinsbee (975) also indicated that as late as the early 970s caribou still calved north of the Churchill Falls Road. Before the flooding these areas adjacent to Michikamau Lake had the largest areas of muskeg in central Ungava (fig. .) and were prime calving habitat for the Lac Joseph herd. By flooding this area, the small ponds that would have had open water by –7 June became inundated by the reservoir, which does

The Abundance and Distribution of Sedentary Caribou | 8

not have open water until after calving (5 June). If a reservoir of this size had been created 250 km farther south it would have been open  June (fig. 2.3) and would have provided extensive shorelines and islands as calving refuges. One of the last remaining relic herds in Ontario has been able to survive because a large natural lake (Lake Nipigon, 83 km²) provides open water at calving and dozens of safe islands for calving (fig. 2.6). Originally 2,03 km², Michikamau Lake was increased to 6,572 km² in the Smallwood impoundment, but because there was no open water at calving to provide safe havens, there was actually a reduction of 4,500 km² in muskeg habitat for calving. Another consequence of such extensive flooding of muskeg calving sites is that it compressed the calving density, reducing the maximum dispersion that females sought at parturition. Paré and Huot (985, 54) noted relative to the flooding of Lac Caniapiscau that “the main impact of the change in calving sites distribution might be in relation to predation as an increase in the density of calving females might attract wolves.” Population Dynamics Background The measurement of population changes in caribou numbers is determined either by counting numbers between years or by comparing recruitment (R) – the proportion of young animals that join the herd – with mortality (M) – the proportion of adult animals that die (Bergerud 968). R/M schedules are used to calculate the finite rate of increase (λ) where lambda λ = ( - M)/( - R) and R and M are expressed as percentages of the total herd (Hatter and W. Bergerud 99). R can be expressed either as a percentage of total animals or as calves/00 females, but the statistic need for λ is the percentage of calves of total animals. However, calves/00 females is a more accurate statistic, especially if the proportion of males varies between years. Nonetheless many of the earlier aerial classifications were done from fixed-wing aircraft from which observers were unable to distinguish between adult females and males and could only tally calves as a percentage of total animals seen. The measurement of the contribution of the size of the new cohort (R) to the dynamics of the population must be done when the mortality rate of this new generation has acquired mortality rates similar to that of the adults they replace. In herds where there is extremely high mortality of calves between birth and 6 months of age, R can be approximated by counting the number of calves in the fall (Bergerud 97b; Bergerud and Elliott 986). In these instances those calves still alive are probably the most viable and are thus no more vulnerable than adults. On the other hand, in those herds that go to calving grounds north of tree line, there are generally large numbers of calves still alive in the autumn, since wolves are more common on winter ranges (Heard and Calef 986), and in these herds calves continue to die at greater rates than adults over winter. In these

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latter cases R is best measured at an age of 0–2 months, just as the animals return back across the tree line to the tundra and move away from a major proportion of the denning wolves (Heard and Williams 992), and just prior to the birth of the new cohort (which in turn deflects predation away from the previous year’s cohort). Predation by wolves is the most limiting factor in the growth of caribou herds (Bergerud 974a, 980). Since wolves kill both recruits and adults, R and M schedules are negatively correlated (calf survival declining as mortality of adults increases). In one analysis of 7 herds, the regression of adult mortality on the percentage of calves was Y = (20/(X + 3.4) R² = 56%, where adult mortality Y was predicted from the percentage of calves X (Bergerud 988b). However, a more precise use of the R/M calculations to measure population growth quantifies adult mortality instead of using the regressions based on recruitment. But the problem in many studies is that the mortality rate of females is known from radio telemetry studies but that of males is not, since many biologists do not radio-collar this segment of the herd. However, our major method for estimating male mortality was through an equation that incorporated adult female rates (based on radio telemetry) and the sex ratio tabulated from recruitment and adult composition classifications: Mm = [ - (Mf + βr)(M₂/ F₂ - αr)](F₁/M₁) where Mm = male mortality, Mf = female mortality, r = ratio of calves/females, α = the fraction of male calves, β = the fraction of female calves, F₁ = number of adult females st year, F₂ = number of females 2nd year, M₁ = number of adult males st year, and M₂ = number of males 2nd year (Daniel Bergerud, professor of mathematics, Camosun College, Victoria, BC ). The formula can be reduced if there are constant autumn sex ratios of adult males Mm = Mf + (αF/M - β)r. We assumed a constant sex ratio (Bergerud 980) and used the shortened version developed for the George River herd of M m = Fm(0.2627)R (Bergerud 996). The adult male mortality rate (including males >  year) was then combined with the adult female mortality rate based on the proportions of males and females in the herd in order to calculate population change. The combined mortality rate was then incorporated into the finite-rate-of-increase equation ( - M)/( - R). Because of the correlation between R and M, we can often use only R to predict population growth. A regression of lambda (λ) on the percentage of calves in sedentary herds based on R/M schedules was Y = 0.758 + 0.05X, r = 0.748 (n = 8); and based on census data it was Y = 0.756 + 0.06/X, r = 0.747 (n = 4 herds) (fig. 4.5). A finite rate of increase of .00 (no change) occurred at R 6.5% calves from the R/M schedules and the R of no change based on the census method was 4.6%; those recruitments that give no population growth are termed the stabilizing R (R s). The generalization is that the percentage of calves at 6–0 months of age needed for herds to increase should be > 5% if hunting is less than 5% (Bergerud 992).

7

1.15

2 8 4

11

1.10

22 6 5

( ) CENSUS Y = 0.756 + 0.016X r = 0.747 n = 14 RS = 14.6

RATE OF INCREASE ( λ )

1.05

21

4 10 19

18

5

2 1 7

1.00

14

15 20

16

0.95

13

12

8

3 3 6

1

15 9

0.90

( ) R / M SCHEDULE TOTAL

Y = 0.758 + 0.015X r = 0.748 n = 18 RS = 16.5

0.85 17

Y = 0.757 + 0.016X r = 0.737 n = 32 RS = 15.6

4

0.80

5

10

15

20

25

PERCENTAGE CALVES (FALL OR WINTER) 1. 2. 3. 4. 5. 6. 7. 8.

RED WINE 9. LEVEL-KAUDY 17. MEALY MT. 10. COLUMBIA MT. 18. SPATSIZI 11. TELKWA 19. FINLAYSON 12. GRAND JARDINS20. WELLS GRAY 13. CANIAPISCAU 21. HORSERANCH 14. LAC BIENVILLE 22. BURWASH 15. NC ALBERTA ITCHA-ILGACHUZ16. NE ALBERTA

QUESNEL PUKASKWA COLUMBIA MT. RANCHERIA WOLF LAKE LAC JOSEPH

Fig. 4.5 The finite rate of increase (λ) for the sedentary herds in North America can be estimated based only on recruitment (R) since the percentage of calves in the herds and adult mortality rates (M) are negatively correlated (fig. 4.4) (Bergerud 1988b). The stabilizing recruitment where R equals M ( Rs ) for 18 herds was 16.5% calves and similar to that generated by census data in which λ equaled 1.00 (no change) that occurred when recruitment reached 14.6% calves (n =14 herds). This fig. was first published in Bergerud (1992).

84 | TH E R E T U R N O F C A R I BO U TO U N G AVA 0.30 0.32/km²

ISLAND HERDS WITHOUT WOLVES 2–16/km² TREND BASED ON CENSUS OR R/M RATIO

WOLVES REDUCED

TREND BASED ONLY ON R

CARIBOU PER km²

0.20

0.10

MEAN 0.06

REDUCED DUE TO MAN RED WINE

MEALY MT.

LAC JOSEPH

CANIAPISCAU

LAC BIENVILLE

VAL D’OR

GRAND JARDINS

NIPIGON

PUKASKWA

WABAKIMI

NE ALBERTA IRREGULAR LAKE

NC ALBERTA

WC ALBERTA

COLUMBIA MT.

QUESNEL

WELLS GRAY

ITCHA-ILGACHUZ

SPATSIZI

TWEEDSMUIR

HORSERANCH

FINLAYSON

RANCHERIA

WOLF LAKE

BONNET PLUME

BURWASH

HART RIVER

0.00

NAME OF NON-INSULAR CARIBOU HERD Fig. 4.6 The mean density of 27 herds in North America was only 0.06 animals/km². In general, herds in habitats with unmanaged wolf populations were increasing if their densities were less than 0.06/km² and decreasing if their densities were greater than 0.06/km². The density of 0.06/km² is considered the stabilizing density (Ds ) in populations regulated by wolf populations. However, if there is additive mortality due to human influences densities would be lower (Bergerud 1992).

A final background point is that wolf predation is not only the most important limiting factor but is also regulatory, in that predation of calves and adults is density-dependent. The mean density of 27 sedentary herds (including those from Ungava) was only 0.06 caribou/km² (fig. 4.6). When the herds had densities greater than 0.06 they were often declining; when densities were less the herds

The Abundance and Distribution of Sedentary Caribou | 85

were usually increasing (figs. 4.5, 4.6). The size of the ranges of these herds, used to calculate densities, was based on the maximum dispersion of the animals at calving (see figs. 2.4–2.6) as determined by radio telemetry locations of parturient females. The predation of wolves on calves is density dependent because cows show philopatry to calving locations. As a herd decreases, the space between calving females increases because of this fidelity. This increased space results in less effective searching by wolves. When herds are low, females are farther apart and harder to locate, and since wolf numbers depend on the prey biomass (Fuller 989) wolf numbers also decrease. The caribou density where R = M is called the stabilizing density, Ds (Bergerud 992) and populations should increase when numbers are below this level and decrease when higher as long as man-made influences are held to a minimum (figs. 4.6, 4.7). Lastly, both hunting mortality and mortality from wolves are additive. The reproductive rate of sedentary caribou is high; generally 80–85% of the females are pregnant because of the extremely low densities (high phytomass/animal). Thus major changes in mortality rates do not result in compensatory increases in birth rates. The additive nature of mortalities means that Ds will be lower in a heavily-hunted population. For example, a common natural sequence is for R s to be 5% (5% R = 5% M) at a Ds of 0.06 animals/km². Add an additional 5% mortality from hunting and we need 20% calves for R = M; however, the only way to improve R (from 5% to 20%) is for animals to space more widely in summer so the searching time of predators increases. An R of 20% can only be achieved with a reduced density of 0.02–0.03 animals/km² (fig. 4.7). Population Dynamics of the Major Herds In the following section we discuss the population dynamics of the southern sedentary herds. These herds probably provided alternative prey, a refugium for wolves, when the George River herd was scarce. Most of the data in the literature was collected in the 970–980s when Quebec Hydro sponsored a flurry of research relative to the impacts of the hydro damming of two major rivers, the La Grande and Caniapiscau (fig. 2.7). Much of this information is from inhouse government reports, although there may be considerable literature from Quebec that we did not have access to. The only analysis of these early findings (as well as a synthesis of other relevant investigations) was done in 986 (Brown et al. 986) and was not widely circulated. Little has been done in recent years on these herds, with the exception of the Red Wine herd (Schaefer et al. 999). These herds have seriously declined and most are threatened both by further economic development and by faunal diversity changes that will follow global warming. We need an accounting of their past as a reference for the future. As late as 996 Serge Couturier, the biologist most familiar with these herds, stated

86 | TH E R E T U R N O F C A R I BO U TO U N G AVA

VAL D’OR (n = 3) RED WINE (n = 3) MEALY MT. (n = 14) CANIAPISCAU (n = 6)

PERCENTAGE CALVES OF TOTAL HERD

30

LAC BIENVILLE (n = 3) LAC JOSEPH (n = 12) OTHERS: WABAKIMI (n = 1) NW ALBERTA (n = 1) NC ALBERTA (n = 1)

Y=

25

22.9 1 + 8.56X r = 0.646

20

15

NO SIGNIFICANT SLOPE < 0.03/km² n = 15

10

RS = 15.0% ←→ 0.0615 / km2

5

0 < 0.01

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

CARIBOU PER km² Fig. 4.7 In nine sedentary herds where both densities and recruitment have been measured, the stabilizing Rs was 15.6% and intercepted the calculated curvilinear equation at a density of 0.06/km², additional evidence that this density should stabilize population size and approximates Ds. To evaluate the question of the stabilizing density, the occupied area should be determined when the females are maximally dispersed at calving. (see fig. 2.2).

that the status of the small sedentary herds in Quebec totalling less than 0,000 animals was unknown (Couturier 996). More recently Courtois et al. (2003) was more conservative, estimating these herds in Quebec at only 3,000 animals, but this total was not based on recent aerial surveys. The first census of the sedentary herds in central and eastern Quebec in 963 gave estimates of 60,000 animals (Des Meules and Brassard 964, recently quoted by Courtois et al. 2003). This estimate may be too high. Des Meules and Brassard’s count included animals of the George River herd. The large aggregations

The Abundance and Distribution of Sedentary Caribou | 87

they observed north of Schefferville would not have been sedentary animals. Their counting technique included leaving their flight transects and herding the animals into large groups regardless of whether the animals were in the transect census strip before being disturbed. When a caribou yard was encountered and no animals were seen, they concluded that animals were present in 50% of the observations and assigned totals to these yards on the basis of the animals counted in occupied yards. Caribou are exceedingly mobile but also highly visible in the winter when tracks are a guide for the scanner. The combination of fresh tracks and no observable animals usually means they have moved out of the counting transect and should not be tallied. Certainly this ecotype was more abundant in the 960s before increased access. If the animals south of 54° N in the 960s were at the stabilizing density of 0.06/ km², numbers could have been 30,000 animals. Since then all the herds have had major declines, primarily from hunting, because access has improved with new roads to hydro sites, the Schefferville railroad, and – most of all – the arrival of the skidoo. Lac Bienville Herd

The western end of the continuous distribution of caribou across Ungava has been called the Lac Bienville herd (fig. 2.7, Brown et al. 986). Banfield and Tener (958) saw 22 animals in this region in March 956. An additional 50 animals were seen August 956 (Hayeur 979). This area was first censused in 964 (Des Meules and Brassard 964) and the estimate was apparently about 900 animals (Audet 979). Brassard’s census in 972 gave 2,200 animals south of Lac Bienville and south to the La Grande River. Another group (the Lac Mistassini herd), located between the Témiscamie and Opinaca rivers, was estimated at ,500 caribou (Brassard 972). A survey in April 973 estimated 300 at Lac Bienville (Brassard et al. 973), but this survey did not search farther south. From 977–79 the herd was estimated at ,500 animals but after 98 the George River migratory herd moved into the area in the winters and obscured census results (Paré and Huot 985, 986). The herd was said to range over > 35,000 km². If the herd in 972 ranged south to the La Grande River, the area would have been nearly 45,000 km². A maximum density then could have been 2,200/35,000 or 0.06/km²; a minimum figure would have been ,500/45,000 or 0.03/km². The recruitment of calves was high in the late 970s, at 25.6% calves in March 977 (n = 399); 22.6% in February 978 (n = 477); and 20.% in March 979 (n = 73), with a mean of 22.8% (Le Henaff and Hayeur 983). Such high recruitments (R > R s) suggest that the lower density (0.03) was closer to the truth than the 0.06/km² option. The rate of increase 977–79 can be estimated based on R/M schedules. Recruitment averaged 22.8% (42.9 calves/00 females). If the mortality of females was 5.6% and the adult sex ratio 33.6% males (table 4.), male mortality would be

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Table 4.1 rate

The adult sex ratio, percent parous females, and adult female mortality

Herd Name

Mealy Mountain Red Wine

Caniapiscau Lac Bienville Lac Joseph

% Males (years)

33.5 ± 1.71¹ 38.9 (1981–88) 28.6 (1993–97) 39.7 ± 3.02 (2001–03) 31.3 (1981–84) 33.6 (1978–79)² 30.0 (1984–86) 43.1 ± 2.75 (2000–03)

Parous/Pregnant Females (n)

Mortality Rate Females (yrs)

86.5 (37) 79.9 (96) 71.0 (4 years)

15.0 (1985–87) 17.4 (1982–88) 29.9 (1993–97)

83.3 (12) 80.0 (20) no data

13.9 (1977–84) 15.6 (1977–79) 9.7 (1984–86)

¹ Based on 8 years between 97 and 2002, Y = 96.588 - 0.082X, r = -0.843 ² Winter Sources: Hearn and Luttich 987, Veitch 990, Huot and Paré 986, Le Henaff and Martineau 98, Le Henaff and Hayeur 983, St. Martin 987, Schaeffer et al. 999, Schmelzer et al. 2004

26.9% [Mm = Fm + (0.2627)R] (Bergerud 996) and total adult mortality would be 9.3% and λ = ( - 0.93)/( - 0.228) = .05. However, based on census data, the herd declined from 2,200 in 972 to ,500 in 978. In this case lambda (λ) would have equalled 0.94. In this latter sequence, since R equalled 22.8%, mortality would have had to be in the order of 28% (0.94 = [ - 0.28]/[ - 0.228]), but since natural mortality would not be that high at such a low density, the added mortality was from hunting and it was this that caused the decline. Caniapiscau Herd

The distribution of animals to the east of Lac Bienville has been called the Caniapiscau herd. It was first located by Banfield and Tener (958) on 0 April 954 when 82 animals were seen just west of Schefferville (they called it the Kaniapiskau River herd). Des Meules and Brassard (964) found large numbers here in 963 but an estimate is not feasible since their methods had several biases. The next census was February 973, with an estimate of 2,745 animals (Pichette and Beauchemin 973). Brassard et al. (973) again counted the herd in April and estimated 2,700. Le Henaff and Martineau (98) counted 926 in 977, but Brown et al. (986) put the number at 600 animals in 977. Brown et al. (986) and Paré and Huot (985) spoke of a minimum range of 4,000 km² or, based on 2,700 animals, a density of 0.065 caribou/km². Recruitment for the Caniapiscau in February–March for the 976 and 978 cohorts was 9.9% ± 2.%, n = 2 years (Le Henaff and Martineau 98). Recruitment at 6 months of age for the 98–84 cohorts in October averaged 22.4% ±

The Abundance and Distribution of Sedentary Caribou | 89

Table 4.2

Mortality factors of radio-tagged females

Herd Name

Wolf Predation

Number of Females That Died from Bear Predation Poaching

Other¹

Caniapiscau Mealy Mountain Red Wine Lac Joseph

4 1 12 2

1 1 4 1

5 2 1

3 3 4 1

Totals

19

7

8

11

¹ Others: drowning, disease, and unknown. Sources: Huot and Paré 986, Brown 986, Hearn and Luttich 987, Veitch 990. Schaeffer et al. 999 listed  of 8 deaths 98–83 from wolf predation and 8 of 2 deaths from wolves, 993–97.

0.72%, n = 4 (Huot and Paré 986). Adult mortality based on radio collars was 6.2% (n = 6 females) in 977–78 (Le Henaff and Martineau 98); and 4.2% (n = 63) in 98–84 (Paré and Huot 986). Wolf predation was the chief cause of death 98–87 (table 4.2). Thus conservatively using the R from the 976 and 978 cohorts and mortality 98–87, λ = ( - 0.42)/( - 0.99) = .07. But census results indicated a decline 973–77 of 66% (2,700 to 926) or 76% (2,700 to 648). There is evidence that the flooding of Lac Caniapiscau starting November 98 and completed September 984 affected calf survival. The percentage of collared cows with calves seen each June was lowest after the initial flooding and then increased each year as flooding continued. The percentages were: 50% in 98 (n = 24); 68.4% in 982 (n = 9); 70.4% in 983 (n = 27); and 84.0% in 984 (n = 3). The overall percentage was 68.2 ± 0.966 (Huot and Paré 986). The percentage of cows with calves in June before flooding was 83.0% (n = 3) (Le Henaff and Martineau 98). In comparison the percentage of cows with calves in June for  cohorts in southern Ungava not subject to flooding was 78.6% ± 4.05 (three cohorts from Lac Bienville, two cohorts from Lac Caniapiscau, and six cohorts from the Red Wine herd). Our assessment is that initial negative impacts of the flooding were mitigated later by the presence of this lake. This large water body would have provided an open expanse in the winter for spotting wolves that would serve as antipredator habitat and provide shallow snow for escape. In the growing season the extensive area of open water and extensive shorelines would provide water escape after the reservoir cleared of ice. McPhadyen River Herd

A group of caribou distributed in the vicinity of the McPhadyen River was briefly studied by Phillips (982a) and St. Martin (987). St. Martin placed radios on 7 animals in April 984 and followed them until October 986. The notable obser-

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vation was that the animals showed little philopatry to their previous calving sites. Surveys were –5 June 984; 4–5 June 985; and 2 June–2 July 986. Mean distances (km) between calving areas were 55.8 ± 23.6 km (n = 5) in 984–85; 67.5 ± 3.80 (n = 4) in 985–86; and 44.3 ± 7.8 (n = 4) in 984–86. This lack of philopatry in contrast to other sedentary herds sheds doubt that such a scattering of caribou ought to be called a herd and managed as a unit. At any rate it needs to be explained. Lac Joseph Herd

The distribution of caribou in central Ungava has been called the Waco or Lac Joseph herd. The animals generally occupy an area south of the Smallwood Reservoir south to 5° N and between 66° and 62° W (fig. 2.7). The animals calved on the large muskegs and string bogs north of 52° N (fig. .) and wintered on the uplands and lichen woodlands on sand flats along river courses south of 52° N. Before the flooding of the Smallwood Reservoir in 969, these northern muskegs were the most extensive in central Ungava (fig. .). The winter movement was to areas of less snow cover in the uplands and also to more southern latitudes with reduced snow loads due to the oceanic effects of the Gulf of St Lawrence. The herd was first located in March 958 when Bergerud saw 82 animals within an 0.8 km census strip and estimated 500 animals north of 52° N (Bergerud 958). Other estimates between 964 and 972 included: 5,200 in December 964 – strip census (Brassard 972); 5,600 in 967 – total count (Brassard 972); 4,376 in March 968 – major groups counted (Brassard and Bouchard 968); 5,629 in March 968 – strip census (Brassard and Bouchard 968); 6,000 in June 970 (Pilgrim 98a); 4,000–5,000 in March–April 972, vertical photography (Brassard 972; Brassard and Potvin 977). The 970 census is the most reliable because of the random selection of census blocks and the low statistical variance. The best time to census is in June when the George River herd is absent and the animals are widely dispersed and stationary in the open, feeding on new greens. The counts between 964 and 968–70 suggested a stable population, given that methods varied. All the counts 964–72 suggest 4,500–6,000 animals. Assuming a total of 5,500 and a pre-Smallwood Reservoir range of 80,000 km², the density would be 0.06/ km². This density is the Ds for sedentary herds (figs. 4.6, 4.7). The Smallwood Reservoir possibly contributed a total loss of 6% of the range (4,500 km²), or possibly 0% of the calving range, and would have increased calving densities to > 0.0/km². After 972, the censuses – as well as hunting success and the number of caribou seen per hunter – indicated a major decline (table 4.3). There is considerable disagreement as to the figures. The most accurate census between 972–78 was a strip census in March 975 (Folinsbee 975) of 3,050 animals. We have used this figure and theoretical population estimates in 970 of 5,000, 5,500, and 6,000 along with estimates of R, and have calculated M schedules to generate popula-

The Abundance and Distribution of Sedentary Caribou | 9

Table 4.3 Census estimates, recruitment, and hunting statistics from the Lac Joseph herd (western Labrador region) Year or Cohort

1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978³ ¹ ² ³ ⁴

Population Estimate

Calves (%) Winter

5,200 – – 5,600 4,376, 5,629 – 6,000 – 4,000–5,000 2,100 – 3,050 – 1,000–2,000, 1,317 3,400, 562

– – – 16² – 9 6.9 12 10 19.8 10.6 – 6.7 14.6⁴ –

Caribou Seen per Hunter per Day

– 32¹ 12 10.3 7.6 7.9 9.8 13.1 10.1 7.8 8.7 5.6 1.8 2.5 0.5

– 8.5¹ 2.5 2.8 1.2 1.4 1.7 2.5 1.7 1.5 2.2 1.3 0.4 0.6 0.4

% Success

– 90¹ 46 50 38 45 40 51 59 62 49 47 15 18 24

First year figures appear biased. Observed March 968, hence 967 cohort population. Other census estimates were: 986 450 animals; 988 ,300 animals; and 2000 ,0 animals. Other calves recruitments: 998 .8%, 2000 7.4% (472), 200 6.2 % (73), 2002 4.9% (47), 2003 9.8% (96). Data from Nfld. wildlife reports and Schmelzer et al. 2004.

tion projections to better understand the decline between 970–75. The recruitment (R) in January–March averaged .5% for seven cohorts (table 4.3) and since this R was less than R s the herd should have declined (fig. 4.6). Our estimate of natural mortality was 3.4% based on the equation from Bergerud (988b) of M = 20/(.5 + 3.4). If we assume a maximum mean harvest of 400/5,000 = 7% (a harvest of 420 estimated for 975–76 [Folinsbee 976]) then λ = [ - (3.4 + 7.0)/ ( - .5)] = 0.899 and the generated population estimate for 975 is 2,900–3,500 animals (table 4.4), similar to Folinsbee’s estimate of 3,050 animals. To estimate the population changes 975–78 we can use the formula λ = ( - M)/ - R). Two estimates of hunting mortality are 76+ in 976–77; and 258 in 977–78. Hunting mortality would have been possibly 0% (300/3,000). R for the 976 cohort was 6.7% and for the 977 generation 4.6% (mean = 0.6). Natural mortality would have been 20/(0.6 + 3.4) and λ = [ - (0.0 + 0.4)/( - 0.06)] = 0.85. The estimated population in 978 was ,800. After the population was reduced by half by 975, we might expect wolf numbers to decline. A natural mortality rate of 4% for adult caribou is high. A possibility is that the herd declined so quickly from poor calf recruitment and over-

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hunting that there was a lag in the decline of wolves. The winter surveys of 975, 977, and 978 all stressed the abundance of caribou killed by wolves. The number of tallied wolves and their kills were: 7 kills and wolves present at 3 kills in 975; 0 kills and 4 wolves seen at 2 kills in 977; and 28 wolves observed in 7 packs and the density said to be 6 wolves/000 km², an extremely high and unlikely figure, in 978 (Folinsbee 975, 978, 979; Pilgrim 978a, 979a, b). The flooding of 4,500 km² of the Smallwood Reservoir in 969 appears to have reduced calf survival based both on the counts of calves seen per 00 females in June and the percentage of calves recorded in the herd in October–November or in March. Before flooding the percentage of calves in March 968 was 6% and in October 969, 6.9%. The calves/00 females in June 970 after flooding was 28/00 females (n = 7) and by March was only 8/00 females. The 97 cohort had 7.4% calves in November and 2% in March 972. The 972 cohort had only 20 calves/00 females in June 972. For comparison the Red Wine herd averaged 80 calves/00 females for 5 cohorts in June classifications (Veitch 990). Further analysis of the distribution of calves at Lac Joseph in June 970 showed no calves with 23 females in four sections flooded and 3.3 ± 3.28 calves/00 females in three sections not flooded (Pilgrim 98a). The four cohorts born after flooding averaged 8.8% calves or a 50% reduction compared to the two cohorts tallied prior to flooding. The loss of space and loss of philopatry seems to have resulted in expanded mortality of young animals. The recruitment of the herd remained below R s for the 974, 976, and 977 cohorts (table 4.3; fig. 4.8). This could still be an aspect of flooding but in addition there could have been a numerical wolf response. With the herd reduced by half in only five years, wolves may not have been able to adjust their numbers to the reduced biomass and would have remained at numbers above that predicted from ungulate abundance (Fuller 989). The high number of kills and wolves seen 975, 977, and 978 would be this numerical lag response. The major decline 970–75 was the result of the classic combination that has resulted in most caribou declines, over-hunting and low recruitment. Even without the high hunting losses after skidoos replaced dog teams, the herd would have declined from low recruitment. The loss of space and home range fidelity resulting from the Smallwood flooding appear to be at the centre of the recruitment failure. A more recent census was a fixed-wing strip survey of 22,000 km² of southern Labrador and Quebec in the winter of 988 (Renewable 989). Survey lines were between 53° N and 50°30' N and 65°45' W and 58°50' W. Coverage ranged from 2.5–5% (9,594 km flown) and a strip width of 0.5 km at 20 m altitude and speeds of 40–60 km/hr. Our estimate of the herd in 988 from their data is ,300 animals, or about 0.05/km². Such a low density (below stabilizing R) is further suggested based on R/M schedules documented by St. Martin 983–86 (R > R s and M < Ms). Recruitment from his classifications in late winter were: for the 983

PERCENTAGE CALVES (WINTER)

The Abundance and Distribution of Sedentary Caribou | 93

30

RECRUITMENT LAC JOSEPH MEALY MT. RED WINE

25 20

RS

15

RS

10 5

FLOOD SMALLWOOD

0 1960

1965

1970

1975

1985

1990

1995

2000

2005

1990

1995

2000

2005

HERD SIZE

5

LAC JOSEPH MEALY MT. RED WINE

DS LAC

4

EPH

JOS

3

YM AL

ME

2

T.

THOUSANDS OF CARIBOU

6

1980

DS

RED WINE

1

0 1960

1965

1970

1975

1980

1985

Fig. 4.8 A summary of recruitment and population trends for the Lac Joseph, Red Wine, and Mealy Mountain herds in Labrador from 1958 to the latest count in 2003. The recruitment for the Lac Joseph herd declined below RS coincident with the creation of the Smallwood Reservoir (references in text).

cohort, 20.% calves; 984, 23.%; and 985, 5.2% with mean = 9.5% ± 2.30% (34.5 calves/00 females). The mortality rate of radio-collared females for the interval April to April, 984–86, was 9.7% (four died out of 4). Thus R is greater than R s and M is less than R, which is the expected consequence of reduced densitydependent predation. The rate of change of the herd 984–88 can be estimated based on the R/M statistics gathered by St. Martin (987). With female mortality estimated at 9.7%, adult male mortality can be calculated from the equation Mm = Mf + (0.2627)R or Mm = 0.097 + (0.2627)0.345 = 8.8%. Males represented 30.0% of the adult popula-

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tion in three classifications in the autumn (n = 54 adults, table 4.), hence total adult mortality should have been 2.4%. With recruitment at 9.5%, the rate of increase of the herd should have been: λ = ( - 0.24)/( - 0.95) = .09. The most recent census in 200 was based on a Lincoln index (review Schmelzer et al. 2004). The count is not significantly different from that in 988, given the different technique used; the herd appears to have maintained its status 988–200. A summary of the population estimates, then, are about 5,500 in 964; 5,500 also in 970; 3,200 by 975; ,900 in 978; only 96 left in 985; and an increase to ,00–,300 by 988–200. Thus the herd probably was stable or increased in the years that the George River herd was present to shift hunting pressure. The density in 964 approximated Ds ; therefore there is no reason to believe a pristine population was higher. Apparently in the many years between the building of the Schefferville railroad – but prior to use of skidoos – the herd maintained numbers in the face of native hunting. The flooding of the Smallwood Reservoir appears to have reduced recruitment at the same time that the skidoo replaced dog teams and heavy (excessive) harvests commenced. Dominion Lake/St. Augustin Herds

In March 958 Bergerud observed 24 caribou near the St Augustin River and 23 animals near the Mecatina River (Dominion Lake herd). The St Augustin herd is said to range west to the Mecatina River and the Dominion herd to occupy the space between the Natashquan and Mecatina Rivers (Folinsbee 979). Both herds may have calved as far north as the Churchill River. Some animals from the Red Wine herd have at times been located just south of same river (Brown 986). Bergerud (967) estimated the two herds in 958 based on stratified sampling at 50 animals each with perhaps 200 more scattered (Bergerud 958). The estimate seems low in light of the work done in the years since and also with the reported harvest at the time. We have recalculated the results, pro-rating the 47 animals seen in the transect to the entire area of tracks, or 22,800 km² – an unstratified census. The census lines included 382 mi² or 989 km², or a density of 0.0475/km² (47/989), or an estimate of ,00 animals. This density seems more reasonable than the previous estimate of 0.02 km², which is far below Ds of 0.06/km². In 958 the animals were still relatively safe, lost in space in those halcyon days before skidoos changed travel (and hunting mobility) in the North irrevocably in the 960s. At the time of the 958 census, the calves in the 957 cohort represented only 6.9% of the herd (2 in 29 animals). The reported kill from St Augustin, St Paul, and Natashquan was 26 animals for 956–57, statistics more consistent with a density of 0.05/km² than with 0.02/km². In 963, 943 animals were observed near Natashquan and in 972, 46 were estimated near Mecatina and St Augustin Rivers (Des Meules and Brassard 964;

The Abundance and Distribution of Sedentary Caribou | 95

Brassard 972). Prior to the 972 estimate of 46, a herd reportedly numbering 500 animals was heavily exploited by hunters from St Augustin (Folinsbee 979). Again, the original estimation in 958 seems too low. Exploitation of these herds continued by both Labrador and Quebec residents until the herds were virtually extirpated (Folinsbee 979). Ten years later in February 983, Barnard (983) counted caribou and moose in fifteen 60-km² blocks; he saw only 0 caribou (0.0/km²). In 988 Renewable recorded tracks in 0 areas from the Natashquan east (excluding possibly Mealy Mountain animals). The total area might represent 22,000 km² and based on 0.0/km² there may have been 200 animals remaining in this area at the start of the 990s. Caribou still existed there in 2003 (Schmelzer et al. 2004). White Bear Lake Herd

In the 958 survey, six track groups were located west of Makkovik/Postville in an area of ,000 km² (Bergerud 958). The winter locations of the animals reported by hunters in 958 were Double Mer Barrens, Three Knobbed Hill, Lake Michael, Metchin Nepee, Marrow Bone Hill, Spout Lake, Gerald’s Hill, White Bear Lake, Micmac Hill, and Ghost Lake. These sites cover a total area of 2,000 km². The harvest of this herd in the 950s was: 8 animals in 954 (4 groups); 25 in 955 (22 groups); 407 in 956 (26 groups); and 403 in 957 (3 groups), a mean harvest of 277 animals. If the entire range of the herd was 7,000 km² and Ds was 0.06/km², the total was ,000 animals. Possibly this herd was being over-harvested even as early as the 950s, but there was some confusion, since the Mealy Mountain herd was then crossing Hamilton Inlet and some of the hunters thought animals were moving into their area – this is reflected by the increase in groups seen 954–57. The herd became extinct in the 970s after the skidoo replaced the dog teams. In figure 2.7 you will see that the sedentary ecotype has also disappeared from the James Bay side of the distribution – another example of the extinction of accessible animals. Red Wine Herd

The Red Wine animals ranged in the early 980s in an area of about 25,000 km² in central Labrador (Brown 986). The range was bordered by the Churchill River to the south, the Kanairiktok River to the north, Grand Lake to the east, and the Smallwood Reservoir (Lake Michikamau). In the first survey in 958 we located 8 track groups in the Red Wine Mountains and saw 3 animals between the Kanairiktok and Naskaupi Rivers (Bergerud 958). At the time these animals were listed with the northern migratory ecotype (the George River herd). There were 5 transects across the distribution for a searched area of 53 mi² or 395 km². This scan gives a density of 0.08/km² (3/395), a density above Ds, and an estimate of 880 animals (,000 km² x 0.08).

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Table 4.4 The population estimates and recruitment of calves in late winter of the Red Wine and Mealy Mountain caribou herds Year Herd Counted

1958 1968 1974 1981 1983 1984 1987 1989 1993–97 1997 2001 2002 2003

Red Wine Herd Total % Population Calves

880 900 no count 751 736 796 610 687–741 151 72–189 no count no count – – – – – –

11.9 (84) no count 12.5 (170) 21.0 (366) 16.8 (285) 16.4 (305) 19.2 (367) no count 8.9 (±2.38) not known 12.5 (64) 18.8 (50) 26.9 (92) – – – – – –

Year Herd Counted

1958 1959 1960 1961 1962 1963 1970 1971 1974 1975 1977 1981 1985 1987 1989 1990 1994 1997 2002

Mealy Mountain Herd Total % Population Calves

2,600 no count 1575 no count no count 833 788 800 264 284 207 701 no count 1,932 no count no count too low too low 2,585

11.0 (476) 15.0 (595) 13.0 (476) 11.0 (469) 14.0 (323) 4.0 (336) no count 26.1 (69) 14.8 (81) 21.1 (284) 20.9 (67) 18.3 (409) 22.7 (759) 17.7 (1371) 12.2 (727) 12.0 (741) 12.8 (492) no count 28.8 (118)

Sources: Bergerud 967, Hearn and Luttich 987, Schmelzer et al. 2004.

Other census estimates (table 4.4) are: 900 in 968 (Folinsbee 974); 75 in 98 (Phillips 982b); 73 and 796 both in 983 (Brown 986); 60 in 987; 74 in 988; and 659–687 in 989 (Veitch 990). The regression of numbers on years (958 to 989) is Y = 5,253.24 - 7.32X, r = -0.8258, P < 0.05 with 6 df. The last censuses in 997 and 2003 showed 00–5 animals, and the population appears headed for extinction (Schaefer et al. 999; Schmelzer 2004). A complete set of population dynamic figures was gathered by Brown (986) and Veitch (990) and summarized by Schaeffer et al. (999). The percentage of pregnant females 982–88 based on calves seen with radio-collared females was 79.9% (n = 96), certainly a minimum figure. Mean recruitment at 0 months of age for 4 cohorts 980, 982, 983, and 986 was 8.5 ± .8 (37.8 calves/00 females). The total mortality of radio-tracked females for 6 years was 7.4% ± 5.05%. The major loss was from wolf and bear predation (Veitch 990; table 4.2). The sex ratio of adults was 36:64 based on fall classifications in 5 years (table 4.). The mortality rate of males should be about 27.3% [Mm = 0.74 + (0.2627)0.378], which makes the total mortality of adults 2.2%. The finite rate of increase, then, for the

The Abundance and Distribution of Sedentary Caribou | 97

years prior to 989, is: λ = ( - 0.2)/( - 0.85) = 0.97. The decline 989–97 (687 to 5) in 0 years is λ = 0.86 Schaeffer et al. (999) felt that the huge decline in numbers between 989– 97 could have been partly affected by emigration of Red Wine animals to the George River herd. We strongly disagree that the sedentary ecotype, with their different antler morphology and body dimensions (table 2.6), would permanently emigrate. Philopatry to individual calving areas is an essential characteristic of the sedentary ecotype. When the George River herd entered the range of the Caniapiscau herd in the 980s some radio-collared females did go north with the George herd (as far as 525 km) but all returned for calving (Brown et al. 986). The evidence for the emigration of the Red Wine animals in the 990s consists of five radio-collared Red Wine females who joined George River animals in October and November and moved ≥200 km beyond the Red Wine range. However, one of these females returned and the other four died within months while still north of the traditional Red Wine Range. Two of the remaining four females had turned around and were moving south before they died; they had left the George River animals still going north (both groups had satellite collars providing location at daily intervals). To demonstrate egress it must be shown that the animals did not return to show philopatry at calving. The 80% death rate of the five Red Wine females may well mean that their sedentary lifestyle was maladapted to the constant mobility of the migratory ecotype and the degraded flora of the George River range (chapter 7). Schaeffer et al. (999) provided sufficient demographic statistics to evaluate an internal herd explanation for the decline of the herd of λ = 0.86. Their data for the period 993–97 listed () 7% of the cows were pregnant; (2) the recruitment of calves was 8.9% (7.0 calves/00 females); (3) annual survival rate of females was 70%; and (4) the sex ratio of adults was 40 males to 00 females. The male mortality rate should be Mm = 0.30 + (0.2627)0.70 = 34.4%, or a total adult mortality rate of 3.2%. Calculating λ = ( - 0.32)/( - 0.089) provides a rate of decline (λ) of 0.76, even lower than the decline of 0.86 that was based on the two censuses (989 and 997). The decline was caused by internal demography; egress was not needed as an explanation. The population parameters of the herd were deteriorating rapidly after 989. Nor can this headlong rush to extinction be attributed to disturbance by low-flying jet aircraft (see Harrington and Veitch 992). These flights had been on-going for years prior to 993, during which period the herd’s numbers had remained relatively stationary. There is an additional explanation for the negative demography that occurred in the 990s. These are the years that the George River herd invaded the range of the Red Wine herd (fig. 4.9). We noted, as have other biologists, that the expansion of moose into woodland caribou habitat has enhanced wolf predation of caribou and resulted in declines. The Red Wine population in 989 was 700 and holding its own with a density of 0.02–0.3/km² (based on 25,000–46,000 km²

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0 0

50

100 KILOMETRES 50

100 MILES

HAMILTON INLET

RED WINE LAKE MELVILLE 2600 (2002)

800 (PRE-1987) 150 (2003) ROAD

MEALY MT. GEORGE RIVER HERD SOUTHERN BOUNDARY 1100–1300 (1988–2002)

LAC JOSEPH RAILROAD

Fig. 4.9 In some years in the 1990s the George River herd invaded the range of the Red Wine herd. Earlier in the 1980s the Red Wine herd occupied 25,000 km² north of the Churchill River (Brown 1986). However, since about 2000 the herd has been said to range 45,000 km² (Schmelzer et al. 2004), even though only 150 animals remain. This enlarged range may have included the distribution of calving females not originally included in the herd’s range north of the river in the 1980s. It is unlikely that females shifted their calving locations. Also the Red Wine Mountains were no longer the centre of the herd’s distribution in the late 1990s after the herd had declined. The fig. includes the most recent census results and distributions of the Mealy Mountain and Lac Joseph and Red Wine herds based on Schmelzer et al. (2004).

(from Brown et al. 986 or Schmelzer et al. 2004). The population was at or below its stabilizing density and recruitment had been adequate (table 4.4). The George River herd in several years of the 990s abrogated the spacing strategy of resident animals. This increased ungulate biomass should have resulted in an increase in wolf numbers (a numerical wolf response). When the George animals left the area to migrate to their calving ground, the wolves would be left behind to den, resulting in an increase in the functional predator response directed at the remaining Red Wine animals. Calf and adult mortality would have skyrocketed.

The Abundance and Distribution of Sedentary Caribou | 99

Schaefer et al. (200) reported that the three sub-populations of the Red Wine herd that overlapped the George River distribution in the 990s had increased mortality compared to the one sub-population that had the least overlap in distribution. As a result the distribution of the Red Wine herd in the 2000s is no longer centred on the Red Wine mountains but is mapped much farther south (fig. 4.9, Schmelzer et al. 2004). Schaefer et al. stated that their results reiterated that refugia from other ungulates may be important in the persistence of taiga dwelling caribou. This concept is consistent with the theory that an increase in species diversity results in caribou declines, be it moose or white tail deer (Bergerud 2000); and perhaps we can also add caribou of another ecotype to that list. Such a scenario might synchronize declines of both ecotypes. When the migratory herds reach high numbers prior to a density-dependent decline, they commonly invade more southern ranges in winter, and possibly thereby affect the demography of the sedentary ecotype. These analyses admit a shortcoming, however, and that is that no one has censused wolves in southern Labrador in the 5 years since the first caribou census. We should be wary, at the very least, of drawing the boundaries of a “discrete herd” based on radio tracking collared animals when those animals are captured in different seasons and at different locations. Brown (986) captured his Red Wine animals in March 982 and 983 on the Red Wine Mountains and constructed the boundaries of the “herd” based on their movements. The animals that were radio tracked in the 990s were captured during the growing season in more lowland habitats. Some of these later animals, who had not previously been assigned to the Red Wine herd, calved south of the Churchill River. Thus the map locations of these different cohorts implies that the herd has shifted its distribution south, whereas a segment of a continuous distribution to the north has experienced a major decline (fig. 4.9). If we are counting animals and comparing demography from a continuous distribution based on radio tracking animals captured at two different time periods and locations there could be considerable noise in the demographic data. In 986 the Red Wine herd ranged over an estimated 25,000 km² north of the Churchill River (Brown 986); in 2003 that estimated range was over 46,000 km² – much of it south of the Churchill River (Schmelzer et al. 2004) – and yet censuses indicated an 80% decline between 989–97 (table 4.4). Brown (986) and Theberge (989) presented a laboured argument that the Red Wine herd faced a major limiting factor with the deep snows and forage problems – a so-called “nutrient-climate ceiling.” Veitch (990) did not agree; nor did Schaefer et al. (999); and nor do we. The winter with the deepest snow cover was 984–85 (Veitch 990) and that was the winter that all the radiocollared cows survived (Veitch 990). And, in fact, the survival rate of the females was higher in the winter than in the summer, at 0.92 ± 0.075 vs 0.894 ± 0.0706. The correlation between winter mortality rates and snow cover for six years was

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r = -0.84. The blood parameters that Brown (986) presented showing the animals in poor condition are not valid indexes to nutritional welfare (Messier et al. 987, see also Veitch’s comments). If animals were winter-stressed, some calves would be inviable at birth (Miller 974) or more susceptible to predation (Adams et al. 995a, b). Yet calf mortality was so low that the calves/00 females seen in June approximated parous percentages for caribou. The correlation between calves/00 females in November and December and the prior winter snowfall was r = 0.520 (n = 5). The more snow the previous winter, the more calves who lived until the following fall. Nor did calves starve in the winter. Calves/00 females in November 982 was 23, and in April, after a hard winter (558.9 cm), the ratio was 30; in December 986 there were 22 calves/00 females, and following a mild winter (374.5 cm) there were 42 calves/00 females. With a winter starvation hypothesis, adult males should starve more than females (Bergerud 980) but the sex ratio for the Red Wine herd was 36:64, the normal expected ratio (Bergerud 980). Note also that the parous percentage of 80% is normal, whereas pregnancy rates declined below this figure recently in Alaska following hard winters and late springs (Valkenburg et al. 994; Adams and Dale 998a). The caribou of the Red Wine provide some insight on how well caribou can cope with deep snows above the so-called threshold values reported in the literature, but this deep snow cover neither limited nor regulated numbers. The herd faces extinction for the classical reason, as the well-documented case-history study attests, and that is increased predation (Veitch 990; Schaefer et al. 999). The light at the end of the tunnel is that density-dependent predation should moderate at very low numbers because of the spacing of females and the concomitant increase in calf survival (table 4.4). But when that point is reached, all hunting must be prohibited and the restrictions enforced. Once the tradition of a spaced-out calving range is lost, it is nearly impossible to recover. Mealy Mountain Herd

The Mealy Mountain herd ranges in a 22,000 km² area south of the Hamilton Inlet, west to the Kenamu River, and east to Sandwich Bay. The herd has been censused  times between 958–2002 with recruitment measured for 6 cohorts (table 4.4). The herd declined from 2,600 in 958 to 833 in 963, λ = 0.80 (Bergerud 967). The estimated hunting mortality was 26% and natural mortality was 5% in this decline, with R .3 ± .6% (n = 6). The herd remained stable in numbers 963–7 in the absence of hunting: 833 animals in 963; 800 in 97. Why didn’t the herd increase with the addition of eight cohorts when densities were only 0.036/km²? The predicted mean R for the eight cohorts was 9.2 (fig. 4.7), which would have provided λ = .07 (fig. 4.5). The low recruitment of the 963 cohort (4.0%) could possibly have resulted from the rapid decline from hunting, concentrating natural predation losses. Illegal hunting must have continued (season closed 965–72). If λ = .00 based on censuses

The Abundance and Distribution of Sedentary Caribou | 0

and R projected as 9.2, the total M would have been 9%, a high mortality percentage for natural causes only. From 97–74 the herd decreased λ = 0.69 (800 to 264), even though the 973 cohort was 4.8% calves, sufficient to maintain numbers. Hunting must have continued in 97 and 972 at densities of 0.02 to 0.04/km². With only 200–300 animals remaining (0.0/km²), the law of diminishing returns could have ended the illegal harvest: Surveys in January and March 975 and in December 977 showed that remaining animals were mostly in the Mealy Mountains where they would have been difficult to access (Pilgrim 978b, 980). This retreat to the mountains gives us an important insight into caribou biology. Range extensions/contractions into sub-marginal/optimum habitats are a major theory of stability for the species (Skoog 968). When numbers are low and phytomass above tree line is sufficient, the animals retreat to their centre of habitation, where they are most secure from natural predators. This is the first time, however, that this concept can be applied to a sedentary population, and not only did the retreat succeed in moving R > M for natural predation, it succeeded in removing it for local hunting as well. Apparently the Mealy Mountains are sufficiently rugged that even in the day of the skidoo there are places hunters can’t follow. With a retreat to optimum habitat, the R for the 973, 974, 977, and 980 cohorts was 4.8, 2., 20.9, and 8.3 respectively, with a mean of 8.8 ± .47 (table 4.4) and λ should have been .06 (fig. 4.5). When the George River was low in numbers in the 930–40s its centre of habitation was east of the George River and included the Torngat Mountains. Skoog (968) gives other examples. Both the Western Arctic and the Kaminuriak herds remained mostly above tree line when numbers were low (Simmons et al. 979; Davis et al. 982). Both the numerical and functional responses to wolf predation are reduced when animals move from sub-optimum habitats below tree line (the lichen pastures) to optimum environments above tree line (Bergerud 996, 2000). The return of the population from 70 in 98 to ,932 in 987 must have included a lag in searching by predators and hunters. Census results and R/M schedules give different rates of increase. From census results λ = .8 (70 to 932), but from R/M comparisons λ = .04. In the calculation of λ = .04, recruitment for two cohorts was 22.7 (984) and 7.7 (986), providing a mean of 20.2 ± 0.97 (37.3 calves/00 females, data from Hearn and Luttich 987). The M for radio-tagged females was 5.0% and the mortality rate for males should have been 24.8% [Mm = 0.50 + (0.2627)0.373]. The ratio of males to females for three classifications (98, 985, and 987) was 37:63; hence total adult mortality is estimated at 8.6%. Therefore the final estimate of λ based on R/M comparisons is λ = ( - 0.8.6/ ( - 0.202) = .02. The discrepancy between λ = .8 and .03 could be explained if the radio-tagged animals had higher mortality rates than the untagged. The total mortality rate of the combined males and females would have had to be only 6% for λ = .8.

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The R for the 988 and 989 cohorts was only 2% and λ should be 0.94 (Bergerud 992). Such a decline is expected with densities such as those in 987 of > 0.08/km² (see Hearn and Luttich 987). The herd should have declined naturally regardless of hunting mortality until Ds was reached or 0.06/km² (or ,300 animals). Predation is density-dependent and drives both R and M schedules. Luttich had noted in 987 that wolves were increasing. A census in 994 gave only 500+ caribou. Apparently the herd had been over-harvested once again after a 0-year increase (fig. 4.8). In 2002 the herd was censused at 2,600, the same figure we saw at the start of management in 958 (Bergerud 967; Schmelzer et al. 2004). But what happens now? Will we repeat the mistakes of the past? If we manage both hunting and wolves could we have an eruption similar to that witnessed on the Avalon Peninsula in Newfoundland, where Avalon Wildlife Officer M. Nolan halted illegal hunting and the herd increased from a mere 7 animals in 956 (Bergerud personal files) to 7,000 over the course of 30 years? Now that there is a road to reach the herd, will we have better law enforcement or, on the other hand, will we simply provide better access to illegal hunters? We can only hope that the law of diminishing returns once again saves the Mealy herd from extinction. Population Regulation and Management The survival of calves of the sedentary ecotype in Ungava was density-dependent. A nonlinear relation existed between recruitment and the density of the population determined by dividing numbers by the square kilometres occupied by the herd at parturition (fig. 4.7). At extremely low densities of 0.0–0.03/km² the percentage of calves in winter was greater than R s since the stabilizing recruitment of 5.6% calves occurred at a density of 0.06 animals per km² (figs. 4.6, 4.7). This density is greater than the densities of 0.03/km² for the herds reported by Brown et al. (986); thus an increase in the populations could have been expected in the absence of significant hunting losses. We believe this density-dependence in calf survival relates to the success of wolves and bears in searching for calves dispersed with their cows in spring and summer. This hypothesis has been proposed for the sedentary ecotype that disperses in mountains in British Columbia, Alberta, and Alaska (Bergerud et al. 984; Edmonds 988; Adams et al. 995a), and is consistent with the improvement seen in calf survival in British Columbia when wolves were reduced in numbers (Seip 992). The primary cause of the natural mortality of adults in the Ungava herds was predation (table 4.2). These natural mortality rates (table 4.) should also be density dependent, but as yet no one has monitored mortality rates over a long enough period and range of densities to test the relationship. The only herd that has fluctuated sufficiently since data on mortality rates could be secured

The Abundance and Distribution of Sedentary Caribou | 03

from radio-collared animals has been the Mealy Mountain herd (fig. 4.8). However, the emphasis in research in recent years has been directed to the Red Wine herd (Brown 986; Vetich 990 Schaefer et al. 999) for political reasons – i.e., the native peoples’ concern about the negative impact of low-level jet aircraft flights from the Goose Bay NATO base (Harrington and Veitch 992). These fears did not stand the test of scientific enquiry, however; increased predation was the explanation for the decline of the Red Wine herd, and the decline was not compounded by disturbance interactions. The stabilizing density of 0.06 caribou/km² should also be relevant to historical densities if the predator fauna was similar to the present. It is difficult to evaluate if there have been past fluctuations other than those caused by over-hunting. The early travellers in southern Ungava in the 800s generally spoke of the scarcity of deer (Low 898; Hubbard 908), but they were summer travelers, when even a normal density of only 0.06/km² would make deer seem scarce. Then when the animals were encountered in the winter they would seem common because they were concentrated and aggregated on ranges with low snow profiles. One might even generate cycles of abundance by comparing summer vs winter observations in different time frames. When the Mealy Mountain herd was rapidly declining 958–63 it was impossible to convince local hunters that the herd was crashing. As the herd went down it shifted to the south shore of Lake Melville in winters to avoid deep snows. In December and January 958–59, 700 animals were taken on these lowland flats, and an additional 200 were killed south of the Mealy Mountains. Together these excess kills removed one-third of the herd in a single season! And yet the hunters had never seen so many caribou, with such easy access on the sea ice up Lake Melville (Bergerud 967). Indeed, the herd appeared so abundant that the hunters refused to believe our census results. As a result, the harvests 958–63 precipitated the decline from 2,400 animals in 958 to < 800 animals by 963 (fig. 4.8). The problem is that it is impossible to gauge the abundance of the sedentary ecotype based on changes in distribution in the winter when they may be massed in a small area and thus seem superabundant. But even as a populations declines, the animals still maintain the extent of their spring and summer distribution. Individuals are farther apart and thus present a truer picture of population densities. It is this spacing that drives the mechanics of density-dependence in encounter rates with predators. Over-hunting thus is a real problem for this ecotype and remains today the major limiting factor for the sedentary herds in Southern Labrador (Schmelzer et al. 2004). The winter distribution of the migratory herds changes between winters, increasing unpredictability for searching hunters. But sedentary animals do show considerable fidelity to the same low-snow winter ranges. Neither white settlers along the Labrador coast nor people of the Innu Nation (Montagnais and Naskapi) have shown any harvesting restraint when they have encountered the

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winter herds. Possibly the historically-low numbers of this ecotype plus the lack of alternative food supplies has led to the practice of killing whatever one can at the moment. But abstaining from harvesting will not increase the herds if the animals are maintained by predation at a density of 0.06/km². Only when densities are below 0.06/km² would numbers respond. The equation at higher densities is asymmetrical: Herds will not expand as a result of conservative harvests, but they will decline when harvesting is added to natural deaths. In 2004 a caribou recovery plan was published for the three major herds in Southern Labrador: the Red Wine herd, the Mealy Mountain herd, and the Lac Joseph herds (Schmelzer et al. 2004). The recovery team was composed of 6 members, including native representatives. The proposal is comprehensive and reflects a broad understanding of caribou biology and the scientific literature, and primary credit is due to the senior author, biologist Isabella Schmelzer (Cornerbrook, Newfoundland). The problem of illegal hunting is fully addressed. However, the other major limiting factor – wolf predation and management – is only mentioned in outline form. The proposal states that “because of the sensitivity and uncertainty associated with predator control it will not be undertaken unless () the herd is at risk of extinction; (2) the predator populations are themselves at risk; or (3) continuous long-term predator control is deemed necessary for the long-term recovery of the herd. Relative to the third point, Aldo Leopold, the father of wildlife management, defined (game) management (Leopold 948, 452) as “the art of producing sustained annual crops of wild game for recreational use.” In other words, wildlife management is not a one-shot deal; it must go on and on if a harvestable game population is to be sustained. The recovery analysis states that (p. 40): “non-aboriginal people, especially those with longstanding associations with roots in Labrador, would like to see the recovery of Labrador woodland caribou to a level that would support a hunt” (the season has been closed since 976). It is ethical in management to periodically reduce wolf populations to secure sustained yields of caribou which would also support a greater number of wolves between reductions since wolf numbers depend on the ungulate biomass (Fuller 989). Certainly the situtation of the Red Wine herd – which is facing extinction at possibly only 00 animals and needs wolf reduction now – is relevant to the report’s control condition () for wolf management. When the last animal is lost, so is the philopatry to that range (as happened with the White Bear Lake herd). The second area that should be considered for predator management is the area south of Lake Melville. The Mealy Mountain herd has recovered to its 958 herd size of 2,600 animals, having previously declined due to over-hunting and low recruitment (Bergerud 967). The decline this time will again include reduced calf survival since the herd is well above the predation stabilizing density of 0.06/km² (fig. 4.8). Illegal hunting could skyrocket when the planned road is constructed from Goose Bay to Cartwright, threatening a repeat occurrence of the 958–63

The Abundance and Distribution of Sedentary Caribou | 05

crash. It will require increased monitoring, law enforcement and wolf management to maintain the herd and build the population higher to provide reliable, substantial harvests as outlined in the recovery goals. Since long-time residents of the Labrador coast still have a close affinity with the outback and trapping and hunting remain major activities, we believe that if they were canvassed and informed that reducing wolf populations would increase the supplies of caribou they would embrace the plan – possibly even reduce poaching – regardless of the public criticism elsewhere. The irony is that these herds do not have food problems at such low densities and could exist at densities > /km² if natural predators were managed. The range that is presently north of high moose and deer distributions still comprises 600,000 km² (fig. 4.2), and with wise harvest management there is potential for 40,000 animals instead of the current 5,000+. If wolves were managed, a half million animals could be supported on the range. On the Slate Islands in Lake Superior, a caribou herd inhabiting a spruce-fir boreal forest in the absence of wolves maintained an average density of 7 caribou/km² over a 27-year period (extremes were 3 to 7 animals per km² [Bergerud 200]). Habitat is not the limiting factor, predation and illegal hunting are. Unfortunately public sentiment in many parts of Canada no longer sanctions the harvesting of wolves, either for pelts or for maintaining caribou herds, and this view has been incorporated in the Newfoundland/Labrador caribou recovery plan (see Schmelzer et al. 2004). We could have so much but without management, we will have very little. Instead we’ll travel the endless miles in a vast wildness of lakes, muskegs, and conifer forests without sighting either the major native ungulates or their predators. It will remain “a hungry land.”

CHAPTER FIVE

Past Population Fluctuations

Postglacial Distribution of Ungava Caribou The late Wisconsinan ice sheet began to decay in Ungava prior to 9,000 BP, and the northern coastal sections were free of ice by 9,000 BP (fig. .8; Ritchie 987; Faunmap 994). The upper George River deglaciated 8,500 years ago and created Lake Naskaupi, which collapsed about 7,000 BP (Clark and Fitzhugh 990). However, there were still some ice remnants and large glacial lakes 5,000 BP that would have impeded the movement of caribou (Jordan 975; Samson 978; Lauriol and Gray 987). Even though temperatures were warmer than at present, it took hundreds of years for primary plant succession to accumulate sufficient organic matter for herbaceous plants. Sparse tundra Cyperaceae developed at Indian House Lake by 4,000 BP followed by an invasion of spruce and larch by 3,800 BP (fig. .8, Samson 978). Ancient Indian hunters of the Maritime Archaic culture were at Indian House Lake (fig. 5.) waiting for migrating caribou by at least 4,000 BP, although their position was precarious until 3,800 BP, when trees provided shelter and fuel for fires. Indian House Lake continued to be used as a focus for hunting for the next 2,500 years. Two sites show artefacts that may come from the Point Revenge culture (see fig. .3) and there is one site that shows occupation by Dorset people (palaeo-Eskimo). A pre-Algonkian culture hunted the area ,400–900 BP, but the Indian House crossing was unoccupied from 500–800 AD , possibly because of the southern extension of the Dorset culture to Hamilton Inlet about 500 AD (Samson 978). The modern Naskapi arrived at the site in about 839 AD , perhaps

Past Population Fluctuations | 07

NEAR TREES

RUNNING OUT

NAIN PEOPLE DROVE ANIMALS INTO WATER 1790

WEDGE POINT

AUGUST DISPERSAL

LAC MISTINIBI

INE

EL

N

INDIAN HOUSE LAKE

TRE

Fig. 5.1 The locations where natives speared caribou at Indian House Lake and Lac Mistinibi in late summer and the fall in eastern Ungava from 1700 to 1900 AD. Most of the camps were on the west shore of Indian House Lake (Lac de la Hutte Sauvage) so the hunters could see the animals coming from the east (based on Cabot 1912, Taylor 1969, 1979, Samson 1978, Loring 1997).

BELIEVED TO BE LAKE TURNER

CROSSINGS MAJOR CAMPS MINOR CAMPS

0 0

10

20 KILOMETRES 10

20 MILES

in response to the establishment of a string of Hudson Bay trading stations by J. McLean. The Naskapi (Mushuau Innu) were the most important ethnographic group that specialized in interior caribou hunting, and the remains of 780 habitation structures at 49 different locations averaging 20–25 tent rings/site have been located at Indian House Lake (fig. 5.). This is an interesting figure in light of the generally small band size. Clearly the people moved up and down the lake in response to the crossing of caribou in the mid-summer and fall migrations. When Mrs M. Hubbard (908) visited these Indians in 905, there were 30 people in camp. In 90 when Cabot (92) visited the Indians there were possibly 20 tents and nearly everybody was still on the land. However, the Naskapi deserted the crossing in 96 (Elton 942) when the caribou crossing failed. As late as 945 Rousseau (949) thought four to six familes had hunted the area recently. These Naskapi probably stopped relying on spearing or shooting swimming caribou after 96, for when Strong (930) travelled with Naskapi Indians in

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927–28, they were winter hunters using dog teams and rifles. Banfield and Tener (958) observed the Naskapi near Mistastin Lake in the winter of 954; Bergerud visited them in 958 in the same area; and Henriksen (973) lived with the Davis Inlet band between 966 and 968. The Naskapi are true caribou Indians whose mythology can give us insights into the past distribution of caribou. In their mythology, the caribou resided in the summer at a high mountain called Caribou House. The Indians of the Ungava Band (fig. .4) – those who hunted on the Koksoak River – thought that this mountain was located in the interior between Ungava and Hudson’s Bay in a distant country where no Indians would go, within a range of mountains pure white in colour formed not of snow, ice or rock but of caribou hair (Speck 935). But Waspistan Diem of the Barren-Ground Band – those who hunted the upper reaches of the George River (fig. .4) – told Speck that the mountains were partly of stone and caribou hair and were near the sea between Ungava Bay and the Atlantic Ocean. This tells us that two groups of Indians waited at two different crossings and both thought that the home of the caribou was in a bleak treeless barren from which they came in the late summer with fall migration. Strong (930) indicated that the Naskapi believed the Caribou chief of all the deer lived up in the north-eastern barrens, on a high mountain known as ahtee-whi’ch-oo-ap or Caribou House. Here the caribou summered, and when the overlord was pleased, he allowed the deer to come out of the country in the fall, passing between mountain portals near Caribou House. If the overlord was displeased by the smell of the annual slaughter at Indian House Lake, he refused to let the herds come south. Even as late as 906–0, the Indians took some precautions to cast the caribou remains into the water so as to not displease the Caribou God (Cabot 92). This mythology would not have evolved in only the most recent occupation of Indian House Lake (839–96); rather it must have preceded that period by many generations. The Indians always looked to the east or north for the migration of caribou in mid-summer or fall. Nearly all the campsites and lookouts at the crossing of Indian House Lake are on the western shore (fig. 5.), even those that are very much older and date from the time the lakeshore was 06 m, 5 m, and 22 m above the present shore (Samson 978). The caribou have summered northeast of the Lake since they returned possibly 7,500 years ago and probably moved back and forth across the lake at least 4,000 years ago. This pattern has persisted whether the climate was colder or warmer than at present. We can also surmise that the caribou have crossed the upper Koksoak for many hundreds (possibly thousands) of years, since the hunters at these crossings also believed that their Caribou House was on the Upper Ungava Peninsula. The Indians seldom ventured out into the tundra, and because the historical boundary between the Indians and Eskimos was in the vicinity of the Leaf River (Speck 935; Vézinet 979), the Indians at the Koksoak would not have been aware that the caribou that calve

Past Population Fluctuations | 09

on the Labrador Peninsula were the same animals that they saw moving west in the fall. The failure of the migrations after 900 (Elton 942) would not have been the sole basis for the belief that the Caribou God had to be pleased to allow the caribou to come south to Indian House Lake. The mythology of the Naskapi suggests that caribou abundance has fluctuated back through time. The migrations of caribou are commonly characterized as unpredictable. However, the Indian House crossing is in juxtaposition to the calving and summer range, and when these summer ranges are fully occupied even a short southern movement in the autumn would bring the animals to the lake. The failure of the animals to cross Indian House Lake would indicate that the herd had declined in numbers, had become more sedentary and had abandoned its westerly trek, remaining instead near the summer and calving range or moving south of tree line west of Nain in search of lichens. We believe that the George River herd has traditionally summered northeast of Indian House Lake for the past 7,500–4,000 years and has probably from the beginning been hunted by native peoples. During this time, numbers have fluctuated sufficiently that major migrations have ceased and native peoples without alternative food sources have faced famine. Historical Distribution As migratory caribou herds increase they expand their distribution south of tree line (Skoog 968). The correlation between caribou numbers and the size of annual ranges was r = 0.805, P < 0.00, for 4 herds in North America (Bergerud 980). In fact the regression was linear: One could predict the total animals if one knew the total range. Thus a tool is available to postulate past numbers if the former distributions are understood. As the George River herd increased 974– 84 it expanded its range (Messier et al. 988). We have used information on both the distribution and abundance of the George River herd 974–94 to postulate historical numbers based on the distributions of caribou recorded by early travellers in Ungava (such as John McLean who travelled the interior 838–40 AD , and A.P. Low, who surveyed the coast from Richmond Gulf to Fort Chimo, now called Kuujjuaq, in 896. Extensive historical reviews are available in Elton 942, Harper 96, and Trudel and Huot (eds.) 979). During the years 958–93 the herd was available year-round to eastern hunters when it numbered less than 200,000 animals; hunters in central Ungava had access to the herd when it expanded beyond 200,000 and the hunters of western Ungava (the Hudson Bay Coast) could find animals in their areas when numbers went beyond 400,000. We postulate that when eastern, central, and western hunters each in turn had access in the previous population cycle, caribou numbers were similar to the levels of abundance recorded when regular counts had commenced in the 970s.

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Low (896) proposed that there were three major migratory herds in Ungava at the turn of the last century and discussions by Elton (942); Banfield and Tener (958); and recently Courtois et al. (2003) followed this division. Low described a Western herd that summered on the tundra highlands of the northeast coast of Hudson Bay and migrated south to at least Richmond Gulf (56°5' N) in winter. Low (90) actually observed caribou – the herd we now call the Leaf River herd – along this coast on 3 July and 3 August 898, north of 6° N to Diggs Island (62°30' N). The Central herd that Low discussed was thought to live in the centre of Ungava and to migrate across the Koksoak River. Low noted heavy trails as far south as Lac Cambrien (56° N). McLean indicated that animals usually made their appearance at the Koksoak River in March, directing their course eastward to bear their young, then returned in the fall moving westward through the interior to winter. Turner (894, quoted in Elton 942) indicated that the animals that passed by the Koksoak in the fall going west had calved on the tip of the Labrador Peninsula in the Torngat Mountains. Low’s Eastern herd – the distribution we now call the George River herd – summered in the tundra of the Labrador Peninsula and migrated in the fall westward across Indian House Lake. This herd, he thought, ranged as far south as the Mealy Mountains (54° N), 200 km farther south than the Western herd or the main trails of the Central herd. This extension farther south is interesting because we have postulated that a migratory herd formerly calved at Harp Lake and migrated as far south as Lake Melville, avoiding the area of deep snow in the Red Wine country. We now know that Low’s belief that the animals migrating annually across the Koksoak were a distinct Central herd is mistaken, and that it was instead the Eastern herd (i.e., the George River herd). Harper (96) was one of the first to realize that the caribou crossing Indian House and the Koksoak in autumn were the same animals. He said (p. 38), “The fact that the very striking reduction in numbers in the Koksoak River area within the 96–9 period coincided more or less with a similar reduction crossing the George River, suggests that the same aggregations of animals migrated back and forth between these two areas, across a largely forested country about 200 miles in width.” J. McLean had also realized in the 830s that the caribou that went by Chimo in the spring went to the George River (McLean 932/849). Low’s mistake is understandable, when you consider the classical view that caribou migrate in a north-south direction. However, caribou actually migrate at right angles to the arctic tree line (Banfield 954; Kelsall 968), which means that the George River herd could migrate north and south across the tree line that runs between Indian House Lake and Nain if the herd is remaining east to winter. When numbers are higher, the herd commonly moves west, crossing the tree line in the vicinity of Indian House Lake where the tree line runs north and south, parallel to the George River.

Past Population Fluctuations | 

Fort Chimo (Lower Koksoak R.) is at a crossroads for caribou because of a combination of environmental variables. Firstly, the tree line reaches nearly to the coast and the shortest route by these forests or following a tree line ecotone is via the coastal tundra. Secondly, the southern edge of Ungava Bay is an area of low snowfall (fig. .6), which again channels caribou. Thirdly, Fort Chimo lies adjacent to the eastern shore of the Ungava Peninsula, and animals moving southeast would be deflected by Ungava Bay and pass near Chimo. It is possible that there were three large migratory herds in the 880s. One herd may have calved on the eastern shore of Hudson Bay (north of 6° N); the second on the western coast of Ungava Bay (6°3' N); and the third east of the George River and north of the Fraser River. However, these early workers (Low, Payne, etc.) did not reach the tundra on the Ungava Peninsula until July. The caribou they saw along the two coasts may have been moving, after calving, to the seashore to gain insect relief. In this case, there would have been only one calving ground on the Ungava Peninsula, as there is at present, in the vicinity of Payne Lake (now they are much farther north although still centrally located). Recent studies in 200 – at a time when the Leaf River herd exceeded 600,000 – show there was only one central calving ground in the centre and at the north end of the peninsula. However, the fall migration trek divided into two routes, one on the west side of the Peninsula and the other on the east side adjacent to Ungava Bay (Couturier et al. 2004); hence animals that sought insect relief in July on both coasts came south in two distinct streams. Historically, natives hunting the upper Leaf River (Lake Minto) communicating with those hunting the lower Leaf would have assumed two herds, a western and a central one. The HBC journals 925–39 (reviewed by Luttich 983) indicated successful hunting on the east shore of the peninsula from Wakeham Bay in the months of March through June, but not on the western shore from Povungnituk (table 5.). These hunting records indicate a more easterly calving location when numbers are extremely low. Spiess (979) showed a calving ground for the Leaf River herd for the late 880s across the entire northern coast of the Upper Peninsula, based on his review of Low’s observations (898). With such a wide west-east distribution, the animals could aggregate along the north coast of the Upper Peninsula in the summer to escape insects and then split into two migratory streams southwards along the east and west coasts, providing two widely-separated fall migrations. If so, Low’s assumption of three migrating herds in Ungava is more understandable. Such an extreme calving location on the tip of Ungava Peninsula is consistent with selecting sites of low predation risk, exhibiting both a maximum distance from tree line and a selection of areas with reduced snow cover (Crête and Payette 990). Several other caribou herds in North America calve adjacent to the Arctic coastlines, generally at maximum distances from tree line. Similarly, some of them have increased their distance from tree line when numbers increased.

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Table 5.1 Abundance of caribou based on harvest (reported kill that year), unsuccessful hunts reported, and journals indicating the post had no kill that year. Journals searched where located in the HBC archives, Winnipeg (Luttich 1983) Year

Upper Ungava (Leaf River Herd) Kill/No. Kill/ Unsuccessful Posts Journals Journal Hunts No kill

Labrador (George River Herd) Kill/No. Kill/ Unsuccessful Posts Journal Journal Hunts No Kill

1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1937 1938 1939 1940 1941 1942

0/2 9/3 77/2 29/3 117+/4 0/6 6/6 53+/6 32/6 15+/7 28/7 –/1 33/6 144/6 – – –

0 3.0 38.5 9.7 29.3 0 1.0 8.8 5.3 2.1 4.0 0 5.5 24.0 – – –

– 2 1 2 1 1 1 2 2 1 1 – 1 – – – –

1 – – – – – 1 1 2 1 – – 1 – – – –

8/3 6/6 10/5 23/6 few/3 –/2 110/3 few/3 6+/3 4/3 –/1 –/1 13/2 43/2 –/1 –/3 –/2

2.7 1.0 2.0 3.8 some 0 36.7 some 2.0 1.3 0 0 6.5 21.5 0 0 0

– – 2 2 6 – 1 2 – – – 1 – – – – –

1 3 3 3 – – – – – – – – 1 – 1 3 2

Total

543/65

8.4

15

7

223/51

4.4

14

17

Ungava Journals searched: Fort McKenzie 30–34, 38–39; Leaf River, 28–35, 38–39; Payne Bay 30–32, 34–35, 38–39; Wakeham Bay 25–26, 29–35, 38–39; Sugluk West-East 25–26, 29–3, 30–35; Povungnituk 25–28, 33–39; Port Harrison 25–35, 38–39. Labrador Journals: Port George River 30–35; Fort Chimo 25–29, 3–35, 38–39; Port Burwell 25–34, 38–39; Hebron 26–28, 4–42; Nutak 4–42; Nain 26–28, 40–4; Davis Inlet 25–28; Hopedale 26–29. Other comments of deer: UNGAVA : 926: Port Harrison – deer plentiful April. 928: Leaf River – few April, many May. 929: Wakeham Bay – lots deer May. 93: Fort McKenzie – more plentiful January. Wakeham Bay – some mention June. 932: Payne Bay – deer meat December, February. Port Harrison – shortage March, April. 933: Wakeham Bay – deer scarce March, April. 934: Leaf River – deer inland February. 936: Wakeham Bay – deep plentiful March. 939: Fort McKenzie – deer meat/skins January; Payne Bay – few sign January, very scarce February, Good sign April. LABRADOR : 925: Port Burwell – some meat May. 927: Port Burwell – party of deer January, scarce February; Davis Inlet – deer plentiful October; Hopedale – large herd April, good sign May. 928: Hopedale – plenty April; Makkovik – herd May. 929: Port Burwell – deer meat galore February; Hopedale – deer inland September. 93: Fort Chimo – few January; Port Burwell – deer in George River; Port George River – good sign September. 932: Fort Chimo – deer inland October. 933: Port Burwell – good sign deer carcass April. 934: Fort Chimo – deer coming around February. 939: Port Burwell – herd of 20 March, plenty deer May.

Past Population Fluctuations | 3

Recently the Dolphine-Union herd in central Canada resumed its trek to Victoria Island after many years of calving on the Arctic mainland coast (See Banfield 954). During this study, the Leaf River herd increased rapidly in the 990s and extended its calving ground at Payne Lake nearly to the Arctic coast, consistent with the view that there is only one historical calving ground on the Ungava tundra north of the Leaf River. Past Fluctuation of Numbers In figure 6. of the next chapter we review an elegant, independent index to population changes 848–992 based on the age of scars on conifer roots made by caribou hooves (Morneau and Payette 2000). In this chapter we present our interpretation of past population numbers independent of this scar data, and based on our historical review of 988 (Bergerud 988a). It was often impossible to clarify the comments of early travellers as to whether the animals they saw belonged to the Western /Leaf River herd or to the Eastern /George River herd. The observations of early explorers/naturalists can only be related to specific herds when these early workers made summer observations of caribou north of the Leaf River (Western/Leaf herd) or on the tundra of the Labrador Peninsula (Eastern/George River herd). The identities of the two herds could not be distinguished when the animals were observed on winter ranges below tree line since these two herds have in recent times shared winter ranges and probably did so in the past. Historical records relating to caribou distributions and numbers commenced with the establishment of HBC posts on the east shore of Hudson Bay and the Moravian Mission in Labrador. The earliest posts were established in 737 at Richmond Gulf; in 74 at Eastmain River; in 750 at Nemiscau; in 805 at Fort George; and in 86 at Nichikun (Morantz 979). On the Labrador coast, Nain was established either in 770 (Brice-Bennett 977) or 77 (Elton 942); Okak in 776; and Hopedale in 782. Unfortunately, the archives for the Moravian Missions were not available to us. The HBC posts on the east coast of Hudson Bay were all south of 57° N so past records could pertain to either sedentary or migratory ecotypes. We can expect that past numbers of the George River herd only reached the east coast of Hudson Bay, south of 57° N, when numbers were high. The current George River herd did not reach the east coast of Hudson Bay until 98–84, when the herd numbered more than 400,000 animals. We can assume that the George River herd did not reach the southern portions of the east coast of Hudson Bay until numbers were even higher. In the current high it reached Nichicum (57° N, 7° W) in 985–86 and numbers totalled > 600,000 animals. The herd reached Nichicum in previous highs in 746, 78, and 820 (Morantz 979). Caribou appeared to be common at Lake Mistassini 720–30 and inland from Eastmain

4 | TH E R E T U R N O F C A R I BO U TO U N G AVA

in 746; in 78 there was a general trade at Eastmain, with caribou skins traded in most years between 736–800. At the start of the 9th century, a large kill of 200 caribou was made northeast of Lake Bienville (820) which should have been migratory caribou. Caribou were common at Lac Nemiscau in 808 and Nichikun in 824 (data from Morantz 979). On the Labrador coast, Elton (942) does not present any data much before the 870s. Wolves should be common when caribou are abundant and possibly peak as caribou numbers start to decline, so one index is the number of wolves harvested per wolverine for the Moravian Missions. Wolverines, which are primarily scavengers, might show less fluctuation with caribou abundance than wolves. Wolves were common compared to wolverines in 834–43 in the few returns from Labrador (fig. .0), which suggests that caribou were or had recently been numerous. A second index to abundance on the Labrador coast is the effort spent by hunters to secure caribou. At Okak, the traditional hunting season prior to about 80 was in August and hunters travelled inland as far west as 64°30' (Taylor and Taylor 977). When these hunters were unsuccessful, they would return to the coast in September; if caribou were common, they would remain inland until October or November (Taylor and Taylor 977). These summer hunters were most unsuccessful in the period around 795 (fig. 5.2). We believe that this lack of success is actually evidence that the George River herd was high in numbers. During the period of abundance in the 980s, the herd migrated west in July and August from an overgrazed summer range and was much less frequent near the area where the Okak people hunted than when the herd was low in numbers in the 970s. The reduced hunting success in the early 800s should mean that the herd was > 400,000 animals and was residing more to the west after the insect season, out of range of the hunters. Yet we can expect shifts, and in 809 Okak people killed 700 animals (fig. 5.2), again consistent with the theory that caribou were abundant but also consistent with the idea that a portion of the herds was still present in August on the uplands inland from Okak. We conclude that the George River herd was common in the period 750–820 and probably exceeded 400,000 animals. Sometime after 820, the migratory caribou in Ungava declined. The decline was first felt in the south and then proceeded north. Natives starved at Eastman (52° N) in 835–40; at Nichikun (53°0' N) and at Fort George (55°5' N) in 839–40 (fig. 5.3, Morantz 979). Cooke (979) reported starvation for the Central Ungava Naskapi – those who hunted between Fort Nascopie (55° N) and the Koksoak – for the years 843–44, 846–47, 847–48, 848–49, 85, and 857. He attributed this starvation to the fact that the HBC would not sell ammunition to the natives. The HBC may well have been niggardly in dealings with the Naskapi but the starvation occurred primarily because of a lack of caribou. The Naskapi had not lost their pre-contact skills by 843: In fact they actually continued to wait at

DATE HUNTERS RETURN (OKAK)

DEC

NOV

OCT

SEP

AUG

S

S

S S

S = DEER REPORTED SCARCE

LENGTH OF TRIP (NUMBER OF DAYS)

100

80

60

MEAN SUMMER TRIP 67.7 ± 6.15 DAYS n = 21 ( )

Y= 40 MEAN SPRING TRIP 36.7 ± 4.48 DAYS n = 21 ( )

20

300 1 + e 0.0491X − 86.62 CARIBOU FURTHER EAST (LOW NUMBERS)

CARIBOU FURTHER WEST (HIGH NUMBERS)

HIGH HARVEST 16 MAY 1809 700 ANIMALS 1775

1780

1785

1790

1795

1800

1805

1810

1815

1820

1825

1830

YEAR Fig. 5.2 The length of hunting trips of Inuit from Okak, 1776–1829. It is hypothesized that when the George River herd was high in numbers it left the Labrador tundra earlier in the fall and went farther west – hunting trips were longer and hunters returned later in the fall. When the herd was lower in numbers it remained farther east and was more easily located by coastal hunters. During the current caribou high (1980s), caribou left eastern ranges where former Labrador residents hunted more quickly after the mosquito season than when numbers were lower in the 1960–1970s (data from Okak from Taylor and Taylor 1977).

6 | TH E R E T U R N O F C A R I BO U TO U N G AVA

NUMBER OF REPORTS OF STARVATION OR NATIVES CHANGING SETTLEMENTS

4

3

DEER COMMON ?? NO REPORTS

DEER COMMON ?? NO REPORTS

n = 14

n = 19

2

1

1799 1800

1819 1820

1839 1840

1859 1860

1879 1880

1899 1900

1919 1920

Fig. 5.3 Reports of Innu and Inuit starving and/or moving locations because of food shortages. These observations suggest low caribou populations in the mid-1840s and in the late 1880s (most of the observations from Elton 1942).

ambushes and spear caribou until 96 (Elton 942). Denton’s (979) interpretation of the ammunition-starvation scenario was that a shortage of caribou left hunters with less time to spare for trapping activities, which meant fewer furs, less trade. This in turn led to reduced purchases of ammunition and less success in the food hunt. The original independent variable was the lack of caribou. This mid-century decline involving starvation should relate to both the migratory and sedentary ecotypes, since some of the native groups affected had access to caribou south of 56° N, within the range of the Lac Bienville, Caniapiscau and McPhadyen sedentary herds. Also we would expect that both the migratory Leaf and George River herds contracted their range with a decline in numbers and that this contraction would be felt first at the southern latitudes. The decline in caribou also precipitated declines in wolves and wolverines (fig. .0). As late as 828, Hendry reported that wolves and wolverines were common along the Larch River. However, there were few reports of wolves in the middle of the century (review by Harper 96). More wolves were harvested in Labrador at this time than in the western regions, suggesting (Elton 942) that there had been a shift to the east of both caribou and wolves. We believe that this mid-800s decline of caribou did not proceed to such low levels as that which occurred after 920. Firstly, in the mid-800s, there were no reports of starvation of the barren-ground Naskapi at Indian House Lake in the eastern part of the George River herd’s range. Nor was there any starvation

Past Population Fluctuations | 7

reported for the Montagnais, who hunted at the crossing between Michikamats and Michikamau Lakes. However, Taylor (979) reported that in the middle of the 9th century, the people at Okak had so few caribou skins that only one or two persons per family could be outside in winter at the same time. Secondly, the wolverine population survived the decline in the 800s, but we believe it went extinct in the north in the prolonged caribou decline after 920. Harper (96) spoke to Sebastien McKenzie (factor at Fort McKenzie 96–36), who reported that an old Naskapi said there were plenty of deer 825–30 but then ensued a period of 20 years when there were “no more.” Certainly McLean’s several trips between Fort Chimo and Fort Nascopie in 838–40 verified a lack of caribou; on one trip he nearly starved, and on none of the treks did he encounter more than a few caribou (McLean 932). But by the year 870, natives – who had come out to the coast about 850 for lack of caribou – were again hunting inland (Trudel 979), which suggests a relatively rapid recovery and more caribou during this low phase than during the later low in the 920s. We can gain some understanding of the size of the George River herd based on McLean’s knowledge of the distribution during 838–4 when he travelled between Fort Chimo, Fort Nascopie, and Hamilton Inlet, and even up the George River in the summer of 839. He stated (p. 253) that “does (female caribou) arrive in Ungava (Chimo) at the beginning of March, coming from the west and continuing along the coast until they reach the George River where they bring forth their young in the month of June; in the meantime, the bucks divide into separate herds and pursue a direct course through the interior, heading for the same river (the George) and remain scattered about the upper parts of this river until the month of September when they assemble and proceed slowly towards the coast. By the time the does move onward towards the interior, the fawns have now sufficient strength to accompany them and they (females and fawns) follow the banks of the George River until they meet the bucks, when the rutting season commences in the month of October. The whole herd then proceeds together through the interior to the place whence they came.” This is a remarkable insight, as it so closely approximates the movements of the George River herd in the 970s. It is not clear how much of this pattern McLean observed, and how much he learned from the natives from earlier times, although he actually caught 300 caribou in a trap that he constructed at Fort Chimo. However, in the period 977–80 the caribou rutted in the approximate areas that McLean described, and during the increase phase in the 960s and 970s, the George River herd was first known to be wintering west of the Koksoak in 973. Thus, based on numbers in the 970s, the population in the 820–830s may have been ± 200,000 animals. We know that caribou were abundant in the 870s since the distribution had reached Hudson Bay and was available to hunters. This expansion was probably the George River herd since the root-scar index gathered on the summer range of the George River at Indian House Lake in the 980s showed that caribou were

8 | TH E R E T U R N O F C A R I BO U TO U N G AVA

abundant in both the 880s and 870s and we know that the George River herd, during the current expansion in 950–84, reached Hudson Bay about 98/82, when there were possibly 400,000 caribou. If we assume that the herd increased at λ = .3 from 850–70, then the herd might have declined to as few as 25,000 caribou at about 850. With the caribou so scarce, the herd would have remained on the eastern ranges in winter, and the central and western natives would have found famine, as noted, although the eastern Indians may still have had some caribou at crossings that intercepted caribou on the Labrador tundra west of Indian House Lake – at Mistinibi Lake, for instance. The Naskapi at Indian House Lake had an especially effective strategy inasmuch as the crossings were relatively close to the calving ground and August range and they hunted at crossings arranged in an “L” shape (fig. 5.). When the herd was abundant and migrated to western ranges, they intercepted them at Indian House Lake and had a north-south cruising radius along the lake of about 00 km; when the herd was low in numbers and wintered on eastern ranges, the Naskapi could intercept caribou on Lac Mistinibi, which runs east and west (55 km). When caribou numbers were low in 90, Cabot (92) found these Indians at “Tshinutivish,” at the “running-in” of Lac Mistinibi. From this position they could move to intercept either a westward or a southern migration (fig. 5.). There are several historical references to the fact that these eastern Indians had a more reliable source of caribou and were less dependent on trade and European goods than were the Indians who lived along the east coast of Hudson Bay. The Western and Eastern herds must have both reached high numbers again by 870–80. During this abundance, Western herd caribou occupied the entire Ungava Peninsula to Cape Wolstenholme and there was also a heavy harvest at Fort Chimo of the Eastern herd. A similar distribution occurred after 990. Thus the total of both herds may have been higher in the 880s than in 984, or, more possibly, the western calving population (Payne Lake–Leaf River) represented a greater proportion of the total Ungava migratory population than did the Eastern herd. There are ancient lead fences and stone blinds at Diana Bay, Lac Roberts, and Lac Klotz, all dating back to a period before European influence, which strongly suggests a period of vast historical abundance on the Ungava Peninsula. Elton (942) felt that the Western herd started to decline 880–90s, since a shortage of caribou moved people from Little Whale River and Fort George across to the Chimo area in 883. The Central herd was thought to decline in the late 890s, the Eastern herd after 904 (Elton 942). We now know that this is not some kind of domino effect but a major decline in the entire migratory population, with a contraction in range of at least the Eastern herd. It probably involved both herds since there was starvation. Furthermore, the population continued down for possibly 40 years 880–920, but the decline was probably more precipitous in the early years, 880–905, than later, 905–20. Caribou no longer crossed at Chimo by 96 (Elton 942; Harper 96). During the most recent increase

Past Population Fluctuations | 9

phase 950–84, caribou migrated by Chimo again only from the early 970s. Possibly the population around 96 was similar to that in 963 when DesMeules and Brassard (964) found caribou as far north as 57° N but west only to 69° W. Such caribou would not cross the Koksoak but would have been available from Fort McKenzie. It was in 96 that Fort McKenzie was established because of the shortage of caribou at Fort Chimo. By 96, there may have been < 30,000 caribou. At present, it is assumed that distributions of ranges during contractions and expansions are similar phenomena as populations both increase and decrease. The caribou failed to appear along the Lower Koksoak in 892/893 and 50– 200 Naskapi starved (Elton 942). The starvations presumably included some of the people who had earlier moved to the area in 883 from the Little Whale River and Fort George when the caribou in their old hunting area declined. The caribou population at this time could still have been substantial, although the animals in 893 simply remained on their eastern ranges. In 974 and 976, the caribou rutted east of the George River and Indian House; as well they spent most of the winter east of 68° W; at this time the herd numbered less than 200,000 animals. At the time of the failure at Chimo, the harvest increased dramatically along the east coast for the native peoples who hunted as far west as the George River. Caribou skins traded at the Moravian missions numbered 9,575 for the period 884–93 but grew to 3,567 for 894–903 (fig. .0). This increase does not reflect an increase in the herd; rather, it indicates the restriction of caribou to the eastern ranges during the winter. Again, this concentration on eastern pastures suggests < 200,000 animals remained, since during the increase phase in the 970s the herd – when about 200,000 strong – remained mostly on the eastern winter ranges until it had increased well beyond that figure. After 893 the herd rapidly declined. The number of skins traded during 904–  declined to 2,650 (compared to 3,567 894–903) or λ = 0.84 (fig. .0). The Naskapi came out to the coast in 906 for lack of game inland. Fewer caribou were killed in 906–07 (Elton 942). After 903–04, nearly all the skins that were traded were from Hebron and Okak, with few from Nain, Zoar, or Hopedale (Elton 942). Hence, not only were the animals restricted primarily to eastern ranges, but in the early 900s they no longer undertook long north-south migrations parallel to the coast, remaining instead mostly north of the Fraser River. A decline rate of 0.84 is extremely high, but it is consistent with the demography of other caribou herds, suggestive of both a failure in recruitment and of high natural mortality. The crossing at Indian House Lake failed in 96 and the Naskapi moved out to the coast. Here they contracted influenza in 99, with extreme mortalities resulting. The Naskapi never returned in large numbers to live year-round with their families in the interior and to ambush caribou at lake crossings. Rousseau

20 | TH E R E T U R N O F C A R I BO U TO U N G AVA

(950) reported only 36 people in this George River band in 924, although Strong (930) indicates 94 people living in the vicinity of Davis Inlet in 927. We suggest that by 96 there could well have been fewer than 0,000–5,000 caribou in the George River herd. Also, the harvest of wolves by the Labrador Inuit declined dramatically between 903–3 and 94–23 (43 to 8, λ = 0.85) and fur returns from Fort Chimo 98–27 showed only two wolves harvested (Elton 942). Cabot (92) in his travels from the Labrador coast to Indian House Lake in 906 and 90 continually mentioned previous reports of abundant wolves, but he saw only one. This near absence of wolves after 94 suggests a very low abundance of caribou. The decline, then, as we reconstruct it, was that possibly 50% of the total loss occurred around 880–93 (400,000–600,000 to 200,000 caribou) and the remaining decline of 50% occurred from 893–96 (200,000 to < 30,000 caribou). This major decline then spanned 36 years with a annual rate of loss around λ = 0.90. We would understand the decline better if we knew when caribou first stopped migrating by Chimo in the fall and spring. Wallace (907) reported a large fall harvest in November 905; another large kill occurred in 92 near Chimo (Flaherty and Flaherty 924). He also noted that for several years (about 905) only small bands had been seen and the Indians had to go inland 40–50 miles to secure animals. The sequence suggests that the animals deserted their western winter ranges before their use of the central interior in the fall. The failure of the crossings at Chimo in 96 (Harper 96) is in agreement with the failure of the fall crossing in the same year at Indian House Lake (Elton 942); and it is consistent with the concept that the Eastern herd was greatly reduced and thus no longer made long western movements to locate winter ranges. Fort MacKenzie was established in 96 because of the failure of caribou to cross the Koksoak. There would still have been animals available after 96 for hunters trading at Fort McKenzie. In the 950s when the herd could have been smaller than 20,000 animals, Banfield and Tener (958) and Bergerud (967) found a major proportion of the George River herd in the winter west of the George River in the lichen woodlands of the central interior. Hunters trading at Fort McKenzie after 96 could also have harvested animals from the sedentary herds such as the Caniapiscau and Red Wine herds. However, the Red Wine herds were also scarce in the early 900s, based on summer observations. In 903, Leonidas Hubbard, travelling through the area occupied by the Red Wine herd, saw five caribou in 08 days in an overland journey that resulted in his death from starvation (Hubbard 908). In 905 Wallace travelled for 73 days and saw only eight caribou in this herd’s range (Wallace 907), and Mina Hubbard, in 37 days of travel between Northwest River and Michikamau Lake in 905, saw only one caribou. Mrs Hubbard did encounter the George River herd south of Indian House Lake on 8 August 905, reporting thousands of caribou. This large aggregation was in sharp contrast to the

Past Population Fluctuations | 2

scattered groups she had seen in the Red Wine country only days before and is a striking example of the contrast in mid-summer aggregating behaviour of sedentary and migratory caribou at a distance of only 00 km. With the scenario we have constructed of 200,000 declining to 30,000 from 897 to 96, there could have been > 30,000 caribou in the George in 905. Rousseau (952b) estimated the caribou in all of Ungava at 3,500 head around 947, based largely on the view of B.M. May, the old factor at George River, and on Rousseau’s own interior trips. We would amend this estimate to apply it only to the George River herd and not to all of the caribou in Ungava (a decline of 30,000 to 3,500 96–45 gives λ = 0.93). This low estimate appears reasonable. Clement (949) reported that the caribou no longer came to Indian House in the mid-940s. He saw only one caribou near the Indian House weather station in a year’s stay during World War II (letter to S. Luttich). The caribou were incredibly rare during this period, almost nonexistent (see the discussion in Harper 96). Rousseau (952b), in his trip down the George River in the summer of 947 through the heart of the occupied range, saw signs of only 20 caribou (including tracks). Rousseau (950) estimated the harvest during these low years at 500 animals (based on discussions with B.M. May) but this total seems too high. The hunting trips of Wheeler (930) and Strong (930) with the natives of Nain and Davis Inlet suggested annual kills for each native group of ≤50 caribou. The HBC journals (925–39) reviewed by Luttich suggested that in the 940s the only settlements having any hunting success were George River and Port Burwell (table 5.), and although hunters from Hopedale killed some caribou, these could have been the woodland type. Possibly the total kill for the George River herd would have been ± 200 animals/year. In the near absence of wolves, recruitment should have been > 20% and natural mortality around 5–7% (Kelsall 968; Skoog 968; Bergerud 980). If the population was stable (R = M), then the population could have been as low as 2,000 (harvest 200); or it could have been 3,500 (harvest of 500), if May’s estimate was closer. The increase of the herd from 2,000–3,500 caribou around 950 to 600,000 animals in 984 is the most spectacular in all the caribou literature (λ = 0.6–8) in a 34-year period. There were apparently fewer caribou remaining on the Upper Ungava Peninsula during 90–940s (Western/Leaf River herd) than on the Labrador Peninsula (the George River herd). Flaherty (98) crossed from Lake Minto to Chimo in March 92 and saw five caribou. This is prime winter range at high numbers but the caribou likely remained north of tree line when numbers were low. Flaherty (98) made two July trips in 98 across the Peninsula using the Payne Lake and the Leaf River route, and saw but one caribou. Rousseau (949) crossed by the same routes (Payne Lake and Leaf River) and saw three. Doutt (954) searched for wildlife near Clearwater Lake–Seal Lake, 5 July–2 August 953, but saw only tracks; at this season, migratory caribou (Leaf River herd) would be farther north. Doutt (954) reported that Indians said they had seen a small herd of

22 | TH E R E T U R N O F C A R I BO U TO U N G AVA

30–40 in the area in winter. These observations would be woodland caribou (the Lac Bienville herd) and they were also extremely scarce, coincident with the low in the Leaf River herd (also Banfield and Tener 958). Banfield and Tener saw 22 caribou on 26 March 956 north of Lake Minto, and they estimated the Western herd at 450 caribou. We have also estimated the size of the Western/Leaf River herd 925–39 based on reports in the Hudson Bay Company journals from the six settlements that hunted the herd (table 5.). Based only on journals that listed total kill or none killed for a harvest of 380 animals or 4/settlement/year, we reach a total of only 84 animals harvested per year from the herd. If the stable herd prosperities were the same as we postulated for the George River herd, i.e., a calf percentage ≥20% and 5% natural adult mortality (based on Skoog 968 and Kelsall 968), then the herd could have numbered 600 animals. This estimate suggests no change in numbers 925–54 (see Banfield and Tener 958). Interestingly, at this low the George River herd had 4 times the Leaf River population, yet the Leaf River herd had a potential summer range four times that of the George River (fig. 2.7). There may have been < 000 caribou on the Upper Ungava Peninsula during the low years. This is an area of 250,000 km², suggesting < 0.004 caribou/km². Biologists are often concerned about a lower threshold of numbers of caribou, i.e., that there is a minimum density where breeding will not take place. Here we have a density for the migratory ecotype that is one magnitude less than the lowest density of 0.03/km² reported for the sedentary ecotype in Ungava by Brown et al. (986), yet the migratory population persisted for 40 years at extremely low densities. We have tried to piece together the past as objectively as possible, but alas there were few note-takers that long ago and reality may have been different, however logical our reconstruction. We learned only in 200, for example, when both the George River and the Leaf River herds were censused, that the Leaf River was increasing (628,000 animals) whereas the George River was decreasing (385,000 animals) and that there is considerable exchange between these populations that would have modified past fluctuations (Couturier et al. 2004). As observers continue to follow the caribou, more of the past will become clearer. Regardless, the pulse of life on these arctic prairies – the ebb and flow of these wonderful deer and their transformation from a scattered few to a massing of thousands – makes an astonishing story.

At Home in the Wilderness: The Mushuau Innu and Caribou

STEPHEN LORING Arctic Studies Center, Smithsonian Institution

Nitassinan – our land” – the vast interior of the Quebec-Labrador peninsula, is the traditional homeland of those Innu whose lives and destiny have been irrevocably linked to the coming and going of caribou. More than 7,000 years ago, while the last vestiges of the glacial ice sheet that once covered much of northern North America still lingered in the George River valley, and much of Nitassinan was covered by huge pro-glacial lakes, small intrepid bands of Innu ancestors waited at crossing places to ambush the animals on which their lives depended. Archaeological research, much of it conducted by the Innu themselves, confirms what Innu oral traditions and stories have long affirmed – that the pursuit of caribou has been an integral aspect of Innu lives and identity for millennia (Loring 997, 998, 2000; Loring and Ashini 2000; Loring et al. 2003, Samson 983). Around 600 AD , during the time the Innu tenure of Labrador extended to the forested coast and inner bays from the Quebec North Shore to the vicinity of Nain and Okak, the expanding European and Inuit presence along the central Labrador coast led some Innu groups to take up year-round residency in the heart of the George River caribou country. While reciprocity and kinship networks linked these northern Innu to other hunting bands throughout the peninsula, these northern-most Innu – the Mushuau Innu, the Innu of the George River country – developed a remarkable specialized caribou subsistence lifestyle predicated on interception of the migratory George River caribou herd. While periodic fluctuations in the size of the George River herd, coupled with unanticipated changes to migration patterns and local climatic variations, sometimes resulted in starvation for some of the scattered Innu hunting camps, Innu culture endured, even flourished.

24 | AT H O M E I N TH E W I L D ER N E SS

The contingencies of a life-style predicated on flexibility and mobility placed a high value on ingenuity and self-sufficiency. The outward trappings of a modest material culture inventory have led some to construe Innu culture as marginal and impoverished, a perception that ignores the profound complexities of the intangible dimension of Innu culture, the rich maze of social and spiritual relations that united a far-flung, dispersed population and conferred an unprecedented understanding of their northern ecosystem and the relationship between human beings and animals. A central figure of the hunting camps was the kakushapatak (shaman) a powerful spiritual leader who, aided by his mishtapeu (a spiritual intermediary between the world of human beings and the world of the animal masters), could influence the movement of the caribou, the weather, and mitigate the causes of sickness, suffering, and death. Innu history has numerous accounts of occasions when shamans used their powers and presence to call the caribou and avert starvation. Formerly, Innu hunters wore elaborately painted caribou skin coats that depicted an intricate landscape of spiritual dimension. Similar designs, painted on special robes, were used by shamans to call the caribou to the waiting hunters. While many vestiges of the spiritual compact between the Innu and caribou have faded with village life, older hunters still observe the proper way to care for and dispose of animal remains. Beginning in the late-960s the Innu abandoned a permanent residence in the George River country by adopting a village life. Yet their culture and their identity as a people remains inextricably linked to the country and to caribou. The raised earthen-wall tent-rings left by their ancestors are still scattered across Nitassinan at fishing places, rendezvous places, and caribou-crossing places in mute testimony to their former way of life. The antiquity of the relationship between human beings and caribou extends back to the Ice Ages. It is not improbable that we became human because of caribou: that core human traits such as cooperation, language, and social identity were first forged, or certainly reinforced, around Pleistocene campfires in both the Old World and New as families of hunters sought both to capture and kill caribou and to appease the spirits of the animals and the Animal Masters. A deep abiding knowledge and respect for caribou is an Innu legacy and a lesson to be remembered and relearned as we contemplate the future of caribou in Nitassinan and across the circumpolar world. REFERENCES

Cabot, William Brooks. 92. In Northern Labrador. Boston: Richard Badger. – 920. Labrador. Boston: Small, Maynard & Co. Loring, Stephen. 987. Arctic Profiles: William Brooks Cabot (858–949). Arctic 40(2): 68–69.

Stephen Loring | 25

– 997. On the trail to the Caribou House: some reflections on Innu caribou hunters in Ntessinan (Labrador). In Caribou and Reindeer Hunters of the Northern Hemisphere, eds. Lawrence Jackson and Paul Thacker, 85–220. London: Avenbury Press. – 998. Stubborn independence: an essay on the Innu and archaeology. In Bringing Back the Past: Historical Perspectives on Canadian Archaeology, eds. Pamela Jane Smith and Donald Mitchell, 259–76. Mercury Series, Archaeological Survey of Canada, Paper 58. Hull, Quebec: Canadian Museum of Civilization – 2000. Hunters of the Hunter’s World: Some reflections on Innu and Inuit Drawings in the National Anthropological Archives. American Indian Art 74–8, 02. Loring, Stephen and Ashini, Daniel. 2000. Past and future pathways: Innu cultural heritage in the twenty-first century. In Indigenous Cultures in an Interconnected World, edited by Claire Smith and Graeme Ward, 67–89. (St. Leonards, Australia: Allen and Unwin). Loring, Stephen, McCaffrey, Moira, Armitage, Peter and Ashini, Daniel. 2003. The archaeology and ethnohistory of a drowned land: Innu Nation research along the former Michikamats lake shore in Nitassinan (interior Labrador). Archaeology of Eastern North America (3):45–72. Loring, Stephen, and Spiess, Arthur. 2007. Further documentation supporting the former existence of grizzly bears (Ursus arctos) in northern Quebec-Labrador. Arctic 60 ():7–6. Samson, Gilles. 983. Prehistoire du Mushuau Nipi, Nouveau-Québec: Étude de mode d’adaptation a l’interiieur des terres hemi-arctiques. Ph.D. dissertation, Department of Anthropology, University of Toronto.

Many of the photographs on the following eight pages were taken by William Brooks Cabot, a Boston engineer with an unusual proclivity for northern travel (Cabot 1920, Loring 1987). Between 1898 and 1925 he made dozens of excursions, by snow-shoe and canoe, into the Indian country of northern Quebec and Labrador. Between 1903 and 1910 he followed the traditional Innu travel route between the Hudson’s Bay Company trading post on the coast of Labrador at Davis Inlet and their caribou hunting camps on the George River. His photographs and journals provide a unique window into Innu life at the turn of the century, at the hey-day of their specialized caribou-subsistence lifestyle.

The Innu fall caribou-hunting camp at Tshinuatapish on the George River at Indian House Lake, August 1910 ( SI /NA A WBC 1910:73). Small aggregations of Innu families gathered together in the fall in anticipation of intercepting the George River caribou at one or another of their crossing places.

Innu man and caribou-skin tent at Mistinibi, 1906. ( SI /NA A WBC 1906-89)

Innu woman at Mistinibi 1906. Caribou skins were used for clothing and tents and cut into strips for making babiche used in weaving snow-shoes.

Innu hunters waiting and watching for caribou at the caribou crossing place on Mistinibi Lake, September 1906 ( SI /NA A WBC 1906-94). At this camp in 1906, eight men and boys had speared “no less than twelve or fifteen hundred deer in a few weeks” (Cabot 1912:239).

Skinned and butchered caribou pulled up on the Mistinibi shore just above the 1906 camp. The animals have been skinned and gutted and choice selections of meat and fat removed, some of which is drying on boulders. ( SI /NA A WBC 1906-96).

Women cleaning caribou skins and making pemmican at the 1906 Mistinibi camp. ( SI /NA A WBC 1906-101).

(above) Windrows of caribou antlers at the Innu camp on Mistinibi, September 1906. The Innu believed that the antlers of slain caribou had to be kept together, an act that would assure the continuity of the herds (Cabot 1912: 242). It was believed that any careless or inappropriate treatment of caribou bones and antlers would offend the caribou and drive them away ( SI /NA A WBC 1906–97). (left) Bear skulls were carefully tied to poles, frequently with a plug of tobacco placed between the jaws, as a propitious show of respect for the bear and its guardian spirits. This skull, photographed in 1910 by William Cabot at an Innu camp on the travel-route between Mushuaushipu (the George River) and Emish (Voisey’s Bay) is thought to be the skull of the extinct barren ground Labrador grizzly bear (Loring and Spiess 2007).

Drawing by Tuma, an Innu hunter, in 1928, depicting caribou caught in snares. In addition to spearing caribou as they crossed rivers and lakes, the Innu formerly employed drive systems and corrals made of fallen trees and branches to surround and capture caribou. Drawing collected by William Duncan Strong during the winter of 1928 (William Duncan Strong papers, NA A /SI ).

Innu trading party, Kogaluk River, 1904. An extraordinary degree of mobility characterized traditional Innu life in the country. Carrying few possessions, and relying on cached equipment and canoes, small parties of Innu hunters could cover a tremendous territory while gathering information about the location of the caribou as well as that of other Innu bands ( SI /NA A WBC 1904-48).

Ancient ancestral Innu artifacts from the caribou-crossing place at Kamestastin (Mistastin Lake), northern Labrador. The earliest assemblages of stone tools from the George River country are over 7,000 years old (a), later groups of hunters, between 6,500–4,000 years ago, also congregated at the caribou-crossing place, leaving behind spear points (b) and knives (c) made of distinctive Ramah chert and ground-slate celts (d, e). Tshikapisk Foundation collection, Sheshatshit, Labrador, photograph by Christina Leece and Stephen Loring.

CHAPTER SIX

Causal Factors in Historical Fluctuations

We will base our discussion of possible causal factors in population fluctuations on our analysis of the past fluctuations of the George River herd as indexed by root-scar data presented by Morneau and Payette (2000). They developed an original technique to measure past abundance by quantifying the scars on living conifer roots that bisect caribou trails. This scar index was conducted over a 44year period from 848–92 (fig. 6.) in the vicinity of Indian House Lake, the very centre of the historical range of the George River herd. Their index was highly correlated with population estimates derived from census data 954–88 (Morneau and Payette 2000, fig. 4). The scar index was also consistent with the historical review in chapter 5 that we prepared independently in 988 (Bergerud 988a). As well, their index indicated a high population of the George River herd in 873–77, in agreement with historical citations, and it showed a population in the 870s similar in size to that documented by census (Morneau and Payette 2000, fig. 6) for the 980s. Their index further supported procedures discussed in chapter 5 in which we relied on range contractions and expansions (historical distributions) to postulate past population trends. A number of authors have discussed the decline of caribou from around 880–920 without reaching any consensus (including Low 896; Anderson 939; Manning 948; Dunbar 948; Rousseau 952b; Banfield and Tener 958; Bergerud 967; Crête and Payette 990). The most common explanations have been: loss of range through forest fires, density-dependent overgrazing of lichen ranges, ice storms with glitter, and starvation, over-hunting, and predation. We feel that an adequate explanation of the decline would address and account for the following: () previous fluctuations (i.e., the low population in the 940–50s); (2) the general

ROOT SCAR RESIDUALS AVERAGE TEMPERATURE NOV–APR MAY–OCT TREE-RING W I D T H I N D EX

10 8 6 4 2 0 2 4 6

RELATIVE CARIBOU ABUNDANCE

600–700k

700k??

CARIBOU HIGH

SPANISH INFLUENZA

400k R/M SCHEDULES

COLD CARIBOU LOW LONG

16 15 14 13 12

STARVATION

GROWING SEASON TEMPERATURE QUEBEC CITY

WINTER TEMPERATURE QUEBEC CITY

-4 -5 -6 -7 -8

CENSUS 5k

SHORT

OKAK TRIPS

STARVATION

COLD

COLD

1.5

GROWTH OF WHITE SPRUCE SCHEFFERVILLE

1.0 0.5 0.0 0.5 1.0

MORTALITY TREE-RING INDEX WIDTH (mm)

1.5 0.5 0.4 0.3 0.2 0.1 0.0 30

GROWTH OF BLACK SPRUCE 57° 47´N / 75° 45´W SIMILAR SEQUENCE AS 1700 TO 1800 BACK TO 1400

MORTALITY OF BLACK SPRUCE

20

57° 47´N / 75° 45´W

10 1700

1750

1800

KRAKATOA ERUPTION 1883

TAMBORA ERUPTION 1815 1850

PINATUBO ERUPTION 1991 NO DATA

1900

1950

2000

YEAR

Fig. 6.1 The relative abundance of the George River herd 1800 to 1993 compared to long-term climatic factors. The root-scarring index adapted from Morneau and Payette (2000); the Quebec City temperatures from Crête and Payette (1990); the growth of white spruce from Enright (1984); the growth of black spruce from Payette et al. (1985) as well as the graph of the mortality of black spruce in the 1880s (bottom). Note that the failure of spruce occurred in the decade 1880 to 1890 in the same decade that the volcano Krakatoa, lying between Sumatra and Java in the East Indies, had a huge explosive eruption in 1883. “The dust veil in the atmosphere cooled the planet, which

Causal Factors in Historical Fluctuations | 37

decline in the population for 75 years (880–954); and (3) the synchrony in the decline of sedentary and migratory ecotypes. The tree-root scar index indicates that the overall decline from 880–950s was not as consistent as earlier authors mentioned assumed. There were in fact two smaller increases in the root-scar index after 880 and prior to 954, after which census data showed a steady increase for at least 35 years until 988. A small population peak occurred about 895–902 and a second, even smaller, high about 925–34 (fig. 6.). Changes in distribution could partially explain these scarring increases, but we feel they represent valid increases in numbers because the scar data was collected adjacent to the George River and the Caribou House calving ground, the herd’s historical centre of habitation. Early Explanations Fires

The pollen diagrams presented by Samson (978) and Jordan (975) show that the frequency of fires back to 7,000–5,000 bp are correlated with climatic warming periods and very generally with the presence of spruce forests. Jordan (975, 2) remarked that fires have always been present in Hamilton Inlet, even before human occupation, and that increased fire activity is associated with the onset of the spruce forest. The peak in forest fires at Lac des Roches, Indian House Lake, occurred in about 3,000 bp and has declined ever since (Samson 978). The first reference of recent fires is Hind (863, 208), who felt that great tracts of forest along the Gulf of St Lawrence had been burned. He mentioned great forest fires in 785, 84, 857, and 859. These fires do not correspond with a reported low in caribou in the period 839–5. Low (896, 3) mentioned that at least one half of the forest area of the interior had been totally destroyed by fires within the past 25–30 years, which would have been about 866–7. Again this is not synchronous with a decline – the herds were increasing during this period. Low (896) reported that the greatest fire that he knew of was in 870 or 87, and here again, caribou numbers were high and probably increasing. Forest fires should be most common with warm summer temperatures and low rainfall. Summer temperatures, as reflected by growth rings, were decreasing 800–40 (fig. 6.), suggesting fewer fires, but the population declined; tem-

didn’t warm back to normal for five years” (Quammen 1996, 142). This story was repeated 100 years later in 1991 when Mount Pinatubo in the Philippines erupted, polluting the upper atmosphere and cooling temperatures, negatively affecting the demography of the George River herd and other herds across the Arctic in 1992 (chapter 16). Earlier in 1815 Mount Tambora erupted. Harington (1992) called the following year 1816, the year without summer. Was this another bad period for the herd? It may have been declining (top left).

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peratures were increasing 880–920 (more fires) when the population declined a second time. The patterns are not consistent (Enright 984; Payette et al. 985). Forest fires are much more frequent in the boreal forest than on the tundra. The synchrony in the abundance of sedentary and migratory ecotypes does not fit this pattern, especially when one recalls that the centres of habitation for the migratory caribou were north of tree line. When caribou were low in numbers, as in 920–45, they were generally north of tree line and able to start their recovery while subsisting on the reduced phytomass of alpine lichens as opposed to those lichens in sheltered woodlands which are more susceptible to fire. Weather and Starvation

Elton (942, 367) reviewed the literature suggesting that caribou on the Belcher Islands died out about 840–50: “The reason given by those Eskimos for the dying out of the herd was that a great thaw with heavy rain occurred around the month of January, causing a flooding of the caribou feeding grounds … It then, after a few days, set into winter weather again, when the water covering the moss froze solid, resulting in a great food shortage for the caribou, which eventually killed them off by starvation.” Elton reasoned that such icing might occur on the mainland. Caribou biologists now accept the idea that caribou on islands in maritime situations can starve (Skoog 968; Miller 982), but this scenario has not been documented for mainland herds where continental snow conditions exist and emigration can occur. In Greenland, there have been major cycles in caribou, with population highs 840–50, 90–20, and around 975; starvation as a result of weather is considered a major factor there (Vibe 967; Meldgaard 986). These caribou are restricted to a coastal strip where maritime conditions have an influence, but these conditions are not similar to those of the George River herd, which generally avoids the coastal strip in winter. Additionally, the cycles in Greenland and Labrador are completely out of phase. Some icing in Ungava has occurred in recent winters, including 974–75, 976– 77, and 977–78. In 974–75, it was the central plateau that developed ice, and the herd moved east, where Luttich censused them in February. The unlimited mobility of the George River herd from latitudes 52° N to 60°30' N made massive mortality from icing impossible. Nor would such an explanation satisfy either the conditions of the synchronous decline of woodland and tundra animals, or the many years of decline. Icing should occur during a period of climatic warming, but one decline took place when temperatures were dropping, the other when temperatures were ameliorating (fig. 6.). Over-harvest

Over-harvest is always a possible explanation for declines, as many authors have suggested. Loring (997) noted that the ambushing method of spearing swim-

Causal Factors in Historical Fluctuations | 39

Table 6.1 The change-over from summer hunting at Okak after the introduction of the musket in 1785 Years (7 Year Periods)

1775–81 1782–88 1789–95 1796–1802 1803–09 1810–16 1817–23 1824–30

Number of Arrivals and Departures (Hunting Parties)

16 10 31 52 14 25 15 19

Percentage of Observations Summer Winter

100 100 93 52 57 16 20 32

none none 7 48 43 84¹ 80¹ 68¹

Summer was August and September, winter March and April ¹ Involved large parties, often most of the village

ming animals was a highly effective technique, requiring limited manpower, and that the crossing points would be well known to interior hunters. Elton (942) quoted several earlier authors who felt that the introduction of the repeating rifle might have increased kills, resulting in the decline. However, since the repeating rifle was not available until the early 900s, it would not explain the declines from 840–50 or from 880–900. In fact it was the introduction of the musket about 785 that gave native peoples more versatility in hunting outside the open water season (the ambush technique). The Inuit of the Labrador coast were the first people to change over from summer to winter hunting (table 6.). When William Turner hunted with these Inuit in 780, they had to portage their kayaks from sea level 800 m to the interior plateau, then surround the caribou to drive them into inland lakes (Taylor 969). The first reference in the Moravian records to winter hunting (March–April) was in 795, just 0 years after Okak hunters started using muskets (Taylor and Taylor 977). By 80, spring hunting with guns had nearly replaced late summer hunting (table 6.). However, the arrival of the musket, like that of the rifle, does not coincide with the decline of caribou, which occurred some 40 years later. Nor did the Naskapi change their style of ambush summer-hunting to that of winter-hunting with rifles until after the caribou herds had greatly declined in the period 905–6. One can make a reasonable estimate of the historical harvests, especially for the period after the great 880 decline and prior to 96. Maximum kills recorded in the literature include: Hopedale in 895–96, 800 caribou; Hebron in 897, 500; and Okak in 904–05, 500–600. Low (897) reported a winter kill of 5,000 animals by Davis Inlet people in 895–96. It’s hard to imagine a kill of this size in winter by non-ambush methods when the animals should have been far inland.

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In 809, 00 years earlier, the Okak people had killed 700. The Naskapi at Indian House made maximum kills of ,200–,500 in 906–0 and were apparently quite satisfied with the magnitude of the harvest (Cabot 92). Even though this Indian House Lake harvest was late in the decline, it should not have been restricted by caribou numbers since the herd had confined its distribution to the eastern ranges after 900. The Naskapi Indians at the Koksoak River may have killed more than the Naskapi at Indian House Lake since they numbered about 350 people in 892 (Elton 942). There were only about 50 Inuit living inland year-round in the interior of the Ungava Peninsula (Vezinet 979), but they were joined in the summer by up to 250 more people. Furthermore, there were not great changes in the native population except those caused by starvation and disease (especially typhoid and influenza on the Labrador coast in 905 and later). Population estimates for the Inuit at the Moravian settlements were: ,460 in 735; ,204 in 856; 048 in 866; ,76 in 874; and ,08 in 904. Indian House Naskapi numbered: 50 in 857; 30 in 905; and 97 (they had now moved to Davis Inlet) in 927. Naskapi along the Koksoak and Ungava Bay were: 350 in 892; 50 in 896; and 458 in 924 (from a variety of sources). We estimate that the very maximum annual kills of caribou by people during the 870–90 declines were as follows: Naskapi: Indian House Lake Naskapi: Koksoak and Ungava Bay Montagnais: Michikamau Lake Inuit: Ungava Peninsula Indians: Hudson Bay Coast Inuit: Labrador Coast Total

2,000 3,500 ,000 3,000 ,500 3,000 4,000

If the herd was at least 400,000 caribou in 880 (the root-scar index is similar to the 980s, see fig. 6.) with a recruitment of 20% and a natural mortality rate of 2%, the animals lost/year would be 46,000 caribou [(400,000 - 4,000) X 0.2] and the annual recruitment would be 88,500 calves [(0.20 X 354,000)/0.80X] or λ = ., or 44,250 animals available for harvest without depleting the resource. This schedule of numbers, harvest and Mn are all maximum figures and the surplus available could have been much larger. Only if recruitment was much less and natural mortality greater could hunting have been a factor. It is quite likely the R was less than 20%, but we have used a relatively high figure to see if hunting alone could trigger a decline. Once R < Mn (Mn = natural mortality), then of course hunting will contribute to the rate of decline. Native harvests would have had little impact when populations exceeded 400,000, but they could have been instrumental in the second decline 895–902.

Causal Factors in Historical Fluctuations | 4

The scarring index then indicated a much lower caribou population, possibly less than 50,000 (fig. 6.). The heavy hunting by the Naskapi and Labrador Inuit during 894–903 (Elton 942) must have increased the rate of decline when the population had already declined and had shifted to the eastern ranges. The harvest from the Moravian missions reached its highest level recorded 894–903 (Elton 942, table 48). We attribute the small increase in the herd in the 920s and 930s to a major decline in the harvest. Elton (942, 386) documented the increase in his meticulous review of historical caribou numbers, saying: “The introduction of fire-arms may have extended the ‘searching power’ of the Indians to send the deer population tobogganing down. Only in Labrador, some curious (our italics) change occurred that broke the migration circuit and allowed the deer to rebuild their numbers within the double refuge of the northern Labrador fastness and the rather casual game laws of the Newfoundland Government.” That curious factor, we believe, was the arrival of the supply ship Harmony that docked at Hebron in November 98 and brought not only supplies but the deadly Spanish Influenza as well. Within nine days only 4 of 00 natives were still alive. From Hebron the ship continued south, reducing the population at Okak from 266 to 59 (Dunn 994). The remaining survivors moved to Nain, removing hunting pressure from nearly all of the northern Labrador tundra. Ironically, the Naskapi had left the isolation of the interior only two years before the deadly disease swept their settlement, having moved to Davis Inlet on the coast in 96 when the caribou crossing failed at Indian House. In a matter of three years the harvest ceased. The root-scar data provide a compelling record of this disaster for the hunters and the return of their major inland prey (fig. 6.). We believe that when these native populations regrouped, their hunting caused the decline after 935 and kept the population low in the 940s and early 950s. When the herd had declined 840–50, the natives had only muskets and Cook (979) believed they were denied ammunition. By the 930s the natives had rifles and the winter hunt was a way of life (table 6.2). No longer were natives dependent on ambushing at crossings. They had increased mobility and could hunt throughout the year. It is clear that hunters travelled further and stayed in the country longer (table 6.2) as the herds declined and remained at low numbers (Strong 930; Banfield and Tener 958; Doutt 954; Bergerud 967). It was the rifle that denied the law of diminishing returns and prolonged the decline after 935. In the first decline of 840, high numbers followed low in 20–30 years; in the second decline, it took nearly 00 years for numbers to return to a level similar to that of about 880 (fig. 6.). Some authors have suggested that there are regular cycles in caribou abundance (Clarke 940; Kelsall 968). There is some regularity in caribou high populations in Ungava (800, 880, and 980s) which could imply synchronicity with weather and sunspot activity, or, more likely, with density-dependent influences.

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Table 6.2 Months

Months that native peoples hunted caribou, 1925–42 Number of Reports

January February March April May June July August September October November December

Percentage

13 14 21 21 15 1 1 0 12 8 0 7

12 12 19 19 13 1 1 0¹ 11 7 0 6

113

101

¹ Before the introduction of the musket, August was the primary month Inuit hunted for skins by spearing at water crossings

Density-Dependent Winter Starvation

A common belief is that high caribou numbers will exceed a lichen carrying capacity and starvation will result (Juniper 980; Messier et al. 988). There are no reports in the historical literature of natives or early naturalists finding starved caribou. On the other hand, Prichard (9) reported that according to the Indians caribou sometimes died from insect harassment. We can only judge this hypothesis by what has occurred since 984 when the population was approximately 600,000 – although this still translates as fewer than one caribou/km², which is not an excessive density for lichen winter ranges (Reimers et al. 980). The back fat of the George River herd decreased after the winter of 98–82 when the herd began to travel as far west as 75° W to locate winter ranges, but mandible and marrow fat reserves remained well above starvation levels, even for calves (Bergerud 996), and the animals have been in better condition in the spring than in the fall in recent years (Huot 989; Crête and Huot 993). Predation

The role of predation in earlier declines is perhaps the hardest hypothesis to evaluate since there are no recruitment or mortality statistics for the abundant years that precede these declines. The most striking point one encounters in reviewing the literature is the obvious scarcity of wolves for long periods and their apparent abundance at other times. Clearly there were marked cycles, and in this simple

Causal Factors in Historical Fluctuations | 43

ecosystem of only one ungulate, the abundance of wolves is dependent upon caribou abundance. Payne (887) saw no wolves at Wakeham Bay, but natives reported them as having been numerous at one time. Hawkes (96) reported that wolves were rare, but again the Inuit said that formerly wolves had been quite numerous. Low (898) did not see or hear a wolf on his 896 summer trip from Richmond Gulf to Chimo. Turner, in 780, found that wolves were common inland from Nain, and that wolves killed some of their dogs even though it was summer (Taylor 969). W. Hendry reported that wolves and wolverines were common along the Larch River in 828 (Elton 942). Low (896) reported that wolves were formerly plentiful along the Hudson Bay Coast but were then rare. Cabot (92) believed that wolves were common between Davis Inlet and Indian House Lake in 905, when he estimated having crossed tracks of 200 wolves. He also reported that wolves had been numerous along the coast of Nain in previous winters, stating that a few years earlier the wolves passed near Nain for “ … three days in swarms like deer.” Wallace (907) also found that wolves were common in the east in 905 and so abundant at a caribou kill site between George River and Chimo in November that their howling kept him awake at night. Clearly, there was a huge decline of wolves coincident to or after the caribou decline 880–920. Tallies of wolves harvested at the Moravian missions are: 00 in 884–93; 76 in 894–903; 43 in 904–3; 8 in 94–27. Elton (942) thought that the wolves were gone by 90. Fur returns for the other posts are consistent with this: Wolf Davis Inlet Fort Chimo HBC Ungava Posts

88–90 98–27 930–34

8 2 0*

Total Animals Harvested Wolverine Black Bear 78 26 

90 55 256

*all in Labrador and none in western Ungava

In 958 the wolves were still low and Bergerud (967) saw none during his winter survey. Interviews indicated that wolves had been rare for 30 years (reports by individual hunters are listed in chapter ). These results are consistent with Elton’s data that wolves disappeared about 90 or after, remaining rare until at least the 960s. Thus wolves could not have played a role in the low number of caribou 96–45. The caribou population declined, possibly at an annual rate of λ = 0.84, 894– 903 to 904–3 (Elton 942, table 48). The decline occurred when wolf numbers were relatively high, the declines were synchronous for sedentary and migratory ecotypes and they occurred over a period of two decades. We also know that calf survival and adult mortality are correlated with wolf numbers for other herds in North America (Bergerud 988b). Thus the sequence of these declines is con-

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sistent with the view that natural predation could have been a component in the declines. A Recent Hypothesis: Increased Snow Cover Crête et al. (996: 34) stated: “Among the factors proposed to explain rarity in the Quebec-Labrador Peninsula during the first half of the xxth century (predation, hunting, destruction of winter range by fire, or by overgrazing lichens, climate), a high incidence of wet and snowy winters during consecutive decades appears the most plausible explanation” (Crête and Payette 990). Temperature records are available for Quebec City, Quebec, between 876–986; according to Crête and Payette (990), these show a warming trend from 880–950 (fig. 6.). These authors further document that the increase in temperatures in northern Ungava were correlated with those for Quebec City where records are concurrent. With warmer winters they postulated an increase in snow depths up to 20 cm, based on vegetative studies by Payette et al. (985). Greater snow cover could reduce food availability on calving grounds and increase energy expenditures in winter (Crête and Payette 990). Our historical review indicated that the George River herd started to decline about 880, a conclusion also reached by Elton (942) and consistent with the root-scar data (fig. 6.). At the start of this decline the temperatures at Quebec City were the coldest in 0 decades (fig. 6.). Temperatures were also low in northern Ungava (Uebe 909). The warming trend that Crête and Payette identify did not occur until 890, a decade after the herd started down (fig. 6.). This warming trend should have advanced spring phenology and improved plant growth and phytomass in the summer, which are favourable parameters for increasing calf weights at birth and improving maternal condition during lactation (Crête and Huot 993, Russell et al. 993). Another problem with the snow hypothesis is that warm winter temperatures in the second half of the 20th century did not result in more snow cover in the spring. The correlation between annual winter snowfall and annual temperatures at Schefferville 955–56 to 99–92 from October to April was only r = 0.0367, n = 36 (fig. 6.2). Snowfalls did not increase with an increase in temperature. A better index to the snow cover that would affect calf viability and maternal condition is the snow on the ground the last week of May, prior to parturition. However, snow depths in the last week of May and prior winter temperatures (the sum of monthly mean temperatures, October to May) were negatively correlated (increasing warmer winter temperatures plotted on the X axis) based on Schefferville statistics (972–73 to 992–93 broken, r = -0.483, P = 0.0360). This correlation means there is less snow on the ground after warm winters, not more. For example, the warmest winter during our investigation was 979–80; the total of monthly mean winter temperatures was -85.3°C but there was only 0.8 cm of

Causal Factors in Historical Fluctuations | 45

T O T A L S N O W F A L L ( m) (B I O L O G I C A L Y E A R O C T– J U N E )

6

5

4

3

r = 0.0367 n = 36

2

-7

-8

-9

-10

-11

-12

-13

-14

-15

-16

END OF MONTH SNOW DEPTH (cm) (MAY)

MEAN TEMPERATURE C (OCT–APRIL 1955–56 TO 1991–92 80 1992 70

Y =−5.737 + 4.589X n = 20 r = 0.643

60 50 40 30 20 10

1993

0

-3

-4

-5

-6

-7

-8

-9

-10

-11

-12

MEAN APRIL TEMPERATURE C

Fig. 6.2 (above) Winter snowfall in Ungava and winter temperatures show that snow was not correlated with warmer winter temperatures as hypothesized as a factor in past declines for the George River herd in a model proposed by Crête and Payette (1990); (below) The snow on the ground the last of May was correlated with April temperatures, recorded at Schefferville.

snow at the end of May. In the coldest winter 99–92, the total of monthly mean winter temperatures was -4.5°C, and these temperatures were accompanied by the greatest snow depth recorded in the study at the end of May, 66.9 cm. Schefferville is about 200 km from the Caribou House calving ground. Snow statistics were also checked for Indian House Lake where a weather station operated adjacent to the calving ground, 948–64. The mean depth of snow was 49.0 cm ± 7.0 cm (n = 5) for the end of April and 9. cm ± 2.48 cm (n = 7) for the

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end of May. Neither of the two snow depths were correlated with mean winter temperatures October to May (April r = 0.25, May r = 0.3). Nor were midwinter temperatures (December to March) correlated with spring snow levels. Again, contrary to Crête and Payette’s hypothesis, snow depths were not correlated with warmer winter temperatures. April temperatures were the best predictor of the end-of-May snow depths at Schefferville; colder temperature in April resulted in more snow on the ground at the end of May (r = 0.643) (fig. 6.2, below). This correlation is reasonable since the greatest snow depths in Ungava occur in April (fig. .7). In the current study snowy winters did not lead to reduced physical condition in the spring. We will document in chapter 9 that the depth of back fat retained by animals after they returned to the April and May ranges was related to the distances they travelled in spring migration and that these distances were independent of snow cover. We do agree that snow depths can have important effects on calf survival and spring foraging. The remaining snow cover in the spring is a function of spring temperatures; the independent variable is temperature. The warmer springs at the beginning of this century (fig. 6.; Crête and Payette 990) should have resulted in less snow and increased plant growth, both favourable factors that would not lead to low numbers of caribou 880–950. Shortage of Green Forage and Cold Springs During the most recent high in numbers of the George River herd 984–88, the herd overgrazed its summer range above tree line (Bergerud 988a; Crête et al. 990a; Crête and Huot 993), and this reduced pregnancy rates and calf and adult survival (Messier et al. 988; Couturier et al. 990; Crête et al. 996). We postulated > 600,000 animals in 880, similar to numbers in the 980s. Thus the range would have been overgrazed in the previous century and the population prone to unfavourable demographics similar to the ones identified in the 980s. The decade from 880–90 comprised very cold summer and winter temperatures (fig. 6.; Crête and Payette 990). Indeed the climate was so severe that spruce trees died, leading to deforestation (bottom of fig. 6.; Payette et al. 985). These low temperatures would have resulted in late spring phenology, reduced spring and summer plant growth and probably more snow cover in May and June. Since calf viability at birth depends on birth weights and these in turn are correlated with the weight of females (Bergerud 97b), a late phenology and snow cover would reduce female condition and calf viability. For example, the spring of 992 in central Ungava was the most delayed since records have been kept. The ice did not leave Knob Lake until 29 June (fig. .4); there was 66 cm of snow remaining on the ground at the end of May at Schefferville; and the mean May temperature was -2.2°C, the coldest May since 956. The mean birth

Causal Factors in Historical Fluctuations | 47

weight of calves captured in 992 was 5.08 kg ± 0.0 kg (n = 49) and of the calves found dead 4.08 kg ± 0.7 kg (n = 3) (Couturier personal communication). Large numbers of small calves died and the summer mortality of adult females was the highest since monitoring commenced 983–84. In our study calf birth weights decreased when the weather in May was cold and females could not find greens prior to calving. If the spring weather was as cold in the 880s as the Quebec City records suggest (fig. 6.), and if these severe temperatures were coupled to a range denuded by high numbers of animals, this could explain the major decline 880–93 that we postulate reduced the herd by two-thirds, a reduction also consistent with the root-scar data. Consider the mechanics of such a decline: In North America, when caribou herds decline recruitment can be as low as 5% and annual adult mortality ≥20% (Bergerud 974a; Bergerud and Elliot 986; Bergerud 988b; chapter 0). These statistics provide a finite rate of change λ of 0.84 (λ = ( - M)/( - R). The regression of λ on R for 8 herds in North America based on R/M schedules was Y = 0.758 + 0.05X (r = 0.748) (fig. 4.5); with 5% recruitment, the rate of decline was 0.83, and with 0% calf recruitment, λ would be 0.9. A rate of decline of 0.84 would reduce 600,000 animals to 00,000 in 0 annual cycles. Calf percentages of < 0% are not unreasonable for the George River herd; since 974 there have been six cohorts with ≤0% calves at 0–2 months of age 986–9 (chapter 0). These reduced additions resulted from an overgrazed summer range (chapter 7) and occurred in a period of favourable, warm, May temperatures (mean May temperatures 986–9, .6°C ± 0.57° vs 954–85, 0.8°C ± 0.36°). With cold springs in the earlier century and the subsequent reduced phytomass, the consequences would have been even more dramatic. With the population down to 00,000–200,000 by 893, the condition of the herd should have improved with reduced grazing pressure and warmer temperatures. But in fact the herd continued to decline (fig. 6.). This is consistent with a recent theory that posits a distinction between those factors that cap population growth and initiate the decline and those factors that continue it. We believe these latter – and ultimately decimating – factors are predation by wolves and mortality from hunting. The wolf population was high in the 890s (Elton 942) and the ratio of wolves/caribou would have increased as predator numbers lagged behind prey. Hence the effect of wolf predation on caribou numbers could have been inversely density dependent (increasing with low caribou numbers) as suggested by Messier et al. (988). If there was more snow cover (Payette and Crête 990), cows would have calved closer to the tree line (Fleck and Gunn 982; Eastland 99) and denning wolves (Kyte 972; Heard and Williams 992), thereby increasing the mortality of neonates (Bergerud and Page 987; Bergerud and Ballard 988; Edmonds 988). Even though the herd shifted from the Hudson Bay coast as it declined, it was still accessible to hunters in Central and Eastern Ungava. In addition, some

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natives from Hudson Bay moved to Fort Chimo rather than starve (Elton 942). The total harvest after 893 by Montagnais at Michikamau; Inuit on the Labrador coast; natives at Chimo; and Naskapi at the Caniapiscau and Koksoak Rivers and Indian House Lake would have exceeded 9,000 animals, or 9% of the herd if it was 00,000, and > 5% if larger. Even in the 950s when the herd numbered 5,000–5,000 animals, the kill exceeded 5% (Banfield and Tener 954; Bergerud 958, 967). Generally caribou herds can remain stable with harvests < 5% and wolf populations at normal levels but they decline with larger human kills (Bergerud 980). The mean rate of population growth for 3 herds in North America with normal wolf numbers where hunting took > 5% was 0.88/year (Bergerud 980). Such a scenario would take 50,000 animals in 893 to 40,000 by 903 and to 8,000 by 96 (when the crossings at the Koksoak/Caniapiscau Rivers and Indian House Lake failed and the Naskapi gave up the inland hunt and moved to the coast). A herd of 8,000 animals would keep its centre of habitation mostly above tree line, which explains why the herd would not have crossed Indian House Lake. The subject of cycles in caribou has long been debated (Elton 942; Skoog 968; Kelsall 968); documented in Greenland (Vibe 967; Meldgaard 99); and proposed for the George River (Messier et al. 988). We have suggested peak populations in 800, 880, and 984–88 – a periodicity of 80–04 years. Following these peak populations in all three cases were major volcanic eruptions that drastically curtailed the growing seasons: Tambora erupted in 85 (The year without a summer?: world climate in 86, Harington 992); Krakatoa in 893; and Pinatubo in 99. The decline after 880 was similar but this time it was more difficult to determine when the lowest numbers were reached since the population remained depressed for decades without a major increase until the 950s. Still, the harvests 925–39 were extremely low and many hunting parties were unsuccessful despite long searches (table 5.). The wolves also disappeared (Elton 942; Bergerud 967). We postulate a 40-year lag for both cycles. Restating our hypothesis for the 880–920 decline: () the main limiting factors were a densitydependent shortage of green food in the growing season compounded by cold spring and summer temperatures that reduced calf survival and capped the increase, causing a major initial decline, and (2) the decline was prolonged by a protracted draw-down caused by a continual hunting mortality and natural predation. The same factors that caused the decline of the George River herd in the 990s (density-dependent summer food shortage [chapters 7, 9, 0]) occurred 00 years earlier but were more severe because of extremely cold spring weather. It is interesting to compare the contexts for these declines. For instance, when the population reached its nadir in about 840, hunters still commonly hunted by ambushing caribou at crossings and many native peoples starved, which in turn reduced hunting pressure. By the second low in the 920s, even the Davis Inlet

Causal Factors in Historical Fluctuations | 49

band had given up ambush and hunters – now equipped with effective firearms and adequate supplies of ammunition – travelled in the winter, extending the search area (table 6.2). As Elton (942, 374) quotes Hutton (926), “The practice was to go inland until they found the deer however far that was.” Thus, the bottom of the first cycle had aspects of a natural adaptive race between human predator and prey. That was abrogated in the second cycle, however, by technology and human ingenuity, which effectively neutralized the natural defensive spacing of the caribou in their centre of habitation. Consider how much more skewed the balance is today, when animals are satellite-collared and game officials report the herds’ daily locations to hunters in aircraft and skidoos.

CHAPTER SEVEN

Forage and Range

In the 940s–950s the terrestrial lichen ranges in the central interior of Ungava were the most extensive in North America and possibly the world (fig. .; Hustich 95). The range extended from the closed canopy line of the Eastman River (52° N) north to Kuujjuaq (58° N) in central Ungava. This lichen woodland of scattered black spruce and larch was protected by some of the greatest snow depths for an extensive region in North America: Lichen heights in climax Cladonia rangiferina, C. alpestris (now Cladina stellaris) stands were often 0–5 cm deep with a biomass estimated at 2,500 kg/ha (Hustich 95; Fraser 956). The percentage of this lichen woodland burned in the period 920–49 was about 5%, giving a fire rotation period of 00 years (data from Hare 959). Here was a range of some 750,000 km² with practically no caribou. There were few signs of caribou grazing in the central interior, nor were there major caribou leads below the tree line in 958 when Bergerud censused the herd (then wintering south of the tree line and east of Schefferville). And yet the root-scar data indicated that there had been hundreds of thousands animals only 80 years earlier (chapter 6). The area in the 950s was analogous to a virgin island prior to an introduction of caribou. Hustich (95) estimated it could support at least 0.5 million animals, a prophesy verified 40 years later. But an even more profound insight of Hustich’s was his suggestion (ibid., 42) that “winter pastures should be comparatively better than the summer pastures in many areas in the interior of Labrador.” We first became concerned about potential forage problems in 98 when we noted that the dates of calving were one week later than in earlier years (chapter 9). A late-calving sequence could be attributed to inadequate forage in the summer and late ovulation (Reimers 983a, 997) or to inadequate winter nutrition and prolonged gestations (Bergerud 97b; Skogland 983, 989a). Huot noted

Forage and Range | 5

in 983–84 that the caribou were in poorer condition in October than they were in April, which suggested a summer rather than a winter problem (Huot 989). Furthermore, the extent of the summer range above tree line of the George River herd is small (47,000 km²) compared to seven other large migratory herds in North America (their mean tundra ranges averaged 55,000 km² ± 26,000 km² (Bergerud 996). If the herd contained 600,000–700,000 caribou in 984–88 (Crête et al. 99), then there were 4 caribou/km² impacting the range above tree line, 0 more per km² than any other herd in North America. Again, aggregation sizes of the herd were large in June and July: The animals were even retracing their routes in mid-summer and grazing some areas twice (Camps and Linders 989). In August many of the animals remained above tree line feeding on the leaves of birch (Betula glandulosa) and Salix (Crête et al. 990a). Additionally, there was little snow cover in these months to protect the flora from trampling, unlike there is in winter. We knew from studies of several sedentary herds that cows with calves were prepared to sacrifice optimal foraging in June and July to reduce predation risk; the same situation has been noted in Norway, even though there are few predators (Skogland 989a, 99). Since the herd in 984 was the largest in the world (Williams and Heard 986), what were the forage resources, and how had caribou impacted both summer and winter pastures? By contrasting both winter and summer pastures, this study sheds light on the controversial question of which grazing regime dominates caribou dynamics. The traditional view posits the winter lichen range as the critical habitat. Thomas (980) argued that most biologists believe that available forage on winter ranges is the key governing the potential upper limit of population size. But this view has been questioned by Reimers (980, 983b), Bergerud (974a, 996), and Russell et al. (993). In a review, Reimers (997, 05) reminded readers that “a yet unresolved question is whether reindeer body weight and hence reproductive performance and neonatal mortality are more strongly influenced by winter than by summer grazing conditions.” To resolve these issues we conducted an extensive range survey of both summer and winter pastures of the George River herd in 988 and 989 with additional measurements on energy budgets for the period 988–92. Although these measurements were made two decades ago, the George River herd at that time was at peak numbers with densities higher than that quantified for any of the major migratory herds in Canada since scientific censuses were inaugurated in the 950s (Bergerud 996). By providing insight on how maximum numbers of non-insular caribou interact with their fragile arctic flora, these findings help to resolve carrying-capacity questions. Range Survey, 1988–89 We designed the range surveys of 988 and 989 to emphasize forage composition on upland dry sites, in particular the lichen woodlands below tree line on the

52 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Labrador Peninsula and in central Ungava. The graminoid communities had not been obviously damaged by grazing, although some areas had been lost to trail systems (see also Crête et al. 990b). There is considerable literature suggesting these monocots can not only withstand heavy grazing but increase their biomass as well (Thing 984; Ouelett et al. 994). On St Matthew Island, sedges and grasses increased, even at densities of nearly 20/km² (Klein 968), and on South Georgia – where graminoids were the primary food – densities of approximately 0/km² were maintained (Leader-Williams 988). The experiment was designed to have one range station in the centre of a habitat block gridded by longitudinal increments of one degree and 30 minutes of latitude. Transects were walked in the lichen woodland or shrub-tundra, where vegetation was measured with a point intercept procedure (Bergerud 97a) by quantifying the ground cover immediately in front of each foot landing. We walked the lines following compass courses without scanning the vegetation immediately ahead. The lines were 500 m in length in 989, 800 m in 988. We were especially concerned with determining the extent that caribou had denuded the vegetation by plant removal and trampling. When we intercepted non-vegetated ground other than a trail, we recorded the substrate as sand, rock, or dirt/turf. When the landing was on dirt/turf we decided (subjectively) if it had been caused by caribou trampling or by other environmental factors such as frost heave or wind abrasion. The extent of caribou trails plus turf created by caribou gave us an estimation of the amount of land surface that no longer supported vegetation due to the impact of caribou, primarily the action of their hooves. Other items recorded were caribou pellet piles in a 50 cm x 25 cm grid at each foot landing. Broad vegetative categories that we listed were shrubs, forbs, upland graminoids, bryophytes, wood and litter, broken twigs on the ground, reindeer lichens, and other lichens (Cetraria spp. [C. nivalis most common], Alectoria ochroleuca, Cornicularia divergens, Sphaerophorus globosus, Thamnolia vermicularis, Stereocaulon paschale, Dactylina arctica). The percentage of lichen cover was recorded, the mat was frequently picked, and the height was measured in order to estimate the percentage of mat removed or damaged. We also looked for natural exclosures to record height and cover and we recorded the percentage of the mat disturbed, (i.e., podetons not upright and fragment pulled from the mat). We did not specify the species of grasses and sedges or bryophytes (except Rhacomitrium lanuginosum), but we did identify forbs and shrubs and several lichens by species. We estimated the depth of snow cover by noting the height of the snow abrasion gap on the stems of black spruce, as described by Hustich (95). The range stations located by the systematic aerial grid design in 988 and 989 resulted in 72 grid stations in 988 and 9 in 989. The stations spanned Ungava from 60° N to 50°30' N and from 74° W to 62° W – an area of 296,000 km² (fig. 7.). Thirty-four additional stations were located near field camps 988–95, both above and below tree line. In our analysis of the vegetative sites we divided the

Forage and Range | 53

TREE LINE

UNGAVA BAY LEAF RIVER n=4

WESTERN TUNDRA n = 11

L TA AS A CO NDR LIEF TU T RE 9 EC INS n = WESTERN MIGRATION n=6

WESTERN LICHEN WOODLAND nn==17 3

CENTRAL MIGRATION n = 13

CENTRAL LICHEN WOODLAND n=8

BOUNDARIES RANGE REGIONS TORNGAT MTS. n=3

n = 4 NUMBER OF RANGE STATIONS

GEORGE RIVER CALVING n=9 EASTERN TUNDRA SUMMER n=9 MOVEMENT n = 17 EASTERN LICHEN WOODLAND n = 14

0 0

50

HEAVY LICHEN DISTRUCTION (SATELLITE IMAGES)

100 KILOMETRES 50

100 MILES

Fig. 7.1 The boundaries used in the regional analysis of the range surveys completed in the summers of 1988 and 1989. The area listed as heavily trampled was based on Landsat imagery taken from anonymous (1992).

study area into 2 regions (fig. 7.). First we separated areas above and below tree line. We then further divided these areas as to patterns of caribou use, i.e., calving areas (both the George River and Leaf River herds); tundra summering areas (both on the Labrador and Upper Ungava Peninsula); a coastal insect relief region; a summer movement region adjacent to the George River; migration regions between summer and mid-winter ranges (central and western); and wintering ranges of lichen woodland (western, central, and eastern). All this can be viewed in figure 7.. On the flights between aerial landings at grid stations in 988, Bergerud recorded the direction of caribou trails, their abundance (0 parallel leads equaled one trail system), the color of the lichen mat, and the length of the aerial transects that crossed recent burns. On sunny days the lichen mat was bright white when it had not been disturbed; when fragmented by caribou, it appeared grey or grey-white (lichens on cliffs provided a reference for colour, even on heavily-utilized ranges). The burns recorded dated back perhaps 20 years and were distinguished by reduced lichen cover, dead conifer stems, and low, scattered, spruce regeneration.

54 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Food Preferences and Fecal Nitrogen

In addition to the vegetative transects, at these field camps Camps estimated food preferences by recording the plant associations that an individual caribou fed on during a five-minute scan. Individual animals were selected after a horizon scan on this basis: The animal was active (not lying down); and it was the undisturbed animal closest to Camps, who recorded the time the animal fed in various plant associations in seconds. The plant associations included birch; grass/sedge; tundra shrubs (excluding tall birch and willow); tall willows; lichens; tundra shrubs plus grass/sedge; birch plus grass/sedge; birch plus tundra shrubs; and others (such as forbs and birch plus lichens). At the end of each feeding watch, Camps visited the feeding area and measured the distance the animal had travelled, estimated the percentage of plant cover, and measured the green phytomass by clipping the vegetation in a 0.25 m² quadrat. He then took a second reading of the plant cover and phytomass that lay adjacent to where the animal had fed but had been bypassed. These two adjacent measurements were not meant to quantify the removal of forage by the animals but to evaluate whether the feeding animals were selecting feeding sites with greater vegetation or feeding at random locations as noted by White et al. (975) and Skogland (980). To measure the quality of the spring and summer diet, fresh pellets (that day) were collected for fecal nitrogen readings in June 988 and June–August 989. The object in 988 was to compare the diet quality of males below tree line with that of the cows on the calving ground (Bergerud 996). Commonly we could distinguish the sex of the animals. The object in 989 was to collect feces samples every day and compare them with daily nitrogen measurements taken from Betula glandulosa and Salix planifolia. Some vegetative samples were also measured for nitrogen from green graminoids and the leaves of Vaccinium spp. and Arctostaphylos spp. The Growth of Birch

If overgrazing affects demography, information on plant condition can help evaluate whether or not ungulate-forage models (Caughley 977) are correct in predicting equilibrium between resources and animal numbers. To determine range trends Camps and J. Aalbers (University of Tilburg, The Netherlands) travelled down the George River from 3 August to 5 September 993 (56°06' N to 57°30' N) conducting range transects and collecting the stems of Betula glandulosa to measure the width of past annual growth rings. Caribou travel routes along the Lower George River – consistently used to travel between the calving grounds and the Ungava Bay coast – were known to be heavily grazed from our surveys in 988 and 989 and from Landsat aerial images (fig. 7.). Birch cores were collected at 9 sites and sectioned, and the slides were read by N. Van der Putten, who measured ring widths to 0.000 mm and counted cells between growth rings.

Forage and Range | 55 100

OTHERS TUNDRA SHRUBS TUNDRA SHRUBS / GRASS

90

PERCENTAGE

80 70

GRAMINOIDS

60 50

BIRCH / GRAMINOIDS

40 30

BIRCH

273 OBSERVATION HOURS

20 10 0

WILLOW 10–22 23–27

28–2

3–7

8–12

JUNE

13–17 18–22 23–27

JULY

28–1

2–6

7–11

12–15

AUGUST

MEAN

Fig. 7.2 The observed food habits of caribou (1988 to 1992), documented in five-minute test periods of individual animals and noting the plant communities the animals were foraging.

Activity and Energy Budgets

At our field camps, we tabulated activity budgets by horizon scans at least four times a day 988–92, tallying the standard caribou activities – lying down, standing, walking, and feeding. Budgets were segregated according to the presence or absence of biting and parasitic insects, and the sample size totaled 93,000 animals. Only since the 980s have caribou activity budgets and forage abundance been quantified and integrated into energy budgets that compare energy expenditure with metabolizable energy intake (MEI). We estimated energy budgets in four summers 988–92 following the procedures outlined by Fancy 986; Kremstater et al. 989; Hovey et al. 989; and Russell et al. 993 (see Camps and Linders 989, as well as Appendix). Food Preferences The food preferences of reindeer/caribou have been quantified for some 80 years in North America (Hadwen and Palmer 922; Palmer 926) and the menu has remained the same. Lichens dominate in the winter selections; graminoids in the spring; and deciduous shrubs in the summer, whether willow in Alaska or birch in Labrador. The choices in Ungava were no different, comprising terrestrial lichens and evergreen shrubs in winter, sedges in spring, and birch and willow in summer. We have no additional information on the George animals’ winter

56 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 7.1 The phenology and utilization of birch (Betula glandulosa) in July 1989–92 (lat. 56º49’ N, long. 64º50’ E) Growing Season

Date of Blooming or Full Leaf

1st Date Birch > 20% of Diet

% Diet July Diet

28 June 18 June 28 June 29 June 8 July

23 June 19 June 29 June 28 June 8 July

34.2 ± 4.37 (17¹) 58.1 ± 7.01 (15) 66.1 ± 7.59 (14) 41.4 ± 6.79 (15) 58.0 ± 6.43 ( 6)

1988 1989 1990 1991 1992 ¹ Days feeding recorded

food preferences, but we have observed their growing-season preferences over five summers 988–92 on the upland barrens of the Labrador Peninsula (fig. 7.2). The George River herd made a major change from a diet predominantly of lichens in March (Drolet and Dauphiné 976; Gauthier and Shooner 988) to one of dried grasses in April (Parker 98), a change made possible by migrating approximately 200 km south from the Ungava Bay region to the tundra west of Nain in Labrador 56°30' N (Parker 98; Vandal et al. 989). We hypothesize that this southern movement not only provides a change from lichens low in protein to dried grasses higher in protein (Scotter 965; Bergerud 97a), but that these open hydric communities also provide caribou with their first early greens in May. There was a definite reduction in daily travel rates in mid-May (chapter 3), then shortly before calving there was rapid movement to the calving grounds farther north. We have two observations of the early use of greens: At the Ford River (58° N) in the first week of June 978, Bergerud noted cows pawing for the green rhizomes of graminoids. Ten years later we noted bulls actively searching for the first green shoots of bog bean (Menyanthes trifoliata) in shallow warm ponds at Lac Privet (56° N) in the first two weeks of June. We believe that animals can locate early spring greens – possibly two weeks before the official start of the growing season (as delineated by widely spaced government weather stations). These are the most important weeks in maternal nutrition as the fetus nears term. In our five summers of observations, caribou fed in plant associations dominated by graminoids and deciduous shrubs (fig. 7.2), with birch the most important forage species in July and August (table 7.). However, these were summers of high numbers when grazing and trampling had reduced both the phytomass and the selection of other species. The results agree with Crête et al. (990a), who gave the percentages in  rumens for the George in July 988 as 8% lichens; 40% deciduous shrubs; and 34% grasses and sedges (they reported the diet of the Leaf River herd on the western tundra at the same time as comprising % lichens;

Forage and Range | 57

55% shrubs, of which Vaccinium ulignosum was important; and only 3% monocots). Gauthier and Shooner’s (988) list for the diet of the George River herd June 987 is: 38% lichens; 38% grasses; and 8% shrubs. For the Leaf River herd they list: 53% lichens; only 33% graminoids; and 0% shrubs. Our range studies showed that lichens were much more abundant on the tundra used by the Leaf, while shrubs were more abundant on the George River range (fig. 7.3). In the tundra of Ungava, the abundance of lichens decreased as shrubs increased (fig. 7.3) – this is a general botanical finding and it occurs because of competition between the two plant groups (Bergerud 97a; Thomas et al. 996) – but lichens were more abundant in the west in the range of the Leaf River herd, whereas shrubs dominated to the east in Labrador. The George River animals were foraging fewer lichens than the animals in the Leaf River herd as expected based on abundance, but also fewer shrubs – even though our surveys showed that shrubs were more abundant here than they were on the Leaf River ranges. However, many of shrubs – especially Vaccinium ulignosum and birch – had been recently defoliated and/or killed on the summer range of the George River herd, and thus the animals were relying more on the grass/sedge communities. Forbs can be a major source of nitrogen and phosphorus (Bergerud 977; Klein 990), the two nutrients most commonly correlated with food preferences (Bergerud 972; Bergerud et al. 984; Leader-Williams 988; Russell et al. 993). Forbs were equally as important as shrubs in the summer diet of the Porcupine herd (Russell et al. 993). Forbs represented 7% of the (superior) summer diet of caribou on Southhampton Island (Ouellet et al. 993); but they were not important in the diet of the George River herd in the late 980s (fig. 7.2; Crête et al. 990a). Forbs were likely an important element in the diet formerly, but we cannot evaluate how important they were since we have no summer studies of the rumen contents prior to 986. The absence of forbs is a factor in the inadequate nutrition reported by Crête and Huot (993) and the decline in physical condition that we discuss in chapter 9. We measured the quality of the June diet in 988 based on fecal nitrogen. The percentage of nitrogen for females was .58% ± 0.032% (n = 7) and for males .97% ± 0.42% (n = ). Both nitrogen readings were significantly lower than for five other herds in North America that were not reported to have summer forage problems in June (Bergerud 996). Fecal nitrogen readings (FN) may not be representative of dietary nitrogen and digestibility, however, because of plant secondary compounds such as phenols and tannins (Kuropat and Bryant 983). We collected vegetative samples and the feces of males and females daily in 989 from 5 June until 3 September to decide if FN was representative of plant protein. These results indicated that FN was similar to the major plant species eaten in July and August, birch and willow (table 7.2; fig. 7.4). Prior to 25 June, fecal nitrogen readings were considerably less than the vegetative nitrogen in birch/willow buds; that was not due to digestive

85

REGIONS

80

WESTERN TUNDRA LEAF RIVER CALVING COASTAL TUNDRA INSECT RELIEF GEORGE RIVER CALVING TORNGATS SUMMER MOVEMENT EASTERN TUNDRA

75 70 65

PERCENTAGE LICHENS

60 55 50 45 40 35 30

Y = 4.94X 0.765 + 95 r = –0.708 n = 55

25 20 15 10 5 0 0

5

10

15

20

25

30

35

40

45

50

55

60

PERCENTAGE SHRUBS Fig. 7.3 The percentage of lichens and shrubs for seven regions. The range studies in 1988 and 1989 indicated that abundance of lichen cover decreased as shrub cover increased in seven regions in Ungava, a concept well recognized in the caribou literature (Bergerud 1971a, Thomas et al. 1996). There were more lichens and fewer shrubs on the western tundra of the Ungava Peninsula than on the tundra of the Labrador Peninsula (see fig. 2.7 for the location of these major tundra regions). This reduced abundance of lichens on the Labrador tundra was partly due to overgrazing and fragmentation from the large summer aggregations, but another factor was that there was more alpine and exposed terrain in the east than the west. In the 1988 range survey we could still estimate the percentage of the lichen cover on the Labrador tundra, even when it was heavily disturbed, since small lichen fragments were still visible.

Forage and Range | 59

Table 7.2 in 1989

The percentage of nitrogen in the forage and droppings of caribou

Plant Species

Graminoids Tundra Shrubs³ Birch Willow⁴ Caribou pellets ¹ ² ³ ⁴

June¹

1.83 (1) 2.83 ± 0.20 (7) 3.84 ± 0.12 (15) 4.39 ± 0.20 (12) 2.61 ± 0.46 (32)

% Nitrogen ± SE (n) July August

2.15 ± 0.25 (8) 1.97 ± 0.11 ( 9) 2.71 ± 0.08 (22) 2.73 ± 0.10 (19) 2.60 ± 0.06 (41)

– 1.70 ± 0.05 (4) 2.35 ± 0.11 (15) 2.04 ± 0.10 (13) 2.20 ± 0.06 (21)

September²

– – 2.30 ± 0.37 (3) 1.95 ± 0.21 (3) –

5–30 June –3 September Vaccinium uliginosum and Vaccinium angustifolium Mostly Salix planifolia

problems, however, but to the fact that the caribou were still relying on graminoids that were less nutritious than the emerging shrub buds. For example, on 22 June the FN from three males was 2.3% ± 0.06%; on 2 June the nitrogen in birch was 3.5%; in Salix planifolia (the preferred willow) it was 3.07%, and in the mixed array of graminoids being utilized, .83%. The nitrogen contents of the caribou diet improved dramatically when they switched to birch in the last week of June (figs. 7.2, 7.4; table 7.2). The quality of diet declined from a high in nitrogen of 3.04 (n = 8) from 27 June–2 July, to a low of 2.02 (n = 9) during the last week of August (fig. 7.4). After 27 June the diet of the caribou always contained more protein than that provided by green graminoids and tundra shrubs, primarily V. uliginosum (n = 5) (table 7.2). Crête et al. (990a) documented the heavy use of V. uliginosum for the George River herd in July 988 but little for the Leaf River herd. Our analysis indicated that uliginosum was less nutritious than either birch or willow. The use of willow increased in August (fig. 7.2). This cannot be explained on the basis of a decline in protein in birch (fig. 7.4, table 7.2). However, the digestibility of the leaves should decrease by August as the phenol content of the leaves increases (Haukioja et al. 978). By August the birch phytomass had been reduced; furthermore, the dams were more prepared to increase risk by feeding in tall willows with reduced visibility once the calves were less vulnerable to predation in July. Indeed others have noted that caribou with neonates seem reluctant to enter vegetation with reduced visibility (Roby 978; Bergerud et al. 984). Chapin (980) reported that the clipping of Salix pulcha by grazing delayed phenology by a month – another possible explanation – but our phenology notes suggested a similar leaf-out for both birch and willow, as did the FN readings (fig. 7.4). This does not rule out the possibility that birch also was delayed by grazing pressure, however.

60 | TH E R E T U R N O F C A R I BO U TO U N G AVA

O

W

BIRCH n =55 WILLOW n = 47 OTHER PLANT SPECIES n = 51 CARIBOU n = 94

H

RC

4

BI

PERCENTAGE OF NITROGEN

W

IL

L

5

3

BIRCH 2

WILLOW

OTHE

R SPE

CIES

1 BIRCH 20% OF DIET JUNE 19

0

15

20

JUNE

25

30

5

10

15

20

JULY

25

30

5

10

15

20

25

30

AUGUS T

Fig. 7.4 The percentage of nitrogen in major summer forage species compared to that found in caribou feces in 1989. The dominant summer forage was birch, and the nitrogen in the feces was similar to that of birch in July and August. But in June fecal nitrogen was less than that in birch and willow because the animals were still foraging on graminoids prior to the full leafing of the deciduous shrubs. The other plant species graphed on the fig. with lower nitrogen percentages were primarily Vaccinium and Arctostaphylos shrubs.

Birch was the mainstay in the summer diet in both quantity and quality (fig. 7.2); fecal nitrogen percentages closely mirrored nitrogen readings in that species (fig. 7.4). Changes in the phenology of birch between years may have contributed more to annual changes in summer nutrition than any other single environmental variable, including insect harassment. The Condition of Winter Pastures Lichens are the fare of winter and the leaves of green deciduous shrubs that of summer, yet as the abundance of lichens increases, that of shrubs decreases (fig. 7.3, Bergerud 97a). The lichen mat suppresses regeneration of woody stems. In Ungava there were large lichen supplies in 988 above tree line in the west north of the Koksoak River (figs. 7.3, 7.5), but far fewer supplies in the eastern tundra east of the George River. Crête et al. (990b) reported 2,564 kg/ha in the west, north of the Leaf River, and this exceeds the lichen quantities on extensive areas of the tundra ranges in North America with the exception of the Seward Pen-

54

86 33

67 63 61 72 72

74 84 82

53

65 55

86

70

73 83

79 84

86 73 87

86 53 86

65

34

18

46 70

69 59

67 27

61 79 50 64 86 71 69 74 65 67 88

82

63 69

82

72

62

8

8

4

6

97

43

4 7

9

10

43 59

65

88 53

27

11

5 20

73

81 75

36

61 66

RANGE STATION < 20% LICHEN COVER > 70% LICHEN COVER TREE LINE 0 0

73 D

21 12

50

100 KILOMETRES 50

100 MILES

25 D

41 D

51 94 D 100 78 92 99 D 64 98 80 100 24 35 100 100 100 35 100 48 34 84 39 100 31 100 53 41 31 80 57 100 32 28 31 24 23 29 100 25 41 100 19 19 12 19 25 12 16 44 12 13 27 17 12 5 27 11 10

41 51 D D 44 38 D D 11 40 30 D 21 13

5 4

2

19

12

D

8

RANGE STATION MANY LICHENS DEAD NOT DUE TO GRAZING 30–50% UTILIZED > 50% UTILIZED TREE LINE

Fig. 7.5 (above) The percentage of the ground covered with lichens in 1988; (below) The percentage of the lichen mat that was disturbed by caribou grazing and trampling documented the heavy impact of caribou east of the George River. Our study was timely since the peak population of the George River herd was in 1988 (see fig. 10.4).

62 | TH E R E T U R N O F C A R I BO U TO U N G AVA

insula in Alaska (Swanson et al. 985; see review in Russell et al. 993). Portions of the George River herd have wintered north of the Koksoak in several winters since 984, especially in years when snows were deep in the lichen woodlands south of the tree line, but they did not winter in the eastern tundra in large numbers during this study until 992–93 and after. In March 958 when the herd only numbered 5,000 animals, nearly all the animals were in the east, south of the tree line in the lichen woodlands in the vicinity of White Gull Lake. In 988 and 989, when the herd exceeded 600,000, we noted that major impacts of caribou on the lichen flora were ubiquitous (figs. 7.5, 7.6). Caribou trails were everywhere, with the mean number of trails/km² in the central migration region as high as 22 trails/km². However the impacts were of longer standing on the eastern ranges – in both tundra and lichen woodland habitats – than in the west, since a much higher proportion of these trails were bare of lichens (fig. 7.6). There were three regions in 988 in which a high proportion of the trail systems remained vegetated: the Leaf River calving ground (north of 59° N) where 83% of the leads still had lichens present; and the western and central lichen woodlands, where 79% and 75% of leads respectively still contained lichens. The Leaf River herd first used the area we surveyed east of Payne Lake for calving in 984; the George River herd first wintered there in 984–85. The western lichen woodland was first occupied in recent times in the winter of 98–82 and the central woodland did not have large numbers of animals until 985–86, based on satellite telemetry and harvest statistics. These consistent results verify the western and northern extensions of the herd as it increased 98–86 and demonstrate the viability of using the presence of lichens on caribou leads as a measure of past range extensions. The major impacts of the caribou on the lichen community were a reduction in the thickness of the mat by trampling and utilization (figs. 7.5–7.7) and the complete elimination of the mat in trails and the creation of turf (fig. 7.8). The combined habitat altered or replaced by turf and trails was 6–8%. Both the percentage of the mat shattered and the percentage of turf within stations on winter ranges were correlated with pellet piles (fig. 7.6). The percentage of turf was correlated with lichen cover (P = 0.024, n = 53) but not with shrub cover (P = 0.52, n = 55). The percentage of turf was also correlated with the percentage of shattered lichens recorded at stations (P = 0.02, n = 5) and with broken twigs (P = 0.0008, n = 57) (fig. 7.6). Hence the turf had been removed from the lichen cover but not from shrub habitat, and the impact of hooves was of greater importance in shattering both lichens and shrubs than was the actual ingestation of forage. The impact of peak numbers in 988 had a greater impact in the eastern tundra than in the western tundra (fig. 7.7). Still, despite the heavy use of lichen supplies, the winter pastures were extensive in 988 and 989. The percentage of the regions recently burned varied from .0% ± 0.65% for the eastern lichen woodland to 6.5% ± 0.50% for the central

HEAVY USE

30 36

UNGAVA

36

BAY

35

40 77

28 0

UNGAVA

1

BAY

4

38

12

88

HEAVY USE

4 35 36 69 52 80 71 41 43 4 11 36 23 79 18 30 16 28 104 35 25 3 76 62 39 48 5 13 34 60 42 0 0 16 24 26 53 62 64 9 35 70 64 8 0 10 20 40 30 12 4 27 74 4 0 19 0 64 44 35 12 25 18 27 16 2 4

68 76 100

100 11 17 41 79 71 100100 100 100 22 23 9 20 68 25 100 86 100 100 89 56 18 37 38 50 54 55 88 100 100 14 13 14 13 47 46 67 36 76 72 4 37 45 20 28 76 50 61 75 62 2 7 2 20 17 43 20 59 23 45 42

9

0

0

20

BARE TRAILS (%)

PELLETS / 1,000 m²

HEAVILY GRAZED

HEAVILY GRAZED UNGAVA 0.7 0 1.7 0.8

BAY

1.3 0.4

0.2 0

3.1 0

0

0.8 4.4

2.2 1.5 0.7 1.2 1.6 3.2 3.8 5.1 9.3 1.5 0 0.2 0.9 1.6 0 1.0 0 1.8 4.4 7.8 0.2 0.4 0.4 1.7 1.0 0 0 1.0 0.7 1.6 4.1 6.8 0.2 0.4 0 0.4 0.8 0.2 0.4 2.0 1.2 0.4 2.5 2.5 1.8 2.2 0.6 0 0 0.2 2.1 0.2 1.0 5.4 0.3 0.8 1.5 0.6 0.2 0 0.9 1.5 0.6 2.2 0 1.3 0

0.5 1.5

2.0

UNGAVA

8.9

BAY

4.7 13.6

15.0 7.1

3.2

4.8 8.2 8.9 9.9 11.9 9.3 11.5 25.5 17.8 13.0 2.0 3.0 3.2 3.9 0.5 8.6 2.4 12.3 36.8 24.1 7.5 0.7 0.7 2.9 5.0 0.4 1.9 5.8 0.4 0.3 1.4 0.6 3.9 5.0 1.4 2.8 0.4 0.9 3.8 3.0 2.3 2.3 1.5 0.9 0.8 0.6 6.2 2.5

19.5 1.4 17.7 25.6 34.6

4.3 17.4 16.7 4.6 4.3 2.8 21.8 16.2 3.6 1.4 1.5 14.0

1.8 1.3 0.9 2.5

0.2 0.2

BROKEN TWIGS (%)

TURF (%) HEAVILY GRAZED

24 40 13

UNGAVA

27

BAY

17 100 52

18

HEAVILY GRAZED UNGAVA 9

13

16 17 18 47 64 56 66 99 98 40 10 26 13 38 50 43 34 100 100 100 19 4 3 1 23 39 29 30 52 77 75 100 16 12 4 21 9 22 16 32 23 23 83 52 8 6 8 10 15 40 8 15 15 11 85 8 3 5 6 4 12 43 15 16 4 8 11 3 11 10 5 2

3.9

1.8 0.2

0

8 28

BAY 25

30 19

70 42

17 30 42 69 38 20 43 4 8 11 31 35 28

15 21 14 37 13 18 8 25 16 14 22 11 20 19 15 26 0 0 17 0

20

48 44

10

2

19 22

1 9

1

SHATTERED LICHENS (%)

DEAD BIRCH (%)

Fig. 7.6 The distribution of caribou foraging and trampling impacts on six variables. The six variables were all heavily impacted and located primarily on the Labrador Peninsula tundra. The six indices were all significantly correlated. Only systematic stations shown.

n=9

n=7

n=9

COASTAL TUNDRA RELIEF

EASTERN TUNDRA GEORGE RIVER CALVING

n=4

n = 11 n = 13

CENTRAL MIGRATION

WESTERN TUNDRA

LEAF RIVER CALVING

1

10

% BARE TRAILS

n = 17

SUMMER MOVEMENT

n = 17

WESTERN LICHEN WOODLAND

PELLETS/m²

30

5

60

% SHATTERED LICHENS

20 20

30

% SAND + ROCK

5

0. 2

2

% TWIGS

0. 4

% TURF 10

40 % LICHEN REMOVED

n=6

% DEAD BIRCH

WESTERN MIGRATION

SCALE

n=8

CENTRAL LICHEN WOODLAND

n = 14

EASTERN LICHEN WOODLAND

Fig. 7.7 The foraging and trampling impacts by regions. The larger the polygons, the greater the impacts (see fig. 7.1 for regional boundaries).

SHATTERRED LICHENS (%)

Forage and Range | 65

100 80 60

WINTER r = 0.417, n = 57 SUMMER r = 0.656, n = 25

40 20 0 0

5

10

15

20

25

30

35

40

15

20

25

30

35

40

10

WINTER r = 0.430, n = 57 SUMMER r = 0.627, n = 23

9

PERCENT TWIGS

8 7 6 5 4 3 2 1 0 0

5

10

PERCENT TURF

Fig. 7.8 Three impacts of trampling were shattered lichens, broken twigs, and turf. The damage to all three was correlated and greater on summer ranges than winter due to the concentration of caribou on the smaller range above tree line than those occupied in the winter below tree line. Also, in winter, snow cover reduces trampling effects despite the damage done in digging feeding craters.

region. The grid with the greatest burned area was between 69° W and 56°30'–57° N with 9% burned; the second highest burned block was just west of Schefferville, at 7%. Our estimation of the percentage of the lichen biomass removed from the unburned mat by grazing and trampling varied between regions from 3–0% in lichen woodlands to 26% on the migration ranges where the mat was more exposed to trampling by the lack of snow in the autumn (figs. 7.5–7.7). Even in the western tundra region, where the caribou had been present in seven winters since 973–93, only an estimated 4% of the lichens were degraded. We weighed lichens in only three quadrats, but the biomass was considerable: 23 gm/m²,

66 | TH E R E T U R N O F C A R I BO U TO U N G AVA

399 gm/m² and 429 gm/m². Crête et al. (990b) reported a mean of 20 gm/m² with 44 stations and estimated the animals removed 0.5–0.9% per year. Hustich (95) had estimated 2.5 metric tons/ha (250 gm/m²) for the central interior when the population was nearly extinct in the late 940s. Measuring the height of the molariform teeth is a method of range assessment that is independent of plant measurements. Skogland (988) showed that the wear on these teeth accelerated in herds in Norway that had reduced winter lichen forage (more grit and dirt). We measured the heights of the P₄ and M₁ teeth following the methods of Miller (974) for 87 females killed in 980 (Parker 98) and 35 cows collected in 992. The 980 animals were an index of range prior to high numbers; the 992 collection was dominated by cohorts born during high numbers in the early 980s. The slope of the combined height of P₄ + M₁ on age in months for the 980 sample vs the animals collected in 992 did not differ (P = 0.353), nor were the slopes different from that secured by Miller (974) for the Kaminuriak herd, NWT, in 966–68 when numbers in the herd were low (Parker 972a), animals were in good condition (Dauphiné 976), and lichen forage was abundant (Miller 976a, 976b). Our measurements of lichen abundance (as well as those of Crête et al. 990b) and of tooth wear indicated that the George River herd did not have winter lichen shortages in the 980s or 990s when numbers exceeded 600,000 animals and overall densities in winter habitats were –2/km². These results are consistent with findings elsewhere. In Norway, the herd with the highest reproductive rate and highest survival (and, as well, good body weight) was the Knutshø herd with a winter density of .4/km² (Skogland 985). Six of the seven other major migratory herds in North America have had maximum winter densities less than 2/km² (Bergerud 996) and have had satisfactory demography (Davis and Valkenburg 99; Bergerud 988; Fancy et al. 994). The physical condition of the Porcupine and Beverly herds (NWT) was assessed frequently in the 980s and spring condition was satisfactory despite variations in annual snow depths and the availability of lichens (Russell et al. 993; Thomas and Kiliaan 998). The winter range of the Beverly herd had the highest frequency of forest fires of any of the caribou ranges in the NWT (Scotter 964; Miller 976; Thomas 99; Thomas and Kiliaan 998), and yet it maintained a high reproductive rate and experienced little loss in condition over the winter (Thomas and Killian 998). The Condition of Summer Pastures Forage Shattered by Trampling

Our range surveys in 988 and 989 indicated that the impact of caribou trampling had been much more severe on the summer pastures above tree line on the Labrador Peninsula than it was on migratory and winter ranges and on tundra ranges further west of 68° W (figs. 7.7, 7.9, 7.0). Nearly all the areas disturbed

Forage and Range | 67

35

30

PERCENTAGE OF GROUND SURFACE COMPOSED OF TURF

MEAN FOR EAST 25

20

15

WESTERN TUNDRA (WEST OF 68° LONG.) EASTERN TUNDRA (EAST OF 68° LONG.)

10 MEAN FOR WEST 5

r = 0.636 n = 34

0 0

1

2 3 4 5 6 7 8 PERCENTAGE OF TWIGS WITHOUT LEAVES COVERING SURFACE

9

10

Fig. 7.9 A comparison of two impacts, defoliated dead or broken twigs and the percent of the ground covered with turf compared between the western tundra on the Ungava Peninsula and the eastern tundra on the Labrador Peninsula. Each data point is from a range station in the centre of the long. x lat. grid system of the range survey.

were north or east of the limits of forest fires (fig. .). The indexes we had established to measure caribou impacts (i.e., shattered lichens, broken twigs, etc.) were correlated, indicating a common dominator (tables 7.3, 7.4). The regions more severely denuded were the George River calving ground, the travel route along Indian House Lake, and the lower George River (Summer Movement Region), as well as the insect relief habitat adjacent to Ungava Bay (fig. 7.7). These results indicated that 37,000 km² had been degraded and an independent assessment based on Landsat imagery showed a thrashed June/July range of 46,000 km² (fig. 7.) (Anonymous 992).

68 | TH E R E T U R N O F C A R I BO U TO U N G AVA

PERCENTAGE OF SURFACE COVERED WITH TURF

40

WESTERN TUNDRA EASTERN TUNDRA

30 MEAN FOR EAST

20

10

0

MEAN FOR WEST

0

5

10

r = 0.675 n = 34

15

20

25

PERCENTAGE OF SURFACE COVERED WITH SHRUBS

30

35

45

Fig. 7.10 The percentage of turf compared to the percentage of shrubs. The eastern tundra on the Labrador Peninsula had more shrub cover, resulting in greater caribou activity leading to an increase in turf compared to the western tundra on the Upper Ungava Peninsula.

Nearly all the trails (96%) on the George River calving ground were free of lichens, indicating a long history of use; indeed, we know the area has been used every year since at least 973. The percentage of turf was correlated with broken twigs and shattered lichens, verifying our interpretation that it had been been created by trampling (fig. 7.8). This region, known as Caribou House in Naskapi mythology and a place of continual use that goes back centuries, is the core of the centre of habitation for the George River herd. It is here that the caribou persisted in the previous low in the 940–950s. The lichen mat on the Labrador tundra was severely degraded by caribou compared to that on the Upper Ungava Peninsula (figs. 7.5, 7.6, and 7.7). But can we attribute all these differences in lichen abundance to caribou? E. Mercer, a biologist, conducted a range survey in 975 in the vicinity of the George River and he argues that lichens were not abundant along the George River even before high numbers (personal communication). As a further test, we calculated the predicted abundance of lichens on the Labrador Peninsula based on shrub cover,

Forage and Range | 69

Table 7.3 The correlation matrix of range impacts compared between 11 regions (correlation coefficients and probabilities)

Lichen Cover Shrub Cover Pellets per m² Shattered Lichens % Bare Trails % Turf % Twigs % Lichens Removed %

Shrub Cover

Pellets per m²

Shattered % Bare Lichens Trails

% Turf

% Twigs

% Lichens Removed

Dead Birch %

-0.939 0.0001

-0.720 0.013

-0.753 0.008

- 0.899 0.0002

-0.864 0.0006

-0.709 0.015

-0.781 0.004

-0.415 0.204

0.672 0.024

0.578 0.062

0.832 0.002

0.722 0.012

0.525 0.097

0.598 0.052

0.260 0.440

-0.254 0.451

0.736 0.010

0.472 0.143

0.235 0.487

0.541 0.085

0.175 0.607

0.616 0.044

0.817 0.002

0.810 0.003

0.899 0.0003

0.758 0.007

0.804 0.003

0.662 0.027

0.611 0.046

0.454 0.161

0.935 0.0001

0.838 0.001

0.430 0.185

0.763 0.006

0.507 0.111 0.485 0.131

regressing lichen cover (Y) on shrub cover (X) for 2 stations from the western tundra where impacts had been low. This analysis indicated that although caribou had reduced supplies in the east, there was an additional, unexplained reduction (fig. 7.). The reduced supplies in the east are not explained entirely by impacts, but are also reduced due to the topography of the Labrador Peninsula, which is higher and more rugged than that of the Upper Ungava Peninsula. The mean elevation of the eastern tundra is about 55 m higher than it is in the western barrens; the topography is also more undulating, exposing slopes to more wind action and reduced snow cover. Lichen supplies decrease with increasing elevation in the sites examined from five regions above tree line (r = -0.908). It is recognized that increased exposure to winter winds and snow abrasion retards the growth of the Cladonia/Cladina genera (review Mulhern 987). Mulhern (987) studied edaphic factors along a transect at Schefferville and noted that the podetial diameters of C. stellaris declined with elevation and that the abundance of the total lichen mat decreased with increased slope angle. The higher, more rugged eastern ranges never had an abundance of lichens to the degree that the western tundra did, and yet the former has long been the centre of habitation of the George River herd. Obviously an abundance of winter lichens was not their primary reason for

70 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 7.4 The matrix of correlation probabilities between variables measured in the range survey in 1988 (range survey stations in grids below tree line on the upper right [italics] and above tree line on the lower left, n equals number of stations) Lichen Cover

Shrub Cover

% Turf

% Twigs

% Dead Birch

Trails/ km

Lichen Cover

– –

-0.0001 n=55

0.593 n=53

-0.058 n=55

0.104 n=49

-0.012 n=53

-0.013 n=55

0.996 n=31

0.574 n=50

Shrub Cover

-0.0005 n=25

– –

0.808 n=52

0.266 n=54

0.096 n=49

0.152 n=55

0.015 n=54

0.756 n=30

0.157 n=50

Pellets per m²

0.0008 n=24

0.351 n=24

– –

0.038 n=55

0.488 n=48

0.076 n=58

0.220 n=55

0.818 n=32

0.956 n=48

– –

0.306 n=25

0.0008 n=24

– –

0.837 n=49

0.0012 n=57

0.0368 n=57

0.834 n=32

0.061 n=50

% Bare Trails

0.0001 n=20

0.119 n=20

0.799 n=19

0.132 n=20

– –

0.064 n=50

0.030 n=50

0.014 n=27

0.156 n=49

% Turf

-0.007 n=25

0.709 n=25

0.026 n=24

0.0004 n=25

0.022 n=20

– –

0.008 n=57

0.132 n=32

0.967 n=51

% Twigs

0.187 n=23

0.919 n=23

0.031 n=23

0.0001 n=23

0.060 n=19

0.001 n=23

– –

0.945 n=33

0.880 n=51

Dead Birch

0.571 n=20

0.104 n=20

0.004 n=19

0.001 n=11

0.329 n=16

0.361 n=20

0.016 n=19

– –

0.521 n=27

Trails/ km

0.072 n=22

-0.058 n=22

0.037 n=23

0.084 n=22

-0.132 n=18

0.702 n=22

0.903 n=21

0.016 n=18

– –

Shattered Lichen

Pellets Shattered % Bare per m² Lichens Trails

being there. Rather, the eastern tundra is superior for caribou in having a greater abundance of deciduous shrubs (fig. 7.3) and because it has the more exposed insect-relief habitat. These features are major components of successful nutrition during the growing season. Skoog (968) emphasized that the centre of habitation for the Alaskan herds was not contingent upon the abundance of lichens and the extent of winter range below tree line, but upon the presence of the tundra and adjacent tree line habitats. Green Phytomass Removed

Our tallies along the George River at 2 sites showed that forbs represented only 0.27% ± 0.099% of the ground cover. Of the species Mercer had found at two sites where he had conducted tallies in 975, 55% were missing (table 7.5). Even in the more lightly-grazed eastern tundra region, we found only 0.98% ± 0.25% forb cover at seven stations. The leaves of birch replaced monocots in the diet in late June, becoming then the most important single food item in the growing season (fig. 7.2) and provid-

Forage and Range | 7 70

PREDICTED Y=

75 1 + e 0.270X + 27.29

50

HE LIC

OBSERVED

40

Y=

75

NS

PERCENTAGE OF GROUND COVERED WITH SHRUBS OR LICHENS

60

1 + e 0.402X + 26.76 r2 = 0.86

30

BS

RU

SH

20

10

Y = 1880.38xe 0.128X r2 = 0.89

0 73.5

71.5

69.5

67.5

65.5

63.5

61.5

WEST LONGITUDE Fig. 7.11 The observed abundance of the ground covered with lichen fragments and shrub cover compared moving from west to east. The observed lichen cover is less than predicted from the abundance of shrubs as one travelled east. This reduction is not entirely explained by caribou impacts but is hypothesized to have an added reduction due to a harsher climate for lichen growth on the higher and windswept Labrador tundra.

ing the greatest source of nitrogen of the summer forage (Camps and Linders 989). However, our survey showed that 28–39% of the leaders of birch were dead on the calving ground, along the George River and in the coastal insect relief region (figs. 7.6, 7.7). Most of the plants were still alive and this genus is moderately resistant to browsing (Haukioja and Neuvonen 985). The percentages of dead birch were correlated with the percentages of shattered lichen and twig fragments (table 7.4) and correlated with pellets/m² (r = 0.624, n = 9). Clearly caribou can overgraze birch by repeatedly stripping the leaves. On the more lightly-grazed summer range of the Leaf River herd, only % of the leaders were

72 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 7.5 Comparison of the abundance of forage at two sites in 1975 and 1993 (based on the Blaun-Blanquet sampling method) Plant Species

Shrubs Betula glandulosa Salix Uva-ursi/arctica Empetrum nigrum/hermaphroditum Arctostaphylos alpina Loiseleuria procumbens Vaccinium uliginosum Vaccinium angustifolium/caespitosum Vaccinium vitis-idaea Ledum groenlandicum/palustris Diapensia lapponica Lichens Stereocaulon paschale Cetraria nivalis Cladonia rangiferina Cladonia alpestris Bryophytes Rhacomitrium lanuginosum Species found

Shrubs Forbs/herbs Lichens ¹ ² ³ ⁴

Percentage Change 1975 to 1993 Wedge Hill Indian House Lake 57º11' lat. 56º36' lat. 65º21' long. 64º47' long.

-75 -84 +42 -69 – -72 -69 -73 -38 -84

-31 -81 -29 -20 -89 -20 -80 -51 -77 -96

-66 -55 -25 -31

-67 -70 -95 -61

-38

-90

1975

1993

11 24¹ 25

12 11² > 6³

5 species received a score of 2 7 of 8 species were traces only, and  species at  station was < 5% in 993 All lichen species were fragmented –3 mm and difficult to identify Original survey 975 conducted by Eugene Mercer (Nfld biologist)

dead. Some of this mortality may have been dieback of mature bushes – especially those stems exposed beyond protective snow cover. But if % mortality is standard, then caribou browsing is responsible for reducing birch supplies by 7% on the calving ground, 23% along the George River, and 28% adjacent to the Ungava coast. We measured the green phytomass both at sites where caribou were feeding and at adjacent, randomly selected sites. Caribou were choosing sites with a higher-than-average phytomass (table 7.6), as reported elsewhere (White et al.

Forage and Range | 73

Table 7.6 The percentage cover and phytomass of green forage at feeding sites and at random sites adjacent Plant Categories

Graminoids Cover (%) gm/m² Birch Cover (%) gm/m² Tundra Shrubs Cover (%) gm/m² Forbs Cover (%) gm/m²

TOTAL

Cover (%) gm/m²

Feeding Site

Random Sites

30.4 ± 5.87 (13)¹ 47.4 ± 9.97 (12)

15.6 ± 3.47 (11) 23.3 ± 8.62 (11)

23.7 ± 8.13 (13) 54.7 ± 28.3 (6)

14.6 ± 3.80 (10) 33.6 ± 9.85 (7)

21.0 ± 3.24 (13) 28.6 ± 6.56 (13)

12.6 ± 2.37 (10) 22.6 ± 6.52 (12)

1982. In the early years the histogram showed a normal distribution of sizes but became skewed to the smaller sizes after 1982. The mandible sizes of pregnant yearlings 1974–81 were > 260 mm (n=13), but after 1982, the mandibles of pregnant yearlings included several smaller females.

Body and Antler Growth | 99

ADULT FEMALES

290

> 34 MONTHS

LENGTH OF MANDIBLE (mm)

280

Y = 849.175  0.286X r = 0.627

34 MONTHS

n = 14 270

Y = 293.511  0.264X r = 0.324

833 FEMALES

n = 14

290

144

280 270 260

22 MONTHS Y = 1980.566  0.869X r = 0.869

250 240

n=4

n = 13

230

139 n = 10 220

10 MONTHS (

210

Y = 2097.771  0.948X r = 0.786 n = 9 96 CALVES

72

74

76

)

78

80

82

84

86

? 88

n=4

90

92

94

YEAR Fig. 8.6 The size of the mandible of females segregated by age generally decreased during our study from 1973 to 1993 with the possible exception that calves may have shown an increase in size in the latter years. The figure is segregated according to age.

the small calves in 984 (29.2 mm ± .80 mm, n = 9). Since body weights were linearly correlated with mandible lengths for both calves and yearlings (fig. 8.7), the estimated weight of the 979 calves was 49 kg and for 984, 43.5 kg, a decline of %. The length of the calf mandibles in  years was not correlated with several prior environmental factors that might affect growth. The probability of July rainfall affecting plant growth and hence size was P = 0.547 (n = ). Valkenburg et al. (994) had suggested rainfall might affect calf survival for the calves in the 40-Mile caribou herd in Alaska. There was no significant correlation with July/

200 | TH E R E T U R N O F C A R I BO U TO U N G AVA 90

10 MONTHS

80

22 MONTHS

BODY MASS (kg)

70

60

Y = 97.255 + 0.642X r = 0.931 n = 60

50

40

30

193 200

210

220

230

240

250

260

270

280

LENGTH OF DENTARY BONES (mm) Fig. 8.7 The growth in the mass of calves and yearlings in April plotted against mandible size. Mandible size increased at similar rates for both cohorts. This regression was used to estimate some body weights when only mandible size was known.

August rainfall, P = 0.434 (n = ) nor with hours of sunshine in July and August, P = 0.754 (n = ). Total sunshine hours might be an index to oestrid harassment, which can affect condition. Winter snow depths in Ungava were two times greater than in Alaska and the Northwest Territories (Van Ballenberghe 985; Thomas 99; Valkenburg et al. 994), and were weakly correlated with mandible size. The data show a positive correlation, the more snow the longer the mandibles (r = 0.554, P = 0.077 [n = ]). Again mosquito harassment has been cited as a factor in weight gain and survival in reindeer (Helle and Tarvainen 984; Helle and Kojola 994). We measured mosquitoes, black flies and oestrid abundance over four years (988–9), as well as the avoidance behaviour of caribou (body shakes, foot stomps, etc.) (chapter 3). Insects were more severe in 988 and 990 than in 989 and 99, yet the mandible length of seven calves 0 months old for the 988 and 990 cohorts were significantly longer than the cohorts of small calves 982 to 986 (n = 49) (table 8.7). This latter finding was in agreement with our energy budget determinations (Appendix), which showed that the dry

Body and Antler Growth | 20

INCREASE IN MANDIBLE LENGTH BETWEEN SEASONS (mm)

50

THE SMALLER THE INITIAL SIZE THE GREATER THE GROWTH THE NEXT YEAR

1982 COHORT

1987

40

1978 1984

10 MONTHS TO 22 MONTHS

1983

1985

Y = 217.457  0.830X r = 0.596 n=9

1986

22 MONTHS TO 34 MONTHS

30

Y = 223.600  0.816X r = 0.801 n=9

1974 1990

1985

1981

20

1984 1989 1986

AGE 10

SLOPE CORRELATION

34–46 mo. 46–58 mo. 58–70 mo.

0.428 1.161 0.558

0.473 0.857 0.568

1982

1983

n = 10 n=9 n=9

1977

1973 0 200

210

220

230

240

250

260

270

MANDIBLE LENGTH AT START OF GROWTH (mm) Fig. 8.8 There was compensatory growth in mandible lengths in later years when cohorts initially lagged in growth.

matter intake of lactating females increased 988–9 despite changes in insect abundance (fig. 7.2). The length of 22-month-old females’ mandibles decreased over time 975–88 (r = -0.648, n = 2 cohorts) (table 8.7). However, there was probably no decline prior to the 982 cohort, as the significant overall slope resulted because of the

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Table 8.7 The length of mandibles of females compared between cohorts and animals aged 10–70 months Year Born

1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992

10 mo.¹

– – – 228.7 ± 1.00 (3) 224.3 ± 1.25 (2) – – 221.7 ± 5.78 (3) 227.4 ± 1.20 (38) – 242 (1) 214.3 ± 3.71 (7) 219.6 ± 2.70 (16) 219.2 ± 1.80 (19) 213.6 ± 0.74 (5) 218.9 ± 2.75 (2) 222.4 ± 2.07 (10) 224.7 ± 8.37 (3) – 223.7 ± 6.33 (4) – 210 (1)

Age 22 mo.

34 mo.

– – 266.1 ± 0.64 (7) 256.2 ± 3.57 (6) – – 267.2 ± 2.17 (16) 259.8 ± 0.42 (18) – – 256.6 ± 3.57 (5) 261.1 ± 2.52 (12) 256.3 ± 2.00 (26) 254.2 ± 0.43 (13) 247.2 ± 5.41 (4) 249.7 ± 0.43 (17) 260.3 ± 5.31 (4) – 252.4 ± 3.01 (10) 248.8 ± 4.21 (6) 245 (1) –

– 277.5 ± 2.50 (2) 268.0 ± 1.11 (3) – – 272.2 ± 0.83 (13) 273.1 ± 0.43 (16) – 269.9 ± 1.16 (9) 278.6 ± 3.38 (7) 279.3 ± 3.48 (3) 274.1 ± 1.37 (14) 268.0 ± 2.10 (20) 273.0 ± 2.54 (5) 270.0 ± 0.42 (17) 265.0 ± 2.62 (9) – 272.9 ± 1.79 (15) 268.3 ± 3.30 (11) 265 (1) – –

Means and cv (%)

221.5 ± 1.35 (2.1)

256.6 ± 1.75 (2.5)

272.1 ± 1.14 (1.6)

1974–81 1982–87

225.5 ± 1.57 218.0 ± 1.38

260.0 ± 2.55 254.8 ± 2.28

274.6 ± 1.85 270.0 ± 1.65

¹ Male calves included, samples of  excluded

shorter lengths after 982 – especially the 984, 986, and 987 cohorts (table 8.7). The sizes in the 973 and 977 cohorts were significantly larger than the individual cohorts of 983, 984, 986, and 989 (table 8.7). Disregarding cohort means, but comparing individual animals, the yearlings born 974–8 were significantly larger (26 mm ± 0.9 mm) than those born in 982 or later (254. mm ± 0.90 mm) (fig. 8.5). The distribution of sizes for the 973–8 cohorts was normally distributed, whereas the distribution of the 982+ cohorts was skewed to the right; these presumably had been the larger calves but may have included some animals that continued to nurse over the winter. There was some compensation in growth rates, as the animals became older. If calves or yearlings were small (982–86 cohorts), then some of the short fall

Body and Antler Growth | 203

Year Born

46 mo.

Age 58 mo.

70 mo.

1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992

288.2 ± 3.97 (5) 291.5 (1) – – 279.3 ± 0.62 (6) 282.3 ± 2.60 (8) – 271.2 ± 2.53 (11) 272.9 ± 1.67 (10) 277.5 ± 0.27 (10) 279.3 ± 2.60 (12) 277.7 ± 1.86 (21) 270.3 ± 1.60 (15) 277.0 ± 35.0 (21) 278.0 ± 1.84 (20) – 275.0 ± 2.29 (17) 272.7 ± 2.93 (9) 271.7 ± 6.93 (3) – – –

– – – 282.9 ± 1.04 (11) 280.1 ± 2.54 (17) – 276.7 ± 0.73 (3) 284.3 ± 2.30 (6) 281.0 ± 4.36 (3) 283.4 ± 2.08 (12) 280.6 ± 2.38 (12) 275.1 ± 1.14 (36) 279.2 ± 0.99 (34) 279.6 ± 1.52 (21) – 276.2 ± 1.45 (14) 276.9 ± 3.41 (10) 277 (1) – – – –

– – 281.3 ± 0.82 (5) 284.4 ± 3.54 (14) – 270.1 ± 0.87 (4) 280.0 ± 7.00 (2) 285.9 ± 3.70 (7) 282.6 ± 2.95 (7) 278.3 ± 2.01 (17) 278.9 ± 1.41 (26) 281.9 ± 1.00 (37) 281.7 ± 2.00 (12) – 275.0 ± 2.42 (14) 276.1 ± 1.83 (9) 280 (1) – – – – –

Means and cv (%)

276.7 ± 1.31 (1.8)

279.7 ± 0.86 (1.1)

279.7 ± 1.26 (1.6)

1974–81 1982–87

277.1 ± 1.72 277.4 ± 0.87

281.3 ± 0.97 277.4 ± 0.87

280.0 ± 1.97 278.7 ± 1.82

was accounted for by increased growth the next year (fig. 8.8). For example, the 982 cohort had the second smallest mandibles of the cohorts measured in the spring (table 8.7) but the greatest gain in length between 0 until 22 months of age, 47 mm (fig. 8.8). The smallest cohort at 22 months (the 985 cohort) had the greatest gain until 34 months of age, 22 mm (fig. 8.8). There continued to be some compensatory growth until at least 58 months of age (fig. 8.8). The increases were significant between 22 and 34 months (r = -0.80, n = 9) and between 46 and 58 months (r = -0.857). A second line of evidence was that the George River herd had the greatest increase ratio in body weights between the 0-month-old calves and the 22month-old yearlings, .57 ± 0.05, greater than four other herds in North America

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Table 8.8 The ratio of increase in spring weights for females for several herds in North America Age

Mean Weight, kg (sample size)

Ratio of Change

Between 10–12 and 22–24 months Kaminuriak Herd, NWT 1966–68¹ Beverly Herd, NWT 1980–88² Nelchina Herd, AK ³ Western Arctic Herd, AK ³ Mean George River Herd⁴ 1976 1980 1984 1986 + 1987 1988 + 1993 Mean

37.0 – > 52 (20/12) 47.4 – > 61.7 (31/65) 53.5 – > 74.5 (4/8) 37.0 – > 53.8 (3/6)

1.41 1.45 1.39 1.45 1.43 ± 0.02

56.0⁵ – > 80.4 (3/3) 45.1 – > 71.3 (16/20) 44.2 – > 67.1 (9/7) 38.6⁶ – > 67.5 (13/3) 45.0 – > 71.3 (3/4)

1.44 1.58 1.52 1.75 1.58 1.57 ± 0.05

52.0 – > 66 (12/18) 61.7 – > 76.9 (65/87) 71.5 – > 88.5 (8/4) 53.8 – > 70.5 (6/19)

1.27 1.25 1.24 1.31 1.27± 0.02

83.4 – > 99.8 (1/4) 71.3 – > 91.5 (20/20) 78.5 – > 92.9 (2/13) 67.5⁶ – > 78.6 (3/7) 71.3 – > 86.1 (4/7)

1.20 1.28 1.18 1.16 1.21 1.21 ± 0.02

66.0 – > 71 (18/16) 72.9 – > 79.4 (87/65) 88.5 – > 100.0 (14/29) 70.5 – > 73.5 (19/59)

1.08 1.09 1.13 1.04 1.09 ± 0.02

99.8 – > 102.5 (4/6) 91.5 – > 93.5 (20/9) 92.9 – > 94.8 (13/12) 78.6 – > 87.2 (7/10) 86.1 – > 90.0 (7/7)

1.03 1.02 1.02 1.11 1.05 1.05 ± 0.02

Between 22–24 and 34–36 months Kaminuriak Herd, NWT Beverly Herd, NWT Nelchina Herd, AK Western Arctic Herd, AK Mean George River Herd 1976 1980 1982 1986 + 1987 1988 + 1993 Mean Between 34–36 and 46–48 months Kaminuriak Herd, NWT Beverly Herd, NWT Nelchina Herd, AK Western Arctic Herd, AK Mean George River Herd 1976 1980 1982 1986 + 1987 1988 + 1993 Mean

References: ¹ Dauphine 976, fig ; ² Thomas and Kiliaan 998; ³ Skoog 968; ⁴ Drolet and Dauphine 976, Parker 98, Huot 989, and S. Couturier pers. comm. ⁵ Based on 3 male calves ⁶ Includes males and females

Body and Antler Growth | 205

(.43 ± 0.02) (table 8.8). This increase in weight gain likely occurred in the animals’ second growing season since there was no evidence of overwinter weight gains for yearlings. This increased growth post weaning in the second summer suggests that maternal nutrition and lactation problems in the first summer were not adequate. The weight gains in the George River caribou herd between 22 and 34 months old and between 34 and 46+ months old were similar to other herds in North America (table 8.8). The major variation in growth, then, occurred in the first and second summers and this suggests that maternal nutrition and lactation differences were major components in the growth equation. George River caribou herd animals did decline in size as shown by Couturier et al. (989), but accelerated growth rates, especially in the second summer, partially compensated for the earlier retardation. Wairimu et al. (992) has also reported a catch-up in the size of yearlings when red deer (Cervus elaphus) calves were small the prior year. However, Ver Hoef et al. (200) found no compensation in the growth of mandibles of the Western Arctic herd (AK) between animals collected in the 960s when the densities on the summer range were approximately 0.6–0.8/km² and in the mid-970s (0.300.40/km²), but these densities were much less than those of the George River in the 980s. Skogland (983) showed that the ultimate size of Norwegian reindeer in 2 herds depended on their size after the first growing season. Data calculated from Skogland (990) show a correlation between mandible lengths of calves and yearlings within the same herd (but different cohorts) of r = 0.953 (n = 4), and no increase in the rate of growth of yearlings relative to the size of calves (the finite rate of increase of yearling lengths on calf lengths, r = 0.47 [n = 4]). With a winter food shortage in Norway there was no compensation for small body sizes. In Ungava with summer food shortage there was growth compensation and this growth increase should have occurred in the animals’ second summer when most were no longer nursing. Skogland (990) later argued that a 30% greater birth weight and a calving date eight days earlier would result in an expected increase of 40% in the body size of adults. We could not verify these results from the George River herd. The mandible size of 0-month-old calves was not correlated with their birth weights in seven years (r = 0.203) or with the date of calving in eight years (r = -0.433). In 978 and 979, calves were heavy at birth (a 2-year mean of 7.5 kg ± 0.5 kg) and cows calved about 6 June. In 987 and 988 the mean birth weight was 6.5 kg ± 0.20 kg and calving centred on 2–3 June (chapter 9). The mandibles in April 979 and 980 averaged 224.5 mm ± 2.85 mm and were not significantly larger than those in 988 and 989 (223.6 mm ± 0.80 mm) (table 8.7). A conservative test of Skogland’s (990) hypothesis was the 979 and 992 cohorts. In these two years we had the extremes in birth weights and calving dates. Calves in 979 weighed 7.4 kg ± 0.0 kg (n = 3) and were born on a mean

206 | TH E R E T U R N O F C A R I BO U TO U N G AVA

date of 7 June. The temperature in May 979 was the highest in 39 years, 4.4°C, which should have resulted in calves averaging 7+ kg (fig. 8.4). In 992 calves weighed 2.7 kg less than in 979 (4.7 kg ± 0.3 kg, n = 80) and were born about eight days later than in 979 on 5 June (chapter 9). But in this case the temperature in May 992 (-2.2°C) was the coldest since 972 and the ice went out of Knob Lake on 29 June, the latest recorded in 37 years. The predicted weight of the 992 calves based on the May temperature was 4.7 kg (fig. 8.4). Given these extremes in temperatures, birth weights, and calving dates, we still could not document a size difference in calves from these cohorts in April 980 and 993. The late, small calves of the 992 cohort weighed 52.2 kg ± 5.78 kg (n = 7) in April 993, had mean heart girth measurements of 94.7 cm ± 0.69 cm (n = 7) with metatarsals averaging 36.8 cm ± .24 cm (n = 5). These measurements were not significantly smaller than the 979 cohort measured by Parker (98) in April 980. Differences between the Norwegian data and the George River caribou herd may partially be explained by range and density differences. Recall that the Norwegian herds generally had heavily overgrazed winter ranges with much lower densities on the summer ranges while the George River caribou herd had adequate winter forage throughout our study but a deteriorating summer range in the mid- and late 980s. The overall decline in size of George River caribou herd animals was 2–4% and affected both males and females. The mandible size of adult males in the 960s was 32.3 mm ± 0. mm (n = 249) (Bergerud 967) but by 987–88 had declined 4% to 308.5 mm ± 0.5 mm (n = 7). Females in the 960s averaged 288.5 mm ± 0. mm (n = 58) (Bergerud 967) and in 986–88 averaged 276.3 mm ± 0. mm (n = 5) (Couturier et al. 989), a 4.2% loss. Different workers measured the mandibles, so different procedures could be a factor. Also mandible size may be a conservative measurement of body size and change. Still, the female mandible lengths in 980 averaged 283.0 mm ± 0.0 mm (n = 74) (Parker 98), which is 2% greater than in 986–87, (fig. 8.6). Also Couturier et al. (989) showed that the mandibles of the George River caribou herd were less than the adjacent Leaf River caribou herd. Total-length measurements of females made in April 979 and 993 (all measurements by Luttich) were also consistent with mandible measurements indicating a decline in body size. Total lengths (> 34 months of age) measured along the body contour were 3% less in 993 (77.4 ± .4, n = 28) than in 979 (83.0 ± .23, n = 4). Measurements in 982 were: 89.4 ± 0.97, n = 43, suggesting that animals in 993 were smaller, and that the decline in size occurred after 982. Whether the animals were larger in the 950s (Bergerud 967) than when Drolet and Dauphiné (976) and Parker (98) first quantified their body size in 976 and 980 remains an unresolved puzzle. Female mandibles collected in 963–65 were 288 mm, whereas the mean in 980 was 283 mm ± 0.90 mm. The herd in

Body and Antler Growth | 207

the 950s grew from some 4,000 animals to 5,000 (Banfield and Tener 954; Bergerud 967). By the mid-970s, numbers exceeded 50,000 animals (Messier et al. 988). There were so few animals in the 940s and 950s that the rapid increase that followed could be termed an eruption; a number of eruptions on islands have resulted in larger-bodied animals. The high-quality, untouched “ice-cream” herbs in those early years would have been plentiful and the herd had reduced energy expenditures relative to movements. We have stressed the decline in size after 982, but indeed the animals may have been even larger at the start of their increase phase in the 950s. Adult Body Mass Several ungulate species in the northern hemisphere show annual cycles in weights, with maximum weights reached at the end of the growing season and the lowest mass occurring at the end of winter prior to the appearance of green forage. The classical example of these cycles in mass for caribou was the fluctuation Dauphiné (976) documented for the Kaminuriak herd in 966–68, the migratory population that ranges the taiga/tundra to the west of the George across Hudson Bay. Dauphiné weighed males and females in three separate years in September, November–December, April, June, and July. The study was massive in scope and comprehensiveness. A clear cycle was evident, with both males and females reaching peak weights in September/October and low weights in April with little recovery by June. For adult females (> 3 years) the upper autumn asymptote was approximately 9 kg greater than the April lower asymptote, providing an average loss of 6–% during the period the animals depended on lichens. However, the spread in the upper and lower mass asymptotes for males increased as they aged, from 28 kg for 4-year-old males to 50 kg at 7 years of age. These losses occurred despite the fact that the herd was at low numbers (Parker 972a) and the ranges had not been heavily burned in recent decades (Miller 976a, b). The next large Canadian study of the growth and size of migratory caribou was conducted by Thomas and Kiliaan (998), who measured male and female animals from the Beverly herd in December and March, 980–87. Their results showed that males lost weight over winter, conforming to the Kaminuriak model. Females, however, maintained their November–December mass until at least March, despite the fact that the population was high in numbers (densities > 3 times the Kaminuriak in 966–68); furthermore, the winter range was acknowledged as the most heavily burned in northern Canada (Scotter 964, 965; Miller 976a, b). Both herds had adequate forage above tree line in the growing season. The question for us was this: With such contrary findings in the NWT, what could we expect for the George animals, for whom winter lichens were still abundant but whose summer range produced a shortfall?

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The Mass of Females

In Ungava females reached their lowest mass in June, even declining after they had moved to the tundra in April (fig. 8.9). The animals appeared to maintain their mass in the winter months. The major decline from the previous fall occurred in the spring during the return trip to the tundra and in the later stages of pregnancy and not in the months when the animals were more localized in the taiga (December to early March) (fig. 8.9). Captive female caribou from the George River that did not calve lost weight from January to April (approximately 3%), whereas females that had conceived gained or maintained their weights in winter on an ad lib high-quality diet (fig. 8.9; Crête et al. 993). The weights of gravid females that we measured in March/April showed no consistent trend over an 8-year interval 976–93, r = 0.04, n = 0 years (table 8.4) and averaged 94. kg ± 0.49 kg, n = 0 years. However, the weights of parous females in June averaged 83.3 kg ± 3.92 kg, n = 8 years (986–92),  kg less than in April (table 8.4). The only cows weighed in June prior to high numbers were five females in June 978 that weighed 0.8 kg ± 5.37 kg. Even though there were no annual trends in March and April, with time there were still differences between years; for example, females were heavier in 976 than in 980 (table 8.4). In this case, the females in 976 were still on the winter range and the 980 animals had migrated to the eastern pastures west of Nain. Not only was there no trend between years in the March/April weights but there was no consistent trend over winter (fig. 8.9). The weight of 9 adult females in October 983 was 93.5 kg ± 8.09 kg and for 4 pregnant females in April 984 83.9 kg ± 5.2 kg (Huot and Goudreault 985), a 0% decline. For September/October 986, 7 females that were lactating weighed 95. kg ± 2.67 kg and in April 987,  pregnant females weighed 96.2 kg ± 3.86 kg (Couturier et al. 989). In October 98 two lactating females weighed 00.0 kg ± 4.0 kg and in April 982, 26 pregnant females averaged 98.0 kg ± .67 kg (this study). The average weight change between fall breeding masses and spring parturition measurements (r) for 7 populations in the Holarctic was -3%, or 2 kg (table 8.3). The weight changes for the George River caribou herd between fall and June fell within this range (fig. 8.9). Reimers (983b) showed that in 20 populations of female reindeer and caribou, 9 populations gained weight over the winter, 8 lost weight, and 3 showed no change. He documented that if the summer range and winter pasture were overgrazed, the animals lost weight over the winter. Reimers (983b) speculated that growth through winter is possible only in those situations where maximum growth had been arrested in the summer. The growth rates of the George River herd were arrested in the summer but there was no winter compensation; females had weights in March similar to the previous autumn, both before and after the summer ranges were degraded starting about 982 (fig. 8.9). These early spring

FEMALES CAPTIVE DID NOT CALVE CAPTIVE CALVED WILD 1983–87 WILD 1976–82, 88, 93

BODY MASS OF FEMALES (kg)

140 130 120 110 100

73.438X X  21.125 n = 16, (302 )

Y=

90 80 70 60 190 180

BODY MASS OF MALES (kg)

127.033X 86.022 + X n = 13, (168 )

Y=

122.867X 96.651 + X n = 13, (124 )

Y=

66.827X X  18.905 n = 11, (75 )

Y=

J

F

A

M

J

M

J

A

S

O

N

D

N

D

MALES 1976–82, 1988–93 1983–87

170

167.360X 29.382 + X n = 20, (45 )

Y=

160 150 140 1976 n = 30

130 120 110 100

1986–87 n=5

90 80

RUT

254.908X 145.547 + X n = 14, (14 )

Y=

J

F

M

A

M

J

J

A

S

O

JULIAN DATES Fig. 8.9 (above) The mass of females was less in 1983–87 when densities were greater than in earlier or later years. There was also an annual cycle in mass, with the lowest weights in June for females. Captive females fed a high-quality spring and summer diet did not show a strong annual cycle. The highest mass of females occurred in the fall and generally did not decline further until spring migration; (below) Body mass peaked for males at breeding followed by major losses that were not compensated for over winter. Males weighed less in March 1986/87 than 1976 yet may have reached similar prebreeding mass (captive data adapted from Crête et al. 1993).

20 | TH E R E T U R N O F C A R I BO U TO U N G AVA

losses followed a return to mostly graminoid ranges and the last trimester of pregnancy. Since non-pregnant females can generally make weight and fat gains in May (Dauphiné 976), the weight loss for pregnant females may relate more to reproductive status than to the graminoid diet. We have argued that the latter was superior to their mid-winter diet of lichen and shrub (chapter 7). Females weighed significantly less in March/April 984 and 986 than in earlier years, before the range had been overutilized, 976 and 980 (Parker 98; Huot 989; Couturier et al. 989). However, the weights of females increased in 988 and remained above the mean (976–93) in 993 (fig. 8.9). We constructed two weight curves, a low line (983–87) and a high line, which included all other years. In both decline schedules, the cows (all females > 34 months old) had similar weight loss curves from  March to  June: approximately 306 g/day for the high line; 234 g/day for the low line (fig. 8.9). The cows on the high line averaged 85.3 kg at the start of calving and those on the low line 76.3 kg, i.e., 9 kg less. The calves at birth would be predicted to be  kg less for the low years (Bunnell 987) and this is what occurred (table 8.4). Thus the cows lost weight in the spring at a similar rate throughout the study, even though the herd increased fourfold (Messier et al. 988). These results – which are in agreement with Crête et al. (990a) – do not fit a hypothesis that the spring range of graminoids was overgrazed. Females of the George River caribou herd captured in the wild but held in captivity on a high-plain diet did not lose weight in the spring as did wild stock (fig. 8.9); instead, they made substantial gains and reached greater weights than free-ranging animals (fig. 8.9). The calves from these dams were not only –2 kg heavier at birth but grew faster than wild animals and reached larger body sizes as calves, yearlings, and 2.5-year-olds than did the wild stock (see Crête et al. 993, table 4). These data thus indicate that adult females that have completed their physical size can still add weight with a longer cycle of weight gain, producing larger calves than wild stock. It is difficult to unravel the relative roles of diet quality versus reduced energy expenditure on these greater growth rates, but the data are consistent with the view that the length of the growing season is a major parameter in ultimate body size of caribou (fig. 2.2). The weight data for George River herd females were insufficient to show a significant difference in gains between high and low weight lines from June until October (fig. 8.9). However, the females weighed significantly more in the autumn for the combined data 976–82 than 983–87 (fig. 8.9). The mean difference was about 8–0kg, and it was this disparity in fall weights that carried over to the March/April weights. The lactating females, unlike males and possibly nonlactating females, apparently could not compensate during the growing season for their initial low body mass in June. Lenvik et al. (988) documented a significant decline in the body weights of Norwegian reindeer females as they aged beyond 5 years. Skogland (984b) showed a decline in weight for females > 7 years old in two herds with depleted

Body and Antler Growth | 2

lichen supplies, but females in a third herd with superior winter forage continued to increase in weight until possibly 3 years. In 976 – when our herd numbered approximately 275,000 – the females continued to gain mass as they got older, whereas in March and April 980 – when the herd approached 400,000 – the females did not gain weight but maintained weights 34 to 90 months of age; the oldest female (24 months) had a low weight of 82.5 kg (fig. 8., data from Parker 98). Females harvested mostly in 988 and 993 may have again put on weight with age, despite herd numbers exceeding 400,000 (fig. 8.). In these two years the animals overwintered nearer to the summer range (chapter 3). Females in the older age classes in the Beverly and Kaminuriak herds in North America maintained their April weights (fig. 8.). The winter lichen ranges were heavily overgrazed in Norway and Finland, but this is not the case for mainland herds in North America, where winter densities have generally been less than 2 animals/ kg² (Skoog 968; Miller 976a, b; Boertje 98; Thomas et al. 996; Fleischman 990; Bergerud 996). Young and prime animals can apparently cope better with winter forage shortages than older females. Skogland (988) documented that there was accelerated wear on the molariform teeth for older animals in Norway when much of the habitat was denuded of lichens. There was no increased wear on the teeth of older females in the George River herd (chapter 7). Thus the decline in weight with age in Norway probably related to increased abrasion of teeth from winter lichen shortages and has not been documented based on a summer shortage of vascular plants. The Mass of Adult Males

We secured little information on fluctuations in mass for males (fig. 8.9). The only significant difference between years was that 5 males in March 986/87 weighed 30 kg less than 30 males in March 976 (Couturier personal communication; Drolet and Dauphiné 976). The animals weighed in 976 were George River caribou collected by Naskapi hunters at Marcel Lake 56°45' N near now-abandoned Fort McKenzie on the Caniapiscau River. In both examples, 976 and 986–87, the animals were on the winter range and had not yet commenced spring migration. Those animals that were heavier in 976 than 986–87 could have the same explanation as the high and low spring weights of females; males in 976 weighed more following the rut than those in 986–87 and both lines maintained these differences until spring. Luttich weighed 29 males 978–93. The largest, collected on 8 June 978 within sight of Hebron Fiord, weighed 86 kg (age 8–9 years). This male’s weight exceeded that of even the large males we measured at the peak of the weight cycle prior to fall breeding (fig. 8.9). The animal had probably wintered near the coast north of 58° N. The general sequence for males was to gain weight from March through to the breeding season, and then to lose as much as 45+ kg

22 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 8.9 Body and antler measurements of adult males from August to November by S. Luttich Date

Age. (yrs)

Antlers (R/L) Length (cm)¹ Cir. (cm)²

Body Length Str/Cont. (cm)³

Prior to 1982 6/11/75⁴ 4/11/78⁴ 4/9/76 20/8/77 21/8/77 22/10/77 29/8/78 27/10/79 2/9/80 9/5/80 8/10/80 8/10/80 27/10/80⁷

3 9 5 >2 >2 5–6 >2 6–7 4 5–6 5 4 7

125/130 127/132 –/70 85/84 81/– 90/91 140/140 142/145 136/133 125/131 120/116 100/110 142/145

20/20 17/17 15/21 – – – 17/16 16/15 15/15 16/16 13/12 11/12 16/15

– – –/205 –/214 –/209 –/209 182/200 202/234 188/190 202/214 192/202 203/222 –/202

Means

5.5

118 ± 4.79

15.8 ± 0.58

194.8 ± 3.60 209.2 ± 3.57

Post-1982 1/10/83⁴ 30/9/83⁴ 30/9/83⁴ 1/1083 3/10/83 4/10/83 10/10/84 11/10/84 12/10/84

7 6 3 7 6 6 8 8 3–4

152/1 142/13 130/131 139/135 128/115 127/118 114/114 115/111 93/89

13/13 12/11 13/13 15/14 12/12 11/11 13/12 –/8 –

– – – 194/209 186/203 192/212 195/215 190/204 183/200

Means

6.1

124.3 ± 4.04

12.1 ± 0.44

190.0 ± 1.91 207.2 ± 2.36

during the breeding season (fig. 8.9). This weight loss is expected. Adult males in the Kaminuriak herd lost 40+ kg (27%) of their mass between September and November during the rut. We segregated the weights of males into a high weight line (976–82 before the herd reached 600,000) and a low line (when the herd comprised 600,000 animals), similar to the analysis outlined for females. The mass of males increased for both high and low lines from March to October (fig. 8.9). Both groups increased during spring migration in April and May and during the summer until breeding in October. These data were not sufficient to document whether males

Body and Antler Growth | 23

Shoulder Height (cm)

Heart Girth (cm)

Total Wt. (kg)

Back Fat (mm)

– – 117 121 126 124 121 – 110 109 119 118 –

– – 134 141 145 148 154 142 131 131 146 138 135

– – – 110.7 126 – 185.5 – 126 160 152 162 –

– – 4 4 5 1.5⁵ 72⁶ tr⁵ 51 7 35 55 0⁵

118.3 ± 1.91

140.5 ± 2.23

146.0 ± 9.87

21.3 ± 8.06

– – – 122 121 122 127 127 112

– – – – 143 140 131 145 127

– – – 164 170 172 – – –

– – – 41 55 60 23 42 30

121.8 ± 2.24

137.2 ± 3.50

168.7 ± 2.40

41.8

¹ Height of antlers (right and left) measured along contour ² Circumference of main beam, right and left, antlers measured between brow and bez tines ³ Total length measured in straight line and following body contour ⁴ Males killed by wolves ⁵ Animals killed postrut, back fat mostly gone ⁶ The maximum back fat, measured by Dauphiné 976, was September, 59.7 mm ⁷ Animal died with locked antlers The only significant difference prior 982 vs post 982 was antler circumference. Heart girths measured by Lo Camps, last of August 989; 28, 45, 40, 45, 3, 3 cm, mean 36.7

prior to high numbers weighed more at the start of the rutting season than in the years when the herd exceeded 600,000. Since mandible sizes decreased 2–4% from the 960s to the 980s (Bergerud 967; Couturier et al. 989), males could have been larger in the 960–970s, prior to high numbers. However, all the males measured by Luttich in the fall 975–84 appeared to have reached similar body sizes consistent with their age (table 8.9). Since males continue to gain weight until 7 years of age (Dauphiné 976), our sample of mixed ages was inadequate for deciding the question as to whether or not males were larger prior to high numbers in the 980s. We will document in

24 | TH E R E T U R N O F C A R I BO U TO U N G AVA

chapter 9 that peak fall breeding was approximately 8 days later in the mid-980s than in the 970s and may have extended over a longer time interval. A later and more extended rut would reduce weights as well as reduce the time available in late fall for recovering some of that loss prior to deep snows. Our data were not sufficient to document mass changes post-rut until March. In the 970s males probably maintained their post-rut weight over winter. In 976, 22 males (> 3 years old) averaged 30 kg in March; if we assume that 40 kg was lost in the rut, their mass pre-rut would have been 70 kg, an expected breeding weight (fig. 8.9), and they would have maintained that lower mass until at least March. Ten years later in March 986 and March 987, five adult males weighed only 86.8 ± 2.3 kg; four males in April 985 weighed 20 ± 4.24 kg (fig. 8.9). However, we have no prime fall weights after 983 (table 8.9) for determining if the overgrazed range in the 980s led to reduced post-rut weights. Males in both the Beverly and Kaminuriak herds lost weight from November/December to March/April (Dauphiné 976; Thomas and Kiliaan 998) with adequate winter lichen supplies. Males in the George River herd in the 980s (when 600,000 animals foraged on shattered lichen mat and made extensive movements west in the fall) may well have lost mass between November and March/April, contrary to the scenario for females (fig. 8.9), but similar to that of the Beverly herd. The major difference between the sexes in terms of changes in mass is that males gained weight during the spring migration in April and May whereas females lost weight (fig. 8.9). Males did not return in the spring to the overgrazed tundra until the mosquito season in late June; instead they moved to optimize foraging opportunities west of the George River in the taiga. The fact that males and females have different migration sequences is well documented in the other large migratory herds in North America. Even on South Georgia – where the seasons are reversed and the migrations are short – Leader-Williams (988) showed that males gained weight in the two months before the cows gave birth, whereas females lost weight. Antler Size The antlers of the George River males in the 970s and early 980s were the largest in North America (table 2.2). In those times of good nutrition, the antler length averaged 20 cm for mature males and 45 cm for females (tables 8.9, 8.0). The male antlers are “woodland” in morphology in terms of their distribution of points and the extensive palmation of brow, bez, and top points; but they are “barren-ground” in beam structure, being both digitate in cross section and extremely long and widespread. The antlers of the males in the George are unique: They can be recognised in antler arrays by this extreme spread and by the nearly horizontal lower main beam that turns sharply upward without a gentle curve, commonly without a rear tine (fig. 2.8).

Body and Antler Growth | 25

Table 8.10 The size of female antlers (≥ 34 months of age) for the George River herd Year

Total Length per Antler Along Contour (cm)

1978–79 1980 1982 1983 1984 1988 Antler Set

1st set 2nd set 3rd set³ 4th set³ 5th set³

Total Points per Animal

39.7 ± 1.69 (12) 47.0 ± 0.75 (100) 42.2 ± 0.94 (94) 38.2 ± 2.24 (18) 32.6 ± 1.71 (6) 39.8 ± 1.41 (33)

1980

31 (1) 259.8 ± 22.95 (18) 467.9 ± 37.55 (18) 391.1 ± 6.84 (8) 492.3 ± 23.6 (61)

10.4 ± 0.56 (7) 10.9 ± 0.52 (60) – 4.6 ± 0.36 (20) 5.7 ± 0.50 (6) 10.2 ± 0.28 (24)¹

Weight of Non-cast Antlers (g) ± SE 1986²

20.1 ± 6.41 (9) 64.1 (1) 209.6 ± 1.37 (5) 255.2 ± 37.35 (16) 325.1 ± 29.51 (12)

% Decline

– – -55 -35 -34

¹ Single antlers collected and points doubled ² Data provided by S. Couturier ³ Weight of cast antlers in 988 75.0 ± 0.65 grams (n = 28), may include some young animals

The antlers of females reached their maximum height by the third season (fig. 8.0) and males probably by 7 years of age (fig. 8.). Thereafter the height of female antlers remained constant but the mass of each progressive set increased (fig. 8.0), a sequence Thomas and Kiliaan (998) also documented for the Beverly herd. The antler mass of males probably decreases with senility, but we had few measurements. The antler length/body length ratio for females was 0.24; for males it was 0.59 (fig. 2.9). The George River caribou herd females and males invested more in antler mass (weight/kg of body weight) than has been reported in the literature for any other herd in North America (see antler and body measurements in Banfield 96). Both female and male antlers declined in mass between those measured in the 970s and those measured in 982 and thereafter. The decline in both sexes was more in mass then total length (tables 2.5, 8.9, 8.0). Antlers in caribou are generally understood to have social significance, inasmuch as they confer dominance relative to other individual animals whose antlers are either smaller or absent. For females, such competition is probably foodrelated: By defending feeding craters, females enhance their physical condition, particularly as it relates to fetus growth, and possibly they enhance the condition of their yearlings as well, with whom they may share craters (Barrette and Vandal 986, 990). For males the competition is for mates (review Butler 986):

26 | TH E R E T U R N O F C A R I BO U TO U N G AVA

ANTLER LENGTH (mm)

600

HEIGHT

500 400

GEORGE RIVER

200

GEORGE RIVER ( )

100

SETS OF 3 TO 13

Y = 397.540 + 14.880X r = 0.742 n = 108

0

n=3

MASS

SETS OF 3 TO 10

500

MASS OF LEFT PLUS RIGHT ANTLERS (g)

Y = 477.000  1.123X r = 0.177 n = 131

300

n=5 400

n=3 Y = 164.867 + 211.250X

300

BEVERLY ( )

200

Y = 175.220 + 13.359X r = 0.949 n = 578

Y = 45.000 + 84.50X

100

SETS OF 3 TO 13

0 1

2

3

4

5

6

7

8

9

10

11

12

13

ANTLER SETS Fig. 8.10 The length of the antlers of George River females by age. The length did not increase after the third set but the antler mass did increase with age, similar to that shown for the females in the Beverly herd (Thomas and Kiliaan 1998).

Intrasexual selection in a polygnous society would favour body size and antler mass. The size of male and female antlers within populations is positively correlated in North America (Butler 986), even though the sexes are asynchronous in antler growth and casting, and competition is for different objectives – food for females and mates for males. Aside from the factor of a common gene pool, a variable common for both males and females within populations is group size.

Body and Antler Growth | 27 160

MEAN TOTAL LENGTH OF LEFT AND RIGHT ANTLERS (cm)

150

143.0 ± 6.00 n=2

134.0 ± 4.90 n=5

140

129.5 n=1

130 119.6 ± 7.34 n=5

120

123.0 ± 5.00 n=2

113.0 n=1

110

114.0 n=1

100 90 80 70

2 SE.

68.6 ± 2.99 n=5

60 50

44.6 ± 2.59 n = 11

40 30

20.0 ± 1.34 n=8

20 10 0 1

2

3

4

5

6

7

8

9

10

11

ANTLER SETS Fig. 8.11 The length of the antlers of males by age. Length continued to increase until at least the seventh set. Antler lengths for all years measured along the contour by S. Luttich.

Relative to the male competition, the George River caribou herd has large groups in the rut; similarly, females face winter – and the competition for craters and food – in large groups. We still need an explanation for the heavy investment in antlers for the George River stock, however. One factor could be the extreme snow depths in Ungava (fig. .6), which combined with the large aggregation sizes would intensify the female-to-female competition, and perhaps result in females favouring

28 | TH E R E T U R N O F C A R I BO U TO U N G AVA

large antlers at the expense of body size. Reindeer females have the largest ratio of antler size to body size of the Rangifer (Butler 986). Reindeer are artificially close-herded with large aggregations, and they winter primarily on lichen ranges where the animals must crater. This combination would maximize food competition. Growth and Demography Neonatal Mortality

The spring of 992 was the latest on record in our area and also in Alaska (Griffith et al. 998) and undernourished cows produced calves of small biomass, many of which died shortly after birth. The weight of 3 newborns found dead by Serge Couturier was 4.08 kg ± 0.7 kg, while those that lived weighed 5.08 kg ± 0.0 kg (n = 49). A similar weight difference has been noted for calves that died in the Hardangervidda herd in Norway; calves that died weighed 2.98 kg ± 0.47 kg (n = 7); those that survived weighed 3.72 kg ± 0.27 kg (Skogland 984b). Similarly, for the Central Arctic/Porcupine herds in Alaska, where there was also an extremely late spring, dead newborns weighed 4.72 kg ± 0.6 kg (n = 5), while those that lived weighed 5.65 kg ± 0.2 kg (n = 0) (Gerhart et al. 996). In each case only  kg separated those that lived from those that died. The same  kg difference, approximately 4.5 kg versus 5.5 kg, applied for calves captured in Newfoundland, 955–66 (n = 322) (Bergerud 97b and personal files). In Svalbard viable newborns weighed only about 3 kg (Skogland 989b), the same weight as inviable calves in Norway. Body size per se as it relates to thermoregulation or mobility cannot be causal in neonatal mortality. Even though the critical neonatal weights for survival vary between genetic stocks, we can standardize them by quantifying viability in terms of maternal investment (g/kcal BMR ), BMR = 70 Body Weight⁰.⁷⁵. Females in the George River caribou herd invested on average about 3.4 g/kcal in the weights of their newborns (table 8.3). Calves in the George River caribou herd in 978 and 979 weighed approximately 7.5 kg, whereas in the 980s they were nearly  kg less. Nonetheless, the female investments were similar since the cows probably weighed 0 kg less in the 980s than in the 970s (fig. 8.9). The maternal investment for calves that died in the George River caribou herd in 992 was 2.8 g/kcal [dead calves 4.08 kg ± 0.7 kg (n = 3) and maternal weights of 80.6 kg ± 2.9 kg (n = 5)]. For the Hardangervidda herd maternal investment for those that died was 2.4 g/kcal (dead calves 2.98 kg and maternal weight 46 kg, Skogland 984b; Reimers 997). For the Central Arctic/Porcupine herds the investment in inviable calves was approximately 2.5 g/kcal (dead calves 4.72 ± 0.6 kg and maternal weight about 78.5 kg, Cameron et al. 993; Gerhart et al. 996). Lastly, in Newfoundland parous cows in four springs weighed 88.7 kg + .45 kg, n = 59 (personal files); based on critical birth weight of 4.5 kg they invested only 2.2 g/kcal. The

Body and Antler Growth | 29

mean female investment in weight at birth in 2 data sets in the Holarctic was 3.4 g/kcal ± 0.088 g/kcal (table 8.3). We can expect calves to be inviable when malnourished females can only invest < 2.5 g/kcal. Conception Rates

It is postulated that some ungulates regulate body mass in relation to autumnspring set points (Ryg 983; Hudson et al. 985; Adamczewski et al. 987a). The autumn target for the Central Arctic herd (Alaska) was graphed at 07 kg, at which point 99% of the females should theoretically have ovulated and conceived (Cameron and White 996). These authors showed that no females made this target and that lactating females of 85 kg were 9 kg less than non-lactating ones and the cost of not reaching the set point would theoretically have reduced fecundity by 28%. Animals of the George River caribou herd are larger than caribou in northern Alaska (Skoog 968); possibly a fall target would be 5 kg. Both pregnant and non-pregnant wild females held in captivity on a high-plain diet reached a 5-kg asymptote (Crête et al. 993). The heaviest free-ranging females we weighed were all pregnant: 2 females April 988 both 26 kg; and one 27-kg female in April 993 (all three were 9 years old). Our estimate was that females weighed about 0 kg less after 982 than previously (fig. 8.9) and this loss pertained primarily to lactating females (Couturier et al. 989). Huot (989) found 7 lactating females in the George River caribou herd in October 983 that weighed 90. kg ± 2.0 kg and  non-lactating females that weighed 99.4 kg ± 2.59 kg, the same difference reported by Cameron and White (996) that should result in a 28% decline in fecundity. The percentage of females pregnant or parous 976–82 was 93.05% ± 0.56% (n = 7 years), and after 982, 69.2% ± 2.80 % (n = 0 years). Fecundity was reduced 26%, in agreement with Cameron and White’s equation. Thus changes in body size in the autumn as it affects conception rates appear to explain all the variation in pregnancy rates that have been reported for the George River caribou herd 976–93. Fecundity of Yearlings

Body growth takes priority over reproductive activity and theoretically females shouldn’t reach puberty until they reach a critical body size (Reimers et al. 983; White 983) that would vary between genetic stocks. Yearlings pregnant in 980 were significantly heavier than yearlings that failed to conceive: 78.5 kg ± .53 kg (n = 9) vs 66.4 kg ± .52 kg (Parker 98) and had significantly longer mandibles (fig. 8.5). The body size of yearlings decreased after 982 (table 8.7; fig. 8.5) but there were still some yearlings that reached puberty (table 8.). The highest percentage of yearlings pregnant was in 988 when 8 of 22 yearlings (36%) were carrying fetuses in April. This high pregnancy rate appears to be a representative sample since the ratio of migrating yearlings to adult females in the collec-

220 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 8.11 Comparison of calf and yearling weights by cohorts and pregnancy frequencies Cohort

1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 Means

April Mass (kg) Calves Yearlings Observed Calculated¹ Observed Calculated¹

% Pregnant

– 56 ± 1.0 (3) – – – 48 ± 1.0 (28) – 66 ± 3.5 (2) – 44 ± 2.1 (9) – 39 ± 1.5 (13) – 42 (1) – – – – 51 ± 0.8 (7) –

50 (3) 47 (2) – – 45 (3) 49 (38) – 58 (1) 40 (7) 44 (16) 43 (19) 40 (5) 43 (2) 46 (10) 47 (10) – 46 (4) – 38 (1) –

81 ± 0.9 (4) – – – 71 ± 1.9 (20) – – – 67 ± 3.1 (7) – – – 71 ± 4.3 (4) – – – – 55 ± 0.8 (4) – –

67 (6) – – 74 (16) 70 (18) – – 67 (5) 70 (12)³ 67 (26) 66 (13) 61 (4)⁴ 66 (20) 70 (4) – 65 (10) 62 (6) 60 (1) – –

100 (1)² – – – 43 (21) – 100 (1) – 11 (9) 25 (8) 21 (14) 0 (5) 36 (22) 0 (3) – 29 (7) 0 (9) 0 (3) – –

49.4 ± 3.50

45.4 ± 1.34

69.0 ± 4.20

66.5 ± 1.10

26.2, 27 of 103

Some data from Drolet and Dauphiné 976; Parker 98; Huot 989; Couturier pers. comm. ¹ ² ³ ⁴

Based on regression, Y= –97.255 ± 0.642X (X = length of dentary bone, fig. 8.7) Samples of one excluded Two yearlings weighed October 983, 78.2 ± 8.27 (Huot 989) Three female yearlings weighed November 986, 63.3 ± 0.73 (Couturier pers. comm.)

tions that spring was similar to the female calf to adult female ratio the previous autumn. Several of the yearlings that were pregnant in 982 (and later) had smaller mandibles than any of the pregnant yearlings prior to 982 (fig. 8.5). The best example was the 986 cohort, where the mandible size of non-pregnant yearlings was 250.2 mm ± 3.68 mm (n = ) and for pregnant yearlings 258.5 mm ± 0.73 mm. However, three of the seven pregnant yearlings had mandibles only 247 mm, 249 mm and 255 mm (fig. 8.5). Their predicted weights would be 6 kg, 63 kg, and 66 kg (fig. 8.7). There was no evidence that the 986 calves were of large body; their mean birth weight was 6.6 kg ± 0.20 kg (n = 24), almost  kg less

Body and Antler Growth | 22

than the birth weight of the 978 cohort (43% pregnant). Their dams in June were nutritionally stressed; the mean weight of 28 parous females was 74.8 kg ± 2.56 kg. Fat indices for the females in June were low: metatarsal fat 68.% ± 8.52 % (n = 8), femoral fat 56.9% ± 8% (8), kidney fat only 0.7 g ± 0.86 g (n = 8), and back fat essentially zero (Couturier et al. 989). As well, the calves grew slowly: Their weight at the end of September was 39.7 kg ± .07 kg (n = 3); by 2–2 November it was 47.6 kg ± 0.46 kg (n = 9), representing a rate of weight gain of 249 g/day – a low rate for caribou (Skogland 984b; Reimers 983b; Crête et al. 993; weights from Couturier, personal communication). We compared the mean annual pregnancy rates of yearlings in 0 years with their measured or estimated April weights (table 8.). The correlation (r = 0.648) suggested a positive relation between pregnancy and body mass but not as close as one might deduce from the literature. Skogland (990) concluded that in the Norwegian Hardangervidda herd there had been selection for increased reproductive effort by small females when winter food had been limiting over a 30year period. If this type of natural selection has occurred for the George River caribou herd, it has been the result of summer nutritional stress and occurred in a matter of a few years. Nonetheless, some yearling females have continued to conceive as the herd reached high numbers after 982. The correlation between pregnancy rate and cohort year for years when samples were greater than  was -0.568 (n = 0, table 8.). The major decline in the conception rate of the George River caribou herd after 982 was thus not simply a matter of body mass as it relates to puberty; most of the reduction resulted because many lactating females could not make the target autumn weight needed for conception. The George River caribou, then, are moderate-size caribou, with body size determined by summer nutrition as moderated by the length of the growing season and the abundance of phytomass as affected by density-dependent grazing pressures. Females and males followed different weight cycles. Females generally lost weight from January to a low in June and reached their peak mass by fall breeding. Body mass was reduced in the mid-980s. The autumn target weight of 5 kg (for estrus) was frequently not reached after 983, reducing pregnancy rates. Males reached their peak weight by the rut with major losses during breeding and were heavier in the winter seasons in the 970s than in the years of high numbers 983–87. The birth weights of calves and early neonate survival were predisposed by the nutrition of preparturient females in the last 30+ days of gestation. Overall body sizes and antler masses were reduced as a result of the nutritional problems in the first growing season but there was some compensation in body growth in later seasons. As this chapter makes clear, the nutrition during the growing season is critical for body size, puberty, and antler development. The lower-quality winter diet cannot compensate for inadequate nutrition during the growing season.

CHAPTER 9

Physical Condition

Circumpolar caribou reside in a pulsating environment where seasons of plenty alternate with seasons of scarcity, and they have evolved an annual cycle of sharply fluctuating body mass and tissue deposition related to life-history consequences. For females, fat reserves and body weights peak in October–November at the end of the season of nutrient rich forage; males also reach peak condition at the time of the rut, but unlike females, males utilize nearly all their fat reserves during the short breeding interval. Females may decline in protein/fat reserves from November to April (Tyler 987), but the loss is extremely rapid from April to June during the last month of gestation (Dauphiné 976; Tyler 986; LeaderWilliams 988). The George River herd is unique among the herds in North America in that its summer range has been degraded by overgrazing while the forage on its winter range has remained abundant. Our concern here is in how this relates to body condition, which in turn impacts demography. Dauphiné (976) also showed that females conceiving in the fall were in superior condition compared to non-estrus females, but that gestation and lactation could so deplete their reserves that the condition of primiparous females might exceed them in the next autumn. Such a system could lead to skips in pregnancy (Cameron 994): A lactating female might not accumulate sufficient reserves during the growing season to come into estrus and would alternate reproductive status between years. Reimers (983a) pioneered the concept that a threshold weight within populations was needed in autumn to come into heat, and Parker (98) demonstrated this concept for the George River herd in 980: Long yearlings that conceived had superior weights and fat reserves to animals of the same cohort that did not reach estrus. Therefore, body condition can be a major factor in the pregnancy rate, especially of young animals.

Physical Condition | 223

Condition will also affect the mortality aspect of the population dynamics of the herd. The physical condition of an animal will be a factor in its susceptibility to starvation; in its ability to escape predators and insect attacks; and its capacity to successfully navigate large bodies of water and rivers in flood. Thus condition drives not only body growth but also the ability of an animal to complete its annual cycle and life expectancy. The emphasis of this study and others of the George River herd has been the spring condition. Drolet and Dauphiné (976), Parker (98), Huot and Goudreault (985), Huot (989), and Couturier et al. (989) all provided autopsy reports of animals (emphasizing females) in March and April. Our collections were also mostly from April and were secured primarily from the commercial harvest made by residents of Nain. Hence the emphasis here is on the spring fat reserves as they related to change in herd numbers as the herd grew from 05,000 in 975 to > 600,000 by 984–88. We also document (974–93) four additional measurements other than fat reserves that we believe reflect conditions, including ) the size of male antlers; 2) the annual percentages of females with hard antlers in the autumn; 3) the dates of peak calving in June; and 4) the weights of livers of females in April. Reimers (993) concluded that the frequency of polled animals in Europe and North America increased in populations that were undernourished. Again, Reimers et al. (983), as well as Skogland (983, 984b), showed in Norway that the calving dates varied with condition. Well-nourished herds calved earlier than undernourished animals in adjacent herds. In Newfoundland, calving was later after hard winters (Bergerud 975), and Cameron et al. (993) noted a similar sequence for the Central Arctic herd in Alaska. But a question was left unresolved: Was the later calving due to a prolonged gestation (inadequate winter diet) or to a late autumn breeding season (inadequate summer diet)? Several authors have suggested that liver weight provided a useful index of condition (Adamczewski et al. 987b; Leader-Williams 988; Chan-McLeod et al. 994; and Gerhart et al. 996). In particular, Gerhart et al. (996) concluded that the mass of such internal organs as the liver or kidney could be useful indicators of metabolic activity and recent nutrition. In this chapter, we compare our condition indices in light of chapter 7, which argued that the growth of the herd in the 980s had resulted in over-utilizing the summer food resources. How did this shortage translate into condition? Was there sufficient synchrony in these indices to pinpoint the year(s) in which condition significantly declined so we could determine what summer densities were too high to sustain numbers? Antler and Calving Indexes The sex and age composition of the herd was tabulated during the fall rutting seasons in October and again in June when the females returned to the calv-

224 | TH E R E T U R N O F C A R I BO U TO U N G AVA

ing ground. In the fall classifications, which Luttich conducted mostly from the air, he segregated females as to the presence or absence of visible antlers in 4 of 9 years, 974–92. Young females were distinguished from adults in 0 seasons on the basis of head length and were mostly long yearlings (7 months of age). Luttich also made distinctions on the basis of antler size in  seasons, including: large males, which he termed regal males; medium males; small males; and long-yearling males. We have used the percentage of regal males to regal males + medium males as an index to condition. Small males were excluded since they probably were not mature and would have confounded the index as cohort contributions varied. This antler index was entirely subjective, but all of the classifications throughout the entire observation interval were made by the same observer. Calving Date Index

If calving dates varied between years it would be either because breeding dates varied – which might reflect condition in the fall; or because gestation varied – which could be a response to winter condition; or because both factors were involved. Luttich, and, for several years, a number of biologists from Quebec, classified females in June as to the presence or absence of calves and antler status (presence or absence of hard antlers). Both indexes have commonly been used in North America to determine calving chronology. With caribou, 90% of the calves are generally born in a 0–4 day period (Lent 964, 966; Dauphiné and McClure 974; Bergerud 975) and most females shed their antlers at about the time of parturition (Lent 965; Bergerud 976). These two indexes were used to calculate the expected mean calving date on the basis of the estimated calving dates of 40 satellite-collared females whose rate-of-travel by 3-day intervals was available 986–93. The estimated date of parturition was considered the date when the rate-of-travel showed a major decline just prior to a period of little movement. Fancy and Whitten (99) quantified this date as the best estimate of the calving dates for 275 satellite-collared cows in the Porcupine herd. Next we regressed daily calves/00 females and percentage of antlered cows statistics against these estimated dates of calving (fig. 9.). The tallies of calves/00 females and percentage of antlered cows each day within a season were considered separate estimates of the calving date that year, and a mean and a standard error were calculated interpolating from the curvilinear lines in figure 9.. Classifications late in June – when nearly all the calves had been born and nearly all the cows had lost their antlers – were not included in these calculations. Fat Reserves and Liver Weights

In March 976, Drolet and Dauphiné (976) measured the maximum back fat of 2 females and 36 males using Dauphiné’s method (976). They also measured the

Physical Condition | 225

Fig. 9.1 Calves/100 females and the percentage of antlered females plotted against the estimated dates of calving of 40 satellitecollared females 1987 to 1993. The calving dates of the satellite females were estimated as occurring on the date of rapid decline in movement followed by a relative stationary period (Fancy and Whitten 1991).

CALVES PER 100 FEMALES OR PERCENTAGE COWS HARD ANTLERS

100

90

80

70

60

( ) CALVES / 100

Y=

50

120 1 + 14.697X 1.115 r2 = 0.688

( ) % ANTLERED

Y=

40

95 1 + 0.0706e 0.247X r2 = 0.709 n = 60

30

20

10

0

-8

-6

-4

-2

0

2

4

6

8

10

12

14

DAYS PRIOR OR POST BIRTH

femoral fat percentage for these animals. Parker (98) continued this work by making measurements of back fat, femoral fat, and kidney fat in April 980. His sample sizes included 34 females and 9 males for back fat; 38 females and 9 males for femur fat; and 38 females and 9 males for kidney fat. Luttich continued Parker’s practice of collecting females in April – either collecting his own or having a wildlife technician accompany commercial hunters from Nain in April. Maximum back fat deposits were secured for 0 years (982–93, 986 and 990 missing), and the fat in the metatarsal bone in 5 years (982, 987–89, 99). Kidney fat measurements were made in March and April 982, April 983, April 984, early May 992, and April 993. We quantified both the total weight of fat attached to both kidneys (Dauphiné 976) and tabulated the kidney fat index (Riney 955).

16

226 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Throughout Luttich’s tenure in Labrador 974–93 he autopsied a number of animals that he collected or that died from natural causes, as well as those of the commercial harvest from Nain. These observations spanned all the months except January and often included measurements of back fat, metatarsal fat, kidney fat, and dentary fat. Labrador technicians who accompanied hunters in August 987 and 989 secured additional measurements. Available in the literature after 980 were fat measurements by Huot in October 983 and April 984 (Huot and Goudreault 985; Huot 989); and by Couturier in March and April 986 and 987 (Couturier et al. 989). Couturier also provided us with his raw data, which included measurements in September 984 (animals that drowned at Limestone Falls) and additional autopsies in the autumns of 985, 986, 987, and 988. Both Huot and Couturier compared fat percentages in the femur and the metatarsal. Their comparisons showed that fat is mobilized commencing first in the femur and then the metatarsal. Hence femur fat is a more sensitive indicator of condition than metatarsal fat. However, femur fat was not available from the commercial cooperative program since deboning hindquarters destined for the dining table was undesirable. Although metatarsal fat is not as sensitive to condition as femur fat, metatarsal fat is one of the last reserves mobilized before death. An animal with low reserves (< 30%) is close to, if not at, the starvation level (review Mech et al. 995, 998). The livers of females in April were weighed in  seasons 982 to 993 (990 missing). Sample size varied from three in 984 to 242 in 987, with a mean of 9.7 ± 25.86 animals per year. Antler Condition Index The size of antlers of males and females decreased between 978–88 (tables 2.5, 8.9, 8.0). The major decline for males occurred between the rutting season of 982 and 983 (table 9.). Male antlers declined more in mass than in total length (table 8.9), but female antlers decreased on both fronts: > 35% between 980 and 986 in mass (table 8.0); and 30% between 980 and 984, or 3.6 cm/yr, in total length (Y = 736.640 - 3.580X, r = 0.979, n = 5). Ninety-eight percent of the females of the George River caribou herd were antlered in the 970s (table 9.) prior to range overgrazing. This figure is similar to the antlered percentages in other large herds in North America that crater in the open in winter in large groups (Kelsall 968; Reimers 993). The current hypothesis as to why female caribou have antlers as opposed to all the other cervids is that antlers enhance social dominance. This may be especially important if the animals face food competition in digging winter craters (Barrette and Vandal 986). According to this theory, percentages of antlered females should relate to both snow depths and competitive group size (see also

Physical Condition | 227

Table 9.1 Antler development in females and males as an index to condition (sample size in parentheses) Season

1974 1975 1976 1977 1978 1979 1980 1981 1982 1983² 1984 1985 1986 1987 1988³ 1989 1990⁴ 1991 1992

Young Females¹

% Unantlered Females (October) Adult Total Females Females

– – – – – 7.6 (33/435) – 2.3 (6/265) 1.9 (2/107) 4.1 (10/242) 14.4 (32/222) 10.4 (38/363) 20.1 (24/119) – 11.9 (22/185) (?/90) (?/133) 12.8 (37/289) 18.8 (50/266)

– – – – – 2.3 (140/6,060) – 2.0 (84/4,140) 1.6 (23/400) 2.1 (50/2,353) 2.3 (61/2,632) 4.2 (165/3,912) 5.5 (59/1,083) – 6.5 (117/1,812) 6.3 (83/1,313) 7.8 (193/2,470) 8.3 (430/5,157) 9.3 (330/3,569)

1.6 (55/3,547) 2.1 (164/7,984) 2.4 (93/3,876) 3.2 (45/1,416) – 2.7 (173/6,495) – 2.0 (90/4,405) 1.9 (25/1,293) 2.3 (60/2,595) 3.6 (93/2,554) 4.8 (203/4,275) 6.9 (83/1,202) – 7.0 (139/1,997) 6.3 (83/1,313) 7.8 (193/2,470) 8.4 (457/5,446) 9.9 (380/3,835)

% Regal Males (of Regal plus Medium Males)

– – – – – 69.6 (2,184/3,137) – 61.7 (647/1,049) 60.5 (348/575) 1.6 (13/800) 5.8 (54/937) 20.8 (299/1,441) 11.5 (38/330) – 23.8 (119/500) – – 9.7 (108/1,119) 25.5 (101/396)

¹ Mostly around 7 months of age ² Animals classified in the Torngats, regal male 62.8% (452/720), unantlered females .% (3/5) ³ Animals classified in the Torngats regal males 59.8% (55/92), unantlered females 4.5% (9/99) ⁴ Not classified by S. Luttich

Schaefer and Mahoney 200). The George River caribou herd craters in deep snow and in large groups, which, according to the hypothesis, should favor the antler phenotype. One expects herds with a high percentage of polled females to feed in small groups and depend to a lesser degree on craters – because of either reduced snow or because they depend more heavily on arboreal lichens. For woodland caribou in eastern North America, the percentage of polled females decreased with more snow cover (fig. 9.2). Another example would be the Svalbard caribou: These animals use windswept slopes and socialize in small groups; polled percentages reported ranged from 4–47% (review Reimers 993). Bald females are also common for caribou that live on arboreal lichens and seldom crater. The percentage of antlerless females was 36% in the Wells Gray Park herd, British Columbia (n = 33, Bergerud, personal files), where the animals depend on

228 | TH E R E T U R N O F C A R I BO U TO U N G AVA GEORGE R.

PERCENTAGE ANTLERED FEMALES

100

RED WINE

N. PEN.

90 80

MEALY MT. HUMBER

70 GASPÉ

60 50

INTERIOR

40 30

Y = 110  6229591X 2.134 r2 = 0.677

20 10

AVALON

0 0

100

200

300

400

500

Fig. 9.2 The percentages of antlered females in various herds was greater when faced with greater snow cover in the winter in Newfoundland, Gaspé, and Ungava. The antlered percentages are from Bergerud (1971 and pers. files) and Brown (1986), snowfall from Thomas (1953).

TOTAL SNOW (cm)

arboreal lichens (Antifeau 987). Caribou on the Slate Islands in Ontario and the Gaspé herd in Quebec are two other herds that take mostly arboreal lichens and feed in small groups; bald females are common in both (Rivard 978; Bergerud, personal files). The caribou that once inhabited the Queen Charlotte Islands in British Columbia would have lived in small groups in mostly closed canopies and they must have depended upon arboreal lichens. Females in this herd apparently did not have any antlers (review Reimers 993). The percentage of females recorded as having no visible antlers in the George River herd showed no trend 974–83 (table 9.), but thereafter increased, reaching 0% in 992 (table 9.). In the late phenology year of 992 there were even polled males. Three were seen from the 99 cohort (n = 266) and two were recorded for males in later years among those males classified as small (n = 535). Reimers (993) has documented that antlerless females increased in two Norwegian herds – Snohetta and Hardangervidda – as their numbers increased and their condition declined. He also mentioned that in Newfoundland the percentage of antlerless females may have increased from 0% in the early 900s (based on photographs in Dugmore 93) to 55% in the 950s (Bergerud 97b). However, the animals in Dugmore’s photographs were of the Northern Peninsula herd that once migrated south from the Northern Peninsula (Bergerud 97b); this herd still had only 2% antlerless females in the 960s (Bergerud 97b). Reimers (993) concluded that antlerless females are few or absent in populations in prime physical condition and more frequent in populations on over-

Physical Condition | 229

grazed ranges. Our data suggest that the increase in polled animals in the George River herd was because some young females delayed growing their initial antler sets or had such minimal growth that it could not be recognized without handling the animals. Antler growth – like sexual maturity – can thus be retarded when inadequate nutrients are directed to body growth. The decline in antlered females in Norway has been attributed to overgrazed winter pastures (Gaare 968; Gaare and Skogland 980). Reimers (983b), on the other hand, thought that it related more to summer pastures. In Greenland, however, Thing et al. (986) also attributed it to the quality of the winter range. In the case of the George River caribou herd, the problem must lie with the summer food shortages since the winter range, even as late as 988, was in satisfactory condition (chapter 7). The summer range had been seriously impacted by both trampling and a reduction of shrub growth and herbs (chapter 7, and Manseau et al. 996). The annual changes in the antlerless index were correlated both with the dates of calving (r² = 0.78, n = 2) (fig. 9.3) and the summer growth of birch (r = -0.942, n = 6) (fig. 9.3). Later in this chapter we will document that conception dates – and hence calving dates – were delayed with poor summer nutrition. Relative to the antlerless condition index, the summer overgrazing became serious in 984 (table 9.). In the case of the correlation between antlerless condition and growth of birch, the annual growth of birch as an indicator of summer forage explained 88% of the annual variations in bald females. Female Antler Casting There is a suggestion in the literature that females in good condition may shed their antlers before those in poor condition (Wika 980; Thing et al. 986; and Gagnon and Barrette 992). Females in the George River herd were less synchronous in their casting chronology when the population was high in numbers 984–93 than prior to that time, but in both periods, 90% of the cows still had hard antlers at the start of calving (fig. 9.4). There are two hypotheses to explain why cows carrying a fetus retain antlers –2 months later than barren females, who commonly cast their antlers in April: () The dominance hypothesis – hard antlers confer a feeding advantage over barren females and possibly help in the disassociation of last year’s calf prior to parturition; (2) the nutrient/fetus hypothesis – the retention of antlers prevents the growth of the new set, thereby reducing competition for nutrients for the fetus in the last stages of gestation. One could even argue that the hormones involved with pregnancy have a linkage with antler retention: Perhaps the drop in their levels following parturition simply triggers antler casting. The data from our study do not support the competition hypothesis. In April the females were generally near tree line feeding on graminoids in localities of low snow – competition for feeding craters should have been reduced. Also,

230 | TH E R E T U R N O F C A R I BO U TO U N G AVA

PERCENT ANTLERLESS FEMALES (AUTUMN)

10 1992

9

1990

1991

8

1988 1986

7

1989

6 1985

5 4

Y = 15.961  62.525X r = 0.942 n = 16

3 2

1977 1979

1984

1975 1983

1976 1981 1982

1974

1 0 0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

GROWTH OF BIRCH (mm) 1992

PERCENT ANTLERLESS FEMALES (AUTUMN)

10 9

1991 1988

8

1990

1986

7

Y=

6 5

33.712 19.410  X r2 = 0.781 n = 12

1989

1985

4 3

1976

1984

1979

1975

1981

2 1 0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

MEAN CALVING DATE IN JUNE

Fig. 9.3 (above) The percentage of females without visible antlers was less in years when there was a decline in the growth of birch that season; (below) Calving dates were later (Y2 ) when the percentage of females without visible antlers was lower in the prior fall (Y1).

during spring migration there was some segregation of pre-parturient and nonparturient females. If antlers were needed for disassociation of yearlings, then they would still be needed at parturition when some yearlings interact with neonates, but it is at that time that antlers are cast. We have seen few antler threats between cows and their yearlings since 988, even though a number of yearlings have remained with their dams in their second summer.

Physical Condition | 23

PERCENTAGE ANTLERED FEMALES

100 90 80

LATE 1986 Y=

70

EARLY 1978 + 1979

60 50

Y= 40

89 1 + 0.0069e 0.258X r2 = 0.920

97 1 + 0.0001X 3.841 r2 = 0.851

30 20 10 0 100

CALVES PER 100 FEMALES

90

EARLY 1978 + 1979 Y = 15.149 + 6.383X

80

LATE 1987 100

r2 = 0.837 Y=

70

1 + 544.158X 2.652

60 50

LATE 1986

40

Y=

30

90 1 + 361.262e 0.361X r2 = 0.741

1978/79 THIS STUDY 1987 VANDAL/COUTURIER 1988 1986 COUTURIER GAGNON/BARRETTE 1986

20 10 0 31

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

JUNE

Fig. 9.4 Specific examples of early calving were in 1978 and 1979 and late calving in 1986 and 1987. Data for 1986 from Serge Couturier (pers. comm.) quoted in Gagnon and Barrette (1986) and for 1987 from Vandal and Couturier (1988).

The second hypothesis, that retaining inert antlers saves nutrients for the fetus, is consistent with our observations. May is the critical month of growth for the fetus and was a major factor in birth weight and hence neonate viability. In the George River herd, females and yearlings even shared calcium in the winter and spring by chewing each other’s antlers (table 9.2). Casting the antlers near the time of parturition and delaying the growth of the new set 2–3 weeks pro-

232 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 9.2 Comparison of the frequency of chewed and unchewed antlers on the skulls of females in April 1980 with age, body weight, and antler size Parameters

Calves¹

22 months

34 months

% Chewed²

50.0 (14)

21.4 (14)

44.4 (18)

Body Weight (kg) Not Chewed Chewed Difference

45.3 ± 1.66 (7) 49.5 ± 1.10 (7) 4.2 (+)

75.1 ± 2.05 (10) 71.8 ± 1.00 (3) 3.3 (-)

90.6 ± 0.54 (10) 93.4 ± 2.06 (8) 2.8 (+)

Antler Weight (g)³ Not Chewed Chewed Difference

– – –

124.8 ± 14.52.(11) 141.2 ± 20.15.(3) 16.4 (+)

196.4 ± 16.53.(10) 272.2 ± 27.36 (8) 75.8 (+)

Antler Height (cm)³ Not Chewed Chewed Difference

13.5 ± 3.53 (7) 8.4 ± 1.58 (7) 5.5 (-)

41.8 ± 2.42 (11) 36.3 ± 5.89 (3) 5.5 (-)

47.9 ± 1.79 (10) 45.9 ± 3.23 (8) 2.0 (-)

Pedicel Size (mm)⁴ Not Chewed Chewed Difference

– – –

335.5 ± 32.25 (8) 441.0 ± 9.0 (2) 105.5 (+)

463.9 ± 17.32 (7) 604.9 ± 91.26 (5) 141.0 (+)

vides maximum nutrients at the time they are most needed by the new nursing neonate. We would disagree with Gagnon and Barrett (986, 992) that the early casting of antlers they reported in 986 is an indication of good condition. Our view is that the late casting was a symptom of atypical/nonsynchronous physiology. There are many indices available in this chapter to indicate that the George River cows were in poor condition in 986: April weights were the lowest recorded; and the views of Messier et al. (988), Couturier et al. (990), and Crête and Huot (993) all concur that the condition of the animals was reduced in years after 984. Chewing of Antlers An interesting observation made by Butler in 980 was that a majority of the females collected by Parker (98) in April had their non-cast antlers chewed and reduced in height by the time they returned from the winter range. The tips had definitely been chewed, not abraded. Her notes indicated that calves, both females and males, were especially susceptible. Her notes for four calves were: “Four inches chewed-down spikes; 3 inches chewed-down spikes; little knobs

Physical Condition | 233

46–106 months

≥ 118 months

65.0 (60)

80.0 (15)

91.0 ± 1.85 (21) 96.0 ± 1.29 (39) 5.0 (+)

97.4 ± 3.49 (3) 92.7 ± 1.79 (12) 4.7 (-)

200.4 ± 17.06 (20) 245.8 ± 16.61 (35) 45.4 (+)

220.5 ± 65.26 (3) 216.3 ± 18.91 (12) 4.2 (-)

45.6 ± 1.49 (21) 42.5 ± 1.19 (30) 3.1 (-)

48.7 ± 3.25 (3) 36.7 ± 2.79 (12) 12.0 (-)

470.7 ± 36.63 (18) 598.5 ± 33.81 (24) 127.8 (+)

456.0 (1) 614.0 ± 74.36 (8) 158.0 (+)

¹ Calves included, both males and females ² Based only on females with hard antlers, if antlers had only a few marks they were not considered chewed ³ Antler measurements based on the mean of the right and left antler and averaged per individual ⁴ Pedicel size based on the width and length of the pedicel, without correction for the oval circumference. Antlers removed by sawing.

chewed down to one-half inch of the head; and one spike broken, remaining down to 9.5 cm.” Calf antlers that were still in velvet had not been chewed (n = 8); nor had antlers of 22-month-old females that still retained velvet (n = 4). Adult females had lost significant portions of their terminal beams from chewing (table 9.2). There were 4 females in the collection that had one antler chewed and one not; the chewed antlers averaged 4.9 cm ± 2. cm and the non-chewed averaged 46.8 cm ± .67 cm, for an estimated 0% loss of antler length. Based on the terminal diameter left below the chewed-off stubs, Butler estimated a mean loss of 6.0 cm ± 0.47 cm for 60 of the females with the most noticeably-chewed antlers. The extreme example of beam loss was a female (42 months old) with approximately half of the left antler gone (28 cm remaining) and 5 cm missing from the right antler (38 cm left). The chewing interaction was not obviously dominance-driven, based on antler size (table 9.2). In fact, females with the largest mass in antlers (weight and pedicel size) had more of their antlers chewed than females with short spindly sets (table 9.2). Butler hypothesized that mutual chewing (grooming?) occurred mostly between a calf and its dam. This would explain the reduced chewing for 22- and 34-month-old animals (table 9.2) that may have been still primiparous. However, of the 9 females with large teats who presumably had a calf the previ-

234 | TH E R E T U R N O F C A R I BO U TO U N G AVA

ous year, four of these females (2%) did not have chewed antlers. Also, three 22month-old males also had chewed antlers, as well as one 34-month-old male that had lost perhaps 0 cm of antler growth. In other years, we never observed chewed antlers in the fall, but we did observe chewed antlers in April 98,  of 3; April 983, 7 of 8; April 982, 0 of 7; and in March 982, but only  of 2. The mutual sharing of calcium may occur more in late winter when the animals switch from lichens to a graminoid diet. The animals in the early 980s were in reasonable physical condition and soil readings of calcium (Fred Harrington, unpubl.) did not suggest an obvious shortage of minerals in the substrate. Chewing of non-cast antlers has also been reported for animals in Norway (Reimers 993). Wika (982), in discussing the chewing of cast antlers, felt that antlers may subserve the mineral householding of the animals, and bringing the antlers to the calving areas would be advantageous in the maintenance of the calcium balance. We now know that many caribou can’t wait until casting to get those extra minerals. We have mutual social tolerance (you can chew my antlers, if I can chew yours), which translates to zero individual distance. Calving Chronology Reimers et al. (983) related later calving between herds in Norway to summer condition. Skogland (983, 990) felt it was a response to winter range conditions. If the late calving were due to summer food, then the fall dates of breeding could be later; if winter range was the problem, then gestation length would vary with winter food/snow problems. In reviewing the literature, Cameron et al. (993) noted four references suggesting variations in gestation and three supporting different breeding dates. In their study, the calving peak was 2 June 989 after a hard winter, and 3–5 June in 988, 990 and 99 when winter snows were less. They concluded that the mechanism by which timing of parturition varies is uncertain. The calving dates for the George River herd have become progressively later after 972 (table 9.3; fig. 9.4, 9.5) (Bergerud 988a; Couturier et al. 990). Biologist Stephen Wetmore found the Caribou House calving ground on 4 June 972 and reported that 75% of the females had already calved and were moving slowly westward. The next year Ian Juniper (unpubl.) identified the calving ground on 3 May; he flew over the area again 5 June and reported that the proportion of calves to adult females was appreciably higher during the second flight. The following year (974), biologist John Folinsbee saw the first newborn calf on 23 May and by 3 May, when the survey was terminated, calves were common. Luttich commenced classification counts starting in 975. Between 5–9 June 975, he tallied 70 calves/00 females, with 70% of the cows still retaining hard antlers (n = 2,3 females). A count in 978 on 30 May gave 4 calves with ,579 females but by

Physical Condition | 235

Table 9.3 The estimated mean calving dates based on calves/100 female classifications and the percentage of females with hard antlers (number of days classified) Calving Season

Calves/100 Females

Estimated Mean Calving Date Antlered Females (%)

1975² 1976³ 1977⁴ 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993

31 May² Most born by 8 June no data 6.0 ± 0.71 June (4) 4.7 ± 2.33 June (3) Most born by 16 June 8.3 ± 3.48 June (3) no data no data 12.0 ± 1.00 June (3) 11.5 ± 3.59 June (4) 10.0 ± 2.09 June (6) 11.5 ± 0.42 June (8) 11.5 ± 1.69 June (12) 14.0 ± 1.12 June (13) 13.7 ± 1.57 June (7) 19.4 ± 1.70 June (7) 13.3 ± 2.39 June (4) 13.8 ± 2.60 June (4)

9 June² 2 June³ no data Would be late May 8.1 ± 0.90 June (9) 7.8 ± 0.86 June (5) 16.7 ± 0.75 June (3)⁴ no data no data 12.0 ± 4.00 June (2) 15.8 ± 0.25 June (4) 14.8 ± 0.60 June (6) 12.1 ± 0.98 June (9) 14.6 ± 0.68 June (14) 10.7 ± 1.84 June (6) 14.9 ± 0.81 June (16) 12.0 ± 0.58 June (7) 17.0 ± 1.43 June (4) 10.2 ± 0.37June (5)

¹ ² ³ ⁴

Mean¹

5 June 2 June no data 6.0 June 6.4 June 7.8 June 8.3 June no data no data 12.0 June 13.6 June 12.4 June 11.8 June 13.1 June 12.9 June 14.4 June 15.7 June 15.1 June 12.0 June

Mean: (mean of calves/00 females + mean of antlered females)/2 975 classified 5–9 June but individual days not tallied thus sample is  976 classified 3–8 Junebut individual days not tallied Not considered valid

6 June the tally was 920 calves and ,420 females. In these years (972 to at least 978) nearly all the calves were born prior to 0 June (fig. 9.5; table 9.3). In contrast to these early calving dates, Gagnon and Barrette (986, 992) observed 2,892 cows 3–9 June 986 and saw only 3 calves (fig. 9.4). Then they shifted their camp to the headwaters of the Ford River and reported many newborn calves 8–9 June, 83 calves/00 females (n = ,225 females) (fig. 9.4). The following year (987) Vandal and Couturier (988) reported the firstborn calf 4 June and by 5 June there were 70 calves/00 females, similar to pregnancy percentages in those years (Couturier et al. 990). Mean calving dates were estimated on the basis of movements of satellitecollared females and the movement criteria established by Fancy and Whitten (99) (fig. 9.). Mean calving dates for the satellite females are as follows: 2 June 987 (n = 4); 2 June 988 (n = 5); 5 June 989 (n = 3);  June 99 (n = 8); 5 June 992 (n = 9); and 4 June 993 (n = 0) (fig. 9.6). However, the movement index

PERCENTAGE ANTLERED FEMALES

100 90 80 70 60 50 40 30

Y=

Y=

1975–80 96

1984–93 94 1 + 0.014e 0.282X r2 = 0.829

1 + 0.0001X 3.939

n = 71

r2 = 0.882

20

n = 21

10

CALVES PER 100 FEMALES

0 100

1975–80 Y = 13.870Xe 0.058X

90

r2 = 0.793 n = 20

80 70 60 50 40

1984–93 Y = 180  284.459X 0.324 r2 = 0.653

30 20

n = 75

10 0 2

4

6

8

10

12

14

16

18

20

22

24

26

JUNE

Fig. 9.5 Calving dates were eight days later 1984–93 than in 1975–80 based on calves/100 females tallies and antler casting. Each data point generally represents > 100 animals.

28

Physical Condition | 237

may not have been reliable in 993, an extremely early year in terms of phenology. In this year the animals increased their travel rates 6–4 June when mosquitoes appeared on the calving ground and the tundra was nearly bare of snow. Regardless, in the late 980s and early 990s peak calving was at least 8 days later than in the years 972–78 based both on calf:cow ratios and antler casting (table 9.3; fig. 9.5). The later calving from 984 onwards (no data for 982 and 983) resulted primarily because fall breeding occurred later (fig. 9.6) and not because of a prolonged gestation period. However, in 992 and possibly in 993 the gestation period may have been prolonged in the satellite-collared animals (fig. 9.6). The natural experiment relative to nutrition and conception/calving dates was that as summer nutrition declined after 983, the mean calving dates shifted from 4 June to 2 June. The reverse sequence occurred when wild George River animals were captured in April 987 and held in captivity on a high-nutrition diet for three years. In the first year (987) the animals calved on 2 June (n = 8) the same as free-ranging animals. In 988 the mean calving occurred 7 June (n = 8) and by 989 they had made the complete transition to the 4 June (n = 8) early calving date (calculations from Crête et al. 993). This transfer experiment was also done with sedentary caribou – possibly from the Caniapiscau herd – from Ungava in 966–67 (Des Meules and Simard 970). Cows were captured in March 966 at 53°0' N, 68° W. In the spring of 966, four captive females calved on a mean date of 5.5 June, and in 967, after 4 months on a high-nutrition diet, calving shifted to 30 May – 6.5 days earlier. The dates of calving at Caribou House were correlated with the growth of birch the previous year (fig. 9.7). We believe the sequence to be the following: The summer nutrition affected the physical condition of females in the fall. With a reduced fall condition, many females reached heat possibly an estrus interval later (approximately 0 days, Bergerud 975). These results are consistent with the observations in Norway that herds in poor condition calve later than those in superior condition; they are also consistent with our range survey, which showed adequate winter forage but seriously depleted summer forage. The major cause of the later calving was the later breeding, but we also believe gestation can be prolonged and this probably happened in 992 (fig. 9.6). Consider that a calf needs a threshold weight to survive. Many calves died in 992 with weights less than 5 kg and fetal growth was only 6 g/day in May, reaching weights of 4.5 kg on day 200 (n = 7) and 4.7 kg at birth (approximately 235 days) (n = 80) (fig. 8.2). Natural selection may have some built-in plasticity to compensate for retarded growth rates by extending the growing period. Our hypothesis differs from that of Skogland (983, 990), which related late calving to winter range conditions. Our data showed that fetus sizes in March were similar regardless of winter severity (fig. 8.2). And actually there was more snow in the years of early calving 973–8 – a mean of 69.9 cm ± 3.58 cm (n = 9) (fig. .7)

30

30

n=4 20

1986–87

10

n=4

229 ± 1.0 n=3

20 10

JUNE 12

OCT 24 0

0

30

30

n=6

20

1987–88

10

JUNE 12

0 30

n=5

20

KILOMETRES PER DAY

20 10

NO CLEAR PAUSE

0 30

231.5 ± 2.33 n=4

n=5

1988–89

10

n=3

231.0 ± 0.0 n=3

20

JUNE 15

10 OCT 22

0

0

30

30

n=4 20

1989–90

10 OCT 25

0

1990–91

JUNE 11 10

OCT 23

0

0 30

n=8

20

1991–92

10

233.7 ± 1.33 n=6

n=9

20 JUNE 15 10

OCT 21

0

30

30

n=8 20

1992–93

10 0

229.3 ± 0.75 n=4

n=8 20

30

0

NO DATA ONE ANIMAL NOT TAGGED OCTOBER

30

n=5

20 10

ONLY ONE ANIMAL

10

0 30

20

20 10

OCT 17

OCTOBER

n = 10 MOSQUITOES JUNE 14

0

JUNE

?

Physical Condition | 239

MEAN DATE OF CALVING IN YEAR 2

20

1991

1992

15

1989 1988 1993

1985 1986

1990

1984

1987

10 1981 1979

Y = 15  16198X 4.915 r2 = 0.691

1978

n = 16

5

1980 1975 1976

0

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

GROWTH OF BIRCH IN YEAR 1 (mm) Fig. 9.6 (facing page) The dates of estimated breeding and calving of satellite caribou 1987 to 1993, based on low rates of travel. The gestation dates are based on individual animals and may not agree with the spread in the mean breeding and calving dates. The long gestation estimate in 1993 may not be reliable since mosquitoes appeared on the calving grounds during calving and cows then increased their movement to insect relief habitats. Fig. 9.7 (above) The mean date of calving in Year 2 was negatively correlated with the growth of birch annulations the previous summer, Y1. The abundance of birch would have affected summer condition in Y1 and thus the dates of fall breeding in Y1.

– than in later years 984–93, where the mean was 470.5 cm ± 3.32 cm (n = 9). Spring phenology in May showed wide variations that led to differences between years in birth mass based on spring break-up (fig. .4). The latest phenology year (992) had the smallest calves (table 8.2), whereas the next year was very early and calves were 2 kg heavier (table 8.2). Nutrition and Antler Casting It is generally accepted that most parturient cows shed their antlers within a few days of birth (figs. 9., 9.5). Nonetheless, Gagnon and Barrette (992) observed that only 63% of the females they saw on the calving grounds prior to calving 3–9 June 986 had one or two hard antlers (n = 2,892). Additionally they noted

240 | TH E R E T U R N O F C A R I BO U TO U N G AVA

PERCENT OF FEMALES WITH HARD ANTLERS

100

90

1978 1988

1979

80

1986 (NFLD)

1976 +4

70

1981 +3

1984 −6 1985

1975 +3

1987

60

1990

Y = 110.757  4.045X

1992

r = 0.736

50

n = 12 (

1986 (QUE)

only)

40

+3 ANTLERS COUNTED 3 DAYS AFTER MEAN CALVING (BIASED LOW)

30

−6 ANTLERS COUNTED ONLY 6 DAYS BEFORE MEAN CALVING (BIASED HIGH)

1989 1991 1993

20

0

5

10

15

20

MEAN CALVING DATE (JUNE) BASED ON CALVES/100 FEMALES Fig. 9.8 As calving became later annually, fewer cows still retained hard antlers at the mean calving date based on calves/100 females. Data points with arrows represent statistics of antlered females on dates that did not include the mean calving date based on calves/100 females tallies. A curvilinear regression using all 16 points would provide a better fit.

that on the days when many cows gave birth in 986 (8–9 June) some of the new mothers had already commenced the growth of the new set. To further evaluate Gagnon and Barrette’s observation of major antler casting several days/weeks before parturition, we estimated the percentage of females with one or two hard antlers on the mean calving dates for those years where we had counted antler possession on at least four different dates. We regressed these antlered percentages on June dates and interpolated the hard-antlered percentage on the peak calving date derived from the independent variable calves/00 females (table 9.3). These results (fig. 9.8) indicated that as Gagnon and Barrette had observed, more cows had shed their antlers by peak calving in years that calving was late (> June 2) than in early calving seasons. In early years prior to 984, nearly all the females still had hard antlers at calving. For example, in 975, 92%

Physical Condition | 24

of 568 cows had hard antlers 26–28 May at the start of the calving season. Again, in 978 on the peak day of calving 6 June on the Ford River – near where Gagnon and Barrette camped in 986 – 90% of ,420 females had hard antlers. However, even in later years, most cows still had antlers as calving occurred. We captured 02 newborn calves in 985 and 97 of the cows had antlers; in 986 all 24 cows with newborn calves still had antlers. Couturier was also afield with Gagnon and Barrette and with us in 986, and he reported 85% of the females still had hard antlers from 3 to  June (n = 454). Antler casting was more synchronous in early years and more extended under poorer nutrition in latter years. Our explanation of the casting extension is that two estrus intervals are involved. Some cows still came into heat in mid-October (calving date approximately 4 June), whereas others had their first overt heat in the last week of October. The reduced synchrony in latter years still does not account for cows with neonates that had antlers already growing, however. Some of the late-calving cows dropped their antlers more in apparent synchrony with what would have been their normal times for conceiving and giving birth. We consider this early casting a physiological maladjustment that is related to poor nutrition. This is contrary to Gagnon and Barrette’s (992) view, who propose that it happens because of good nutrition. Cows conceiving in two intervals 8–0 days apart in the fall suggests a wide range in fall condition – a normal and a late mode. Certainly cows in the fall in the 980s fell into two distinct groups based on condition: the lactating cows that had not rebuilt their condition; and the non-lactating cows which, if they had not given birth, had paid neither a fetus nor a milk-production cost (Couturier et al. 989, table 9). Mitchell and Lincoln (973), observing a similar sequence in red deer, noted that “milk hinds” conceived a week later than “yield hinds.” The cows that had successfully raised a calf the previous year paid a price in condition and they must generally have conceived and calved later the next season. The dates and short durations of calving for caribou (90% born in 0 days, Lent 966; Bergerud 975) are considered adaptations to maximize the flush of spring phenology (Skogland 99; Russell et al. 993) and/or to minimize predation (Bergerud 974b). Extended calving with a later mean is assumed to place calves at a survival disadvantage relative to growth and to increased mortality, especially in the George River herd where the cows are travelling and crossing rivers in flood in the later half of June. Could there be an offspring/offspring aspect to the so-called parent/offspring conflict in skipping pregnancies? Liver Weights Adamczewski et al. (987a) showed an annual cycle in liver weights for the caribou of Coats Island with a peak occurring in August. Leader-Williams (988) also documented such a cycle at South Georgia south of the equator. Adamczew-

242 | TH E R E T U R N O F C A R I BO U TO U N G AVA

1400

2 SE

27

LIVER MASS (g)

1300 1200

SAMPLE SIZE

8

1100 167

1000 46

900

160

150

242

ND 212

3

191

800 111

700 600

1982 83

84

85

86

87

88

89

90

91

92 1993

APRIL SEASONS Fig. 9.9 The weight of the livers of adult females in April (> 34 months of age) 1982 to 1993, 1990 missing. The major difference between 1992, following a long return migration and a cold spring, and 1993, with a short migration and a early warm spring, illustrates the importance of density-independent factors (weather and prior condition, i.e. variable fat reserves from migration distances). Herd numbers had not changed greatly between 1992 and 1993 (fig. 10.5).

ski et al. (987) suggested that liver weight (in caribou) as a fraction of carcass weight would serve as an index of recent nutrition, in contrast to fat and muscle which serve as cumulative measures of nutrition (but see Mitchell et al. 976). The beauty of the liver index is in the low measuring error. The April weights of livers of the George River females (> 34 months of age) measured in  years (n = ,37) were significantly higher in 983 than for the years 984–92 (fig. 9.9). Liver weights were unusually low in the late year 992 and showed a major increase in 993; this is consistent with the small calves born in 992 and the very large calves born in 993 (chapter 8). Fat Cycle There have been a number of thorough studies of fat reserves of caribou in North America to evaluate physical condition (Dauphiné 976; Adamczewski et al. 986a, b; Allaye-Chan 99; Thomas and Kiliaan 998; Russell et al. 993). As mentioned earlier, Parker (98), Huot (989), and Couturier et al. (989) all measured fat reserves of the George River caribou herd. Parker’s (98) data indi-

Physical Condition | 243

70

NAIN

50 40

Y = 39.919 + 1.348X r = 0.930

30 HEBRON

20 10 0 95

NAIN (8)

(14)

PERCENT FEMORAL FA T

Fig. 9.10 The mobilization sequence of femoral fat, kidney fat, and back fat in females is not synchronous. The mobilization sequence was back fat first, kidney fat second, and then femoral fat. Animals collected near Hebron in 1980 had significantly less fat than those collected near Nain in that spring (data provided by G. Parker). We argue that back fat is not a hedge against starvation but has evolved to maintain overwinter body weights (fig. 8.9) and provide the condition for females to make the long spring return migration to calving grounds.

KIDNEY FAT (g)

60

(7)

(19)

(7)

(11)

90

(8)

2 SE

(14)

85

80

75 HEBRON (11)

70

0

TRACE

1

2

3–7

8–12

13–17

>17

MEAN MAXIMUM BACK FAT (mm)

cated that the fat mobilization sequence for George River females was: back fat is mobilized first, then kidney fat, and last femoral fat (fig. 9.0). Combining our data with that in the literature we have graphed the annual fat cycle for males and females based on metatarsal fat, kidney fat, and back fat; and we have compared fat reserves between years based on the collections in March and April 976–93. We also evaluate fat reserves as they reflect energy expenditure relative to travel distances and location, and female age and reproductive status. As Tyler and Blix (990) noted, biologists know a lot about the anatomy of adipose tissue in caribou but the actual function of fat reserves has been far from clear. We think we provide new information in this area. Fat Reserves in Females

Consistent with the literature, fat reserves were higher for pregnant than nonpregnant animals; higher for non-lactating females than those nursing calves

244 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 9.4 Fat indices and body weights comparison between pregnant and non-pregnant females (≥ 34 months) before migration (March) and after migration (April) Collection Dates

March ?/76 1–10/82 14–22/86 17/87 13/93 Means¹ April 4/29–5/4/78 16–18/79² 3–15/80 15–29/82 4/14–5/1/83³ 10–16/84 27–28/84⁴ 3–25/85 7–10/86 5–14/87 20–28/87⁵ 18/88 10–22/88⁶ 25/89 ?/91 5–13/92⁷ 4/27–5/3/93 Means¹

Maximum Back Fat (mm) Pregnant Not Pregnant

28.4 ± 1.70 (21)

–

Total Kidney Fat (g) Pregnant Not Pregnant

–

–

21.4 ± 4.40 (10) 12.7 ± 3.90 (10) – 29.8 ± 4.29 (5) 23.1 ± 3.03

– 6.5 ± 5.50 (4) – 0 (1) 6.5 ± 5.50

213.7 ± 25.60 (9) 55.9 ± 7.62 (12) 34.0 ± 6.50 (4) – 101.2 ± 40.02

– 24.0 ± 5.12 (10) 27.0 ± 4.19 (3) – 25.5 ± 1.50

3.1 ± 0.77 (5) 4.3 ± 1.89 (32) 5.6 ± 2.11 (99) 4.3 ± 0.82 (32) 2.4 ± 0.48 (7) 5.6 ± 2.11 (11) < 1 (3) 1.7 ± 0.21 (138) 2.7 ± 0.22 (187) 1.5 ± 0.75 (14) 1.9 ± 0.06 (205) – 1.6 ± 0.25 (177) 0.4 ± 0.05 (118) 1.9 ± 0.16 (118) 0.4 ± 0.12 (82) 12.1 ± 2.23 (22) 3.3 ± 0.77

0 (1) – 2.5 ± 1.54 (6) 4 (1) 0 (1) – – 1.8 ± 0.90 (19) 0.2 ± 0.15 (25) – 1.0 ± 0.52 (13) – 0.5 ± 0.54 (13) 0.2 ± 0.02 (9) 1.1 ± 0.1 (16) 0.4 ± 0.12 (7) 0.8 ± 0.83 (6) 0.9 ± 0.26

– – 79.8 ± 3.27 (81) 102.6 ± 5.62 (33) 74.8 ± 13.97 (8) 38.3 ± 4.28 (11) 49.3 ± 10.68 (3) – – 41.3 ± 3.28 (12) – 27.6 ± 5.71 (4) – – – 32.6 ± 2.2 (112) 117 ± 0.85 (21) 62.6 ± 10.77

– – 69.8 ± 12.51 (4) 220 (1) 50 (1) – – – – 35.9 ± 5.25 (6) – – – – – 23.6 ± 4.32 (11) 61.5 ± 12.73 (5) 47.7 ± 10.79

(tables 9.4, 9.5); and higher for females of prime age than anile females (figs. 9., 9.2). Back fat was the most sensitive indication of anility (fig. 9.), but kidney fat reserves generally declined after 5–6 years of age (fig. 9.2). There was a general decline in adipose tissue from March to June for females (fig. 9.3; also Dauphiné 976; Russell et al. 993), but it appeared that reserves continued down in July. This is in contrast to an upturn in the Kaminuriak and Porcupine herds (Dauphiné 976; Russell et al. 993) (fig. 9.3). Fat reserves showed an increase from a low in July until the fall breeding season gains of 0.8 mm/day back fat and 0.20 g/day kidney fat ( August to 4 October, fig. 9.3). Nearly all of these readings were taken in the mid- and late 980s after the herd had reached high numbers .

Physical Condition | 245

Fat in Leg Marrow Pregnant Not Pregnant

–

–

83.6 ± 1.99 (9) 85.9 ± 0.83 (12) 86.0 ± 0.05 (2) – 85.2 ± 0.78

– 82.4 ± 2.43 (6) 84.8 ± 0.83 (3) – 83.6 ± 1.20

– – 88.4 ± 0.81 (100) 86.6 ± 0.88 (29) – 84.0 ± 1.18 (11) – – – 85.8 ± 1.03 (12) 89.5 ± 0.30 (199) – 85.9 ± 0.67 (202) 85.6 ± 0.72 (195) 91.0 ± 0.95 (94) – – 87.1 ± 0.82

– – 85.0 ± 0.72 (6) 92.1 (1) – – – – – 80.0 ± 4.5 (7) 89.0 ± 0.77 (9) – 81.4 ± 3.74 (14) 83.7 ± 3.30 (13) 76.8 ± 6.16 (5) – – 82.7 ± 1.74

¹ Data included from Drolet and Dauphiné 976 for 976; Parker 98 for 980, Huot 989 for 984; and Couturier et al. 989 for 986, 987, and 988 ¹ Means exclude samples of  ² Dentary fat % adult females 67.7 ± 2.50 (2) ³ Dentary fat % pregnant females 70. ± 0.73 (36), not pregnant 79.5 () ⁴ Dentary fat % pregnant females 72.8 ± 4.38 (5) ⁵ Dentary fat % pregnant females 80.7 ± 3.49 (4) ⁶ Dentary fat % females 73.6 ± 4.82 (78), not pregnant 7.0 ± 0.57 (9) ⁷ 992 collection made in May

Based on the Kaminuriak model, females should show a decline in kidney fat and back fat over winter (fig. 9.3), but the winter sequence is much less clear for the George River herd, especially since there were practically no measurements in the autumn prior to high numbers. However, the cows in March/April 980–83 and 993 had much higher kidney fat weights than in the years 984–87 (fig. 9.3). These reserves may have been greater than in the fall. After 983 the cows definitely had greater fat reserves in March and April than they had in the autumn, but these reserves were still less than those of the Kaminuriak (fig. 9.3). Lactating females had only 2.8 g ± 2.5 g of kidney fat in October 983 (n = 2), but this had increased to 38.3 g ± 4.28 g for pregnant cows in April 984 (n = ) (Huot 989; Couturier et al. 989). We conclude that a major drop in condition

246 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 9.5 Total fat content ( FATP ) of females on an ingesta–free weight basis using the formula FATP =[(ln kidney fat index of Riney 1955)(3.73) - 3.29], from Huot and Goudreault (1985) Season/Dates Fall

Kidney Fat Index (%) Lactating Not Lactating

Total Body Fat (kg) Lactating Not Lactating

18+24 October 1983¹ 27 October 1983 29 September 1984² 9 Sept.–11 Oct. 1984² 3–12 November 1986² 1–10 November 1987² November 1989³

10.4 (15) – 23.3 ± 3.93 (1) 26.6 ± 1.81 (26) 23.5 ± 3.57 (15) 26.4 ± 5.52 (6) ~10 (7)

15.6 (4) 25.9 ± 2.09 (2) 32.9 ± 6.78 (6) – 34.0 ± 4.52 (7 ) 44.3 ± 6.40 (6) 23 (5)

Mean

20.0 ± 3.16

29.3 ± 4.08

7.6 ± 0.71

9.1 ± 0.55

Not Pregnant

Pregnant

Not Pregnant

10.9 12.3 10.0 9.6 9.5 10.3 12.8 10.2 11.2 11.1 7.8 12.3

10.1 – – – – – 10.2 9.5 12.0 – 6.0 8.7

10.7 ± 0.40

9.4 ± 0.82

Spring

Pregnant

3–15, April 1980⁴ 1–10, March 1981 15–29, April 1982 14 April–1 May1983 28 April 1984 12 and 15 April 1984¹ 14–22 March 1986² 17 March 1987 5–14 April 1987² 18 April 1988 5–13 May 1992 27 April–31 May 1993

45.0 ± 2.45 (67) 65.2 ± 13.27 (9) 35.7 ± 1.44 (36) 31.3 ± 5.00 (8) 31.0 ± 11.00 (3) 38.5 (13) 75.7 ± 13.25 (12) 37.2 ± 11.00 (3) 48.5 ± 2.81 (19) 48.1 ± 6.55 (2) 19.3 ± 1.26 (104) 65.1 ± 4.65 (21)

36.1 ± 6.25 (3) – – – – – 36.8 ± 8.61 (6) 30.9 ± 4.77 (3) 60.5 ± 13.40 (6) – 12.2 ± 4.71 (6) 25.2 ± 6.05 (4)

Mean

45.1 ± 4.78

33.6 ± 6.52

5.4 – 8.5 8.9 8.5 8.9 5.3

7.0 8.8 9.7 – 9.9 10.9 8.4

¹ Huot 989; ² Couturier et al. 989; ³ Crête and Huot 993; ⁴ Parker 98

occurred in the spring between the years of 983 and 984. Prior to the decline, kidney fat indices were superior to the Kaminuriak herd’s; after 983 they were inferior (fig. 9.3). Back fat readings in the spring were also reduced after 983 (fig. 9.3). Prior to 984, the readings agree with those for the Kaminuriak herd, but after 984 they were less (fig. 9.3). Drolet and Dauphiné (976) reported a mean of 28.8 mm of back fat for George River mature females (n = 20) in March 976 at 56°45' N, 68°0' W. This deposition was 2 times greater than that reported for the Kaminuriak herd in September 966 and 967 (5.4 mm, n = 37), and in November– December 966 and 967 (2.4 mm, n = 87); as well as for the Beverly herd in November–December 98–87 (3.2 mm, n = 64) (Dauphiné 976; Thomas and Kiliaan 998). The George River herd also had high levels of back fat – greater

Physical Condition | 247

Fig. 9.11 The reserves of back fat in females in April were greatest for 5-year-old females, thereafter declining with age (all years combined, hence the large standard errors).

MEAN MAXIMUM BACK FAT OF FEMALES IN APRIL (mm)

4

170

3

150

155 95

132

128

2

55

103 65

30

72

1

49

Y = 0.141Xe 0.018X 34 TO 154 MONTHS

SAMPLE SIZE ± 2 SE

0

63 10

22

34

46

58

70

82

94

106

118

130

142

AGE IN MONTHS

than 20 mm – in March 982 and March 993 (table 9.4). In all three examples the animals were still on the winter range prior to spring migration. But when Couturier measured back fat from animals prior to migration in March 986, he found only 2.7 mm ± 3.90 mm for pregnant females (n = 0) and 6.5 mm ± 5.50 mm for non-pregnant animals (n = 4) (table 9.4) (Couturier et al. 989 and personal communication). April back fat readings were identical in April 980 and April 984, 5.6 mm (table 9.4). However, the readings in 980 were taken after migration (Parker 98); and those in 984 were taken prior to spring movements (Huot and Goudreault 985) – winter deposits would have been greater in 980 than in 984. As with the kidney fat index, a major decline in back fat occurred between 982 and 984. The back fat reserves of females available in March were rapidly mobilized in April (table 9.4). The clearest example of this decline was in 982: Luttich examined 0 females near Kuujjuaq, –0 March, that had 2.4 mm ± 4.40 mm of back fat. Seventeen days later after the herd had migrated south to

154+

KIDNEY FAT (g)

250

1980

Y = 3.347Xe 0.014X r2 = 0.762

200

n = 98

150 100 50 0

K IDNEY FAT (g)

300

1982

250

Y = 4.789Xe 0.016X r2 = 0.622

200

n = 36

150 100 50 0

KIDNEY FAT (g)

250

1993

Y = 3.888Xe 0.0119X

200

r2 = 0.702 n = 27

150 100 50 0 10

22

34

46

58

70

82

94

106

118

130

142

154+

AGE IN MONTHS Fig. 9.12 The kidney fat reserves in April declined with female age in the three years that major collections were made. There was so little kidney fat left in April 1992 that this analysis was not possible (1980, based on Parker 1981).

100

Y = 110  49515.2X 1.701

PERCENT FAT IN LEG BONES

90

n = 13, (313 ME TAT ARS AL FA T

80 70 60 50 40 30

) KAMINURIAK

FEMU R FAT

105 1 + 0.050e 0.141X n = 14, (819 )

Y=

POINT USED TWICE

GEORGE RIVER KAMINURIAK

20 120

TOTAL MASS KIDNEY FAT (g)

100

1982 214g n=9

80

1982 n=9 1980 n = 71

1993 n = 27

EXCLUDED

1983 n=9

60

K RIA

INU AM

Y = 0.366e0.016X

K 40 20 0

Y = 145e 0.016X n = 11, (191 )

28

MEAN MAXIMUM BACK FAT (mm)

SHORT MIGRATION LONG MIGRATION POST-MIGRATION

LON

G

Y = 39587.5X2.355

20

n = 13, (212

16

)

SHORT MIGRATION LONG MIGRATION POST-MIGRATION

SHOR T

24

)

IAK

12

K

8

UR IN AM

4 0

n = 13, (123

POINT USED TWICE

Y = 34.50 + 0.146X LONG

n = 16,

Y = 138.07e 0.039X n = 13, (1,099 ) MAR

APR

(313

MAY

JUNE

JULY

AUG

SEPT

)

OCT

NOV

Fig. 9.13 The fat reserves of females (≥ 34 months of age) showed annual cycles. The lowest reserves were in mid-summer, generally less than Dauphiné (1976) reported for the Kaminuriak herd across Hudson Bay from the George River herd. The annual low in fat probably occurred in July rather than in June, as was the case for the Kaminuriak herd (Dauphiné 1976). Animals in June had more back fat when spring migration distances were less than 500 km.

250 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Nain, the mean back fat was 4.3 mm ± 0.82 mm (n = 32), a loss of  mm per day. In this interval there was an expected change in the diet of the animals from one of mostly lichens in March to one heavy in graminoids in April (Parker 98; Gauthier and Shooner 988), but these adipose losses happened too rapidly for the change in diet to be the cause. Again, the energy and digestibility values of lichens vs dried graminoids don’t differ to an extent that could explain such a rapid mobilization; in the literature the digestibility of lichens averages 57.6% (in 7 studies), similar to graminoids, at 49.4% (8 studies), and both lichens and graminoids have similar calorific values approximately 8–20 kj/g dry weight (review Camps and Linders 989). Fat Reserves in Males

The back fat and kidney fat of males, similar to body weight (chapter 8), reached maximum size at the time of the fall rut and then showed a major decline by November (fig. 9.4; Couturier et al. 989). But there was no general increase in back fat or kidney fat from April to August (fig. 9.4), unlike there was in body mass. Protein and fat are not necessarily synchronous in deposition (AllayeChan 99). To achieve the maximum fat values needed for the fall rut, the rate of deposition increased rapidly in September; on 29 September 984, 5 males that drowned at Limestone Falls had a mean of 44. mm ± 2.90 mm of back fat (Couturier et al. 989). Kidney fat showed a similar late increase (fig. 9.4). There was late summer compensation in deposition in these reserves, even with high numbers after 982 and reduced summer forage. Notice in figure 9.4, however, that the fat in these males exceeded that of the Kaminuriak herd. This is a collection problem: Dauphiné (976) made his collections each year (966–68) on the same dates (5–2 September) and then his next measurements were 28 November–2 December. A line graph of fat reserves between these two dates must have missed both a rapid increase and a decline post rut. The calving dates of the Kaminuriak herd are similar to those of the George River (Kelsall 968; Parker 972a); hence fall breeding occurs in the last two weeks of October. We propose that the Kaminuriak – which had no food problems in either summer or winter (Miller 976a, b) – also had an accelerated increase just prior to breeding. The males in the George were able to attain the necessary fat reserves for breeding: These reserves increased slowly in July and August because of the overgrazed summer forage, but much less so in September when they crossed the tree line to better forage. Thus there was compensation. Our data are not sufficient to evaluate whether fat reserves for males increased over winter after the high population numbers (post 982). However, prior to high numbers (March 976), 22 mature males (> 45 months of age) had a mean of 26.5 mm back fat (Drolet and Dauphiné 976), which is a major increase from expected post-rut residual deposits of less than 2 mm. Since adipose reserves

Physical Condition | 25 160 140

7/83

MALES 4/86 4 ANIMALS IN 1986

KIDNEY FAT (g)

120

K IA

100 HEBRON 1/84

80

MI

KA

SHORTFALL

60 4/86

2/84

3/83

1/85

1/85

40 20

3/84

R NU

3/80

1/87

2/85

5/92 2/86

0

50

MALES

≥ 1984 < 1984 n = 184

SAMPLES ≥ 3 SHOWN

n=3 n=5

40

n=7

MAR

n=3

M

n = 18 n = 25

10

SHORTFALL

IN

UR I

20

0

n=3

n = 22

AK

30

?

KA

MEAN MAXIMUM BACK FAT (mm)

60

n=3

APR

MAY

JUNE

JULY

AUG

SEPT

OCT

NOV

Fig. 9.14 Abundance of kidney fat and maximum back fat in males. Males had low reserves in July and August in later years with high populations, but several had made major increases in reserves by the time of the fall rutting season. (Data from Kaminuriak adapted from Dauphiné 1976)

increased over winter for males in both the Kaminuriak and Beverly herds (Dauphiné 976; Thomas and Kiliaan 998), they probably increased for the George River herd inasmuch as winter lichens remained abundant (chapter 7). Energy Expenditure during Migration The rapid loss of back fat in 982 during spring migration prompted us to regress back fat of females against the length of the spring migration for 9 collections of back fat. The migration distances were measured along the migration routes

30

93 76

MAXIMUM BACK FAT (mm)

25

82

20

MAXIMUM BACK FAT (mm)

252 | TH E R E T U R N O F C A R I BO U TO U N G AVA

6

12

80

93

5

79

82

4 78

3

86

83

Y = 5.961  0.303X r = 0.637 n = 14

2 1

85 89

92

84

0 6

7

8

9

10

11

12

13

14

15

16

CARIBOU PER km² ABOVE TREELINE

15 93

86

MARCH APRIL MAY

10

84

80

5

87 88

91

Y = 32  5.604X 0.268 r2 = 0.982 n = 19

82 78

79

83

85 87

86

88

89

92

91 87

0 100

200

300

400

500

600

700

SPRING MIGRATION DISTANCE (km) Fig. 9.15 Back fat of females (≥ 34 months of age) in March and April declined as the length of spring migration increased. Since migration distances were correlated with herd numbers, these back fat reserves were also negatively correlated with animal densities above tree line (6 to 16 animals/km²) but not with densities below tree line (not shown). Distances in 1987 were measured from two discrete ranges.

from the centre of the winter distribution to the collection location. Fat reserves declined as the migration distances increased (fig. 9.5). The regression of fat reserves on migration distance was curvilinear and explained 98% of the decline in the back fat index (fig. 9.5). The high back fat reading in April 993 (2. mm ± 2.23 mm, table 9.4) came in a year when the herd remained east for the winter with reduced travel expenditure. We will document in chapter 2 that migration distances increased with population numbers but that actual densities increased only above tree line and not below tree line (winter distribution), since winter ranges expanded as the herd grew.

Physical Condition | 253

AGE SLOPE COEFFICIENT (×100)

7

6 1980 (n = 140)

MAXIMUM BACK FAT (mm)

5

5 4

Y = 0.205Xe 0.0098X r2 = 0.656

3 2 1985

1

1988 1989

1986

1991 1987 1992

0

310 km P < 0.05

4

1980 6

300

400

500

600

700

LENGTH OF SPRING MIGRATION (km)

3

474 km 1

986 (n =

2

380 k

m 198

680 km 1991 (n = 121 )

500 km 1

1988 (n

7 (n =

189) 365

= 170)

596 km 1989 (n

183)

km

198 5 (n

=1

= 104)

01)

662 km 1992 (n = 72) 0 34

46

58

70

82

94

106

118

130

142

154

AGE OF FEMALES (MONTHS) Fig. 9.16 The loss of back fat of females during spring migration increased with age. Slope coefficients were correlated with migration distances.

The rapid back fat expenditure in the spring was also age-related. Eight annual regressions of April fat of pregnant females on age (x-axis) all had negative slopes and were negatively correlated with migration distances (fig. 9.6). Only the regression for 980 was significant (r = -0.860, n = 4), but all the slope coefficients of the regressions of back fat on age were curvilinear and negatively correlated with migration distances (fig. 9.6, above). The more uniform back fat readings with age following extensive movements may have resulted because older animals had less back fat to lose initially (fig. 9.6) and utilized these reserves even with short movements. With the longer movements, the greater initial reserves

254 | TH E R E T U R N O F C A R I BO U TO U N G AVA

of prime animals were also heavily mobilized. In other words, an anile female could not expend what she did not have. Males, like females, depleted back fat March to April while migrating. On 7 March 986, 7 males had 2.3 mm ± .23 mm; a month later 8 males averaged 0.3 mm ± 0.23 mm. An interesting comparison with these low readings is a measurement Luttich made from an animal collected on 7 February 984 along the Great Whale River (55°30' N, 73°30' W). The body measurements indicated that this was a sedentary male of the Lac Bienville herd. This animal (68 months old) weighed 46.5 kg and had 34 mm of back fat and 235 grams of kidney fat. Without the costs of extensive fall and winter movements, this animal must have made a remarkable recovery from losses in the rut. George River herd animals have not fared as well since movements became extensive post-982. There was broad consensus that the summer condition of the females of the George River herd declined in the 980s with high numbers (Huot and Goudreault 985; Messier et al. 988; Huot 989; Couturier et al. 989, 990; Crête et al. 990a, 996; and Crête and Huot 993). Our fall condition indices of antlerless females and later calving dates reflect this decline in condition. However, there were few measurements of fat deposits or body weights in the autumn prior to 983 to allow comparison with those after 983 in order to quantify the decline on the basis of adipose tissue (tables 9.4, 9.5). Both kidney fat and back fat indexes of females in April had higher values in the late 970s and early 980s than they had later. Males weighed more in March 976 than March 986/87, but their fat reserves after migrating in April 980 were similar to reserves in later years (fig. 9.4) Unlike lactating females, however, they appeared to show rapid summer weight gain and compensations in accumulating fat reserves prior to breeding, even during high numbers. A comparison of the annual April fat reserves of pregnant females with prior environmental factors that might be causative from the current or previous year showed that only spring migration distances were correlated with the deposits (back fat P = 0.000, [n = 9] and kidney fat P = 0.066 [n = 2]) (table 9.6). There were several variables in the previous year that correlated with the April reserves (Year , table 9.6), but in 4 of the 5 cases the scatter diagrams had slopes that did not provide plausible biological explanations, e.g., warmer May temperatures (Y₁) and less fat (Y₂), and more snow in May and more back fat. There was a negative correlation between July temperatures and fat reserves (table 9.6) that may be of biological significance: The lower fat reserves may be related to the presence of more biting insects the prior year. July temperatures were also correlated with the percentage of antlered females in the autumn (r = -0.568, n = 4) but not with conception dates as indexed by calving dates (r = -0.209, n = 6). Our overall conclusion – albeit with reservations about July temperatures – was that there was no detectable carryover in condition between the environmental factors in

Physical Condition | 255

Table 9.6

Comparison of fat indices with prior environmental factors

Year and Parameters

Year 2 / Current Year Migration Distance Snow Depth¹ Snowfall² Year 1 / Previous Year Birch Growth Antlerless Females May Temperature Snow Depth 1 May June Temperature July Temperature July Rain Date Ice-Out Growing Season Days

Back Fat March and April April Only

Kidney Fat March and April April Only

r = -0.850 P = 0.0001 (19) r = -0.326 P = 0.187 (18) r = -0.069 P = 0.776 (20)

r = -0.772 P = 0.0007 (15) r = 0.488 P = 0.065 (15) r = -0.096 P = 0.724 (16)

r = -0.546 P = 0.066 (12) r = 0.085 P = 0.803 (11) r = 0.293 P = 0.356 (12)

r = -0.576 P= 0.104 (9) r = 0.340 P = 0.410 (8) r = -0.103 P = 0.791 (9)

r = 0.120 P = 0.961 (20) r = 0.037 P = 0.883 (18) r = -0.536 P = 0.015 (20) r = 0.342 P = 0.134 (20) r = -0.093 P = 0.697 (20) r = -0.093 P = 0.696 (20) r = 0.031 P = 0.897 (20) r = 0.566 P = 0.009 (20) r = -0.062 P = 0.809 (18)

r = -0.084 P = 0.758 (16) r = 0.122 P = 0.677 (14) r = 0.348 P = 0.186 (16) r = 0.209 P = 0.438 (16) r = -0.096 P = 0.723 (16) r = -0.538 P = 0.032 (16) r = 0.031 P = 0.908 (16) r = 0.467 P = 0.068 (16) r = 0.383 P = 0.892 (15)

r = 0.372 P = 0.234 (12) r = 0.258 P = 0.444 (11) r = -0.291 P = 0.359 (12) r = 0.669 P = 0.017 (12) r = -0.182 P = 0.571 (12) r = 0.146 P = 0.650 (12) r = -0.438 P = 0.154 (12) r = 0.495 P = 0.102 (12) r = -0.164 P = 0.629 (11)

r = 0.143 P = 0.713 (9) r = 0.061 P = 0.886 (8) r = -0.376 P = 0.318 (9) r = 0.659 P = 0.054 (9) r = -0.267 P = 0.487 (9) r = -0.219 P = 0.572 (9) r = -0.454 P = 0.220 (9) r = 0.619 P = 0.076 (9) r = -0.230 P = 0.584 (8)

¹ Beginning of month snow depth summed N + D + J + F + M + (A). April excluded for March fat measurement ² Snowfall for biological year, June to May

the prior growing season (Y₁) and fat reserves in April (Y₂), nor did snow depths in Y₂ enter into the equation. The best example of this lack of carryover was in 992 and 993. The animals in the spring and summer of 992 were in the poorest condition that we recorded: There were low female liver weights; minimal calf birth weights (only 4.7 kg); and 9.9% of the females were without antlers in the fall. And yet in April 993 of the next year the animals had the greatest fat reserves recorded in 4 seasons and produced the heaviest calves. All indices changed from fall to spring during a 6month period in which the animals had made no extensive migrations.

256 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Migration/Habitat Strategies and Fat Deposition Neither Dauphiné (976) nor Parker (98) explored the possibility that the adipose condition of animals within years might vary between collection locations. Thomas and Kiliaan (998) noted for the animals collected from the Beverly herd that fat deposition did seem to vary in 984 for animals harvested at Porter Lake compared to those taken at Sifton Lake. They speculated that they might have sampled two different herds. In 980 Parker (98) collected females from the George River herd at three locations. At the first two locations (2 animals) all the condition indexes were less than they were at the third (and major) collection site west of Nain. The first  animals collected 3 April were shot at latitude 57°50' N, near Hebron Fiord. The other 0 animals low in fat reserves were taken 4 April near the main collection site of 5–5 April. Our hypothesis is that the animals with lower fat reserves had remained above tree line on the eastern tundra during the winter. We have noted that in two years, 984 and 987, males had larger antlers in the Torngat Mountains north of Hebron Fiord than the animals in the main herd (table 9., footnote). Furthermore, the animals we collected in June 978 (males and females) at Hebron were unusually large (chapter 8). On 27 October and 3 October 983 Luttich autopsied two non-lactating females in the Torngat Mountains (approximately 59° N, 64°5' W) that had 29.5 mm ± 2.50 mm of back fat and 6.0 g ± 9.00 g of kidney fat. In the same season, Huot measured four non-lactating females near Kuujjuaq (8–24 October 983) and they had 4.2 mm ± 6.5 mm of back fat and 20.3 g ± 3.80 g of kidney fat (Couturier et al. 989). We also know that some animals have consistently wintered and calved above tree line in the Torngat Mountains and this has led some biologists to consider the animals as a separate herd from the George River herd (Belanger and Le Henaff 985; Couturier 996). We speculate that the females and males collected by Parker in April 980 at the first two collection sites had a different winter/ migration history from the animals with more fat that had been secured from the herd farther south. Parker (unpubl.) documented, based on backtracking, that the latter animals from the main collection site had travelled from the northeast along the traditional migration route (see Vandal et al. 989) and hence had wintered below tree line. Consider that there are two migration/habitat strategies with different fitness options: One option is to remain above tree line at low densities throughout the year with superior food in the growing season. Shrubs are more abundant in the Torngat Mountains than elsewhere (chapter 7) and spring phenology is advanced along the coast; additionally, the high peaks of the Torngat Mountains retain snow throughout the summer, which provides relief from insects. But the tradeoff for the animals remaining north of tree line is less forage in winter. Such a sequence could lead to large antlers in the fall, greater fall fat deposits, but

Physical Condition | 257

reduced fat reserves by the spring. These are precisely the observations we have recorded in the animals in the Torngat Mountains. The other option – to summer above the tree line but winter below it – could reverse the condition indices. That is because the winter range below tree line retained abundant lichens, but the summer range above tree line was degraded. The pattern could result in smaller antlers in the fall but better maintenance of condition over winter, as documented by Huot (989). These two strategies appear to be features of the annual distributions of animals in the Northwest Territories (review Bergerud 996). Fat Deposition Strategies One view is that fat reserves are an important hedge against winter starvation (Thomas and Broughton 979). This likely applies to insular herds and high Arctic populations, but mainland caribou populations seldom starve and extensive fat reserves such as those of caribou in Svalbard have not prevented extensive dieoffs. It seems a poor strategy for winter survival for males to utilize nearly all their stored fat during the fall rutting season. An additional view is that fat reserves are a necessary component of successful ovulation (Thomas 982). However, this view is still contentious. Crête et al. (993) argued that George River females needed 7 kg of fat for successful reproduction. But Huot (989) showed that supplies were below this level in October 983 and April 984. The mean calculated total body fat for lactating females 983–89 was 7.6 kg ± 0.7 kg (table 9.5). In 986 and 987 Couturier et al. (989) reported that 76% of the females > 3.5 years of age were pregnant (n = 83). This is a reasonable pregnancy rate (Bergerud 980) and the survival of these cohorts until autumn was satisfactory. These may have been the years of poorest fall condition: Many of the animals would not have had 7 kg of fat. Russell et al. (993) indicated that in bad years females in the Porcupine caribou herd might have less than 6 kg of total fat but the parous percentages for that herd over  seasons that included bad years averaged 80.9% ± .56% (extremes, 74–89; C.V., 6%) (Fancy et al. 994). Pregnancy rates, when graphed against increments in body weight and kidney fat in April, have sigmoid growth curves (fig. 9.7, also Thomas 982; Thomas and Kiliaan 998). These curves suggest threshold mass and fat levels to achieve conception, provided April values are an index to fall values. However, a plot of individual body mass (75–85 kg) and not kidney fat provided the best threshold index for conceiving (fig. 9.8). Apparently older animals were able to conceive with less fat than younger ones. The George River females came into estrus perhaps eight days later in the latter years of this study; these eight additional days provided them only .5 additional mm of back fat and 3. g of kidney fat. Would such small additions be critical for ovulation? The major decline in pregnancy rates was in the 2- and 3-year-old

PERCENTAGE OF FEMALES PREGNANT

100 90

n = 14

n = 10

80 70 60

n=2

50 40

n=2

1980, n = 134 1982, n = 46 1986, n = 48 1993, n = 32

30 20 10

n=3

0 5.5

25.5

45.5

65.5

85.5

105.5 125.5 145.5 165.5

MASS OF KIDNEY FAT (g) 10g CLASSES

33

100

PERCENTAGE OF FEMALES PREGNANT

49 90 80

26

3

4

28

7

70

41

1

12

3 13

60 50 40 30

ALL YEARS n = 244

9 20 10 0

8 6

≤ 50

1 58

68

78

88

98

108

118

BODY MASS (kg) 5g CLASSES

128

MASS OF KIDNEY FAT (g)

180 160 140 120 100 80 60 40

n = 201

20 0 130 120

LIVE MASS (kg)

110 100 90 80

THRESHOLD

70 60

NOT PREGNANT PREGNANT n = 206

50 40 30 10

22

34

46

58

70

82

94

106

118

130

142

154+

AGE IN MONTHS

Fig. 9.17 (facing page) (above) Females with > 75.5 g of kidney fat were normally pregnant in April, although there were a number of exceptions; (below) Generally females > 88 kg in mass in April were carrying fetuses. Fig. 9.18 Body and live mass indices of pregnancy. A threshold for pregnancy based on April indices was more clearly defined from body weights than the weights of kidney fat.

260 | TH E R E T U R N O F C A R I BO U TO U N G AVA

females (Messier et al. 988; Couturier et al. 990; Crête et al. 996). Females 22 months old that were pregnant in 980 weighed 78.7 kg ± 0.52 kg (n = 8), and non-pregnant females weighed 66.9 kg ± 0.42 (n = 3). Back fat and kidney fat deposits were not significantly different in pregnant and non-pregnant females, but femoral marrow fat was different (Parker 98). One can argue that their failure to reach puberty was not a matter of reaching a fat threshold but of reaching a body-size threshold (Reimers 983b). Calves of the George River herd had high survival in the first summer of life, 984–9, in the years of reduced fat reserves of their dams (chapter ). The year of poorest survival was 992, following a late spring when calves weighed 2 kg less than in other years. Again, the dam’s body mass and protein reserves seem to be more involved in calves’ birth weights than are their fat reserves. Our interpretation of these findings is that animals must achieve a given body weight to produce a viable calf (a calf weight greater than 4.5 kg). The priority is the acceleration of growth – both for survival against predation and for reaching puberty; weight has priority over fat in growing animals (Dauphiné 976). Fat reserves are a physiological adaptation: For males it provides energy for breeding (at the expense of later survival); for females, it is the mainstay for coping with winter predation and for sustaining a return migration to a relatively safe birth site. Additional fat buffers weight losses so fetus growth can accelerate in the last days of gestation to achieve a viable weight. Cows in the Porcupine herd have their maximum reserves just before spring migration (Russell et al. 993). Ringberg (979) speaks of the Svalbard caribou hibernating in the winter with their large fat stores. Tyler and Blix (990) argue that these caribou are saving their fat for lactation. They can save their fat because they don’t migrate. Fat, we believe, is the key to reproductive fitness. It is not a hedge against winter starvation; it is the fuel that enables cows to travel the “miles without measure” to reduce predation risk and enhance their progeny’s survival. The concept that adipose deposits’ primariy function is to fuel energy expenditures – rather than drive conception or buffer winter starvation – may also apply to the Beverly and Kaminuriak herds based on condition studies by Thomas and Kiliaan (998) and Dauphiné (976). The fat reserves of the Beverly herd generally increased from December to March 98–87 (table 9.7, data from Thomas and Kiliaan 998). Fat deposits in the adjacent Kaminuriak herd declined from November/December to April when Dauphiné measured fat stores two decades earlier, 967–68 (table 9.7, data from Dauphiné 976). The differences in body condition between these two herds could not be explained on the basis of winter lichen supplies since the Beverly herd’s range had been extensively burned but the Kaminuriak herd’s had not (Miller 976a, b; Thomas 994). Nor could population densities explain the discrepancy as the Beverly herd numbered > 250,000 animals (Thomas 99) and the Kaminuriak only 63,000 (Parker 972a). At the time of the two collections, the Beverly migrated an average of 42 km ± 23 km (n

Physical Condition | 26

Table 9.7 A comparison of the ratio of change in fat and weight parameters between the Beverly and Kaminuriak herds between November–December and March–April (data from Dauphiné 1976 and Thomas and Kiliaan 1998) Parameter and Season

Back Fat (mm) November–December March–April Ratio of Change

Beverly³

Females¹ Kaminuriak³

Beverly

Males² Kaminuriak

13.1 ± 0.8 (194) 14.3 ± 0.4 (507) 1.09

12.4 ± 1.14 (87) 5.4 ± 0.71 (97) 0.44

2.5 ± 1.4 (6) 4.8 ± 1.4 (28) 1.92

Kidney Fat (g) November–December 80.0 ± 2.3 (166) March–April 104.4 ± 1.9 (413) Ratio of Change 1.31

72.6 ± 3.10 (81) 54.2 ± 2.61 (82) 0.75

68.2 ± 12.0 (6) 50.9 ± 3.81 (19) 79.2 ± 4.9 (28) 65.3 ± 4.59 (41) 1.16 1.28

Femoral Fat (%) November–December March–April Ratio of Change

85.4 ± 0.5 (163) 87.4 ± 0.3 (455) 1.02

73.1 ± 1.15 (82) 66.4 ± 1.43 (93) 0.91

66.3 ± 7.4 (6) 67.4 ± 1.92 (20) 86.1 ± 2.0 (25) 73.3 ± 1.42 (54) 1.30 1.09

Body Weight (kg) November–December March–April Ratio of Change

83.4 ± 0.6 (166) 84.2 ± 0.4 (415) 1.01

88⁴ (46) 74⁴ (70) 0.84

111.2 ± 2.5 (6) 108.6 ± 1.7 (34) 0.98

0.1 ± 00 (21) 8.1 ± 1.11 (53) 81.0

112⁴ (23) 100⁴ (57) 0.89

¹ Age of females for Beverly > 2 years (except weight > 3 years); for Kaminuriak female ≥ 29 months of age ² Age of males for Beverly > 5 years; for Kaminuriak 53 months (November–December) and 58 months (March–April). ³ Collection dates for the Beverly in eight years 980 to 987: spring, 3–25 March, fall, 25 November to 5 December. For the Kaminuriak in three years 966 to 968: spring, 7 April to 2 May: fall 2 November to  December. Collection dates not conservative for test. ⁴ Values read from graph hence no se.

= 7) from the winter range to the calving ground; the Kaminuriak animals, however, averaged 608 km ± 44 km (n = 3) (calculated from maps in Dauphiné 976; Thomas 99; Thomas and Kiliaan 998). The Beverly herd wintered consistently 982–87 relatively near the tree line (Thomas 99). Thomas (99, 994) felt that the animals had been displaced farther north because of extensive forest fires. Had this displacement benefited the condition of the herd? We propose that the differences in the rate of winter fat mobilization between the two herds was due to the greater energy the Kaminuriak herd expended in travelling farther from the calving ground. Also, the Kaminuriak herd was probably cratering in deeper snows (Miller 976a; Thomas 99) and interacting with a higher wolf population (Parker 973). The herds had similar fat deposits in early winter (table 9.7), but the Kaminuriak herd would have expended more

262 | TH E R E T U R N O F C A R I BO U TO U N G AVA

in movement activities, a sequence we have also documented for the George River herd. Trends in Condition Indices The first comprehensive surveys of condition in March 976 and April 980 showed that females in the George River herd had more kidney fat, back fat, and femoral leg fat than the Kaminuriak herd in 966–68 (Dauphiné 976; Drolet and Dauphiné 976; Parker 98). At that time, the Kaminuriak herd was low in numbers and considered in good physical condition. The difference could have pertained to energy expenditures since the Kaminuriak herd was travelling > 600 km from the calving ground and the George River herd in 976 was near the summer range when sampled, migrating only 300 km in 980. The amount of kidney fat in the George River females remained higher in 982, 983, and 993 than that reported for the Kaminuriak for the years 966–68 (fig. 9.3). However, there was a decline in kidney fat in the interval 983 to 984 (Couturier et al. 989, table 39). The regression of kidney fat on year for pregnant females was significant, r = -0.837, n = 7. If the kidney fat in 992 is also included, the correlation was still significant (r = -0769, n = 8), but recall that 992 was both an extremely hard winter and a late spring, and the animals were autopsied later than in other years, 5–3 May (table 9.4). Our measurements of back fat are of reduced value in detecting a trend over time since this index reflects migration distances, which in turn are likely related to grazing pressure. Migration distances increased during the 980s; hence females returned to the eastern range west of Nain with progressively less back fat (fig. 9.9; table 9.4). After long migrations (> 300 km) the animals had essentially no back fat by  June; after short migrations (< 300 km), they had approximately 2 mm remaining (fig. 9.5). Since migration distances generally increased 980–92 (fig. 9.9), there was a significant decline in April back fat against year, r = -0.703, n = 5, (fig. 9.9). Metatarsal fat of females showed no significant depletion as herd numbers increased (table 9.4; Bergerud 996). Monthly fat levels were generally less than for the Kaminuriak herd, but this was due to the more rapid mobilization of reserves in femurs measured in the Kaminuriak than in metatarsal bones assessed for the George. Nor was there a yearly trend in dentary fat for adult females in three Aprils: 983, 70.% ± 0.73%, n = 36; 984, 72.8% ± 4.38%, n = 5; and 988, 73.6% ± 4.82%, n = 78. Our data were inadequate to evaluate whether the reserves of males had declined as herd numbers grew in either the fall or the spring. In contrast to females was the rapid weight gains of males from March to October if March weights were low (chapter 9), and the rapid fat deposition in September after

APRIL KIDNEY FAT (g) APRIL BACK FAT (mm) BODY MASS (kg) MIGRATION DISTANCE (km)

120

1993 EXCLUDED

100 80 60 40 20

Y = 514.454  5.396X r = 0.769 n=8

0 6

12.1

5

1993 EXCLUDED

4 3 2 1

Y = 26.841  0.286X r = 0.703 n = 15

0 110

MASSES REDUCED

2 SE

100

MARCH APRIL

90 80 70 800 700 600 500

APRIL

Y = 1557.081 + 24.073X r = 0.673 n = 13

400 300

MARCH APRIL

200

1993 EXCLUDED

100 0 76

77

78

79

80

81

82

83

84

85

SEASONS

86

87

88

89

90

91

92

93

Fig. 9.19 A summary of fat reserves, mass, and migration distances. There were significant declines in April of kidney fat and back fat of pregnant females (> 34 months of age) as the study progressed if 1993 is excluded. These declines were correlated with an increase in migration distances. The mass of females in March/April showed no trend with time and were lowest in the interval 1983–87. This is projected as the low in condition of the George River herd in this population cycle and coincides with the greatest scarring impact of the herd on conifer roots (Morneau and Payette 2000).

264 | TH E R E T U R N O F C A R I BO U TO U N G AVA

falling behind the Kaminuriak herd in July and August. Males clearly march to a different metabolic drummer than females. This presumably relates to their fitness schedule, which demands peak physical condition at fall breeding regardless of other life history consequences. The March/April weights of pregnant females showed no trend over the course of the study (fig. 9.9), nor were they correlated with migration distances (fig. 9.9). But the combined weight data 983–87 was significantly lower than the 976–82 and 988 and 993 weights. We argued in chapter 7 that summer forage did not decline after 988 and that dry matter intake increased, but still the animals migrated long distances 988–92. These continued long movements and energy expenditures may explain the lack of synchrony between fat and protein trends. The accumulation and utilization of fat and protein tissue need not be synchronous (Allaye Chan-McLeod et al. 995). Animals in the Beverly herd in several winters maintained their body weights at the same time that kidney and back fat tissues were increasing (Thomas and Kiliaan 998). Males seemed to have attained their necessary rutting fat reserves despite the reduced summer range, but like females, males were smaller in body size in the 980s than in earlier decades. Reduced growth in their first and second summers, when the calves and yearling males were still associated with the females on the overgrazed summer range, probably explains their reduced size as adults. It was difficult to decide when physical condition first started to decline, especially since the extremes in phenology (for example 992 vs 993) added variability to the condition indices independent of population pressure. The downturn in the condition indexes after 982 showed some synchrony (fig. 9.20): The first cohort with reduced mandible size were the calves in 982 (chapter 8). Later estrus and calving occurred between 982–84. A major increase in antlerless females was apparent by 984; a decline in April kidney fat occurred by 984; liver weights were reduced by 984; a decline in April back fat was evident by 983; and body mass in April was less 983–87 (fig. 9.9). The growth of birch showed a major drop in 983 and 984 (chapter 7, figs. 7.3, 9.20). Overall there was a rapid decline in the physical condition of the herd in a 3-year span, 982–84 (fig. 9.20). There were major increases in the size of the herd with the additions of the 98 and 982 cohorts. Before this, there was no clear downward trend in physical condition (fig. 9.20). Before these additions the herd was possibly at an upper carrying capacity and had a self-sustaining carrying capacity in condition but the high numbers that started with the summer of 982 over-utilized the summer range. Luckily the herd was counted 982 and 984, so we can calculate rather closely the animal numbers that sufficiently reduced forage to trigger changes in condition that resulted in negative demography. It is still possible that early in the 970s, prior to the major downturn 98–84, a reduction in high-quality summer herbs had commenced a gradual decline in condition indexes.

MANDIBLE (mm) CALVING DATE

% REGAL

% BALD

BIRCH RINGS (mm)

Physical Condition | 265

0.25

−19%

0.20

BIRCH

1983

0.15

MEAN ANNULATIONS / YEAR 56.5 ± 0.39 0.10 10 8 6 4 2 0 70 60 50 40 30 20 10 0

% BALD n = 54,772

+57% 1984

% REGAL n = 10,344

−97%

15

MEAN CALVING DATE JUNE 13.3 ± 0.43

1983

20 MEAN CALVING DATE JUNE 6.1 ± 0.95

10

1984

+45%

5 230

n = 112

220

10 MONTH-OLD (n = 112)

210 1982

74

75

76

77

78

79

80

81

82

−6% 83

84

85

86

87

88

89

90

91

92

SPREAD 3 YEARS

Fig. 9.20 Several condition indices declined in the interval 1982 to 1984. This decline occurred after the large additions of calves from the 1981 and 1982 cohorts joined the herd.

The April weights increased in 988 and 993 (fig. 9.9), suggesting that the condition of the herd improved. But complicating this analysis was a very late spring in 992 that resulted in low fat readings, reducing June cow weights and calf birth weights and cancelling any density-dependent improvement. We believe that the low in condition for the herd occurred in 986 and 987, a result of the high spring and summer densities above tree line. In 989–9 there was an increase in dry matter intake in the summer that is consistent with a reduction in herd numbers based on the scarring of the roots of black spruce after 986–87 (Morneau

93

266 | TH E R E T U R N O F C A R I BO U TO U N G AVA

and Payette 2000). However, the dates of calving were still late after 987 and bald females remained common. In chapter 7 we concluded that the decline in birch and herbs may have ceased by 988 although an improvement was still not obvious. Unfortunately our last year of study was 993, an early phenology year that may not reflect long-term density-dependent trends. The most encouraging sign was that a majority of the herd remained in the east closer to the centre of habitation for the winter (994–96); this entailed shorter migrations and reduced energy expenditure April to June. To summarize: The restricted summer range of the George River herd, in combination with high numbers after 98, led to a density-dependent overgrazing of the summer vascular plants. Reduced intake resulted in inadequate lactation, which in turn led to reduced growth rates of calves. Furthermore, many lactating females were unable to make target weights by autumn, leading to late and reduced conceptions. Animals also made long fall movements to compensate for reduced phytomass. Adequate fall and winter forage – mostly lichens – allowed females to maintain their weight from October to March. But because of spring fidelity to the calving and insect relief range in the centre of habitation, the animals made extensive spring movements which reduced fat reserves and weights by the end of April. Superimposed upon this basically densitydependent movement response were variations in the food intake in the last six weeks of gestation due to weather. This added a density-independent spin to condition. Minimal condition occurred in 992 when the animals not only made a long return migration but faced a late spring phenology prior to parturition as well. The crucial point we make here is that major changes in condition can result from extensive movement. The literature – with the notable exceptions of Boertje (985) and Russell et al. (993) – has emphasized energy intake rather than expenditure (studies of captive animals or insular island populations are not comparable to the energy dynamics of a wide-ranging herd such as the George River herd). Crête and Huot (993) stressed the summer forage problems for the George River herd and Messier et al. (988) argued that the range expansion after 984 was a favourable adaptation for dealing with that. But these extensive movements are not without serious consequences.

CHAPTER TEN

Recruitment, Mortality, and Population Growth

Each mammal species has a characteristic, maximum rate of increase (rm) which is a product of litter size, age of puberty, the adult sex ratio, and longevity (Cole 954). The rm for caribou has been estimated to be r = 0.32 (λ = .37) and has been empirically documented where animals have been introduced to new habitats (especially islands) where there were no predators and summer forage had not been utilized previously (Bergerud 980; Heard 990). However, rm rates do not occur for caribou on established ranges coexisting with their natural predators. The common rates of increase recorded for herds lightly hunted (< 5%) range from r = 0.03 to 0.3 or a finite rate of increase λ = .03 to .4. Nor do natural populations continue to increase indefinitely; rates of natural decline may be as high as r = -0.5 (λ = 0.86) (Bergerud 992). The George River herd showed an unbroken rate of increase 955–84 of λ = .4 (Messier et al. 988). This sequence of increase is unique in both its duration and its magnitude of expansion for a non-insular situation. Yet the observed increase was but half its potential, largely because of native harvests, at least in the early years. At the beginning of this expansion, there were possibly only 5,000 ungulates present in an area of some 700,000 km² of productive phytomass – a density of 0.007/km². That the hunters found these few animals in such a vastness of space using only dog teams speaks of a tenacity in the hunt – and a dependence upon the caribou – that is no longer part of their lives. In this chapter we will examine the pregnancy rates and calf and adult survival rates that we gathered 973–93 in order to evaluate their relative contributions to this high and prolonged rate of increase. After 983 energy expenditures increased from longer migrations and reduced food intake in the growing sea-

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son; after 988 the condition of the herd improved. We will examine the population parameters 984–93 to evaluate if the changes in physical status were translated into altered population parameters and herd growth. Couturier et al. (996) have argued that the George River herd remained relatively constant in numbers or increased 988–93 despite the decline in the animals’ physical condition in the mid-980s. Our data contradicts this; we believe a decline in numbers occurred between 988–93. Basic Indices Pregnancy Rate

The first parameter that can alter population growth is the reproductive rate. For caribou the litter size is one; we found only one set of twins in over 2,000 autopsies 976–93. Pregnancy rates were ascertained both on the basis of autopsies in April and udder counts in June (Bergerud 964a). The udder counts in June involved close inspection of cows through 20X spotting scopes for the presence or absence of a distended udder. We recognized cows that were still pregnant by their low-in-the-belly profile (Bergerud 964b). We did not attempt to classify animals for the presence of udders from helicopter or fixed-wing aircraft: In our experience small, regressing udders cannot be recognized from aircraft. During spring migration and on the calving grounds there is a tendency for expectant females to be at the forefront. Thus autopsies and classifications of these leading animals could be biased to productive females. For example, from 985–9 (990 missing) ,224 females were collected in April by commercial hunters based in Nain; the percentage of pregnant females showed no trend with year (r = 0.088) and was consistently high, 90.7% ± .58% pregnant (CV = 4.3%). Yet autopsies of animals on winter ranges 985–9 showed a major decline in pregnancy from those we measured earlier 976–82. Udder counts are also biased by the segregation of pregnant and non-pregnant females. In 988 we classified females at the southern edge of the calving ground moving north simultaneously with those at the northern edge of the calving distribution. At Indian House Lake on the southern edge, the parous percentage was 46.8% (n = ,785), and at the head of the distribution on the northern edge the percentage was 90.6% (n = 3,37). In 7 years 974–93 (3 years missing), the animals we aged from hunter collections collected at the head of the migration west of Nain in April included 489 34-month-old females but only 248 22-monthold females. There should have been over 500 younger animals, but these nonpregnant young animals lagged behind in the migration. To reduce this segregation bias we have excluded in pregnancy tallies most of the animals collected west of Nain after 984. Prior to 984 the animals made shorter migrations and the segregation bias from autopsies on eastern ranges would not have been as skewed.

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To minimize the bias in udder counts, we secured large samples from several ground stations located above tree line and selected without regard to the boundaries of the calving distributions. These classification sites were commonly field camps, not helicopter landing sites; hence the animals moved though our sites on several days and represented animals coming from a wide distribution. One of our sites used 988–92 was at the running-out of Indian House Lake; animals migrated north though this camp annually for several days each June. Another bias with the udder counts became apparent in June 988 when we observed a number of cows with small udders that were still nursing their yearlings and were not parous that year. Udder counts were readjusted, based on a detailed classification of such small groups in 99 that showed 78 females with udders, 25 females with no visible udders, and 38 yearlings nursing (out of a total of 08 yearlings). Approximately 5% of the uddered females had retained udders from the previous year (38/78), and 35% of the yearlings were still nursing (38/08). This correction factor was applied to udder counts secured 988–92. The only other udder counts in our classifications were in 978, 979, and 980 (table 0.). In those days the herd was in better condition and we did not observe yearlings still nursing at 2 months of age. Calf Mortality Rates

The finite rate of increase of the George River herd can be determined by the equation λ = ( - M)/( - R) where M equals the annual mortality rate of adults and R equals the final recruitment percentage of the new generation. The mortality of adults was based on the death of radio-collared females and tabulated annually from  June to 3 May (984–93). Mortality rates of females (≥34 months of age) were also calculated from the age arrays of females collected west of Nain in April 975–93 (missing years 978, 98, 990, n = 2,086). These arrays were adjusted on the basis of the growth rate of the herd (r) (Taylor 99 and personal communication) and smoothed using natural logs and a least-squares curve fit program (Spain 98). The final recruitment measured was the calves that survived until 0–2 months of age (April–June). One cannot consider the new generation a valid addition until their mortality rates approximates those of adults (Hickey 955). Our studies indicated that calves in their first winter died at rates greater than adults. However, a life table analysis of the George River herd shows that the mortality rates of long-yearling females (> 6 months of age) were similar or even lower than adults. Crête et al. in 996 gave the annual survival rates of yearling females ( to 2 years of age) in the George River herd as 85.0% ± 4.53% (6 years of data) and for adult females as an annual mean of 87.5% ± .67% (0 years). In addition, Fancy et al.(994) reported that the mortality rates of young animals 0 and 22 months of age and adults were similar for both females and males in the Porcupine herd in Alaska.

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Table 10.1 Parturition or pregnancy rates, early calf mortality, and recruitment for 1973 to 1993 cohorts Cohort

Parturition or Pregnancy Rate

Mortality of Calves 10–21 Days Old

1973 1974 1975 1976 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988⁶ 1989 1990 1991 1992 1992 1993 1993 1993

– – – 93.5 (4,121)⁴ 100.0 [21]⁵ 94.3 (6,349) 88.9 (1,279) – 86.3 [124] – 93.5 (4,894) – 68.4 [19] 85.6 [160] 60.0 [20] 75.5 [98] 62.5 (5,156) 61.2 (5,725) 59.1 (4,435) 78.3 (4,464) 75.5 (388) 71.0 [70]⁸ 75.0 [36] 64.4 (4,831) 65.0 [19]

– – – – – – 7.2 (1,479) 7.6 (2,511) 12.8 (5,478) – – – – – – – 8.3 (4,014)⁷ 1.8 (1,304) 4.1 (1,076) 7.9 (743) 20.0 (308) – 3.0 (2,648) – –

Calves per 100 Females 5–6 Months 10–12 Months of Age [ CV ]¹ of Age [ CV ]

56.4 (2,068)² 52.4 (4,331) [23] 51.8 (24,060) [27] 49.3 (7,619) – 56.0 (2,900) 48.3 (27,769) 47.5 (13,938) [14] 54.8 (9,079) [7] 50.8 (14,454) [11] 55.1 (7,258) [6] 50.1 (12,471) [9] 38.8 (12,839) [24] 38.8 (8,388) [27] 40.5 (6,049) [14] 39.7 (2,904) 34.5 (3,714) 35.1 (2,781) [25] 26.3 (4,699) [41] 31.2 (9,369) [42] 24.5 (5,959) [39] – – – –

60.0 (205)³ [37] 33.8 (2,311) 28.0 (4,131) 41.4 (10,565) [34] – 36.0 (3,664) [8] 30.8 (789) [58] 29.3 (14,696) [35] 17.2 (4,355) [26] 33.9 (5,620) [56] 44.2 (7,216) [80] 32.1 (8,676) [56] – 21.1 (454) [51] 18.2 (7,400) [20] 15.7 (11,330) [46] 16.9 (5,835) [57] 11.4 (7,425) [83] 9.5 (8,952) [41] 12.4 (2,886) [38] 19.4 (7,646) [81] – – – –

¹ Coefficient of variation based on different days and/or locations. ² Based on a sample of 2,068 adults and calves. ³ Based on a sample of 205 females. These 0- to 2-month-old ratios are the observed values not adjusted for fewer males or underrepresentation at the front of the migration. ⁴ Based on (4,2) females classified as to parous / non-parous. ⁵ Based on [2] autopsies in March/April. ⁶ Couturier et al. 2004 showed fall ≈calves/00 females, their graph fig. 7, page 30, for the cohorts 988 to 2003 as 32, 36, 25, 32, 25, 44, 36, 26, 36, 32, 44, (999 missing), 7, 46, 9, and 32 calves/00 females. They indicated that 39 calves/00 females in the fall provided stability, hence a major decline since 988. ⁷ Corrected for yearlings still nursing, 988 to 993. ⁸ This pregnancy rate is based on animals that wintered east in the Red Wine Mountains. Note: The correlation between the snow index used by (Adams and Dale 998a) the Late Winter Snowfall ( February to 3 May the prior year) and natality this table was r = 0.683, n = 5 (natality increased with snow). The correlation of natality with year was r = -0.580, n = 2 decreasing with time and increase densities. Some pregnancy/parous ratios are from the literature: Drolet and Dauphiné 976; 980, Parker 98; 984, Huot 989; 986 and 987, Couturier et al. 990; 992, Crête et al. 996.

Recruitment, Mortality, and Population Growth | 27

To try and understand the mortality factors limiting the herd, we divided the mortality rates of calves into three periods: early mortality, summer mortality, and winter mortality. Early mortality was that which occurred between birth and –3 weeks of age. Summer mortality comprised the deaths between birth and the fall (calves approximately 5 months old) and thus included early mortality. Winter mortality was that which occurred between the ages of 5 months (October) and 0–2 months of age (April–June). It was apparent that the survival rates of yearlings approximated adults once the 0- to 2-month-old cohort crossed the tree line in the spring returning to the tundra east of the George River. Our measure of the early mortality rate (birth to 2–3 weeks of age) was the proportion of uddered females no longer pregnant and not accompanied with calves after calving had ceased. This index required that the counts be done while the regressing udders were still recognizable (Bergerud 964a). These counts were made in June 978, 979, 980, and 988–92 (table 0.), and were adjusted for cows whose udders remained visible because they were still nursing yearlings. We had no evidence that females that were nursing yearlings were also currently parous. Summer mortality rates were based on estimating the calves born per 00 females in the spring (percent pregnant or parous) vs the calves still alive per 00 females at 5 months of age. These counts were segregated into three population periods: rapid increase 973–83; high population phase 984–88; and decline period 989–93. The equation was [00 - (calves/00 females in the fall divided by the calves/00 females at birth) multiplied by the summer survival rates of females: [00 - (R f /Rb)Sx]. The summer mortality was based on 9 calves/00 females (973–83) at birth and 69 calves/00 females after 984. The annual summer survival of females (Sx) was estimated at 97% 973–83 and 94% after 983, and was based on the summer survival rate of collared females. Although Hearn et al. (990) and Crête et al. (996) have stressed survival rates, we have concentrated on the converse – mortality rates – in an attempt to understand deciminating factors that limit herd growth. Winter mortality rates were based on the loss of the new cohort of calves between fall and spring (between 5 to 0–2 months of age) corrected for the over-winter survival of adult females: [00 - (short yearlings/00 females in the spring, usually in April, divided by the calves/00 females in the previous fall) x percentage of winter survival of cows]. Adult Mortality Rates

The mortality rate of females was based on three procedures. The first method involved constructing survivorship curves (l x) from the females harvested in April 975–93. Separate curves were established for the phases of () rapid increase 975–84; (2) peak population 985–88; and (3) decline 989–93. The second method was to use the finite-rate-of-increase equation λ = ( - M)/( - R) for the period 974–84 to calculate mortality. Census data was available and there was

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general agreement on the rate of increase (λ) for this period (Mercer et al. 985; Messier et al. 988). Spring recruitment (R) was available for all but one cohort. The third method involved radio tracking females to determine their lifespan (984–93). Both Hearn et al. (990) and Crête et al. (996) have published some results from this latter technique, but our analysis of this data is independent of theirs (Bergerud 988a). Male mortally rates were more difficult to determine: Few males were radiotagged and there were insufficient numbers of males harvested in April to construct survivership curves, although one age array that was available for the latter was a group of males that died at Limestone Falls in September 984. A second method for calculating male mortality rates uses the formula discussed in chapter 4 and published in Bergerud (996). The numerical equivalent of the shortened formula based on data from the George River herd is Mm = Fm(0.2627)R. To use the finite-rate-of-increase equation, R is expressed as a percentage of the herd (calves/total animals) to correspond with adult mortality (M), which is also expressed as a percentage. To secure a calf percentage, we divided the calves/00 females statistics by combining the totals () calves/00 females + (2) 00 females + (3) 57.5 males. The latter figure – 57.5 – is our estimate of the constant percentage of males (long yearlings and adults) to 00 females. The next difficulty in composition classifications is to secure representative composition counts of the herd in the fall breeding season (recruitment at 5 months of age); and in April–June (recruitment at 0–2 months of age). In the fall the sex and age distinctions were: adult males (> 2 years); adult females (> 2 years); long-yearling males and females; and short-yearling males and females. In some years long yearlings were not segregated and in all years some long yearlings and short yearlings (calves) were not sexed. The distinctions in the spring were males (>  year); females (>  year); short yearlings (0–2 months of age), males, females, and sex unknown. We calculated the coefficient of variation (CV) of recruitment (calves/00 females) as a measure of variability of counts between stations and/or counts between days. This statistic confirmed what most caribou biologists assume: Counts in the breeding season correspond to a random and representative sample of the sex and age classes in the population, even when samples are small. The mean CV was 22.5% ± 4.30% (5 years, 2.9 ± 2.24 stations per year). This CV analysis also confirmed an accepted belief that counts made during spring migration when males and females are segregated are much more variable than those made in breeding season segregations; the mean CV in April was 4.6% ± 0.30% ( years, 9. ± .70 stations per year); the variation was 2 times greater than in the fall. The coefficient of variation for the June classifications was even larger, 59.9% ± 9.6%, 8 years, and a mean of 5.4 ± 4.28 stations per year. The mean percentage of male yearlings in April was 48.4% (n = 0,42) and June 40.6% (n = ,98) a t-test of difference between means (t = .06, P < 0.00). June

Recruitment, Mortality, and Population Growth | 273

counts were the most variable and some male yearlings – as opposed to females – were missing). We assumed that we could correct the April–June counts by using the fall counts of both sexes. The rationale was that the missing males in the spring were still alive but had lagged behind in the spring migration, based on the fact that the sex ratio of yearlings in the spring indicated fewer males than in the previous fall. Additionally, Skogland (989b) discussed the idea that males separate earlier from their dams than do females, and we (Bergerud 97b) noted that even as very young calves, males wandered farther from their dams than females. Butler (983) also showed that the maternal investment was less for males than female calves. During our final analysis, we decided that males had been represented in the April counts and that the decline in the percentage of males observed over winter was because males had a higher mortality rate than females. It was, therefore, not a segregation bias relative to the April counts but the result of differential male mortality – a change in the ratio from 53.2 males:46.8 females at 5–6 months to 46. males:53.9 females at 6–8 months (table 0.4). There has been some debate whether fall recruitment is sufficient to explain caribou dynamics (Davis et al. 988). Both Messier et al. (988), Crête et al. (996) and Couturier et al. (990, 2004) built their population models for the George River on the percentage of calves in the autumn. For the sedentary ecotype, fall recruitment may suffice (Bergerud 992; Adams et al. 995b). Commonly these herds lose so many calves in the summer (due to the lack of space for moving away from predators) that the remaining calves are sufficiently rare and probably of sufficient quality for their over-winter mortality rates to be similar to those of adult females (Bergerud et al. 984; Bergerud and Page 987). However, this does not apply to the large migratory herds that migrate hundreds of kilometres to calve on the tundra north of denning wolves: These herds commonly have a high proportion of calves alive by fall. When these herds move south of tree line in the fall, they encounter more wolves than in the summer (Heard and Calef 986; Heard and Williams 992) and calves can die at higher rates than adults (Kelsall 968; Miller 975; Clarke 970). The measurement of recruitment in the spring at 0–2 months of age is a difficult statistic to secure. Without it, however, we have only an incomplete explanation of the dynamics of migratory herds over winter. Pregnancy/Parous Rates Pregnancy or parous percentages were extremely high 976–82, averaging 94% ± 2.74% (n = 6) (table 0.; fig. 0.). Some of these samples were biased to fertile females, since they were secured from eastern ranges mostly at the time of spring migration. A more conservative percentage would be 9% (table 0.). This rate still exceeds that of other herds in North America by ≥5% (Bergerud 980; Davis et al. 99; Cameron et al. 993; Fancy et al. 994; Adams and Dale 998a).

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561 AUTOPSIES 41,642 UDDERS COUNTED

EXCLUDED

90

Y = 989.667  19.767X + 0.106X2 80

5–6 MONTHS OF AGE

CALVES PER 100 FEMALES

70

Y = 67.078  0.193X r = 0.203 n = 11

60

Y = 200.111  1.883X r = 0.874 n=9

50

EXCLUDED

40

30

10–12 MONTHS OF AGE 20

Y = 31.060 + 0.020X r = 0.008 n = 10

10

Y = 84.057  0.774X r = 0.461 n=8

0 73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

YEARS Fig. 10.1 The recruitment to the herd 1973 to 1993 as depicted based on calves per 100 females at birth, at 5–6 months of age, and at 10–12 months of age. The most abrupt change was the major decline between the 1983 cohort and the 1984 cohort. The sample sizes of females counted are given in table 10.1.

A factor in the high rates in early years of population increase was that many long yearlings were pregnant – 48% in sample of 23 (table 0.2). This, too, is higher than it is in most herds, as some other examples from the literature show: 27% of the yearlings in the Denali herd (n = 89) were pregnant (Adams and Dale 998a); only 2% of the yearlings in the Kaminuriak herd (n = 57) were pregnant in 966 (Dauphiné 976); 3% in the Nelchina herd (n = 3) were pregnant 957–62 (Skoog 968). Only the Delta herd had more yearlings pregnant: 67% for a short span of 2 years in 978 and 979 (n = 2) (Davis et al. 99).

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Table 10.2

Pregnancy rates based on autopsies in March and April

Age of Female (months)

Increase Pop. Phase 1976, 1980, 1982

% Pregnant (Sample size) Stable/High Pop. Phase 1983, 1984, 1986

Decrease Pop. Phase 1989–93

22 34 > 34

48 (23) 95 (38) 96 (132)

8 (13) 73 (37) 88 (97)

25 (8) 22 (9) 82 (89)

Total Total Smooth¹

90 (193) 91

80 (141) 78

77 (106) 69

Source: Drolet and Dauphiné 976; Parker 98; Messier et al. 988; Couturier et al. 990; Crête et al. 996. ¹ Smooth age structure following Messier et al. 988

After 982 the pregnancy rate for the George River herd dropped 20–25% (tables 0., 0.2). Fewer yearlings and older females conceived (table 0.2). Whereas the parturition rate had been the highest in North America before, in the space of only five years it dropped to the lowest in North America (see review Bergerud 980). The physical condition of the females in the summers of 985–88 was again as low as any previously published. The animals had such low summer weights (fig. 8.9) that fall breeding was delayed and some females starved in the summer (see table .). These figures – 60–70% parturition 984–90 (table 0.) – may be the lowest in which we can expect most neonates to survive. There is a suggestion in the annual determinations that parturition figures improved slightly in 99–93 compared to 984–90 (table 0.; fig. 0.): 7.5% ± 2.36% (n = 3 years) vs 67.5% ± 0.66% (n = 7 years). Calf Mortality Statistics The mortality of calves at 2–3 weeks of age averaged 8.% ± .85% (n = 9 years). The rates in the years of increase [prior to 984, 9.2% ± .00% (n = 3)] and decrease [after 987, 7.5% ± 2.72% (n = 6)] are similar (table 0.). These rates compare favourably with other migratory herds. Fancy et al. (994) reported that the mortality rate of calves in the Porcupine herd averaged 27% ± 3.59% for the first month of life for the years 983–92; the death of calves in the Kaminuriak herd in 970 averaged % by 2 weeks of age (Miller and Broughton 974); and deaths by 2 weeks of age in the 40-Mile herd (Alaska-Yukon) were 22% (n = 957) in 984 (Bergerud, personal observations). Sedentary herds can have mortality rates as high as 50% for the first month of life (Bergerud et al. 984; Bergerud and Page 987; Seip 992; see also chapter 4).

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In 992 there was an abnormally heavy loss of calves (20%) in the first 2–3 weeks after birth (table 0.). These deaths occurred because the calves were extremely underweight following the latest spring phenology on record (fig. .4). The calves that died averaged only 4.04 kg ± 0.7 kg (n = 3) compared to 5.08 kg ± 0.0 kg for those that lived (n = 49) (Couturier, personal communication). Although the weather in June 992 was extremely cold (fig. .4), the inviability of the calves was due more to low birth weights than to the unusual combination of weather factors and hypothermia. Fall Recruitment

During the period of rapid herd growth (973–83), fall recruitment was high with an average of 53.0 ± .02 calves/00 females per year (table 0.; fig. 0.). If the birth rate was 94 calves/00 females, the mortality until autumn was 42%; if no more than a maximum of 3% of the adult females died over summer,the death rate was 44%. Even if only 85% of the cows were parturient and 4% died over summer, calf mortality would still have averaged only 40%. Summer mortality rates of 40–44% seem high, but compared to many herds in North America they are moderate (Bergerud 980). When the herd was at high densities 984–88, calf recruitment declined about 5 calves/00 females to an average of 38.4% ± 0.63% (n = 4). If pregnancy rate was 69% (table 0.) and summer mortality of females was 6% (see Hearn et al. 990), then mortality rate would be 48%, similar to that when the herd was increasing. The rapid decline in recruitment took place between the 983 and 984 cohorts (fig. 0.) and was later seen in an increase in the mean age of females between 985 and 986 (table 0.3). Over the course of the study birth rates and fall recruitment were correlated r = 0.732 (n = 8). The declines in recruitment and pregnancy statistics (973–83 vs 984–88) were large: from 53 calves/00 females to 38 calves/00 females (28%); and from 9 pregnancies to 69 (24%). Hence this major decline in recruitment until autumn is not explained by increased calf mortality; it is a result of the major decrease in pregnancy rates after 982 and/or 983 (table 0.). Fall recruitment remained low for the 989–92 cohorts, 29.3% ± 2.40% with mortality increasing to 60.% ± 3.26%, and may have had a downward trend (r = -0.792). The spring recruitment (animals 0–2 months of age) necessary for maintaining numbers (R S) for 8 other migratory herds in North America was 25 yearlings (0–2 months/00 females) Y = 0.847 + 0.0062X (fig. 0.2). A similar R was needed to maintain numbers in 22 sedentary herds in North America, but it was based mostly on fall recruitment of calves 5 months of age (fig. 4.5). Note that 25 short yearlings/00 females is the equivalent of calves at approximately 4% of the total herd. Thus a fall recruitment of 29 calves/00 females – assuming winter mortality of calves similar to that of adults – would have been more than sufficient to maintain the herd numbers even with the major drop in fecundity

Recruitment, Mortality, and Population Growth | 277

Table 10.3 The mean age of females based on annulations counted from the incisors of females collected in March and April along the Labrador Coast (primarily from the commercial hunt conducted by residents of Nain) Spring Season

Sample Size by Ages 10 Mo. 22 Mo. ≥34 Mo.

1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993

31 6 1 9 no data 0 16 no data 21 11 37 8 5 3 8 4 no data 1 2 2

30 9 5 4

84 53 53 33

145 68 59 46

41.9² 50.5 58.4 48.6

47.3 45.8 48.0 47.5

-9.9 -11.4 -9.2 -9.7

31 21

135 103

166 140

53.7 55.3

49.3 61.6

-7.8 +4.4

29 19 23 8 11 5 26 7

369 220 145 160 207 243 268 149

419 250 205 176 223 251 302 160

55.1 68.0 57.5 65.0 75.1 79.3 68.3 74.4

49.4 56.1 49.8 56.3 66.0 69.6 65.6 68.1

-7.8 -1.1 -7.4 -0.9 +8.8 +12.4 +8.4 +10.9

7 11 2

149 82 41

157 95 45

74.8 66.0 56.5

71.4 66.3 54.6

9.7

14.4

146.7

171.0

61.7

57.2 ± 2.20

Means

Mean Estimated Age (Months) Total Observed Corrected¹

Difference from Mean

+14.2 +9.1 -2.6

¹ The observed mean age was adjusted to attempt to compensate for the lack of harvest of 0and 22-month-old animals by native hunters. The observed 0- and 22-month totals were adjusted: 0-month numbers were estimated by calculating the female calves recruited based on the proportions in the spring classifications. The 22-month totals were adjusted based on the female recruitment at 0 months of age (females calves/00 females ≥ 34 months of age) and then reducing this total 5% for losses between 0 and 22 months of age. ² The regression of the observed mean age on year (last two digits) was: Y = -44.047 + .265X, r = 0.76, n= 7.

(approximately 24%, or from 9 to 69) after 983. As our study ended, Couturier et al. (996) reported 42.5 calves/00 females for the 993 fall recruitment. Not since 983 had a similar number of calves/00 females been alive in the fall. Spring Recruitment

The mean recruitment of calves at 0–2 months that we tabulated in the field for the 974–83 cohorts was 32.7% ± 2.36% (n = 0), CV 25% (table 0.). This statistic is too low; 33 calves/00 females translates to 7% of the herd. Substituting 7%

278 | TH E R E T U R N O F C A R I BO U TO U N G AVA 10

1.20 9

FINITE RATE OF INCREASE (λ)

7

Y = 0.847 + 0.0062X r = 0.839 n = 11

1.10

1.00

5 6

2

0.90

11

3

8

4

1

0.80

15

20

25

30

35

40

45

50

CALVES PER 100 Fig. 10.2 The finite rate of increase and spring recruitment for eleven other herds in North America. Our counts of the recruitment of calves of the George River herd at 10–12 months of age (fig. 10.1, table 10.1) underestimated the finite rate of increase of the herd based on the census results of the George River herd (presented in fig. 10.4). We established a correction factor by tabulating, from the literature, the recruitment statistics (10- to 12-month-old yearlings) reported for several large migratory herds in Alaska and the NW T that accompanied a change in the size of those populations. The regression of λ on calves per 100 females for these herds gave a finite rate of increase of 1.00 (RS ) at 25 short yearlings per 100 females similar to that for the sedentary herds (chapter 4). The large migratory herds in the Northwest Territories and Alaska were (1) the 40-Mile herd in Alaska (1953–55), (2) the Kaminuriak herd (1968–74), (3) the Nelchina herd (1972–76), (4) the Beverly herd (1955–67), (5) the 40-Mile herd (1981–86), (6) the Delta herd (1983–87), (7) the Kaminuriak herd (1977–83), (8) the Porcupine herd (1977–82), (9) the Western Arctic herd (1976–82), (10) the Bluenose herd (1970–83), and (11) the Bluenose herd (1983–87). herd locations can be seen in Bergerud (2000).

calves in for R in the finite growth equation λ = ( - M)/( - R) where the finite rate was λ = .5 (see Messier et al. 988) results in a combined adult mortality rate (both natural and hunting) of adults (females + males) approximately 7.7%. Historically both Kelsall (968) and Skoog (968) hypothesized low natural mortality rates of this magnitude approximately 5%, but since the advent of radio telemetry in the 970s such low mortality rates have not been documented, although these statistics may be biased since radio monitoring is commonly undertaken

Recruitment, Mortality, and Population Growth | 279

Table 10.4

The percentage of males classified from 1973 to 1993¹ Percentage of Males

Age

Fetuses Total Years Samples Calves/Birth Total Years Samples Calves 5–6 mo. Total Years Samples Yearlings 10–12 mo. Total Years Samples Yearlings 16–18 mo. Total Years Samples Adults > 1 yr Total Years Samples Adult > 2 yrs Total Years Samples

Increase 1973–84

High 1985–88

Decline 1989–93

Total 1973–93

49.2 49.0 ± 2.25 187 (3)

48.7 48.6 ± 0.32 608 (3)

54.2 52.4 ± 2.76 482 (4)

50.8 51.6 ± 1.71 1,277 (10)

64.3 51.5 ± 9.80 28 (2)

53.8 55.0 ± 2.21 160 (4)

56.7 55.0 90 (1)

55.8 54.0 ± 2.53 278 (7)

52.5 54.9 ± 2.66 1,297 (4)

52.5 53.2 ± 1.16 1,774 (3)

54.4 54.7 ± 1.40 2,079 (2)

53.2 54.3 ± 1.19 5,150 (9)

45.0 43.3 ± 2.32 18,086 (11)

39.5 40.9 ± 2.16 2,268 (4)

44.8 43.9 ± 1.96 3,321 (5)

44.4 42.9 ± 1.40 23,675 (20)

45.6 46.9 ± 2.63 9,113 (12)

47.0 43.0 ± 5.85 1,188 (3)

48.8 47.9 ± 2.04 1,347 (3)

46.1 46.4 ± 1.97 11,648 (18)

37.0 36.3 ± 1.86 78,478 (11)

35.2 34.4 ± 1.24 16,838 (4)

35.2 35.8 ± 1.65 10,693 (3)

36.5 35.8 ± 0.81 106,009 (18)

39.1 38.4 ± 1.57 80,877 (8)

34.1 33.7 ± 0.93 12,810 (3)

36.2 36.8 ± 2.35 5,925 (2)

38.3 37.0 ± 1.14 99,612 (13)

¹ Years excluded because of no data, or samples less than 0, or a large proportion of animals unsexed. Fetuses: 972 to 979, 98, 983, 985, 990; Calves  day old: 972 to 977, 979, 980, 982, 983, 984, 989, 990, 99, 993; Calves 5–6 months: 972 to 980, 987, 989, 990, 993; Short yearlings (0–2 months): 972, 973; Long yearlings (6–8 months): 977, 986, 992, 993; Adults >  yr: 972, 978; Adults > 2 yrs: 972, 973, 974, 976, 977, 987, 99, 992, 993.

when herds are in trouble. Messier et al. (988) reported a mortality rate of % of George River females based on the age distributions of animals killed at Limestone Falls 984. Also during this period, hunting mortality was about 4% (chapter ). Based on an observed recruitment of 32.7 calves/00 females, we are left with only 3–4% for natural adult mortality, an extremely low (and unreasonable)

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figure in terms of both the literature and the adult sex ratio. With an adult sex ratio of 36.5:63.5 (table 0.4), males should die at greater rates than females. A total rate for both sexes of 3–4% implies a mortality rate for females of only –2%. Even with a convex survivorship curve, there would be females in the population older than 20 years: This was not the case for this or other caribou herds (Messier et al. 988; Miller 974; Thomas and Barry 990a). We turned to the literature to secure a better estimation of R for 0- to 2month-old animals. Based on this analysis (fig. 0.2), the number of calves 0–2 months old needed to provide λ = .5 for the documented growth of the George River herd 974–83 was 42.9 calves/00 females. This analysis of external data suggests that we underestimated spring recruitment in table 0. by 24% (32.7/42.9). We can also calculate the recruitment necessary for an increase of .5 based on the mortality of George River adult females that died at Limestone Falls in 984; this was feasible since the proportion of males to females had remained constant for 0- to 2-month-old recruits and adults + long yearlings (table 0.4). The annual mortality of adult cows in the 980s averaged % based on l x curves from animals that died at Limestone Falls (Messier et al. 988) and were harvested west of Nain, 980–84 (fig. 0.3). If 00 cows in Y₁ are to increase to .5 in Y₂ after  females have died, we must add 22.5 female calves to the female component. Our correction factor of 42.9 calves/00 females provided 23. female calves/00 females if the sex ratio of the recruits was 46.:53.9 (table 0.4). In this calculation the sex ratio is based on long yearlings: There is no evidence that male and female yearlings had different mortality rates in their second summer; the sex ratio in the fall at about 7 months of age may be more representive of males than that at 0–2 months if any males lag behind in spring migration. A sample of the herd that contained 00 females should also contain 57.5 males, including both adults and long yearlings. If 57.5 males are to increase Y₁ to Y₂ at .5 there will be 64. in Y₂. Our corrected recruitment of 42.9 calves/00 females would contain 9.8 males (ratio 46.:53.9, table 0.4); 64. males minus 9.8 (44.3) would translate to a mortality rate of 23% [(57.5 - 44.3) + 9.8 = 64.]. Based on the George River data, we needed 42.9 calves/00 females 974–84 for an increase of .5, which agrees with that in other herds in North America. Male and female recruits are similar in numbers (9.9 male recruits:23. female recruits per 00 adult females), but the ratio of long-yearling males plus adult males to all females (yearling and adult) was 57.5:00 (table 0.4). This suggests that males die at a much greater rate than females, which has been well documented in the caribou literature (Miller 974; Bergerud 980). We reason that our spring recruitment counts were due to the segregation of pregnant and non-pregnant cows in spring migration. When we compared the CV statistics between classification sites within years for the spring counts (0–2 months of age) vs the autumn counts (5–6 months of age), the mean CV in the spring was 4 times higher than in the fall. This was the result of the segregation

Recruitment, Mortality, and Population Growth | 28

of pregnant from non-pregnant females and of all females from males. Pregnant females were at the leading edge of the migration. A female that has skipped a pregnancy (and possibly her calf as well) is more likely to be farther back. There was also a tendency for yearlings to lag behind the front of the migration. We conducted the spring counts in most years by flying north from Goose Bay and west from Hebron Fiord. Since the caribou were usually migrating south and east in April, the animals we encountered most frequently were the leading animals: We may have underestimated spring calves as a result. Why use spring recruitment if it is biased compared to counts in the breeding season? Fall calf percentages are not a valid index to recruitment for large migratory herds that summer above the Arctic tree line and make long winter migrations below tree. Other migratory herds in which calves died at greater rates over winter than adults are the Kaminuriak, Porcupine, and Baffin Island herds (Clark 970; Miller 975; Fancy et al. 994). In the winter of 98–82 we measured recruitment 6 times over winter: There was a significant decline in the percentage of calves in the herd, especially in November and December (Y = -7.86X⁰.³⁰ + 65, r² = 0.977). This differential mortality of short yearlings may be biased to male calves. Hearn et al. (990) reported a higher over-winter loss of male calves than females for the George River herd in 983–87. One expects calf mortality rates to exceed adults over winter if summer survival is high and calves make up a conspicuous segment of the herd. We observed more wolves at or below tree line than on the tundra. A similar sequence was documented in Alaska and the NWT (James 983; Heard and Williams 992; Heard et al. 996). In this study the survival of calves until fall, as well as spring recruitment (0–2 months of age) showed no overall trend for 0 cohorts (974–83), but there were annual fluctuations (Bergerud 996). There was an increase in calf survival in 98 and 982 when wolves became scarce (fig. .). The 982 cohort was the largest in this study (table 0.) and this was confirmed in the age array that died at Limestone Falls in 984 (see Messier et al. 988, table 5). It is the two cohorts in 98 and 982 that caused the rapid growth of the herd between 980–84 (300,000 to 500,000–600,000), increasing summer density from 6/km² to –2/km² by 984. If fall calves had been the measure of change, this major population eruption would have been missed. Messier et al. (988) spoke of how the great variability in the spring classifications made them unreliable. We acknowledge that representative samples are difficult to secure when the herd is migrating from April to June, but the variability in the over-winter survival between years is real. Without this measure we would be investigating the demography of the species on the basis of only the first 5 months of life instead of the complete annual cycle. The spring recruitments averaged 5.6 ± .45 calves/00 females for the 985 to 992 cohorts (n = 8) (table 0.); if increased 24% (the 32.7:42.9 correction ratio),

282 | TH E R E T U R N O F C A R I BO U TO U N G AVA

recruitment averaged 20.5 calves/00 females. This recruitment would be insufficient to maintain numbers based on R s determinations for 22 sedentary herds (fig. 4.5) and 8 migratory herds in North America (fig. 0.2; Bergerud 992). Converting recruitment to over-winter mortality rates gives a mean winter loss of 3.0% ± 4.4% (CV = 68.9%); [00 - (0- to 2-month-old calves/00 females corrected divided by calves 5–6 months old/00 females) x the winter survival rate of females]. These losses generally increased 985–90. Adult Mortality Mortality Rates 1973–84

The total mortality of adults, both male and female, during the increase phase (973–84) was 7.7%, based on the rate-of-increase equation using λ = .5 and 33.2 calves/00 females (7.2% of the total population). Male mortality rates are commonly twice that of females, resulting in the common sex ratio in North America of  male per 2 females (Bergerud 980). The best approximation of the female and male mortality rates on the basis of a total loss of 7.7% and an M:F ratio of 36.5:63.5 would be 4.6% for females and 3.2% for males. Since the harvest of the herd was 3–4% (chapter ) and many of the harvested animals were females, the death rates of cows must have exceeded 7%. The corrected spring recruitment of 42.9 calves/00 females resulted in an increase in the percentage of the calves in the herd in April–June to 2.4%; substituting 2.4% in the rateof-increase equation [λ = ( - M)/( - R)] gave a total mortality of animals > 2 months of 2.4%. Females would have died at 8.5% per year, males at 9.%. This death rate of females may be low: Messier et al. (988) estimated annual female losses at % based on the age of the cows that died at Limestone Falls in 984. An additional method for estimating female mortality during the increase phase was to calculate  x curves 975–84 based on the mandibles we collected in eight Aprils. This method yielded a mortality rate of 2.% (n = 787) (fig. 0.3). This rate seems slightly too high and could have resulted if the annulations in older females were underestimated. However, using only the 980 collection when the animals were aged in a different laboratory also gave a loss of 2% per year for animals 0.8 to 7.8 years of age. Based on the  x curves and the rateof-increase equation methods (no animals were radio-tagged in this phase), the annual death rates of females during the increase phase was between 9 and 2%. The estimation that males died at twice the rate of females is not surprising given that the sex ratio of recruits was 46.:53.9 (table 0.4), whereas that of adults remained constant at 36.5:63.5. This disparity between the sexes in mortality holds for other caribou herds: The adult sex ratio of 7 herds in North America averaged 35.6% ± .04% males (Bergerud 980), yet recruits joined the herds in more balanced proportions (Skoog 968, Kelsall 968, Bergerud 97b).

6.0

Y = 5.5731  0.107X

5.5

1975–84 λ = 1.117 M = 12.1%

5.0

1985–88 λ = 1.03 M = 11.8%

NATURAL LOG OF ANIMAL NUMBERS

4.5

Y = 12.606  0.708X

4.0

3.5

3.0

1989–93 λ = 0.92 M = 15.3%

2.5

2.0

1.5

1.0

1975–84 1985–88 1989–93

787 MANDIBLES 878 MANDIBLES 421 MANDIBLES

0.5

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

AGE (YEARS)

Fig. 10.3 The survivorship curves for females harvested west of Nain during the increase phase of the George River herd (1975–84), stable or high phase (1985–88), and decline phase (1989–93).

284 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Mortality Rates 1984–93

After the increase phase and for the remainder of the study from 984–85 to 992– 93, we determined the mortality rate of females from radio-collared females. This mortality rate averaged 2.8% ± .59% (table 0.5) and showed a significant increasing trend, Y = -3003.058 + .57X (r = 0.873) on biological year (i.e., June 984 until May 985). Separate mortality estimates for the high population phase 984–85 to 987–88 (n = 4) and for the decrease phase 988–89 to 992–93 (n = 5) were 9.7% ± 2.45% and 5.3% ± .39% respectively. A second estimate based on the array of ages from the Nain collections was divided into periods: the increase phase 975–85 (787 ages); the high population phase 985–88 (878 females); and the decline period 989–93 (42 mandibles). The mortality rates of females were similar in the periods of increase and high population at approximately 2% (fig. 0.3), but increased in the decline phase to 5% (fig. 0.3). These survivorship curves show the expected convex shape of long-lived mammals (Deevey 947). When plotted as natural logs to evaluate rates of change, there were generally two periods of constant rates of decline: one in the prime years, the other in the latter part of life. Biologist Mitch Taylor, Nunavut Director of Wildlife (personal communication, 99), was the first to note these two constant slopes in the George River age distributions. As the total mortality of females increased over the course of this study, it was most apparent in the older age cohorts. For the increase phase (975–84), the mortality rate was relatively constant from 2.8 to 0.8 years; after that age the rate increased (fig. 0.3). For the females collected in 985–88, mortality rates increased after the age-class of 7.8 years, earlier than in the 975–84 collection. By 989–93 this trend towards increasing mortality began even earlier, at 4.8 years. In other words, it was progressively in the older age classes where the increased death rates of females after 984 occurred. If vulnerability to death is a measure of vigour, then senescence arrived at progressively earlier ages after high numbers were reached in the mid980s. The calculated adult male mortality rates for the interval that mortality rates were available from radio-collared females (after 983) were based on the equation Mm = Mf + (0.2627)R and averaged 8.6% (table 0.5). In the increase phase, prior to 984, Mm was possibly twice that of females, but after 984 males died at only .5 times the rate of females. We had worried that when females had a high death rate – such as 9% in 99–92 – it would no longer be reasonable to double that figure to arrive at the male mortality rate. If the sex ratio of adults remained constant given the normal, balanced ratio of female and male recruits (table 0.4), mortality of males had to increase coincident with that of females. However, this may not have happened here because the females returned to the overgrazed summer ranges in late May and were there throughout July; males only arrived with the female mosquito hatch in July. Furthermore, females had the additional

Recruitment, Mortality, and Population Growth | 285

Table 10.5 Calculation of total caribou population in June 1993 based on spring recruitment figures and adult mortality rates (λ = [1 - M]/[1 - R]) starting with a population estimate of 537,000 in June 1984 (A) Based on Male and Female Mortality Rates Year

1984–85 1985–86 1986–87 1987–88 1988–89 1989–90 1990–91 1991–92 1992–93

Mortality Rate Females¹ Males² Total³

5.1 7.6 9.6 16.5 12.8 11.8 15.5 19.3 17.3

14.1 14.9 15.9 21.9 18.6 15.7 18.8 23.5 24.0

Population Size June 1993

8.4 10.3 11.9 18.5 14.9 13.2 16.7 20.8 19.7

% R at 10–12 Mo.4

(1 - M) Adults

(1 - R) Calves

Rate of Increase

Pop. Size

17.8 15.0 13.2 11.6 12.4 8.7 7.4 9.4 13.9

91.6 89.7 88.1 81.5 85.1 86.8 83.3 79.2 80.3

82.2 85.0 86.8 88.4 87.6 91.3 92.6 90.6 86.1

1.11 1.06 1.02 0.92 0.97 0.95 0.90 0.87 0.93

537 596 632 644 592 575 546 492 428

398

(B) Based Only on Female Mortality Rates. Year

1984–85 1985–86 1986–87 1987–88 1988–89 1989–90 1990–91 1991–92 1992–93

Mortality of Females Females Calves/100F Survival Rate % Per 1005 Corrected 6 Adjusted7 Females Calves

5.1 7.6 9.6 16.5 12.8 11.8 15.5 19.3 17.3

– 10.1 11.4 9.9 9.7 6.1 5.1 7.8 10.5

Population Size June 1993 ¹ ² ³ ⁴ ⁵ ⁶ ⁷

– 9.3 10.3 8.3 8.5 5.4 4.3 6.3 8.7

13.7 12.2 13.6 10.9 11.1 7.1 5.7 8.3 11.4

94.9 92.4 90.4 83.5 87.2 88.2 84.5 80. 82.7

86.3 87.8 86.4 89.1 88.9 92.9 94.3 91.7 88.6

Rate of Pop. Increase Size

1.10 1.05 1.05 0.94 0.98 0.95 0.90 0.88 0.93

537 591 620 651 612 599 569 512 451

419

Female mortality rates based on radio telemetry Male mortality based on Mm = Mf + (0.2627)R (Bergerud 996) Male and female rates combined on basis of 57.5:00 Adjusted on basis observed actual 0.76:00 of yearlings (24% missed) Female calves based on sex ratio of recruitment of female:male, 53:47 Adjusted for annual mortality of females 985–86 (92.4 x 0.)/00 = 9.3 Adjusted based on segregation biases observed actual 0.76:00

energy burden of lactation. We found females that had starved in the summer but no males. In lieu of other compensatory factors, such altered mortality rates might in time change the overall proportions of males and females, but we did not document this for the George River herd (table 0.4).

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SCARS (

Y = 0.002e 0.114X r2 = 0.935

AGE 30

EXCLUDES 1988–92

CENSUS (

M/R

)

750 Y= 1 + 1614718e 0.177X r2 = 0.945

400

300

20

SCARS 1988–92

EXCLUDES 1993

AGE STRUCTURE (

25

2001

)

15

Y = 0.0078e 0.137X r2 = 0.982 EXCLUDES 1985 1986 1987

200

M/R PREDICTIONS (

10

FREQUENCY OF SCARS

TOTAL CARIBOU (×1000)

600

500

35

)

SCARS

)

CENSUS

100

5

FORAGE ACCUMULATION 0

0 45

50

55

60

65

70

75

80

85

90

95

YEARS

Fig. 10.4 The growth of the George River herd from 1945 to 1988 and decline after 1988 based on census data, age structure data, tree-root scars, and recruitment/mortality statistics. The tree-root scar information is adapted from Morneau and Payette (2000). The census data are from a variety of sources and do not include calves and the age structure data from the females harvested west of Nain. The population size 1984–85 to June 1993 was based on mortality and recruitment schedules from table 10.5 and graphed fig. 10.5.

Population Growth We have generated three population growth curves for the George River herd 945–93 (fig. 0.4). The primary curve was based on nine separate censuses (the majority of aerial counts in the 970s and 980s were sponsored by the Quebec government). From this data (a partial review is Messier et al. 988) we have calculated the rate of increase using a somewhat different set of total census figures than were available to Messier et al. (988). We included a winter census in 982 conducted by Luttich, and we adjusted the (June) 984 estimate to 338,000 females to comply with Crête et al. (99). With the ratio of males at 36.5:63.5, this gives us a total of 532,000 animals, 60,000 more than in the earlier estimate. We also included the 988 census (Crête et al. 99). The growth rate we project is the same as Messier’s et al., λ = .. We projected a second estimate of population growth based on annual changes in the age distributions of 2,05 females collected over winter 973–74 to 985–86

Recruitment, Mortality, and Population Growth | 287

using the Cagean program, which was developed by fisheries researchers who could not census their fish stocks but had large age arrays available (Deriso et al. 985). The Cagean program projects a growth in which λ = .2 (fig. 0.4), with a peak population in 983–84. We use the mean of λ = .5 as the basis for further calculations. A third estimation of the increase of the herd was based on the trampling damage to tree roots that bisect caribou trails, a revolutionary technique pioneered by Morneau and Payette (2000) and tabulated in 5-year blocks 945–92. Their data showed a peak in scarring 983–87 and a decline 988–92 (fig. 0.4). Although the three curves show a curvilinear slope, this is an artifact of the smoothing (fig. 0.4). Recruitment statistics (table 0.) were uneven; few calves were recruited from the 980 recruits; and large numbers joined the herd from the 98 and 982 recruitments (Bergerud 996). The 982 cohort had the highest survival of any cohorts in the interval 973–93 and together with the 98 cohort, the herd possibly doubled. The caribou population experienced no serious decline between 984 and 988. Another census of cows on the calving ground, corrected for those females not present based on locations of females with radio transmitters, gave 379,800 cows in June 988 (Crête et al. 99); add in the males and the total June estimate is 598,000 caribou. The Decline Phase, 1988–93 After 988, the herd was counted again in 993 by a photo census of both the calving ground (Couturier et al. 996) and the post-calving aggregations (Russell et al. 996). These two counts were not in agreement, however: Couturier et al. estimated 44,000 females in the herd; with the addition of the males, the total comes to 700,000 animals. Russell, on the other hand, estimated 550,000 (females plus males). We believe both estimates are high. There had been insufficient recruitment of yearlings in the 988–92 cohorts to either maintain or increase the size of the herd. The observed mean yearlings per 00 females was 3.9 ± .8. Even after a correction of 24% (a correction discussed earlier), which brings the ratio of calves/00 females up to 8 (or 0% of the herd), recruitment was inadequate. Caribou herds in North America – especially if hunted – cannot maintain their status with calf survival at this level (Bergerud 992; Bergerud and Elliott 998; Bergerud 2000). Crête et al. (996) also believed that the herd had declined between the 988 and 993 censuses, stating (ibid., 33): “It is likely that the George River herd decreased between 987 and 993 because the trend in autumn calf:female ratios and adult survival rates between 984–92 was clearly declining.” Later in this monograph we will present several density-dependent biological parameters that improved after 988, indicating a reduction in the number of caribou.

288 | TH E R E T U R N O F C A R I BO U TO U N G AVA

In addition to the decline in scarring reported by Morneau and Payette (2000) after 987, two additional studies support our view that the population was starting to decline after 988. Boudreau et al. (2003) again measured trampling scars of vegetation using the methods of Morneau and Payette (2000). They reported the general activity of the herd had decreased since the early 990s and that it began to decline between 988 and 993. If the peak population had been in 993, activity should not have decreased. Théau and Duquay (2004) examined Landsat imagery photos of lichen abundance; they noted lichen-rich areas distributed all over the summer range – excluding the calving grounds – as of 998. Since lichens take many years to regenerate, these observations, too, are not consistent with a peak population of 700,000+ animals, Couturier’s et al. estimate for only five years earlier. The calving ground census techniques used in 993 were exceedingly complex and required many assumptions and extrapolations. A major problem with the count was that the herd was moving during the census. The density strata were determined 4–7 June but the photographs were not take until 20–26 June. By this time the southern one third of the high-density stratum was nearly empty of animals (Couturier et al. 996, fig. 2). A basic tenet of this type of census is that the animals be tallied at the peak of calving when they are largely stationary. The post-calving census done by Russell made fewer assumptions and extrapolations since the males had joined the cow groups by this time. But this census also took several days to complete and the movement of animals between the groups may have complicated the identifications. In fact, a number of factors made the spring and summer of 993 a particularly unfortunate year to single out only one of the two major herds resident above tree line in northern Ungava for census. As we have mentioned, the animals censused in 993 were farther north and west than in any of the previous 20 determinations of the calving ground (973–92), and the distribution of animals along the Ungava Bay Coast indicates that they were there to escape insects (not predators). However, this placed the George River animals nearer to the range of the Leaf River herd, which in 99 was estimated at nearly 260,000–276,000 animals, and which would have been even larger by 993 (Couturier 996; Couturier et al. 2004). Some overlap seems inevitable, and indeed, at the time of both counts, 3 out of 7 radio-collared animals from the Leaf River herd were in the census area of the George River herd. The discreteness of migratory herds arises because they select distinct and separate landscapes to minimize predation (Bergerud 996). But the phenology in 993 was early and mosquitoes were common in the normal calving area farther south at the height of calving time. The animals may have continued moving during calving because of insect harassment and/or they may have been tracking early greens. At any rate, the ranges of the two herds were not mutually exclusive and the census was compromised as a result.

Recruitment, Mortality, and Population Growth | 289

Even if an estimate of 550,000 in 993 (Russell et al. 996) is reasonable, we still need to subtract the Leaf River component from the total. In 987 one-third of the Central Arctic herd in Alaska was mixed with the Porcupine herd based on radio collars in a post-calving census; for this reason, those numbers were subtracted from the census total (Fancy et al. 994). Only seven animals in the Leaf River herd had functioning radios in June/July 993, admittedly a pathetic sample. But we do know that the two herds were intermingling since three of the animals were with the George River herd, and it is thus not valid to include them in the census total. If we assume 40% of the Leaf River herd was present during this post-calving census, the total number of George River animals would be reduced to possibly 425,000 animals. At the 7th North American Caribou Workshop, Thomas (998) critiqued the idea of counting caribou by the calving ground technique in the Northwest Territories and the George River herd. In his abstract (p. 5), he complains that “extrapolation of such counts to population size produces unacceptable accuracy and precision. Consequently, no conclusions can be made about changes in population numbers between or among surveys.” Couturier, presenting a paper at the 8th North American Workshop in April 200, also suggested that the Leaf River and George River herds might represent a meta-population; and there has been extensive mixing of the two herds since 999, notably with George River animals moving to the Leaf River herd (Courturier et al. 2004). Because of these census complications, we reconstructed the size of the George River herd 984–93 on the basis of recruitment and mortality schedules where λ = ( - M)/( - R). These parameters also reflect population change (Bergerud 968) but are less biased by small shifts of animals between herds. Annual estimates of R and M were available from 984–85 to 992–93 and were used to generate population estimates starting with the census estimate in June 984 of 537,000 animals (table 0.5; fig. 0.5). The λ values were calculated () based on total M, males + females); and (2) only on females. The latter statistic avoided calculations in the male mortality equation and the assumptions therein; in addition, it avoided the assumption that sightings of male yearlings at 0 months of age are directly proportionate to their abundance. The two schedules both show the population increasing in 985, 986, and 987 and then decreasing. This sequence agrees with our findings of food intake increasing after 988 (chapter 7); of improved physical condition after 987 (chapter 9); and of the damage to vegetation that peaked in 986–87 (Morneau and Payette 2000). Both of our population estimates based on R/M schedules provided estimates in June 988 close to the estimated census of 600,000 animals by Crête et al. (99), at 592,000 and 599,000 respectively. Both total mortality and female-only mortality schedules generated population estimates in June 993 of 30,000 to 70,000 animals fewer than those of Couturier et al. (996) and Russell et al.

TS

MORTALITY RECRUITMENT AD UL

CALVES / 100 RECRUITED MORTALITY RATE (%) AND ADULT

20

15

10

DECREASE

INCREASE

ES LV CA

651  419 = 232k DOWN

5 λ = 1.10

1.05

1.05

0.94

0.98

0.95

0.90

0.88

0.93

n = 537

591

620

651

612

600

570

513

451

419

0

CALVES RECRUITED AND ADULT MORTALITY RATE (%)

20

ESTIMATED FROM REGRESSION 454

15

SAMPLE SIZE 7400

10

11330

S

LT DU

A

7646

DECREASE

INCREASE

7415

C

ES ALV

2886

5

644  398 = 246k DOWN

λ = 1.10

1.06

1.02

0.92

0.97

0.95

0.90

0.87

0.93

n = 537

596

632

644

592

575

546

492

428

398

85–86

86–87

87–88

88–89

89–90

90–91

91–92

92–93

JUNE 1993

0 84–85

BIOLOGICAL YEAR (1 JUNE–31 MAY) Fig. 10.5 The decline of the herd based on mortality and recruitment statistics 1984 to 1993. Mortality rates of females were based primarily on the radio-collared females reported by Hearn et al. (1990) and Crête et al. (1996).

Recruitment, Mortality, and Population Growth | 29

(996) (table 0.5; fig. 0.5), both of which we feel are inflated. For this reason we have used the estimates generated from the female M/R schedule – not the 993 census results – for calculating all caribou densities in this book. Couturier conducted another calving ground census of the George River herd in June 200 (Couturier et al. 2004). Their estimation was then 300,000 animals. All now agree that a major decline had occurred. However, they reaffirmed in their 2004 paper their 993 census estimate of 700,000; they also indicated there that the fall recruitment needed for population stability is 39 calves/00 females. Their data (graphed in fig. .6) showed that fall recruitment was negative (less than 39 calves/00) for the 988, 989, 990, 99, and 992 cohorts (mean 30 ± 2.0 calves/00 females) These are the only cohorts that added recruits between the 988 census (600,000) and Couturier’s et al. estimate in the 993 census (700,000). Their data indicate the George River herd could not have increased between 988 and 993 based on internal recruitment. They also show that the carcass mass of lactating females increased from approximately 48.4 kg in 988 to approximately 5.6 kg by 993 – an increase not expected with the grazing pressure of an additional 00,000 animals. If one accepts the 993 census results, the decline occurred between 993 and 200. If the decline occurred between 988 and 993 with a population of 300,000 in 200, then the population is no longer rapidly declining and is living more within its means. Obviously making the correct conclusion is extremely important for the future of the population. The eruption of the George River herd 950–88 and its subsequent decline as it exceeded the carrying capacity of its summer habitat is the first of its kind to be documented for a mainland carbiou herd in North America since the commencement of scientific studies in the 940s. The sequence is a page from classical eruption theory as it was pioneered by Graeme Caughley, but it was completely unexpected from prior scientific studies of non-insular caribou herds. It is, however, an old story revisited – a story documented by our patron wildlife biologist, Aldo Leopold, who described the eruption and crash 907–39 of the deer population on the Kaibab Plateau in Arizona after the reduction of the deer’s major predators.

CHAPTER ELEVEN

Limiting Factors

Wildlife management in North America has a history of searching for the most limiting factor (Leopold 933), i.e., the mortality loss that holds down the potential rate of increase more than any factor. Once it is found, steps are taken to reduce or manage this loss. Limiting factors do not have to be density-dependent in action. They can reduce numbers whether populations are low or high. The most frequently mentioned limiting factors for caribou are starvation, accidents, hunting mortality, weather-related deaths and natality, disease and parasites, and predation (Banfield 954; Kelsall 968; and Skoog 968; Bergerud 97b; Valkenburg et al. 996a). Table . presents the quantified information available on the mortality of radio-collared females from several of these limiting factors. Starvation Since the earliest studies, researchers have worried about the winter starvation of caribou (Leopold and Darling 953; Banfield 954; Edwards 954; Scotter 964). There have been some spectacular winter die-offs for insular herds (Scheffer 95; Klein 968; Leader-Williams 980), most recently on Coats Island (Ouellet et al. 996). There is some disagreement about the roles of an “absolute shortage” versus a “relative shortage” in these mass deaths. In an absolute shortage, the animals have so denuded the range that they starve; in a relative shortage the animals can’t access the food because of weather factors – excessive snow and/or ice, for instance (Bergerud 974c). Also the effect of weather on caribou populations on Arctic islands can be a major factor in these spectacular winter die-offs (Gunn et al. 2003; Miller et al. 2005). According to conventional wisdom, the food in short supply was lichens. But lichens are not nutritious forage; they are high in energy but low in protein. Reimers (983b) made early arguments that forage in

Limiting Factors | 293

Table 11.1 The causes of death of radio-collared females during the study, 1984 to 1992¹ Cause of Death

Wolf predation Bear predation Predation unknown Accident/disease Summer starvation Hunting Unknown Total

Number of Animals

Percentage

57 4 8 2 7 12 23

50 4 7 2 6 11 20

113

100

¹ Includes 42 deaths reported by Hearn et al. 990

the growing season outweighed the importance of forage in the winter: Highquality summer diets were needed to carry animals through the season of low quality. On the Slate Islands, Ontario, it was the summer diet that determined if caribou died over winter; fall weights were a better predictor if animals would die in the winter than were winter food resources (Bergerud 996). Tyler and Blix (990) argued that caribou are highly adapted to winter food shortages and can endure extended periods of negative energy balance. The evidence of this study did not show that winter starvation was a concern. Generally the percentages of fat that we collected in the metatarsal of calves, yearlings, and adult females were high (fig. .), compared to values in the literature of animals that died from malnutrition. The females in the herd were actually in better condition in late winter in some years after coming off the lichen range than they were when they left the fall range after foraging on an overgrazed summer phytomass. Males are more prone to winter starvation than females, but the proportion of males in the population did not change over the course of the study (table 0.4). Males, even after the rut, had marrow fat reserves equal to females (table .2), higher than those reported for the Denali herd, Kaminuriak herd, and the Western Arctic herd (Dauphiné 976; Davis and Valkenburg 979; Mech et al. 995). We also did not find carcasses in the winter of animals that appeared to have starved. These could have been missed and assigned to wolf predation; however animals that have died first and were eaten later have characteristics unlike wolf kills. Such animals should die in feeding areas and not on travel routes (not on frozen lakes); snow beneath the animals would show signs of melt from body heat; frozen carcasses would have had the soft body parts eaten first; and blood and remains would be more localized in starvation deaths than in deaths from predation (Haber 977).

294 | TH E R E T U R N O F C A R I BO U TO U N G AVA Y = 0.591.47 + 0.335X, r = 0.102, n = 8

Calves

Yearlings Y = 0.790.35 + 0.440X, r = 0.278, n = 8 Females

Y = 624.090 + 0.358X, r = 0.410, n = 10

100

PERCENTAGE MARROW FAT

ADULT FEMALES (TOTAL SAMPLE n = 1050) 2

5

90

2

YEARLINGS

(TOTAL SAMPLE) n = 79

80

6 13 70

4 CALVES

60

50

29

80

6

(TOTAL SAMPLE) n = 61

81

82

83

84

85

86

87

88

89

90

91

92

APRIL SEASONS Fig. 11.1 The percentage of fat in the marrow of leg bones of caribou (femurs or metatarsals) in early spring (mid-March to mid-May) from 1980 to 1992 showed little variation as the herd increased from 300,000 to 600,000+ animals and overgrazed the summer but not the winter range.

There is a debate as to what constitutes a starvation marrow reading (review Mech et al. 995, 998). If ≤ 30% fat in the metatarsal is taken as the starvation limit, we found 0 such animals in the harvest of females in the commercial April hunt in a sample of 847 (%). The mean percentage of these 0 low readings was 6.2% ± 2.32%. Two of the 0 animals were collected in 980 (Parker 98); 2 in 987; 3 in 988;  in 989; and 2 in 99. To improve nutritional monitoring of Alaskan animals over winter, Valkenburg et al. (996b, 2003a, b) measured body mass of females in the fall (5 months of age) and the following spring (0– months of age) from an extensive collection taken from a number of Alaskan herds (99–2002). These weight comparisons were also made in earlier years in the Northwest Territories for the Kaminuriak and Beverly herds (Dauphiné 976; Thomas et al. 998). The mean body mass of female calves in the fall for  herds was 49.2 kg ± 2.99 kg and from

Limiting Factors | 295

Table 11.2 The percentage of fat in the leg marrow of large males in the breeding season, after breeding in November/December, and in the next spring Winter of

August/October (n)

November/December (n)

March/April (n)

1979–80 1985–86 1986–87 1987–88 1988–89 1989–90 1990–91

– 75.1 ± 0.85 ( 5) 87.5 ± 0.39 (32) 78.3 ± 7.21 ( 2) 77.5 ± 4.31 (10) 90.9 ± 2.12 (21) –

– 86.9 ± 2.60 ( 2) – 84.5 ± 1.49 ( 6) – – –

73.0 ± 5.40 (7) 77.6 ± 1.81 (5) 85.1 ± 2.05 (4) 80.1 ± 2.24 (11) 89.4 ± 1.00 (2) 82.4 ± 7.70 (6) 90.0 ± 2.45 (4)

Means

81.9 ± 3.09 (70)

85.7 ± 1.20 (8)

82.5 ± 2.34 (39)

exactly the same herds in the spring prior to the growing season 48.5 kg ± .86 kg. The means of 7 herds were less in the spring and 4 were higher. None of the fall body masses were significantly different from those in the spring, nor do these comparisons address winter energy budgets. Changes in body mass might not relate to over-winter intake of dry matter but to energy expenditures from cratering or mobility that do not reflect lichen abundance. Regardless, calves should be more vulnerable than adults to starvation from a lack of winter lichens, whether absolute or relative. The body mass series spanned  winters for the Delta herd; 6 for the Nelchina herd; 8 for the Northern Alaska Peninsula caribou herd (subject in the past to icing); and 5 over-winter periods for the Beverly herd. These extensive data sets should lay to rest the theory that mainland caribou may frequently starve in the winter Our study did document cases of summer starvation of radio-collared females (table .). In one example a female with a calf crossed a river in July where Camps was watching and then laid down and died. The animal had no back fat and the marrow in the leg bones was runny and red. The low in annual fat cycle occurs in mid-July when mosquitoes severely stress nursing females. The 992 growing season was the latest on record with the birth of the smallest calves that we documented. The increased mortality of females documented by Hearn et al. (990) and in table . is partly a function of summer deaths. Accidents The mother of all accidents occurred in the last week of September 984 when 0,000 caribou drowned at Limestone Falls (69°20' W, 56°28' N) on the Caniapiscau River. At the time, the river was flooding from heavy rains, exacerbated by Quebec Hydro’s release of water from the Caniapiscau Reservoir. Many of the animals that drowned had crossed close to the falls and had made it to a small

296 | TH E R E T U R N O F C A R I BO U TO U N G AVA

island right above the falls, but they could neither continue or turn back because the falls were too close in both directions. The water line along the river below the falls was as high that September as it was in normal spring floods – the riparian willows located at the normal scouring-line (caused by ice and debris in peak spring floods) were flooded then. Natives had long known that the flooding of this river made it a particularly dangerous crossing, and although we noted a few drowned animals there in earlier years, nothing to this extent had happened before. Drowning is probably the most common accident that George River animals face. Spring and summer migration routes are commonly perpendicular to the drainage of major rivers, and Ungava is laced with major lakes – many reflecting glaciations with long linear shorelines that lie at right angles to travel routes. Additionally, the late calving of females in the 980s (a mean of 2 June) coincided more closely with spring break-up at Schefferville than the earlier calving in the 970s (fig. .4). With their ice flows, these spring floods are difficult for young calves to navigate and result in numerous drownings. Lo Camps observed calves drowning on the lower reaches of the Tunulic River on 7 July 990. The caribou were crossing at a spot where the river was .5–2 km wide. It was a calm day with few waves and the animals were walking along the shore downstream to a peninsula to cross. While he watched, 8 calves started across and 6 drowned. Calves became disoriented in the water and some cows turned around to re-establish contact. In a stretch of 500 m along the shore Camps found 3 dead adults and 6 additional dead calves. If there had been a wind, even more would have died. Other places we have found dead calves are the running-out of Indian House Lake, and along the Falcoz and Ford Rivers. The route the cows take north after calving in June exposes very young calves to numerous rivers and in years of late snow melt drowning is frequent. The major accidents that affect adults are those associated with reproduction: the deaths of bulls in the rutting season and the deaths of cows during labour. We located several females that died with parturition problems and Couturier and van Ginhoven (994) located 2 collared bulls that died in fall breeding activities. These two types of death are mentioned frequently in the caribou literature (Bergerud 97b; Miller et al. 985). A common cause of locked antlers is the slipping of the bez between the brow and bez of the opponent (Butler 986). However, the bez tine on the antlers of the males in the George River herd is set low on the main bean (figs. 2.7, 2.8), and there is little space between these tines. Thus locked antlers should be less common in George River animals than in other herds that have a wide gap between the branching of these two extended lower tines, such as the caribou on the island of Newfoundland and on the Arctic Islands (Butler 986). We located only 2 sets of locked antlers in 20 years, a low number given the extent of the helicopter searches and the large number of males in the herd.

Limiting Factors | 297

THOUSANDS OF ANIMALS HARVESTED 1

2

3

4

5

6

7

8

9

10

TOTAL HARVEST (% OF POPULATION)

1987–92 25,000+ (5%) 1982–87 15,000+ (4%) ??

1977–82 10,000 (3%) 1972–77 9,000 (5%) 1967–72 2,000+ (3%)

??

SPORT HUNTING

1962–67

WESTERN LABRADOR

1,500+ (3%)

COMMERICAL HARVEST (NAIN) ??

NORTHERN LABRADOR NORTHERN QUEBEC

1957–62 1,000 (6%)

1

2

3

4

5

6

7

8

9

THOUSANDS OF ANIMALS HARVESTED

10

TOTAL HARVEST (% OF POPULATION)

Fig. 11.2 The estimated percentages of the population harvested based on kill statistics, 1957 to 1992. The various user groups are listed.

Hunting Mortality There is now considerable agreement among ungulate biologists that much of the mortality from hunting is additive and not compensatory to other mortality factors, although there could be a compensatory response in increased breeding success if populations are reduced sufficiently on a degraded range. Hunting

298 | TH E R E T U R N O F C A R I BO U TO U N G AVA

reductions certainly qualify as a limiting factor and have impacted past fluctuations. Over the years we estimate hunting mortality varying from 3% to 6–7% (fig. .2). This does not include crippling losses, which we believe were low; few cripples were noted and few animals appeared to have died from wounds. What has changed over the years are the proportions of the harvest taken by different user groups. In 958 when the herd was small and located in the east, it was the settlements along the northern Labrador coast that had access (Bergerud 967). As the herd grew and shifted farther west, the Inuit – first along Ungava Bay, and then adjacent to Hudson Bay – were the recipients, and it became more difficult to measure the harvest. Then, in the 970s–980s, hunting developed as a sport in Quebec. And finally, when the herd’s range extended south, the Cree and the people in western Ungava residing on the Hudson Bay coast had their day. The summer range was degraded and hunting restrictions were liberal: It was a time of plenty and we subscribed to the view that you can’t stockpile caribou. The philosophy was that if we managed things correctly they wouldn’t overgraze the range: We were wrong. Weather Factors The role of weather in the demography of vertebrates and insects has been extremely controversial ever since vertebrate ecologists and insect ecologists tried to find a unified concept (Nicholson 933; Lack 954; Andrewartha and Birch 954). We discuss weather here since its impact on demography is largely independent of caribou numbers and might be classified as limiting (or as entomologists contend, as a “population control influencer”). Valkenburg et al. (996a, 53) stated: “We conclude that evidence for population regulation in Alaskan caribou is weak, and that herds are likely to fluctuate within a wide range of densities due to complex interactions of predation and weather.” The two density-independent weather/climate factors most often mentioned in connection with the natality of caribou are winter severity (snow depths) and spring and summer temperatures as they affect the growth of vegetation, especially the length of the growing season. In this study, fecundity declined as a result of reduced phytomass at extreme summer numbers of 0/km², clearly in response to densities (table 0.). There was some recovery in 99 and 992, then an additional decline in 993 (table 0.). Our hypothesis is that the 992 reduction resulted from the reduced global temperatures in the summer of 992 that followed the volcanic eruption of Mount Pinatubo in 99 (Minnis et al. 993; also Griffith et al. 998). The summer of 992 was also the coldest on record in Ungava. The May to August mean temperature was 5.9°C vs a 38-year summer mean of 8.°C (second lowest May to August mean was 6.5°C in 972). The normal pause in mobility in September for late greens (fig. 2.3) was largely curtailed in 992 and was the least

Limiting Factors | 299

distinct in the 7 years of satellite monitoring (chapter 3). The mean snowfall 99–92 (October to June) was only 373.2 cm – similar to the mean for 37 years of 359.7 cm ± 5.30 cm (maximum 584.8 cm in 974–75); the mean snowfall from  February to 3 May 992 (the index used by Adams and Dale 998) was 64 cm – similar to the 37-year mean of 57 cm ± 0.8 cm, CV 39% (maximum 272.2 cm in 980–8. Thus it was the cold growing season in 992 – not snow depths the prior winter – that led to many females not conceiving in the fall of 992 and reduced natality the following June (table 0.). The cold growing season and early fall meant that many females – especially those 2 and 3 years of age, did not make the necessary fall weight to conceive. In Alaska and the Yukon, fecundity also fell for several herds in 993. The lower productivity was attributed primarily to severe winter snow conditions (Valkenburg et al. 996a, 2003a, b; Boertje et al. 996; Adams and Dale 998a; Hayes et al. 2003; Haskell and Ballard 2004; Jenkins and Barten 2005). These authors all used different winter severity indexes in their analyses. However, reaching estrus in the fall for spring natality depends on being in reasonable physical condition and achieving the necessary weight by the breeding season (Reimers 983a; Cameron et al. 993, 996; Adams and Dale 998a). The most immediate factor that should affect autumn weights is the summer growth of forage as a function of summer temperatures. Other considerations include the density of the population; whether cows were milk or yeld (Adams and Dale 998a); and insect harassment (Coleman et al. 200; and this study, but see Haskell and Ballard 2004). Haskell and Ballard (2004) further documented that spring productivity in the Central Arctic herd, Alaska (calves/00 females measured one week after peak calving), was correlated with the number of days of snow duration the prior winter over a 25-year period (977–2002) (r² = 0.375). We would prefer to reverse this and subtract the days of snow from 365 days: this shows the same correlation but as a positive response with the length of the growing season (or days free of snow, Boertje et al. 996). Haskell and Ballard’s most significant finding was the correlation of productivity with early snowfall, i.e., the total snowfall between 5 August to 30 September in cm (r² = 0.507). They stated in the abstract (ibid., 7) “Caribou of the CAH may exhibit a seasonal time-minimizing foraging strategy by moderating weight gain during the warm summer insect season and feeding more intensively during the insect-free weeks before the autumn rut.” This latter interval corresponds with the September pause for the George River herd (fig. 2.3). We contend that a long growing season, starting in mid-May and extending well into September and even early October – and not depth of snow cover in the winter – is the key to increased natality in the growth of 2- and 3-year-old animals. The term winter severity is ambiguous because snow lasts into May and overlaps with the start of new plant growth. We have argued earlier that May belongs to the growing season, not to the winter season. The turnaround in the animals’

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Table 11.3 The incidence of parasitism in the George River herd 1978–87 (data 1978–80 from Jean et al. (1982), data in 1983–84 and 1987 from this study) Organ

Parasitic Species

Year

Liver Cestode Trematode

Cysticercus tenuicollis Fascioloides magna

(1978–80) (1978–80)

28.7 (94)¹ 48.9 (94)²

Brain Nematode

Elaphostrongylus cervi

(1978–80)

0.0 (67)

Echinococcus granulosus Echinococcus granulosus Dictyocaulus viviparus Trichinella spiralus

(1978–80) (1987) (1978–80) (1987)

8.1 (61) 11.8 (297) 11.5 (61) 0.0 (52)

Cysticercus tarandi Sarcosporidiose

(1978–80) (1980)

1.1 (88) 10.0 (45)

Ostertagia sp. Nematodirus skrjabini Nematodirella longissimespiculata

(1983–84) (1983–84) (1983–84)

100.0 (41) 100.0 (41) 100.0 (41)

Moneizia sp.

(1978–80)

20.8 (77)

Lung/Diaphragm Cestode Cestode Nematode Nematode Heart Cestode Nematode Abomasum Nematode Nematode Nematode Feces

% Infected (sample size)

¹ Parker 98 reported a 7% infection rate for April 980 ² Parker 98 reported a 5% infection rate for April 980

diet quality starts in May, regardless of persistent spotty snow cover, and includes the first greens at the base of sedges and even digging for rhizomes. Skoog (968) and Miller (976a) both speak of animals seeking greens under snow. Skoog (968, 38) said: “These three plant groups (Salicaceae, Gramineae, and Cyperaceae) constitute the most important part of the diet during late April and May … favored foods at this time of year include the dead vegetation and the new shoots of various grasses” (see also Parker 98). Disease and Parasites The George River herd had a normal complement of parasites (table .3). Jean et al. (982) investigated the virology/bacteriology of the respiratory and digestive system in the serum of 2 animals 978–80. They reported no antibodies to Brucella, Leptospira, and Toxoplasma antigens in these three years. They reported only one reactor to Francisella tularensis and one to Toxoplasma grondii in 979. In 980 a mild reactor to Francisella tularensis was observed in the serum. Reac-

Limiting Factors | 30

tors to infectious bovine rhinotrachetis (IBR ), bovine andenovirus 3 (BAV3), bovine viral diarrea (BVD), and bovine parainfluenza 3 (PI 3) were found during the same period. Over the course of our study we quantified the abundance of warble fly larvae in the April collections of females 977–93 (broken); the presence of the Great American liver fluke (Fascioloides magna) in the liver 982–93 (broken) (see Lankester and Luttich 988); and the common tapeworm of the liver Cysticercus tenuicollis 982–93 (broken). In 987 the lungs of 297 animals were examined for Echinococcus granulosus. Our concern relative to these three parasites was to first determine if these parasites had increased as the herd grew in numbers. Our second emphasis was to evaluate whether the heavy loads of warble larvae and liver flukes had impacted on the spring condition of animals and could have contributed to the increased mortality rates of adults and calves in later years. Animals were divided into a low infection group – animals with less than the mean annual number of larvae or flukes – and a high infection group – animals with loads greater than the annual means. Fat indices and weights were compared between these two groups for the annual spring collections in which there were concomitant statistics by means of the t-test. Marrow fat percentages were transformed to arcsine percentages to correct for normality. The infections of warble larvae and tapeworms in the lungs did not increase as densities increased through the years, but the abundance of liver flukes increased both in frequency and intensity of infection (capsules per infected liver) (fig. .3). The frequency of liver flukes also increased with age, whereas the loads of liver tapeworms declined as the animals got older (fig. .4). Even though loads increased as numbers increased, the condition of the animals was not related to the abundance of liver flukes (table .4). However, in 987 the presence of Echinococcus granulosus tapeworms in the lungs may have influenced condition. The mean maximum back fat for infected animals was .0 mm ± 0.35 mm (n = 32) and for animals free of the parasite 2. mm ± 0.26 mm (n = 20) (P < 0.00), The percentage of marrow fat in the metatarsal for infected animals was 8.7% ± 4.3% (n = 29), and for nonaffected animals 89.5% ± 0.29% (n = 208) (P < 0.00). Relative to warble fly larvae, in all the comparisons in 9 years between animals below and above the mean infection rate, the animals with low infection rates were in better condition than those with loads greater than the annual mean (table .4). But did the warble infections contribute to the decline in physical condition or were animals in poorer condition the previous summer more susceptible to infection, less successful in evasive actions? There was no correlation between the mean annual infection rates and the percentage of antlerless females the previous summer – our index to summer condition (r = -0.322, n = 0). Furthermore, there was no increase in warble frequency in older animals that were more susceptible to wolf predation. Female calves and yearlings had higher rates than adults (fig. .3), but this could have been due to immunological weakness or

MEAN SITES PER LIVER LIVER FLUKE INFECTION (%)

10

0

FASCIOLOIDES ( ) MAGNA

r = 0.699 n = 13 (1,526)

80

r = 0.788 n = 9 (726) KES

LIVER FLU

60 40

LIVER TAPEWORMS

20

120

MEAN WARBLE LARVAE PER CARIBOU

S

FLUKE SITE

5

?

TAENIA HYDATIGENA ( ) (CYSTICERCUS TENUICOLLIS) r = 0.097 n = 9 (1,002)

ALL

( )

r = 0.105 n = 8 (191)

100

CALF + YEARLING

( )

r = 0.031 n = 11 (155)

80

60

40

20

?

ADULT

( )

r = 0.030 n = 12 (1,245)

0 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93

MARCH–APRIL SEASON

Fig. 11.3 (above) Comparison of infection loads of three parasites: liver flukes, liver tapeworms, and warble larvae with year, 1976 to 1993. Warble loads showed no trend even when summer densities of the Labrador tundra exceeded 12 animals/km² in the mid1980s. Males had heavier loads than females, as has been reported by other researchers (Kelsall 1975; Thomas and Kiliaan 1990; and European authors). Liver tapeworms showed no trend with herd growth but liver flukes increased. Fig. 11.4 (facing page) A comparison of the abundance of liver flukes, liver tapeworms, and warble larvae loads with female age. Liver flukes increased in older females, whereas liver tapeworms declined, and warble infection rates showed no trend.

Limiting Factors | 303

WARBLE LARVAE

80 70 60 50 40

Y=

30

r2 = 0.975 n = 10

INFECTED SITES

20 8 6 4 2

FASCIOLOIDES MAGNA

0

Y = 2.028 + 0.041X r = 0.936

80

PERCENTAGE INFECTED

40.6077X X  5.3424

9 YEARS, 769 CARIBOU

FASCIOLOIDES MAGNA

70

Y = 28.459 + 0.380X r = 0.941

60

9 YEARS, 1,466 CARIBOU

50 40 30 CYSTICERCUS TENUICOLLIS

20

Y = 41.803  0.196X r = 0.836

10

8 YEARS, 1,069 CARIBOU

10

22

34

46

58

70

82

94

106

118

AGE IN MONTHS

behavioural difference in young animals or even to a different sequence of molt patterns. However, males had higher infection rates than either young animals or adult females. The oldest males, especially the most mature males, shed their winter pelage earlier than parous females, and their short summer coat provides less of a barrier against the warble larvae’s penetration to the epidermis than does the dense winter coat of the females. In another comparison, the frequency of warble larvae was not higher in nonpregnant cows than it was in cows with fetuses in April: Presumably the non-

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Table 11.4 Comparison of the weight and fat condition indexes between female caribou with high loads of warble larvae and liver flukes and those with low loads of both parasites Warble Larvae¹ > Mean < Mean

P

Liver Flukes² > Mean < Mean

Maximum Back Fat (mm) 1980 3.4 ± 0.90 (43) 1982 4.9 ± 2.04 (16) 1985 2.5 ± 0.36 (32) 1986 0.9 ± 0.18 (131) 1987 2.0 ± 0.91 (81) 1988 0.8 ± 0.23 (73) 1989 0.3 ± 0.07 (47) 1991 1.4 ± 0.15 (64) 1993 6.2 ± 3.30 (9)

6.3+ ± 0.77 (71) 7.7+ ± 1.75 (27) 4.3+ ± 0.45 (47) 2.3+ ± 0.20 (298) 2.4+ ± 0.32 (158) 1.7+ ± 0.3 (14) 0.4± +0.06 (102) 1.9+ ± 0.17 (116) 11.0 ± 2.28 (22)

0.017 – 0.294 5.4+ ± 2.10 (7) 0.003 2.6+ ± 0.42 (20) 0.0001 2.5+ ± 0.46 (51) 0.713 3.5+ ± 1.25 (63) 0.019 1.2+ ± 0.44 (52) 0.137 0.3+ ± 0.08 (42) 0.058 1.6+ ± 0.20 (57) 0.255 10.5 ± 2.94 (11)

Total Mass (kg) 1980 86.6 ± 1.87 (44) 1982 92.5 ± 2.42 (18) 1993 89.4 ± 6.32 (9)

92.0 ± 1.27 (71) 95.6 ± 1.80 (30) 92.8 ± 2.81 (22)

0.020 0.323 0.636

– 94.4 ± 3.84 (7) 92.7 ± 1.73 (11)

– 6.0 ± 1.61 (27) 3.9 ± 0.40 (59) 2.4 ± 0.26 (120) 1.8 ± 0.24 (166) 1.6 ± 0.28 (143) 0.4 + 0.06 (91) 1.7 ± 0.16 (103) 8.7 ± 2.58 (18) – 95.5 ± 1.93 (31) 91.8 ± 4.19 (18)

P

0.84 0.04 0.90 0.19 0.46 0.33 0.65 0.66

0.51 0.80

Kidney Fat (gms) 1980 72.4 ± 4.18 (31) 81.7 ± 4.02 (56) 1982 109.3 ± 14.09 (16) 126.1 ± 11.77 (28) 1993 96.0 ± 17.13 (9) 111.1 ± 9.51 (19)

0.113 – – 0.366 130.0 ± 13.56 (7) 120.3 ± 12.62 (28) 0.60 0.455 117.4 ± 10.07 (11) 99.0 ± 12.14 (17) 0.25

Fat in Femur or Metatarsal (%) 1980 83.3+ ± 2.58 (43) 89.8 ± 0.69 (72) 1987 88.5 ± 0.55 (68) 90.0 ± 0.36 (134) 1988 81.7 ± 1.85 (72) 85.8 ± 0.80 (141) 1991 88.0 ± 2.17 (44) 89.0+ ± 1.40 (83)

0.019 0.025 0.004 0.699

– 90.2 ± 0.48 (57) 83.1 ± 1.5 (60) 87.3 ± 1.94 (45)

88.0 ± 0.46 (166) 0.04 85.0 ± 0.95 (159) 0.31 89.3 ± 1.51 (80) 0.41

¹ Mean warbles: 980, 44.9 ± 3.92 (6); 982, 5.0 ± 5.9 (48); 985, 28.5 ± 2.45 (79); 986, 43.9 ± 2.54 (429); 987, 46.6 ± 2.88 (239); 988, 56. ± 4.02 (28); 989, 49.7 ± 4.77 (50); 99, 56. ± 4.3 (85); 993, 40.5 ± 0.8 (3) ² Mean flukes: 982, .5 ± 0.73 (38); 985, .9 ± 0.5 (79); 986, 2.0 ± 0.3 (7); 987, 2.3 ± 0.3 (26); 988, 2.8 ± 0.42 (223); 989, 4.2 ± 0.6 (33); 99, 2.9 ± 0.30 (65); 993, 9.6 ± .9 (29)

pregnant females as a class were in poorer condition the previous summer than those that managed the weight gains to come into estrus. In the spring of 992 the females had the highest warble loads in our study (fig. .3); the following fall had the highest percentage of bald females; and the mortality rate was high the following year 992–93, at 7% (table 0.5). However, confounding the interpretation that high loads lead to reduced condition and high mortality rates was the fact that the spring and summer of 992 were the coldest on record and could explain the poor summer condition.

Limiting Factors | 305

We agree with Thomas and Kiliaan (990) that warble infection rates can reduce physical status, but we cannot document a density-dependent cause. With summer densities increasing so dramatically during our study, warble fly abundance should have increased as well as the ability of these flies to locate suitable hosts. Warble flies are strong flyers. Nilssen and Anderson (995) have shown that they are capable of flights of up to 500 km. We analyzed summer weather conditions the previous spring and summer to see if we could find an explanation for the annual variation in infection (table .4, bottom), but in these analyses neither June, July, or August temperature parameters, precipitation nor hours of sunshine were correlated with the frequency of warble loads of females the following April. We did not have sufficient data to attempt an evaluation of possible over-winter mortality of larvae. There was a huge range in the infection rate of caribou, ranging from animals with no infection to some that had over 500 larvae, which suggests that over-winter mortality of the parasites varies between caribou hosts. Yet in the late 970s, we had 300,000 animals with 9 million April larvae to pupate; 0 years later twice as many caribou in a restricted summer range had a similar load per host – an interesting density-independent aspect of this parasitic infection. Predation Wolf Abundance

Predation by wolves and/or bears is a major limiting factor in the growth of a number of free-ranging (non-insular) caribou herds in North America (reviews Bergerud 974a, 980, 983, 992; Seip 992; Seip and Chichowski 996; Boertje et al. 996; Hayes et al. 2003). Wolf predation was the greatest mortality factor of radio-collared females in this study (table .). When Luttich began flying in the 970s, wolves had reappeared and residents were harvesting them regularly in Nain and Fort Chimo (fig. .). Apparently the migratory George River herd could not support a resident wolf population in 958 when there were only 5,000 animals, but a herd of 50,000+ in the 970s could. Recall that the alternative prey of beaver, moose, and some mice species were not present in northern Ungava, even at tree line, in the 950–970s. But after wolves repopulated the northern taiga when the caribou returned, they showed no major increases for the next 20 years (fig. .), despite a fourfold increase in caribou. This is a simple predator/prey system: The lack of a numerical response in the predator population goes against theories of predator/prey oscillations that have been developed from the various and elegant mathematical and laboratory models from Gause to Huffacker. Messier et al. (988) offered the following explanations for the low abundance of wolves in northern Quebec/Labrador: () there were no other ungulate species in this area that could sustain an expanding wolf population; and (2) the

306 | TH E R E T U R N O F C A R I BO U TO U N G AVA

long-distance movements of caribou may have prevented wolves from increasing during the 4–5 summer months when wolves are tied to den and rendezvous sites. We certainly agree that extensive migrations of the herd can be an antipredator strategy (Bergerud 974b, 992, 2000). Furthermore, wolf pups do frequently starve on the ranges of arctic migratory herds (Kuyt 972; Williams 990). However, Luttich collected 22 wolf carcasses and/or skulls from the winters of 976–77 to 983–84. These wolves had good fat reserves and a high reproductive rate. Parker and Luttich (986) reported that 60% of the yearlings were breeding and the mean number of embryos or uterine scars from previous pregnancies was 6.8 pups/female. This is an extremely large litter size for North American wolves (Rausch 967; Parker and Luttich 986). A life table analysis by Parker and Luttich also showed high survival of these pups: Winter pups (0.5 year) represented 04 of the 22 animals aged (49%). Survival of adult wolves was 55% (Parker and Luttich 986). The potential for population growth should have been .08 per year (λ = [ - 0.45]/[ - 0.49]). The density of wolves below tree line in the 970s was actually higher than in the 980s (fig. .). It was not until 975–76 that the herd expanded its range as far west as Fort Chimo (Kuujjuaq). We only located two wolf dens in this study, one at Wedge Point (Indian House Lake) and one near Hebron. Adults from these dens would have had access to caribou throughout the summer. The evidence, based on their physical condition and high reproductive and survival rates, shows that wolves in Ungava were not generally short of food. We attempted a census of wolves in March/April 982 while counting the herd in the area between the Leaf/Larch and Koksoak rivers. This estimate was 2+ wolves/000 km². This census was conducted after the wolves had declined from rabies, based on harvest statistics and wolf-sighting statistics (fig. .). The decline was reflected in the mean winter aggregation size. During this census and for the period 980–84, the mean travelling group size was .7 ± 0.7 (n = 27 wolf packs), less than half that seen in 975–79 before the rabies outbreak, at 4.4 ± .8 (n = 8), and also low compared to the period after 984, when harvest statistics indicated an increasing population, 4.3 ± 0.67 (n = 0) wolves per group (fig. .). The most complete harvest statistics for wolves for all of northern Ungava were secured from 974–75 to 979–80; they averaged 262 ± 8.8 wolves. Parker and Luttich (986) felt exploitation of wolves was moderate in Ungava based on the age array of the animals they collected. If the annual harvest of nearly 300 wolves/year took 0–5% of the population, then possibly 2,000–3,000 wolves followed the caribou during these earlier years. In the Northwest Territories and Alaska common wolf densities over large areas are probably greater than those in Ungava but they are still relatively low, commonly 6 or fewer animals per ,000 km² (Clark 970; Ballard et al. 987, 997). Moose can be an important prey for at least three of these herds – Western Arctic, Porcupine, and Blue Nose – yet the winter densities of these herds are

Limiting Factors | 307

Table 11.5 Correlation matrix of indices of canid abundance, Ungava 1974–92, correlation coefficients, probabilities, and sample sizes 1 2 Wolves Harvested Kuujjuaq¹ Nain

1. Wolves Harvested Kuujjuaq 1974–87 2. Wolves Harvested Nain 1975–96 3. Wolf Royalties Kuujjuaq 1974–92 4. Wolves Seen per Trip 1974–91

-0.459 0.13 12

Correlation Coefficients 3 4 5 6 Wolf Wolves/ Fox Royalties Royalties Trip Arctic Red

7 Arctic Fox Harvest

0.549 0.05 13

0.675 0.008 14

0.389 0.18 13

0.428 0.14 13

0.169 0.62 11

0.076 0.78 16

0.312 0.24 16

0.031 0.91 16

0.168 0.53 10

0.757 0.01 16

0.318 0.20 18

0.628 0.005 18

0.705 0.001 18

0.347 0.36 10

0.023 0.92. 18

0.002 0.99 18

0.177 0.60 11

0.759 0.0003 18

0.612 0.06 10

5. Arctic Fox Royalties Kuujjuaq 1975–92 6. Red Fox Royalties Kuujjuaq 1975–92

0.418 0.23 10

¹ Excludes only estimates of wolves harvested Kuujjuaq 988 and 989

similar to the George River (Bergerud 996). The lack of prey diversity and the George River herd’s mobility (Messier et al. 988) do not adequately explain the wolf population’s failure to grow continuously with the herd 973–84. The wolves in Ungava did not increase coincident with the caribou because of periodic outbreaks of rabies. Rabies has been noted for wolves associated with the Porcupine and Western Arctic herds in Alaska (Rausch 958; Weiler and Garner 987; Ballard and Krausman 997). Both these herds and the George River and Leaf River herds have ranges that overlap with Arctic fox, which is the primary carrier of rabies in northern systems (MacInnes 987). Arctic foxes in Ungava range as far south as the Larch River and the headwaters of the George River (Harper 96; Peterson 966). The three canid species in northern Ungava (arctic fox, red fox, and wolves) fluctuated in numbers 973–92 based on fur returns and the wolves observed/ caribou survey. These fluctuations showed some synchronization, suggesting a common cause, which we believe was rabies (table .5). Wolves could have contacted rabies from killing foxes. Parker and Luttich (986) noted fox remains in

RABIES

RABIES

RABIES

70

RABIES

308 | TH E R E T U R N O F C A R I BO U TO U N G AVA

WINTER CALF MORTALITY (%)

60

CALF WINTER MORTALITY

50

40

30

NO CLASSIFICATION

20

10

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

COHORTS

Fig. 11.5 The mortality rate of short yearlings in April–May showed major decreases in years following an outbreak of rabies in the wolf population.

7% of the wolf stomachs collected 980–8 to 983–84. Both species of fox as well as wolves reached an extremely low point after the 982 rabies outbreak (figs. .9, .). Wolf Predation

Despite the low numbers of wolves in northern Ungava, they were still the chief factor in the death of radio-collared females. They also heavily impacted the growth of the herd by preying on calves in the winter. Following 3 of the 4 rabies outbreaks, three calf cohorts 976, 982, and 992 showed increased survival over winter (fig. .5). The improved survival of these three cohorts is prima-facie evidence that wolf predation is responsible for most of the winter deaths of calves. The correlation coefficient between winter mortality of calves and the harvest of wolves at Kuujjuaq (our best index to wolf abundance) was highly significant (r = 0.665, P = 0.0068, n = 5). Our conclusion is that wolf predation was the major cause of death of both calves and adult females. The rabies outbreak in 980–82

Limiting Factors | 309

Table 11.6 A comparison of the age of caribou killed by wolves over winter in the early 1980s between males and females and compared to a random sample of the population drowned at Limestone Falls in September 1984. Age of Death

% Males in Dead Drowned Wolf Predation

Chi Square

% Females in Dead Drowned Wolf Predation

Chi Square

Calves 1 to 3 yrs 4 to 7 yrs Old 8+

19% (107) 32% (180) 39% (218) 10% (55)

20% (7) 23% (8) 17% (6) 40% (14)

0.08 0.93 4.38 33.05

13% (130) 41% (407) 30% (305) 16% (163)

none 23% (8) 29% (10) 49% (17)

– 2.68 0.03 22.64

100% (560)

100% (35)

38.40

100% (1,005)

101% (35)

25.35

Total

Also killed by wolves, sex unknown: 6 calves, 6 animals –3 years, 7 animals 4–7 years, and 7 animals 8+ years. Age and sex unknown 2 animals, age unknown 7 females and 5 males. Total killed by wolves 42 females and 40 males.

resulted in a loss of possibly 60–75% of the wolves. Following this outbreak, the excellent survival of the 98–83 calves doubled the size of the population, and is clear experimental evidence that wolf predation was the most significant limiting factor on the growth of the herd in the 980s. In the winters of 98–82 and 982–83 we made special searches for the remains of caribou killed by wolves to ascertain if the predation was heaviest on undernourished and young and old animals. The percentage of fat in the bone marrow of males killed by wolves was 83.5% ± .29% (n = 4) and for  females 8.8% ± 2.22%: This was not significantly different from that of 33 females we collected for comparison, at 86.2% ± 0.89%. However, wolf predation was heavily biased to older females and males (table .6). It has been suggested that large, prime males are more susceptible to winter predation because of the weight and fat loss during the rutting season (Dauphiné 976). But in this study it was not the prime bulls (4–7 years of age) that were susceptible, but the older animals (table .6). Large bulls had similar metatarsal fat throughout the fall and winter (table .2) and used primarily back fat and kidney fat as an energy source in the rut (fig. 9.4). For the entire study, 44 males killed by wolves were located and 49 females, a ratio of 47:53, whereas the living population based on classifications was 36.5:63.5 (n = 06,999 animals classified over 8 years) (table 0.4); and the sex ratio of the adults that drowned at Limestone Falls was 34:66 (n = ,6). Additionally, the search for animals killed by wolves was heavily biased towards females that had been radio-collared. Still, bulls were killed more frequently than females: The ratio of living animals was  bull to 2 cows; the kill ratio was even. The role of wolves in predation of calves and adults in summer was less clear. When wolves were present they were highly successful in killing calves (table .7). Surplus killing of young calves has been well documented by Miller et al.

30 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 11.7

Observation of wolves killing caribou calves in 1989 and 1991

Total Wolves Total Time Watched Calves Killed/Wolf Mean Chase Time (sec) Mean Time to Abandoned Chase (sec) Mean Time between Kills (sec) Killing Time (sec) Initial Handling Time (sec)

17 June 1989

2 July 1991

2 13 min. 6 sec. 5/0 38 ± 13.6 (5) – 61.5 ± 26.74 (4) 22.4 ± 9.21 (5) –

3 84 min. 28 sec. 5/1/5 19.9 ± 2.6 (9) 29.0 ± 7.0 (2) 782.5 ± 434.16 (6) 49.5 ± 5.50 (2) 100.2 ± 8.77 (5)

July 2 An example of seeking water escape: time 4:50, great big grey wolf chases lone calf into water and keeps pursuing it from shore; 4:52–53, calf goes back on shore and is killed.

(985). However summer calf recruitment was extremely constant for the 973–83 cohorts (53 ± .72 calves per 00 females in the autumn (CV = 7.4%), in a period when wolf numbers fluctuated. The overall correlation between the wolves harvested at Kuujjuaq and a summer mortality index of calves (pregnancy rates minus fall recruitment) was r = 0.748, P = 0.002, n = 4. The significance in this relation was largely due to the inclusion of crude estimates of the number of wolves taken at Kuujjuaq in the winters 989–90 and 990–9 (200 animals); these were not quantified by fur returns, and would not have been as accurate as the estimates 973–74 to 986–87. Without these two data points the correlation between harvest and the summer mortality index was r = 0.486, P = 0.09, n = 2, which is suggestive but not significant. Still, wolf predation was likely the chief cause of death of calves in the summer. The annual surveys of the calving ground only located 3 possible bear kills in 20 years. But scavenging cannot be ruled out, since females frequently die during parturition. Our observations suggested that bears were most common above tree line. Veitch and Harrington (995) showed that bears in the Torngats had large home ranges in the summer and that caribou were an important aspect of their diet. In August 990, September 990, and August 992, Veitch and Krizan (995) saw bears feeding on seven adults (6 females,  male) that they believed the bears had killed. Their analysis of 803 scats over 5 years found that caribou was present in the diet throughout the year, occurring in 26.4% of scats (or 8.3% of the total volume). Differential Mortality of Males and Females Biologists have had a keen interest in the sex ratio of mammals since the days of Darwin. Caribou males grow old faster than females; their M₁ tooth is worn to

Limiting Factors | 3

the gum line by at least 0 years of age, whereas females probably don’t reach a similar state until 3 years (Miller 974). The oldest male among the adult animals that drowned at Limestone Falls in 984 was 2.5 years (n = 560); the oldest female was 5.5 years (n = 005). The maximum longevity of males is approximately 3 years; for females it is 7 years (Flower 93; Bromée-Skuncke 952). In this study we have measured the proportion of males and females as fetuses (in 0 years, n = ,277); at birth (in 7 years, n = 278); at about 5 months of age (in 9 years, n = 5,50); at 0–2 months of age (in 20 years, n = 23,675); at 7 months of age (8 years, n = ,648); and as adults >  year (8 years, n = 00,609) and > 2 years (3 years, n = 99,62) (table 0.4). These are the largest samples in the caribou literature and they provide new information on differential mortality between the sexes. One ordinarily tests for significant deviations from the expected evolutionary sex ratio of 50:50 by using the binomial distribution. This requires large departures from the expected 50:50 to show significance (see Thomas et al. 989). In our testing we have applied the “equality of two percentages test” (Sokal and Rohlf 969, 608), and we have used the total sample sizes recorded over several years as the test numbers, rather than sample sizes secured annually. It was valid to combine samples between years because the sex ratios of the George River herd showed no significant trend 973–93 (fig. .6). The sex ratio of fetuses represents the closest ratio we have to conception and is thus of particular interest for testing the evolutionary Fisher Principle that evolution proceeds according to a 50:50 ratio, with maternal investment equal between the sexes. There is no compelling evidence in the caribou literature of widespread abortions of early embryos; certainly in the later stages of pregnancy abortions have not been documented (see Dauphiné 976). The fetal sex ratio for the George River herd was 50.8% males (n = ,277) and showed no detectable change between growth phases of the herd (table 0.4). In a sociobiological context, it is predicted that females should produce a higher proportion of males when they are healthiest because these offspring will mate most successfully and produce the maximum number of grandchildren (Trivers and Willard 973). The females in the George River herd were healthiest in the increase phase and undernourished after 984–85, yet the ratio of males to females was not significantly different in either phase. Skogland (986a) reported more male fetuses than females born to females of undernourished herds in Norway, which is also contrary to the Trivers and Willard investment hypothesis. We further compared the physical condition of females carrying male vs female fetuses in April (table .8). There was no difference in the health of females at that late date relative to the sex of their future offspring. These condition indexes refer to winter condition but indices such as kidney fat should still have a basis in summer condition that might affect the sex ratio at conception. A further test of the Trivers-Willard hypothesis was to compare the fetal sex ratio of young females with better dentition with that of old females with

32 | TH E R E T U R N O F C A R I BO U TO U N G AVA 60

5–6 MONTH CALVES Y = 191.165 + 0.1224X r = 0.134 n = 9 years

55

LONG YEARLINGS Y = 488.905  0.223X r = 0.162 n = 18

PERCENTAGE MALES

50

FETUSES Y = 74.850  0.012X r = 0.009 n = 10

45

SHORT YEARLINGS Y = 336.008 + 0.191X r = 0.180 n = 20

40

35

> 1 YEAR Y = 85.928  0.025X r = 0.044 n = 18 years

30

EXCLUDED

25

20 1972

74

76

78

80

82

84

86

88

90

92

1994

YEARS Fig. 11.6 The proportion of males to females (sex ratio) by age classes. At birth males represent approximately 52% of the viable calves but as adults the ratio is 1 male to 2 females and this remained constant for the George River as the herd grew to 600,000 animals. However adult males have a shorter lifespan than females. The sex ratio of the adults that died at Limestone Falls in 1984, age nine years and older, was 25% males and 75% females (n = 218). The fall classification counts of adult males in 1991 and 1992 underestimated the proportion of males; we observed a greater proportion of males further west on the migration route but did not quantify them.

worn incisors and molariform teeth. Thomas et al. (989) reported that young females –4 years of age produced more female calves and females older than 0 years gave birth to more males in the Beverly herd (NWT). We could not show a change in the sex ratio of fetuses with female age (fig. .7; table .9), even though our largest samples came in the latter years when the summer ranges had been over-utilized. Our data did not support the theory that differences in the ratio of

Limiting Factors | 33

Table 11.8 The physical condition of females carrying male and female fetuses in the spring (April and May) Good Nutrition Years

1980 Kidney Fat (gms) Back Fat (mm) Body Weight (kg) 1982 Kidney Fat (gms) Back Fat (mm) Body Weight (kg) 1993 Kidney fat (gms) Back Fat (mm) Body Weight (kg)

Females w/Female Fetuses

Females w/Male Fetuses

83.3 ± 4.27 (53) 6.6 ± 0.94 (47) 91.9 ± 1.35 (55)

83.1 ± 5.78 (39) 5.8 ± 1.30 (34) 91.1 ± 1.53 (49)

98.6 ± 7.29 (18) 5.7 ± 1.24 (15) 93.2 ± 1.82 (19)

111.5 ± 9.35 (18) 3.1 ± 1.00 (17) 97.9 ± 2.02 (16)

119.2 ± 12.87 (12) 10.9 ± 3.37 (12) 96.9 ± 2.39 (12)

122.0 ± 10.52 (9) 13.8 ± 3.23 (9) 98.0 ± 4.10 (9)

Poor Nutrition Years

1983 Kidney Fat (gms) Back Fat (mm) Body Weight (kg) 1992 Kidney Fat (gms) Back Fat (mm)

67.0 ± 16.58 (4) 1.3 ± 0.90 (4) 87.7 ± 7.88 (3)

83.3 ± 24.30 (4) 1.8 ± 1.44 (4) 87.5 ± 3.50 (2)

16.4 ± 1.48 (47) 0.7 ± 0.22 (71)

16.6 ± 1.61 (56) 0.4 ± 0.11 (84)

Table 11.9 Comparison of the fetal sex ratio between females of different ages and between years of good summer nutrition 1980–83 and 1993 (> 80% pregnant) and poor nutrition 1985–92 (< 75% pregnant) Age of Females

Good Nutrition

Poor Nutrition

% Male

Young 1–4 Years Prime 5–9 Years Old 10+ Years Total

34 M:39 F (46.6%) 38 M:44 F (46.3%) 12 M:14 F (46.2%) 84 Males:97 Females (46.4%)

172 M:154 F (52.8%) 243 M:226 F (51.8%) 51 M: 55 F (48.1%) 466 Males:435 Females (51.7%)

51.6 51.0 47.8 50.8

males to females were related to the condition or ages of the mothers, a finding Reimers and Lenvik also reached (997). The sex ratio at birth favoured males (55.8%, n = 278) (table 0.4), but as in other studies the samples weren’t large enough to show a significant departure from unity. Still, the results that males predominate at birth have been so consistent in all the major caribou studies (Kelsall 968; Skoog 968; Bergerud 97b) that it is time to accept it. We should call this the sex ratio of the living at birth.

34 | TH E R E T U R N O F C A R I BO U TO U N G AVA (160)

160

MALE FETUS

(142)

140

NUMBER OF FETUSES

1980–93

(152)

(130)

TO

FEMALE FETUS

120 (105) 100

(99) (80)

80

(65)

(63)

(70)

60

40

20

(12)

0

1

2

3

4

5

6

7

8

9

10

>10

FEMALE ADULT AGE CLASS (YEAR)

Fig. 11.7 There was no significant trend in the proportions of male and female fetuses with maternal age.

These rates are commonly based on the captures of -day old calves without including calves that died shortly after birth. Perinatal mortality is significant in caribou (Miller and Broughton 974; Miller et al. 985; Whitten et al. 992) and is heavy to the smaller calves. Since females weigh less than males (Bergerud 975) they would be more susceptible to these early viability losses. The 962 cohort of the Kaminuriak herd was a weak cohort in age arrays of animals collected by Miller (974) in 966–68 and males predominated for this cohort. The maternal females for this cohort faced maximum snow depths in 96–62 (Dauphiné 976) and some adults starved before reaching the calving ground (Kelsall 968). The smaller female calves may have died following birth (Bergerud 996). But contrary to this, Couturier (personal communication) found that equal numbers of underweight male and female calves in the George River herd died shortly after birth in 992 (20% neonate mortality) and the proportion of males and females in the fall classification in 992 favoured females (55%, n = 943). The percentage of male calves at 5 months was 53.2% (n = 5,50), similar to that at birth 55.8% (n = 278). Thus males and females probably died at similar rates over the summer, when the two major losses are predation and drowning. We have no information as to whether wolves/bears were selective. In New-

Limiting Factors | 35

foundland lynx took more male calves than females because males wandered farther from their dams (Bergerud 97b). In the Nelchina herd in Alaska there were fewer male calves in years of high wolf numbers (correlation coefficient of percentage of males on wolf numbers, r = -0.72; Bergerud and Ballard 988). Again, in northern British Columbia it appeared that wolves/bears took more male calves than females; there was a correlation between the adult sex ratio – males/00 females – and the size of the fall recruitment – calves/00 females (Bergerud and Elliott 986). Either summer predation in the George River herd was not selective to males or it was compensated by some other mortality factor weighted to females. The other chief cause of mortality of calves after the initial deaths was probably drowning, but among 0 calves that drowned, 8 were male and 2 were female. Miller et al. (985) provided a sex ratio of 54:46 (n = 32) for calves killed or suspected to have died from predation for the Beverly herd. Males do seem more susceptible to predation than females in all of these studies, but that is not the case for the George River herd. Our sample size of the proportion of males and females in the fall was very large – 5,50 calves – and males outnumbered females each of the 9 years that classifications were made (54.3 ± .9) (table 0.4). The differential mortality from predation over winter of potential recruits was clearly heavy to males (table .6). The percentage of males in the fall population of 53% was reduced to 44% males by 0–2 months of age (table 0.4, n = 23,675, P < 0.000). This decline was not an artifact of differential migration rates of males and females in the spring. The proportion of long yearlings at 7 months of age also favoured females, with only 46.% males (n = ,648), also a significant decline from 53% males at 5 months of age. We did not find any yearlings dead between 0–2 and 7 months of age. The decline in males occurred in the first winter of life and not in their second summer. The differential mortality of males over winter was due to wolf predation. There was no evidence of winter starvation. Of 3 calves killed by wolves, 7 were males; the sex could not be determined for the other 6. The age array of calves and yearlings that died at Limestone Falls also showed that males died more over winter than females. There were 07 male calves and 74 male yearlings, a decline of 3%, whereas there were 30 female calves and 38 female yearlings (fig. .8). These comparisons are conservative since the 983 cohort was larger than the 984 cohort. Based on the survival of radio-collared male calves in both the Porcupine herd and the George River herd, males had higher mortality rates than female calves between fall and the spring (Hearn et al. 989; Fancy et al. 994; Crête et al. 996). We hypothesize that in North America the males are generally more susceptible to predation and this applies to calves between the ages of 5 and 0 months as well as adults (Bergerud 980). Miller (974) proposed that the mortality of males and females was similar in the first 4 years of life, but his assumption was based

5.0

1982 COHORT

(138) (156)

(130) (107) 4.5

(113) (94) (83)

(74)

(65)

(61)

NATURAL LOG OF ANIMAL NUMBERS

4.0

(63)

(67)

(53) (53)

(57)

(50)

FEMALES (40)

(40)

3.5

(24)

(23)

MALES

3.0

(19)

(18)

(12)

2.5

2.0

(7)

MALES n = 560 FEMALES n = 1,005

(5) (4)

1.5

(4)

(4)

(1)

1.0

0.5

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

AGE (YEARS)

Fig. 11.8 The proportions of adult males and females that drowned at Limestone Falls in September 1984 provided data on the sex ratio independent of observational bias. The proportion of adult males was 32% (n = 1,216) and not significantly different from the fall classifications ratio 36.5% secured in 13 years (table 10.4). The proportion of males in 18 herds in North America was 35.7% ± 0.99% (Bergerud 1980). This ratio of 1 male to 2 females has been so consistent in the North American herds, including the George River, that major deviations generally imply a sampling error rather than a biological reality. The unbiased Limestone survivorship curves of adults again shows the shorter lifespan of the XY sex, a general characteristic of mammals (Medawar 1957).

Limiting Factors | 37

on a small sample of long yearlings (n = 70) from the Nelchina herd at a time when wolves were scarce (Skoog 968). Miller (974) actually observed 3 male yearlings and 8 female yearlings in April in the Kaminuriak herd. The adult sex ratio of the George River herd was 36.5:63.5; if the recruits joined the adults at a ratio of 46.% males (table 0.4), then 29% of the adult sex ratio is explained by differential recruitment and not by differential mortality of adult males and females. The adult sex ratio (>  year) was 36.5% males (table 0.4) and showed no trend over 8 years (fig. .7). We excluded the October classifications in 99 and 992 from the regression in figure .6. In these two seasons the herd was migrating back to eastern ranges after rutting mostly west of 66° W (98–90). At the front of the migration where we classified, the males were predominantly younger animals; many of the older males were still farther west. The proportion of males in October–November 993 was 33.0% (Couturier et al. 996), similar to that prior to 99–92 (table 0.4). A comparison of the survivorship curves of males and females from the age array of animals that died at Limestone Falls in September 984 indicates that mortality to males increased in the older age classes as opposed to females (fig. .8). This should be expected from tooth-wear schedules and life table analyses as well as from sexual selection in a polygnous mating system. There did appear to be a series of prime years (age 3–7) when male mortality rates were similar to females, as Tyler (987) reported for Svalbard caribou. If this is the case, then the remaining unexplained discrepancy between the male and female proportions in the population would arise from the higher loss of males > 7 years of age. Male caribou just don’t have the longevity of females, as all life-table analyses have shown. There are fewer and fewer males as the cohorts age (fig. .8), a drop from 50.8% male fetuses (as predicted by the Fisher Principle) to 36.5% male adults. Males, as opposed to females, sacrifice their fitness in old age in their intrasexual competition for mates. The most important limiting factor in this investigation was the mortality resultant from hunting and wolf predation. But to halt the march in animal numbers, we need a regulating factor that increases in severity with densities. This regulating factor was the shortage of green phytomass (chapter 7), which reduced fecundity and resulted in smaller animals that were more susceptible to predation. The herd was limited and regulated. In 2000 the Taimyr herd in the Soviet Union reached over a million animals (Kolpashchikov et al. 2003) and has replaced the George as the largest in the world. Wolves are controlled for this herd. We predict that the day will come when a shortage of summer food on the Taimyr Peninsula shuts the door, halting further growth.

C H A P T E R T W E LV E

The Use of Space

Most species of vertebrates have a means of spacing themselves across the habitat. Bergerud’s model (Bergerud 974b) for caribou proposes that these ungulates evolved in recent times in a largely open habitat in the presence of wolves (Canis lupus), resulting in a gregarious lifestyle. This gregarious social structure in the presence of sparse and ephemeral arctic flora, variable snow cover, and insect harassment gave rise to contingencies that required annual cycles in aggregation and movement behaviours. We would like to further document the cycle in mobility and the use of space by the George River caribou herd in Ungava and discuss the enviromental influences that affect their distributions and rates of travel. In the 950s the only large migratory herds on the continent that migrated to calving grounds north of the Arctic tree line were in northern Alaska and the Northwest Territories (Leopold and Darling 953; Banfield 954). In Ungava, an immense wilderness area east of Hudson Bay that was practically empty of migratory caribou, the George River herd was nearly extinct and possibly numbered less than 5,000 animals (Rousseau 950; Banfield and Tener 958). When we first observed the herd in 958 fewer than 5,000 animals were estimated to occupy an area of 90,000 km² or only 0.7 animals/km². This herd then grew to 650,000 animals by the 980s (Crête et al. 99), occupying 750,000 km², and was the largest herd in the world (Williams and Heard 986). This 30-fold increase in numbers in 30 years (955–85) has not occurred for the other large migratory herds. Alaska caribou (R.t. granti) expanded their range from 680,000 km² in 953 to ,200,000 km² in 996 (Leopold and Darling 953; Valkenburg et al. 996a) while the migratory herds in the Northwest Territories (R.t. groenlandicus) have occupied a continuous range of two million

The Use of Space | 39

km² since Banfield first documented their mainland distribution in 949 (fig. I .). Thus the range expansion of the George River herd since 954 is unparalleled in North America and provides us with the opportunity to learn more about how this species perceives its environment and modifies its use of space as its numbers increase. Ungava north of 53° N has remained largely undisturbed (fig. .) and even in the 990s there were fewer than 25,000 native peoples and settlers, most of whom resided mostly on the shores of Hudson Bay, Ungava Bay, and the Labrador coast (fig. .2). The range available to the herd was as it has been since the Laurentide Ice Sheet disappeared 5,500 years ago and the arrival of the natives between 6,000–4,000 bp at Indian House Lake (Hutte Savage Lake) to hunt caribou. Skoog (968) proposed two basic concepts 38 years ago that we believe are the cornerstones of the functional use of space by caribou. These are the “centre of habitation” hypothesis and the “social stimulus” hypothesis. The centre of habitation hypothesis argues that there is a core component of the most optimum habitat to which the caribou restrict themselves when their numbers are low. These areas in Alaska were primarily the tundra biome beyond tree line that included landscapes with the most productive vascular forage. The social stimulus theory suggests that there is a social limitation to population density: When caribou numbers increase to 5–0/mi.² the animals become restless and mobility increases, which results in movements from the centre of habitation. These expansions to more marginal ranges (primarily below tree line) negatively impact demography. Skoog felt that this social stimulus was not triggered by the abundance of winter foods, including lichens, but he never postulated how these density-dependent changes in spacing came about. Neither of these ideas has been fully developed in the intervening years and that is our pursuit here. Aerial Survey and Radio Monitoring Methods The major data presented below was gathered between 974–93, when Stuart Luttich and his assistants, as well as biologists from the Quebec Wildlife Service, monitored changes in distribution based on aerial surveys – primarily in the spring and fall when Newfoundland and Quebec biologists conducted herd composition surveys. All these surveys plotted the locations of major concentrations on topographical maps and indicated their directions of travel. The first VHF radios were placed on George River animals at Indian House Lake in September–October 973 by the Canadian Wildlife Survey (Dauphiné et al. 975). The Newfoundland Wildlife Service first placed radio transmitters on caribou in October 982, intercepting the herd at the Koksoak River. The Quebec Wildlife Service joined the Newfoundland effort in 983 and this monitoring program continued under Luttich’s supervision until 993.

320 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Caribou with these VHF radios were located on 37 searches made between October 982 and October 988 in an area between 53° N and 59° N and from the Labrador Coast to Hudson Bay. Twenty-four of the flights were made in a DC -3 aircraft charted by the Quebec Government (Vandal et al. 989) and flown on transects at intervals of 50–75 km at an altitude of 2,000 m. On these flights caribou with active signals were plotted without visual sightings. The mean search area was 323,084 ± 29,699 km² (CV = 44%) and the success of finding animals believed to be alive at the time of the search was: June: 90% ± 3.5%; December– February: 63% ± 8.8%; August: 6% ± 8.6%; and October: 63% (n = ). The mean number of collared animals thought to be alive during these searches was 75 ± 5.6% (extremes 39–09). Luttich conducted the remaining 3 flights in a helicopter and attempted to ground-truth locations. He generally searched smaller areas, primarily in Labrador, with a major effort directed at finding the collars of animals emitting mortality signals. Renewable Resources Consulting Services also located radio-collared animals between June and October 990–95 in the general vicinity between 54°–57° N and 6°–67° W when they mapped the caribou distributions in the low-level flight zone flown over by military aircraft from Goose Bay, Labrador (reports on file Renewable Resources, Sidney, BC ). From 986–93 satellite radios (UHF radios) were installed on females (n = 4–0/year), mostly when they were on the calving grounds in June or above tree line in July or August. These radios provided location signals at 3–4 day intervals and had both short- and long-term activity sensors (Fancy 983; Camps and Linders 989). In all years 974–93 except 983, the boundaries of the calving distributions were determined by aerial transects (see also Vandal and Couturier 988; Couturier et al. 990; Crête et al. 99; Théau and Duguay 2004). Rutting and winter distributions were plotted 982–83 to 992–93 based on radio tracking. We estimated the centre of these annual distributions (calving, rutting, and winter) and measured the linear straight distances between them to quantify range expansions and contractions. The areas of the rutting and winter distributions were based on the location of the radio animals during these time periods and clearly underestimate the actual size of the distributions. We used the snow depth recorded at the beginning of each month as measured at Schefferville by students at the McGill Research Station 973–74 to 99–92 (no data 992–93) to assess the influence of snow cover on the annual changes in distribution and travel rates. In some comparisons we also used McGill snow statistics that were gathered at weekly intervals. This station had been in operation since 955; snow depths were based on a 0-station route through a cross section of habitats. Students at the research station also recorded the freeze-up and ice break-up dates of Knob Lake near the station biannually 954–55 to 992–93 (fig. .4).

The Use of Space | 32

The Centre of Habitation Skoog (968, 205) said, “The availability of suitable alpine or tundra areas to a great extent determines the centre of habitation of caribou in Alaska.” We expanded this definition to include the calving areas which Skoog (968) felt were the focus of the annual movements of caribou sub-populations. Originally Skoog did not include the lowland coastal calving area of the Porcupine herd in his centre of habitation of Region IV in Alaska. Historically there have been two major calving areas in Ungava, one on the tundra north of the Leaf River on the Ungava Peninsula and one west of the George River on the Labrador Peninsula (Elton 942; Spiess 979). These two distributions are recognized by caribou biologists as the Leaf River herd and the George River herd. These two calving areas and the adjacent tundra used in the summer should form the basis of two centres of habitation. Systematic aerial surveys to determine the distribution of caribou in Ungava first occurred between 9 April 954 and 27 March 955 (Banfield and Tener 958). These workers flew 0,650 miles and observed the George River population adjacent to the Wheeler, Whale, and George Rivers. A second survey in March/April 958 (Bergerud 967) located the George River herd between 66° and 63° W in the vicinity of White Gull Lake (,355 animals seen). Another group was to the north and west of Okak (56 seen). Combining the winter distributions of 954 and 958 gives a winter range of 50,000 km² most of it below tree line and based on a total population of 0,000 animals only 0.2/caribou per km². In the centre of this range was the Lac Champdore calving ground, which was discovered in 970 (fig. 2.), although the area was known to natives in 958 (Bergerud 958), and had probably been occupied throughout the years of scarcity. The Lac Champdore region is a vast area of muskeg interspaced with conifer stands and is approximately 50 km south of the Arctic tree line. The majority of the herd when low in numbers prior to the 970s may have calved below tree line. The calving area of the Leaf River herd when first discovered in 975 was adjacent to the tree line on the Ungava Peninsula (Le Henaff 975), but in latter years as numbers increased shifted 300 km further north. Thus these are two examples of the migratory ecotype calving in forested cover when low in numbers and wolves were scarce. The winter distributions in 954 and 958 accounted for only half the total range of the herd. Interviews with the residents of the weather station at Indian House Lake in 958 indicated frequent crossings of the George River in the summer in those years, and Banfield and Tener (958) noted that summering caribou used the tundra east of the George River. Rousseau (950) as well had seen caribou along the George River in the summer of 950. Thus the total area of the centre of habitation that existed in the low years (920–950s) was about 90,000 km² (fig. 2.).

o

70

o

60

o

65

( KILLINEK )

o

60

o

60

PAYNE BAY 0

UNGAVA

0

50

100 KILOMETRES 50

100 MILES

BAY

LEAF RIVER

GEORGE RIVER

FORT CHIMO

( HEBRON )

TREE LINE GEOR G

( NUTAK ) ( OKAK )

( FORT MCKENZIE )

INDIAN HOUSE LAKE

E R.

LARCH RIVER HERD 1954

NAIN ( ZOAR )

(FORT NASCOPIE)

DAVIS INLET

OF TRE CEN

HOPEDALE

o

55

CANIAPISCAU HERD 1954

o

55

HA BIT ATI ON OF

CARIBOU

RED WINE CARIBOU HERD

PI KA NAS OF N ATIO CE NTRE OF HABIT

o

o

70

WINTER DISTRIBUTION 1954 WINTER DISTRIBUTION 1958 FORMER CALVING GROUND

60

o

65

HUNTING AREAS 1950s GEORGE RIVER HEBRON

CARIBOU JULY / AUGUST 1955, 53, 54

NAIN

CALVING CARIBOU JUNE 1970 & 1972

DAVIS INLET

( ) FORMER SETTLEMENTS

HOPEDALE

Fig. 12.1 The centre of habitation of the George River herd based on the early distributions 1950-1960s when the herd numbered < 50,000 animals. The centre of habitation theory was developed by Skoog (1968) – it is the most optimum and secure area in the range of a herd and the area they occupy at low numbers. This centre is mostly at tree line and above on the tundra. As numbers increase the animals leave this centre more frequently where they encounter more marginal habitats and population growth declines. Also shown is the historical centre of habitation of the Naskapi Indians (Weiler 1988).

The Use of Space | 323

It is significant that this centre of habitation coincides with a map prepared by Weiler (99) based on historical and traditional knowledge of the traditional range of the Naskapi (fig. 2.). Through high and low caribou numbers for several thousand years the ancestors of these hunters followed the caribou across the entire centre of habitation of the George River herd. In her epic journey down the George River in 905, Mrs Hubbard found the Naskapi in residence at Indian House Lake, the very heart of the caribou’s centre of habitation. Fifty-three years later Bergerud found the Naskapi camped at Mistastin Lake waiting for the caribou. When he discussed the low numbers of deer with Chief Joe Riche, telling him that he had seen few from the air, the chief assured Bergerud they’d be along; and so they were. In the 950s there was concern that the George River herd might go extinct. Banfield and Tener (958, 57) remarked that “it was formerly thought the law of diminishing returns would apply to native utilization of caribou: the number of caribou taken would decline as the caribou herds diminished in size until it would not be worthwhile to hunt caribou.” However, they went on to say that observations of natives hunting at Port Harrison, Quebec, in March 956 showed that caribou hunts lasting three to six weeks and involving 00–300 miles travel by dog team could still be unsuccessful. “When they find the tracks of a band of caribou they trail it day and night until all the caribou are killed or a storm obliterates the tracks” (ibid.). These researchers worried that the law of diminishing returns would not apply in Ungava. If the George River herd only numbered 5,000 animals in an area of 90,000 km² as Rousseau (950) postulated and which the census of Banfield and Tener (958) seems to confirm, then the density would have been 0.06/km². This is the stabilizing density of several woodland sedentary herds in North America including those in Ungava south of 54° N (figs. 4.6, 4.7). The stabilizing density was defined as that spacing that resulted in balanced recruitment and mortality rates (Bergerud 992) and occurred when wolf predation was the major limiting factor. The George River herd did recover from this low when wolves were exceedingly rare (Bergerud 958; Novak et al. 987), reaching a density of 0.7/ km² in 958 (Bergerud 967) and continuing to increase for the next 26 years. Thus this spacing density apparently was sufficient relative to native hunting for births to exceed deaths, and the law of diminishing returns did apply, despite the tenacity of native hunters, unaided by aerial surveillance and searching by dog team in the vast space of the centre of habitation. Through the years that followed our study of the George River herd, the females have returned faithfully each year to the calving core and centre of habitation in the Labrador tundra. In 2006 they returned to the height of land southwest of the Hebron Fiord – the same area where they had calved in 979 (see Théau and Duguay 2004, fig. 2). Then the size of the calving ground had been 5,900 km²; this centre of calving was 40 km east of the George, and the herd

324 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 12.1

Minimum sizes of ranges (km² x 1,000) used by the George River herd

Year 1 June–31 May

1972–73 1973–74 1974–75 1975–76 1976–77 1977–78 1978–79 1979–80 1980–81 1981–82 1982–83 1983–84 1984–85 1985–86 1986–87 1987–88 1988–89 1989–90 1990–91 1991–92 1992–93 1993–94

Calving Ground

Rutting Oct./Nov.

Winter Dec./Feb.

Total Range

% Above Tree Line

4.3 7.0 5.8 3.8 5.9 4.6 5.9 7.8 9.3 9.6 – 9.0 14.6 15.7 20.2 23.9 18.5 27.3 33.1 25.3 24.3 –

– – – – – – – – – 39 75 44 60 115 136 94 90 76 46 60 – –

– – – – – – – – – – 132 155 238 171 139 89 106 141 118 99 29 –

– 125 – 91 94 140 – – – 227 228 292 391 429 370 418 316 473 504 422 249 287

– 38 – 43 44 30 – – – 17 11 9 11 11 13 12 13 11 8 13 16 19

had numbered approximately 300,000 (fig. 0.4). In 2006 the calving ground was again only 5,000+ km²; it was centred 30 km east of the George, and the size of the herd was roughly the same. For 27 years the tradition has held fast, passing from one generation of caribou to the next, just as it has passed from the older generation of hunters to the next. The return spoke for the recovery of the vegetation. Range Expansion The George grew exponentially from 5,000 in 958 to 650,000 animals by 984– 88 or at a finite rate of increase (λ) of .4 (fig. 0.4). The overall range expanded from 90,000 km² to 625,000 km² (958–93) or at a finite rate per year of .09. However, the recorded range occupied in any one year based on the satellite collars never exceeded 500,000 km² (table 2.). This expansion took the animals west to the shore of Hudson Bay where the herd had ranged in the late 880s, and north until they had occupied one half of the tundra on the Ungava Peninsula north of the Leaf River (fig. 2.2). However, the expansion to the south only

The Use of Space | 325

UNGAVA BAY 89–90

CALVING IN 5 YEARS

UNGAVA BAY

90–91 83–84

T R EE

73–74

LINE

81–82

PRIOR TO 1973

77–78 79–80

3

4

4

12

5

7

16

15

3

7

14

14

4

8

10

9

RUT

5

8

2

WINTER

4

4

85–86

89–90 86–87

SUMMER

84–85

92–93

82–83 90–91

85–86 87–88

1973–76 CALVING

MAXIMUM EXTENSION AFTER 1994

93–94

CLOSED CANOPY

CL OSE Y D CANOP

0 0

50 100 KILOMETERS 50

100 MILES

Fig. 12.2 The range extensions of the George River herd 1973–94 based on overlaying annual maps of UHF and VHF radio-collared animals. The extensions are believed to represent the first season that large proportions of the herd wintered in the areas in recent times. Numbers on the Labrador tundra refer to the number of years caribou were known to calve in the long. x lat. grid system (1974–93, broken). Also shown are the annual distributions of the herd 1973–76 when it numbered 200,000 animals. In those years the herd rutted east of the George River. Even in these early years there were discrete winter ranges. The wintering of caribou along the east shore of Ungava Bay was an early observation that led some biologists to conclude that there was a discrete herd in the Torngat Mountains (insert map from Juniper 1979).

reached 52° N (987–88), the approximate boundary of the calving distribution of the sedentary woodland herds (fig. 2.7). The southern expansion never reached the northern limit of closed-canopy forest at about 5°30' N (figs. 2.7, 2.2). These forests would probably have acted as a barrier to penetrations by large aggregations because of a reduced phytomass of lichens in the shade of the conifers. The expansion of the herd west from the centre of habitation occurred sometime after 958. A March survey in that year found the herd mostly east of 67° W.

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CALVING CENTRES 1973–93 RUTTING CENTRES 1973–93

D O GO

LIC

WINTER CENTRES 1973–94 (3 MISSING)

S HEN 1993

SETTLEMENT TREE LINE

TREE LINE

0 0

50 100 KILOMETRES 50

100 MILES

Fig. 12.3 Comparison of the calving, rutting, and winter distribution centres based on the approximate centre locations of seasonally discrete distributions. Some years are represented by more than one location in the fall and/or winter. Calving centres were concentrated on the Labrador tundra east of the George River. Rutting centres stretched from the calving locations west across the central latitudes whereas the winter locations were widely spaced both above and below tree line and included western and eastern ranges.

A survey in April 963 found animals near Fort McKenzie on the Caniapiscau River west of 69° W (Des Meules and Brassard 964). Animals were wintering as far west as Kuujjuaq and the Koksoak River 973–74 (Pichette and Beauchemin 973; Juniper 974). The route of dispersal from the centre of habitation was northwest along the tree line past Kuujjuaq and then southwest along the tree line (fig. 2.2). In the years 973–76 most of the herd still rutted in the east between 62° W–65° W long. and summered on the birch vegetation adjacent to the George River; the overall density was ≤ 2/km² (fig. 2.2). By October 977 we found the herd breeding 200 km farther west at 67° W, 58° N. The next year the herd moved a further 60 km west to breed. In the years that followed the herd as it increased continued to push its rutting range west and away from the

The Use of Space | 327

TOTAL ANNUAL RANGE (1,000 km²)

600

500

400

–93 987

1 DS

Y = 19.375 + 0.943X r = 0.926

KA LAS

R HE

A

n = 25

< 1.5/km² RAN

300

RGE GEO

200 ~ = 2 / km²

0 150

250

300

350

G

ER

AGE STRUCTURE CENSUS M/R SCHEDULES

r = 0.803 n = 24

CENTRE OF HABITATION

200

D ATE STIM ERE

RIV

Y = 57.743 + 0.736X

100

ND EU

400

450

500

550

600

650

ESTIMATED TOTAL CARIBOU (1,000)

Fig. 12.4 The increase in total range as numbers increased for the George River herd was similar to recent extensions in the ranges occupied in Alaska. However the expansion of the George River commenced at 2 animals/km², whereas the Alaskan animals expanded their range at a constant rate of 1 animal/km². The many years of low numbers in Ungava may have resulted in a more bountiful initial forage supply than that on the Alaskan ranges, given the longer residency of high numbers in Alaska. The areas and populations of the major Alaskan herds were summed at census intervals (consecutive 1- to 3-year intervals) when most of the herds were counted and included in the analysis. Major references for the Alaskan data were: Williams and Heard 1986, Davis and Valkenburg 1991, Valkenburg et al. 1994, Valkenburg et al. 1996a, Valkenburg 1998.

tundra – west of the George River and the traditional calving ground (fig. 2.3). The estimated herd size in 977 was 260,000 animals. The density of the herd remained below 2 animals/km² for the remainder of its range expansion (fig. 2.4), showing a linear increase of 750 additional km² per ,000 additional caribou. In Alaska when herds expanded their ranges they did so at a rate of ,000 km² per ,000 increase of animals, maintaining an overall density of about  animal/km² throughout expansion (fig. 2.4). The expansion of the George River herd was mostly to ranges below tree line but did include subarctic tundra north of the Leaf River. Since the eastern tundra in Labrador was already occupied, its contribution, after expansion, to the total range beyond the centre of habitation went from 45% to 5% of the total ranges as the range extended from 982–83 to 990–9 (table 2.; fig. 2.5). The predicted percentage of the centre of habitation that was above tree line was approximately 40% based on the total above tree line

328 | TH E R E T U R N O F C A R I BO U TO U N G AVA 50

CENTRE OF HABITATION

PERCENTAGE OF TOTAL RANGE ABOVE LABRADOR TREE LINE

1976–77 1975–76

40

30

1973–74

1977–78

Y = 2466.036X 0.904 r2 = 0.848 n = 17

1993–94

20 1981–82 1992–93 1982–83

1986–87 1988–89 1984–85

10

1985–86

1983–84

0

0

100

200

300

1991–92 1987–88 1989–90

1990–91

400

500

TOTAL ANNUAL RANGE (×1,000 km²) Fig. 12.5 The proportion of the range above tree line of the total annual ranges declined as the herd increased during the study, since range expansions were only of fall and winter ranges that were usually in the taiga rather than the tundra.

on total annual ranges Y = 2466.036X-⁰.⁹⁰⁴, n = 7). But since the Labrador tundra was occupied for the most part even at low numbers, this percentage might not apply to other herds. For example, the tundra available for the Leaf River herd’s centre of habitation is five times greater than for the George (Bergerud 996), but possibly the northern portions were not occupied before the herd began expanding (Luttich 983). As the herd increased 974–87, the total range occupied in any one year increased from possibly 25,000 km² in 974 to 500,000+ km² in 990–9 (table

The Use of Space | 329

CALVES TO RUT RUT TO WINTER

500 1973–84

KILOMETRES BETWEEN

400

Y = 2241.11 + 32.06X r = 0.931

WORST WINTER

300

200

100

EAST AGAIN

EAST

73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93

YEARS Fig. 12.6 As the herd increased in numbers 1973 to 1984 (150k to 550k, fig. 10.4) it was the distance between the calving and rutting centres that increased, whereas the distances between the rutting centres and winter centres (December–February) showed no consistent pattern. Eastern ranges are considered here to be east of 68° W long.

2.). The increase in the total range was mostly due to the animals moving further west in the fall; the expansion was not due to greater movement between the fall and winter distributions (figs. 2.6, 2.7). The animals remained on the eastern tundra in July; hence the actual expansion occurred from August (and possibly) through November prior to snow accumulations exceeding 40–50 cm (fig. .7). The expansion occurred primarily after the September pause (fig. 2.8) – when the animals switched to a diet higher in lichens – and they moved west to ranges where there were fewer shattered lichens (fig. 2.9). There was an increase in the size of calving grounds 974–87 (table 2.; fig. 2.8), but the size of winter ranges December–February did not expand with population growth as did the rutting range (figs. 2.7, 2.8). The winter areas were larger in years of light snowfall than when snow cover was deep (fig. 2.8 above), a finding reported in several other studies (Bergerud 963, 974c; Skogland 978; Russell et al. 993).

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UNGAVA BAY 84

78 79 81

83

77

80

90 89

NE T R E E LI

CALVING 1993

CALVING 20 YEARS 1973–92

82 91

86

76 75

87

87 88

85

73 88

74

91 90

84

RUTTING CENTRE LOCATIONS 1973–76 1977–82 1983–86 1987–89 1990–94 0 0

50

(4) (6) (4) (4) (5)

LITTLE MOVEMENT (IN EAST) SHORT DISTANCE WNW MOVE SE SPLITTING INTO UNITS SOME RETURNING EAST

94

92

93

100 KILOMETRES 50

100 MILES

Fig. 12.7 As the herd increased the rutting areas changed in range rotation, radiating out from the calving centre. The rutting extensions first took the animals WNW, then there was a swing south (1983–86), then a splitting into several separate distributions (1987–89), then a movement back to the east. This scatter pattern distributed impacts and should be considered a density-dependent strategy of optimal foraging of lichens low in nutrition quality.

How far west the animals wintered increased in parallel with how far west they had gotten by fall breeding (fig. 2.0). They then expanded to the south and north, depending on snow depths. In three winters with deep snows, large numbers of animals wintered north of 59° N in the Torngat Mountains (973–74; 976–77; 977–78). When the herd was on the more level Ungava Peninsula, the animals went as far north as 60° in winters of heavy snow (fig. 2.2). Animals pushed south of 55° N in the years of below-average accumulation (985–86, 986–87, 988–89) and farther north above tree line when snows were deeper (fig. 2.). Based on indicators of caribou activity and occupation that were mapped according to the long. x 0.5 lat. grid system discussed earlier (fig. 2.2), and on

The Use of Space | 33

TOTAL RANGE (×1,000 km²)

150

W I N T E R R A N G E ( k m ²)

250 WINTER RANGE (DEC.–FEB.)

Y = 307.6  0.361X r = 0.736 n = 11

200

r = 0.306 n = 11

150

1987

100

100 50

300

400 500 600 S N O W D E P T H I N D E X ( c m)

CALVING RUTTING WINTERING

Y=

1987

14518.490 773.612  X

E NG RA NG I T RUT

r2 = 0.719

50

Y=

30 1 + 13.690e 0.0043X

n = 13

r2 = 0.723 n = 13 1987

1974–87 1983 MISSING

N CALVING GROU

D

NOL O ANNUAL CHRO

GY

0 200

300

400

500

600

TOTAL CARIBOU (×1,000)

Fig. 12.8 The size of calving and rutting ranges increased with the growth of the herd, with peak numbers in about 1987 or 1988, but the size of the winter range showed no density-dependence but expanded in years of low snow cover and retraced in more severe winters (upper left). This expansion/contraction sequence had also occurred for herds in Newfoundland in the 1960s (Bergerud 1974c). After 1987 the size of the calving distributions continued to increase in size as the herd decreased, which provided more foraging space per animal on the reduced phytomass.

the abundance of pellets located in stations below tree line during range surveys in the summers of 988 and 989, snow cover was the driving variable in the winter distribution in 8 years. During that time distributions were correlated not with lichen biomass but with snow depth (fig. 2.2). Range Contraction The first indication that the expansion stage was decelerating occurred in 985 when the centre of the rutting location shifted 300 km farther east from the Leaf

332 | TH E R E T U R N O F C A R I BO U TO U N G AVA

(6)

60

Y = 2,558.258Xe 0.122X r2 = 0.665

(6)

n=9

(5)

40

(6)

(4)

(7)

(6)

30

(6)

20

(4)

TUNDRA

50

LICHEN WOODLAND

MEAN LICHENS SHATTERED (%)

70

RANGE STATIONS

10

RANGE EXPANSION

AREA OF LEAF RIVER HERD 0 73.5

WEST

72.5

71.5

70.5

69.5

68.5

MEAN LONGITUDE

67.5

66.5

65.5

EAST

Fig. 12.9 The basic direction of the expansion of the range of the herd in the autumn was west. The animals were vacating eastern ranges where the lichens had been heavily grazed and trampled (see fig. 7.6).

River to the Wheeler River (fig. 2.7) and closer to the calving grounds. A transition period occurred 987–89 (fig. 2.7) in which one could find animals rutting west of 72° W and more eastern groups east of 67° W. In the years that followed the animals rutted at more than one centre (fig. 2.7), a phenomena Skoog (968) had documented when the Nelchina herd in Alaska was at high numbers. By the autumns of 99 and 992 the majority of the animals had returned to eastern regions and the occupied range had declined by 50,000–60,000 km²+ (table 2.; fig. 2.7). The rutting centres in 99 (56° N, 65° W) and 992 (55°30' N, 64° W) showed that the animals had completed a circuit; the centre of rutting activity in 992 near Border Beacon, Labrador, was only a mean of 07 km ± 9 km from the locations in 973, 974, and 975 (fig. 2.7). The breeding centre in 984 was 500 km west of the breeding areas in 973–75 and 425 km west of the calving grounds. In the latter years of the range contraction 990–93 one could find rutting caribou

79

89–90

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78

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75

LONGITUDE OF WINTER

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90–91

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77–78

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85–86

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66

r = 0.708 n = 34

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63

64

65

66

67

68

69

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71

72

73

74

LONGITUDE OF RUT

Fig. 12.10 After the breeding season the impetus to continue west dissipated. The longitudes of the winter distributions were correlated with how far west the animals had moved to reach their breeding ranges. The hypothesis is that range degradation and searching for optimal forage took the animal west, bypassing earlier ranges that were degraded. With general snow cover the animals then dispersed further, searching for a mix of optimal foraging conditions and safety from predators in low snow profiles. In deep-snow winters the animals were commonly further north on the tundra than during the rutting season. In shallower-snow winters the animals searched for lichens and low-risk habitats generally further south than where they bred, utilizing minimal snow cover and the presence of frozen lakes for safety.

PERCENTAGE WINTER RANGE ABOVE TREE LINE

80

83–84

VHF RADIOS UHF RADIOS WINTER CENSUS

70 60

90–91

Y = 48.156 + 0.181X

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r = 0.661 n = 12

50 40

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82–83

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81–82

89–90

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SNOW DEPTH INDEX (cm)

35 30 25

PERCENTAGE OF GRIDS OCCUPIED IN 18 WINTERS

20 15 10

r = 0.134 n = 50

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PERCENTAGE LICHENS IN GRID

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r = 0.637 n = 52

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SNOWDEPTH IN GRID (cm)

MARCH / APRIL 1954–58 NE

1986–87

1988–89

1990–91

1992–93 LEAF RIVER HERD

LI TREE

1984–85

Fig. 12.11 (facing page, above) In winters with deep snows (see fig. 1.7) a larger proportion of the winter range was north of the tree line on the Upper Ungava Peninsula. The snow depth index is the snow depths recorded at the beginning of each month summed, November to June, recorded at Schefferville. Fig. 12.12 (facing page, below) The distributions of the animals in 18 winters were not correlated with the abundance of lichens but rather animals selected areas with reduced snow cover. The snow depths and lichen cover were based on the range survey in 1988, tabulated only for those grids in which the herd had been present in 18 years. In this survey the snow cover was indexed by the conifer gap (method developed by Hustich 1951: fig 9, 24), and lichen abundance was measured on transects. Fig. 12.13 (above) The winter distribution of the George River herd in 1954–58 when it numbered less than 15,000 animals and years in the mid-1980s when numbers reached 600,000 and again in 1992–93 when the herd had declined and returned and again wintered in the centre of habitation.

336 | TH E R E T U R N O F C A R I BO U TO U N G AVA

4 Y = 4,423 + 279.6X  15.14X2 r = 0.873

3

14 13

2

12 11

Y = 12.10 + 0.749X  0.149X2 r = 0.874

1

10

MEAN KILOMETRES PER DAY PER MONTH

THOUSANDS OF KILOMETRES PER YEAR

5

0 86–87

87–88

88–89

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92–93

BIOLOGICAL YEAR (1 JUNE–31 MAY) Fig. 12.14 With the decline of the herd (fig. 10.4) the travel distances and travel rates per day were reduced (coded 86–87 = 1 etc.).

widely scattered from 74° W to 65° W (see also Couturier and Ginhoven 994). But the major movement was east with the animals returning to a relatively low latitude (between 54°–56° N) whereas the range expansion had gone west in the 970s, generally between 57°–58° N. The long distance between the calving and rutting range in 993 – 450+ km (fig. 2.6) – was not due to moving west for breeding but resulted because the animals calved 60 km further north in 993 than in 992 and the herd also rutted farther south than normal (fig. 2.7). After our monitoring in late September 994, we estimated over 250,000 animals east of 66° W in 994; by 995 30,000 animals were back in the centre of habitation (Renewable 994, 995). Winter distributions mirrored movement east in the fall and range contraction. The size of the annual winter ranges began to contract at about the same time as the autumn ranges did, after 987–88 (table 2.). A complete return to eastern ranges in Labrador occurred in 993 when the radio-collared animals wintered in a small area of 28,000 km², 00 km west of Hopedale and south of Mistastin Lake (fig. 2.3), repeating an old rhythm. It was here that the Naskapi had waited for the caribou 35 years earlier when Bergerud had counted the herd in March 958; but it was also the area they had hunted for decades after they had given up waiting at water crossings. The caribou had returned to the centre of habitation, consistent with a major reduction in numbers (fig. 0.4).

The Use of Space | 337

Fig. 12.15 (overleaf left) The travel routes of the satellite caribou in the 1980s. Caribou were generally collared on the calving ground and followed until they returned the next spring and the collars were removed and in some cases new radios installed. The localized ranges represent areas where there were several radio locations in close proximity, indicating limited local movements. Such localizations were frequent when the animals remained in areas of reduced snow cover (probably to reduce predation risk), when the animals reduced mobility in May before moving to calving sites (an optimal feeding strategy for greens), and when the females were on the calving ground (prior to parturition, during labour, and in the first few days of socializing their progeny). Fig. 12.16 (overleaf right) The travel routes of the satellite animals in the 1990s as numbers declined and the return of the animals to the centre of habitation in 1992–93.

Another indication that the range had contracted was that mobility rates declined after 989–90 (fig. 2.4), indicating a reduced annual range (table 2.). We also noted that the dates that radio-collared caribou (UHF) left the Labrador tundra to cross the George River going west were progressively later after 986. In 986 two animals crossed the George River going west approximately July 4; by 992 the animals remained approximately one month longer as the population declined, crossing about August 4. The mean annual crossing dates (Julian) regressed on year 986 to 992 were Y = -9,875.286 + 5.07X (r = 0.988, n = 7 years, 2– radio-collared animals/yr). Since the animals left the centre of habitation later in the summers in the early 990s, the occupied space should have contracted. The routes travelled by eight satellite-collared caribou in 992–93 compared to the six previous years shows this contraction (figs. 2.5, 2.6). Range Predictability We overlapped the 34 distributions of the positions of VHF radio-collared animals located between October 982 and October 987 and constructed a frequency map using the long. x 0.5 lat. grid system to calculate the probability of the herd’s presence in each grid between October 982 and October 987 (fig. 2.7, top). During this interval the herd increased from 400,000 to > 600,000 animals. The grids that were most consistently occupied were adjacent to the tree line just west of Indian House Lake on the George River and to the tree line that runs southwest from Ungava Bay between the Larch and Leaf Rivers on the Ungava Peninsula (fig. 2.7). One block at Indian House Lake had caribou present in 5 of the 34 surveys (44%). When the herd was at such high numbers the tree line was the spring highway northeast by Kuujjuaq and then southeast to Indian House Lake, the centre of habitation (fig. 2.). A second way of predicting the animals’ locations was based on the time the satellite-collared (UHF) animals tracked 986–92 spent in each of the long. x 0.5

START END LOCALIZED

UNGAVA BAY

HUDSON

1986–87 n=4

BAY

1987–88 n = 2−6

4 COLLARS REMOVED

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100 KILOMETRES 100 MILES

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1989–90 n=4

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START END LOCALIZED

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NOVEMBER TO 31 MARCH

VHF RADIOS 1982–87 34 SURVEYS

3

3 6 6 3 3 6 9 9 9 9 6 6 9 12 21 21 29 38 26 12 9 18 26 32 41 44 29 15 18 29 35 41 32 21 12 29 32 32 29 15 18 12 24 36 26 24 15 24 18 18 21 21 18 18 26 9 21 24 21 15 18 21 3 6 15 21 15 15 12 21 3 9 9 9 9 9 9 9 3 3 6 3 6 6 6 9

3

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100 MILES

0.2 0.1 0.1 0.2 0.3 0.2 0.1 1.5 0.5 0.1 0.7 0.4 0.2 0.4 0.1 1.3 0.5 0.2 0.6 2.2 0.4 1.2 0.2 1.1 0.3 0.2 0.2 0.2 0.1 0.6 0.9 0.7 5 0.9 0.5 0.9 2.1 0.2 0.7 1.1 0.5 0.4 0. 0.1 1.1 0.3 0.7 1.2 0.3 1 0. 0.2 0.4 0.8 0.9 0.2 0.9 1.3 0.7 0.8 0.3 0.3 0.4 0.4 0. 0.5 1.1 1.1 0.9 0.4 0.2 0.9 1.7 1.1 0.8 1 0.2 0.4 0.5 0.7 0.5 0.8 0.6 1.4 0.6 0.5 0.7 0.8 2.0 0.9 0.1 0.1 0.3 0.7 0.4 0.5 0.2 0.2 0.9 0.8 0.6 0.4 0.6 2.2 1.4 0.1 0.1 1.3 1.8 0.7 0.2 0.4 1.2 0.8 1.5 0.6 0.5 1.1 0.7 0.3 1.1 0. 2 1. 3 0.8 0.5 0.3 0.2 0.5 0.3 0.2 0.6 0.7 1.0 1.0 1.0 0.3 0.3 0.2 0. 1 0.1 0.2 0.5 0.7 0.1 0.1 0.1 1.2 0.4 0.2 0.3 0.5 0.3 0.2 0.1 0.7 1.4 0.1 0.2 0.3 0.4 0.4 0.2 0.1 0.1 0.1 0.1 0.1 0.4 0.1 0.2 0.2 0.1 0.2 2.9 0.1 0.1 0.1 0.2

UHF RADIOS

1986–92 2,794 SURVEYS

CALVING CENTRE SETTLEMENT

9

NUMBER OF YEARS GRID OCCUPIED

Fig. 12.18 (above) A histogram of the number of different grids occupied at calving, the rutting season, and winter. Only a few different grids were occupied at calving, indicating a contagious frequency array and heavy repeated selection. During the rut the number of times a grid was occupied was more uniform, indicating a repulsed distribution, i.e., blocks previously occupied were less likely to be selected, presumably because forage had been reduced and the animals went elsewhere – a rotation of pastures. In the winter the frequency of occupation of the grids conformed to a rare selection (Poisson) where the animals occupied grids based on the presence of snow cover, a stochastic varying variable. Fig. 12.19 (facing page) (above) The major direction of caribou leads in 1988 (a lead equals at least 10 parallel trails). An attempt was made to determine the major direction in each quarter of the long. x lat. grids. Between 65° and 69° W long. the routes are mostly east and west. This is the major dispersal direction between calving and fall breeding. West of 69° W they are north and south dispersal routes commonly travelled from the fall to winter seeking low snow cover; (below) The routes of migrating caribou were based on sightings or fresh trails based on aerial flights primarily in the 1970s. This was prior to the radio tracking commencing in 1982. Each arrow shown was actually drawn by S. Luttich on a topographical map at the time of observation. The caribou highway is clearly shown running northeast from 75° W, 56° N, turning east near Kuujjuaq along the Ungava Coast, then turning southeast heading for Caribou House. More spring routes than fall routes are shown because of the greater aerial effort in the spring plus the fact that, in the spring, black trails show more contrast than fall trails on bare substrates or light snow cover.

75 º

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55 º

SNOW

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July/August, as we observed at various camps used in the summers of 988–92. Historically most of the native hunting camps at Indian House Lake were on the west side of the lake, an indication that they looked to the east for the caribou’s arrival in late summer and fall (fig. 5.). However, the first radio-collared caribou captured at Indian House Lake in October 973 moved east to winter (figs. 2.2, 2.7; Dauphiné et al. 975). When numbers were low the animals had occasionally moved east and remained on the eastern tundra to winter. However, in 954 and 958 at extremely low numbers, they wintered near or west of the tree line (Banfield and Tener 958; Bergerud 958). When we camped at the running-out of Indian House Lake in late June 988, 99, and 992, the animals nearly always came from the north and then crossed the end of the lake going west. When we combine the movements in the 970s with those in the 980s, the routes of egress and return ingress from the centre of habitation describe a circle. When numbers increased in the 970s beyond 200,000, the route for expansion was first northwest from Indian House Lake, then west south of Ungava Bay, and then southwest tracking the tree line (fig. 2.9, below). On their return trip in April they retraced this route. However, as numbers increased beyond 400,000 in the 980s, the movement of satellite-collared caribou 986–93 (figs. 2.5, 2.6) showed a more comprehensive network of movements than we had observed from the air prior to radio collaring (compare fig. 2.9 with fig. 2.20). When the herd was increasing and radiating out from its centre of habitation in the 970s and early 980s, it generally left the Labrador tundra in the fall, moving northwest along the northern tree line route, an area of reduced snow cover, and passing by Kuujjuaq. By 988 this route was heavily overgrazed (fig. 2.9) and in August the animals usually left their July locations east of tree line and moved west, perpendicular to the tree line and into the taiga well south of Kuujjuaq and passing nearer to Schefferville. In some winters of reduced snow cover the animals wintered as far south as 52° (fig. 2.2). If the animals were north of 55° N and west of 72° W they returned in the spring to Labrador, moving northeast adjacent to the Ungava Peninsula tree line, then east following the Ungava Bay tree line by Kuujjuaq, a circular route of ,500 km. However, when the animals were south of 55° N and west of 72° W, they took a more direct northeasterly return route in the spring to the Labrador tundra that kept 350 km to the south of the Ungava Bay and Kuujjuaq. The more southerly return route took them through ranges where the lichens existed in a deep cryptogam cover of 73% ± 2% (8 stations) and were little utilized: 0% ± 3% (8 stations) (fig. 7.5). In contrast, lichen supplies had been reduced on the northern route by the 980s; the mean lichen cover along the Kuujjuaq route in 988 had been reduced to 6% ± 5% (n = 7) with 54% ± 0% (n = 7) of the phytomass shattered. Another factor that may have affected the selection of exit and return routes to the Labrador tundra – other than overgrazed lichen stands – is snow cover. In

The Use of Space | 345 75 º

70 º

60 º

65 º

CALVING CENTRE SETTLEMENT

60 º

60 º

55 º

55 º

0 0

50 100 KILOMETRES 50

100 MILES

Fig. 12.20 The major direction of the satellite-collared females 1986–92 in each of the long. x lat. grids. Each arrow represents the major direction of satellite females through a grid in one year, i.e., five parallel arrows in a grid pointing in the same direction means that in five different years satellite females moved through that grid in the same basic direction. Note the turning of caribou as they approach coastlines, etc. A small circle means that the satellite animals made many acute turns in the grid in the process of localizing. This fig. represents a composite analysis of figs. 12.15 and 12.16.

the expansion years (973–84) snow cover was heavier than in later winters (fig. .7). Animals may have been more reluctant to enter the deep snow cover of the central interior in years of deep snow (fig. .4), preferring more northern routes with reduced snow levels. Regardless of the relative roles of snow cover vs lichen phytomass, these movements to and from the Labrador tundra resulted in a rotation of fall pastures and winter pastures (figs. 2.2, 2.3, 2.7). Animals sought reduced snow levels in the winter and since snow cover varied from one winter to the next, contacts were spread over a much larger area than were those in June/July (fig. 2.3). Snow cover also limits the extent to which substrates are cratered and protects ground cover from trampling, in contrast to the exposure of unprotected summer forage species.

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The trail systems we plotted west of the centre of habitation (67° W) showed most of the leads running west and east but a number of them ran parallel to the tree line on the Ungava Peninsula (fig. 2.9). Many directed traffic by Kuujjuaq, where Low in the 880s (898) had encountered animals going east in spring and west in autumn. Elton (942) had noted how in historical times Kuujjuaq had been a centre of caribou hunting when the populations failed along Hudson Bay. Based on our observations of columns of moving caribou and the presence of compact trails in the snow in March/April 973–89, a major trail route ran northeast along the tree line on the Ungava Peninsula to Kuujjuaq, east along the tree line adjacent to the shore of Ungava Bay, then southeast along the Labrador tree line towards the traditional calving grounds east of Indian House Lake (fig. 2.9). As the herd expanded its range after 970, this spring tree line highway retraced routes trekked in September–October. The Kuujjuaq settlement probably owes its location and persistence to the traditional and predictable movements of caribou across the Koksoak River, although these movements did not resume during this study until numbers exceeded 50,000–200,000 in the early 970s. At this time hunters could harvest ,200–,800 animals annually, but prior to the 960s, when the animals remained east in the centre of habitation, the hunters either went without caribou or had to travel long distances for them. Kuujjuaq natives harvested fewer than 50 animals per year on average in the 950s (Banfield and Tener 958). The George River herd is the only large migratory herd in North America calving east of tree line that frequently enters the tundra from the north, moving southeast, and that is because the north-south direction of the tree line in Ungava is unique. The seven other large migratory herds in North America all migrate north, northeast, or northwest to reach their tundra calving sites. There were probably years of high numbers far in the past when the animals passed by Kuujjuaq going east in the spring but missed it on return in the fall because their westerly route was further south. In 96 when caribou numbers were failing, the Hudson Bay Company established Fort McKenzie on the Caniapiscau River 30 km south of Kuujjuaq (Elton 942), right in the centre of the Naskapi’s traditional range (fig. 2.). The new post provided better access to the remaining caribou moving east and west through the taiga south of the Ungava Bay, and it was close to here in the winter of 976 that the Canadian Wildlife Service – with the assistance of the Naskapi – made its first scientific collection of George River caribou (Drolet and Dauphiné 976). We separated the grid blocks crossed by the satellite-collared animals 986–93 into three categories: () blocks where animals commonly reversed or changed direction; (2) grids in which animals travelled several different directions in different years; and (3) blocks where directions showed little variation between years (7 years, 986–93, fig. 2.20). The animals turned as expected on the periphery of their annual distributions, primarily turning south, north of the Leaf River and in the Torngat Mountains. They turned east near Hudson Bay, and turned

The Use of Space | 347

CALVING CENTRE SETTLEMENT 2 OR MORE DIRECTION NO DIRECTION 4 OR MORE DIRECTION NO DIRECTION GRIDS WHERE DIRECTION IS SIMILAR TO ESKERS

0 0

50

100 KILOMETRES 50

100 MILES

Fig. 12.21 The major directions that satellite caribou followed in each grid compared to the directions of eskers. Although caribou often travelled on eskers, these narrow sand ridges deposited in the last glacial epoch were not the basis for directional orientation.

west when they encountered the Labrador coast (fig. 2.20) In nearly all cases the animals could have travelled further on their routes: They were not reacting to actual barriers. The central interior was the region where animals often varied directions between years, and Vandal et al. (989) suggested circular movements in this area based on the location of animals with VHF radios monitored on DC 3 flights 983–87. The animals generally followed a similar route between years that ran along the major tree line highway. In the fall they moved northwest and west past Kuujjuaq, and then turned southwest. In the spring they went in reverse (figs. 2.9, 2.20). The animals also followed consistent directions when crossing west through the central interior in the 980s when numbers were high (fig. 2.20). The routes we documented did not show any consistent pattern to support an hypothesis of topographical funnelling (Bergerud 974b). They did not consistently follow the directions of eskers (fig. 2.2, see fig. .3 for esker locations), although most eskers had parallel leads on their crests. Nor were routes consistent with drainage patterns; animals commonly crossed the major rivers that run north to Ungava Bay. The deep fiords along the Labrador Coast did funnel

348 | TH E R E T U R N O F C A R I BO U TO U N G AVA

movements east and west above the fiords and parallel to the steep cliffs that inhibited movement north or south. The routes we have documented are consistent with the historical records as reviewed by Elton (942). For the many decades between the high numbers of the late 800s (discussed by Elton) and the massive numbers of the 980s, there were few caribou beyond the centre of habitation and neither trails nor individuals to show the way. But with the repopulation of Ungava 00 years later, the animals rediscovered these historical routes, passing by Kuujjuaq twice a year in the 970s, albeit less frequently in the 980s when numbers were high. Releasing/Expansion Densities The growth of the herd (from 77,000 to 650,000 animals) and range expansion 973–90 resulted in a rather constant overall density of .7 animal/km² (fig. 2.4). The density of the herd in 958 was 0.7/km² and although we don’t know exactly when the first expansion occurred, there were probably no meaningful extensions until the early 970s. If 50,000 animals in 970 were still restricted to the centre of habitation, the density would have been .7/km². We postulate that when the density reaches this point a lichen forage shortfall results in increased movement and range rotation. This releasing density is higher that that which has resulted in range expansions in Alaska and NWT (Bergerud 980). Recent range expansion occurred at approximately /km² (fig. 2.4) with the major herds in Alaska. We attribute the higher releasing density for the George River herd to the 40-year absence of grazing pressure 920–60 and the subsequent accumulation of a high-quality phytomass – significantly greater than what is available to herds with more constant numbers that commonly forage at densities of approximately 0.5/km² (Bergerud 980; Davis and Valkenburg 99; Valkenburg et al. 996a). As late as 975 there were 24 species of forbs along the George River; by 993 only  species apparently remained (table 7.5). The growth of birch must have accumulated for decades prior to the 970s; by 984 when the herd exceeded 550,000, annual growth increments (width of annulations) were reduced (fig. 7.3) and the establishment of new birch stems in sites unprotected from browsing were limited. The “Social Stimulus” Concept Skoog (968) pioneered the idea that there is a “social stimulus” that leads – in the absence of a lichen shortage – to emigration and range expansion to more marginal ranges and reduced demography when densities reach 5–0/mi.² (3– 25 animals/km²). The concept is essentially an elaboration of Wynne-Edwards’ view (962) that animals have evolved physiological and behavioural adaptations to assess and self-regulate abundance in order to prevent overpopulation, a theory that fundamentally rests on the principle of group selection. The restless-

The Use of Space | 349

ness and range expansion that Skoog documented in the 960s for the Nelchina herd when numbers were high would relate to an overgrazed summer range. The primary calving and summer range for the Nelchina herd was located at Oshetna River and Deadman Lake, referred to as units 2 and 5 in Skoog’s study area and totalling 7,500 km². With a herd of 60,000+ caribou in the 960s this represented a density of 8+ animals/km². Range studies at the time stressed that the winter lichen range had been overgrazed and trampled (Pegau 968, 972). Although the summer range was overlooked, it had to have been severely impacted and a major contributor to the “social stimulus” behaviour. Skoog documented movements to additional summer ranges and later investigations also documented a decline in body size (Valkenburg et al. 99). In many respects the Nelchina was a dress rehearsal for the George River scenario, but its relevance went unnoticed, overshadowed by the idea that winter lichen supplies are at the core of caribou demography. The “social stimulus” concept is not an assessment of numbers and social interactions per se. It is fundamentally about the animal x green forage interaction that occurs at extreme densities. The animals do not assess the size of population and move to reduce competition. They assess the range and leave it if it is overgrazed or compromises their well-being. The George River herd overgrazed its summer range after 982 when densities exceeded 0/km² on the Labrador tundra. In August after the mosquitoes abated, the animals expanded their range below tree line. Mobility and range expansion continued into the fall prior to extensive snow cover as the animals switched more to a lichen/evergreen shrub diet, but the range expansion did not prevent overpopulation or avert a decline in number. Thus the sequence depicts an eruption which led to forage over-utilization and population decline (Caughley 970). But the food shortage for the George River herd was in summer green forage, not winter lichens. Caribou biologists have had it backwards for decades, arguing that summer greens can withstand heavier grazing pressure than winter foods (lichens). The animals are restless and mobile at these high densities because they need greens – for growth, reproduction, and general well-being. They will pause in September when green foods can be found and then pick up their pace when autumn dieback and winter snows are on the horizon. Density-Dependent Changes in the Use of Space The mean monthly travel rates in seven years (see chapter 3) that led to the changes in distribution were positively correlated with our annual population estimates (table 0.5) in October–November and March–April (fig. 2.22), months in which the animals were dependent on terrestrial lichens (Gauthier et al. 989). In October and November the animals were expanding their range west towards greater lichen supplies (fig. 2.9); in March and April they were retracing their steps, moving east towards more heavily overgrazed eastern ranges (fig.

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CORRELATION COEFFICIENTS OF POPULATION SIZE, AND KILOMETRES PER DAY (ALL POSITIVE)

KILOMETRES PER DAY

25 20

2 S.E.

15

DD

10 5 0

DD

DD = DENSITY DEPENDENT

J

J

A

S

O

N

D

J

1.0

F

M

A

M

MEAN km / MONTH / YEAR vs POPULATION SIZE r = 0.804 n=7

0.9 0.8

P < 0.05

0.7 0.6 SEPTEMBER PAUSE

0.5

WINTER PAUSE

0.4 0.3 0.2 0.1 0.0

GREENS & INSECTS

J

J

A

S

GREENS

O

N

D

J

F

M

A

M

YEAR

MONTHS Fig. 12.22 (above) The mean kilometres per day/month in 7 years; (below) Correlation coefficients between mean monthly daily travel rates in table 13.1 and the population estimates in table 10.5. The correlation was significant in April and approaching significance in the months of October, November, and March and for the total year. Daily travel speeds in turn were correlated with the total km travelled each biological year (fig. 12.14). Our conclusion is that movement and range extensions were driven by densitydependent interactions with lichen forage after the growing season (after the September pause shown in fig. 2.13) and on their return to the Labrador tundra in the spring before the growing season commenced.

7.5) (Crête et al. 990b; Bergerud 996). The contrasts were striking: in October– November snow levels were low but increasing; in March–April snow levels were high but receding, and snow maturation reduced sinking depths. Animals travelled twice as fast in the fall as they did on their return to the tundra in March and April of early spring (fig. 2.22), and these movements were positively correlated with the lichen biomass – faster in the fall as they tracked

The Use of Space | 35

Table 12.2 Synchrony in the dominant activity of caribou during the growing season within aggregations compared with the group size Aggregation Size

Percentage of Animals in Aggregation Engaged in Dominant Activity 1988 1989 1990 1991 Mean (n) Mean (n ) Mean (n) Mean (n)

2–5 6–10 11–15 16–20 21–30 31–45 46–70 ≥ 71

80.5 (211) 77.2 (214) 75.2 (123) 74.4 (73) 73.3 (79) 75.2 (55) 73.3 (35) 69.4 (22)

88.8 (66) 80.1 (39) 77.5 (28) 75.1 (22) 74.5 (20) 72.9 (16) 72.8 (16 67.8 (30)

90.7 (226) 77.5 (161) 74.3 (92) 74.9 (63) 72.3 (60) 69.7 (47) 72.3 (39) 71.4 (59)

88.9 (214) 85.3 (208) 83.4 (127) 85.7 (86) 75.7 (103) 77.8 (77) 72.8 (76) 69.5 (71)

Best fit equations: 988: Y = 82.85X-⁰.⁰³⁷⁶, r² = 0.852; 989: Y = 94.9X-⁰.⁰⁷³, r² = 0.926; 990: Y = 9.72X-⁰.⁰⁶⁵, r² = 0.884; 99: Y = 0.X-⁰.⁰⁷⁸, r² = 0.884. (Note X values used were 4, 8, 3, 8, 26, 38, 58, and 00). Activities were those normal for activity budgets: feeding, walking, lying, and standing.

lichen abundance, slower in spring with the reduced cryptogams, and slower still in the summer growing season, in response to the rich green phytomass. The long moving columns in the spring and fall reduce lichen supplies for those following. Social dominance could also contribute to density-dependence as animals displace subordinates at feeding sites, accelerating movements (Shea 979). Shea showed displacement of individual animals from feeding sites with increasing group size in November and March in northwest Alaska, with displacement distances 9 m in November and 6.5 m in March. Duquette and Klein (987) have proposed that mobility rates increased with group size in April and May from social facilitation. We were not able to show a group-size affect on mobility during the growing season when insect harassment was light (chapter 3). We noted that synchrony in the dominant activity of an aggregation decreased with group size (table 2.2). We saw more interactions in June 978 than in June 988 after the herd had increased by > 300,000 (table 2.3). In the fall and spring when caribou are on the move, they commonly walk single file, which would minimize assessment of other animals. Changes in mobility with numbers appear to relate primarily to the abundance of forage rather than social interactions and facilitation. The higher rates of travel, especially in November and April, are often attributed to a “migration instinct” – a need to get to a winter range (and later to return to the summer range), but we think that the most parsimonious explanation for this mobility is that the animals move along a gradient of lichen availability that can be impacted by high numbers.

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Table 12.3 Comparison of social facilitation parameters in the 2-week post-calving period in 1978 when the herd reached 300,000 animals and in 1988 with a doubling of the herd to 600,000 animals Parameters

Interactions/Hour 2–5 Caribou per Group 6–10 per Group 11–15 per Group 16+ per Group Total Individual Distance between Animals² Mean Group Size

1978

2.7 (3.7)¹ 3.2 (1.9) 4.5 (0.67) 4.6 (7.6) 3.3 (13.4)

1988

0.0 (46.6) 0.16 (6.2) 0.09 (11.5) 0.08 (16.1) 0.09 (80.4)

8.4 ± 1.46 n = 27

11.5 ± 3.72 n = 85

34.6 ± 8.08 n = 34

25.7 ± 2.65 n = 133

¹ Hour watched ² t = .689, P < 0.05, one tailed test, distance based on caribou lengths, recorded as , 2, etc.

We don’t have a comprehensive explanation for the higher travel speeds in the density-dependent fall and spring movements aside from lichen availability. We did not measure the caribou’s bite size nor the number of steps the animals took between feeding bouts for these two periods. On the fall ranges we found large clumps of lichens lying on the cryptogam, indicating large bites; in the spring the lichens may have been more shattered after removal from the frozen substrate and from trampling. Gauthier’s et al. (989) tabulations indicate more dead graminoids in spring fare than in the autumn. In the spring a number of satellite-tracked animals localized for extended periods (figs. 2.5, 2.6), probably in response to a restricted food patch and/or reduced predation risk in an area of reduced snow cover. But we do not discount the hypothesis that the animals understand and remember the distribution and abundance of lichen forage, adjusting travel rates and distances covered accordingly. The apparent lack of significant density-dependence in travel rates during the growing season (fig. 2.22) relates to the May, calving, and September pauses and to the prolonged movements during the insect season when the animals were not feeding. When they did feed, mobility lessened in accordance with phytomass (chapter 3) and animals aggregated in high phytomass communities (Manseau 996). In the winter the animals were stationary, moving in response to snow gradients rather than forage availability. Chapter 3 discusses environmental factors.

CHAPTER THIRTEEN

Environmental Factors in Distribution and Movement

Caribou are continually on the move (figs. 3.–3.3; table 3.). Their gregarious herd structure entails shifting, if for no other reason than the impacts of grazing and trampling on the vegetation. Nonetheless, one recognizes a basic annual cycle of acceleration and deceleration in these movements, or, as Skoog (968) described it, “a cycle of shifts and pauses,” certainly a sequence we found relevant to the annual travels of caribou in Newfoundland (Bergerud 974b). We’d like to quantify this cycle and understand the environmental influences that affect distribution, mobility rates and changes in azimuths, taking into consideration insects, forage, wind, snow, and numbers. Basic Quantification Methods We quantified the travel rates (km/hr) of caribou passing 4 of our ground camps, generally located above or near the tree line on the Labrador Peninsula, in the summers of 988–92. The distance travelled by groups of  to > 50 animals was quantified in one-minute or five-minute tests by ground-pacing between locations. During these transects we quantified the plant communities based on foot strikes during measurement. At several camps we also measured the composition of the upland shrub community in the absence of caribou by line transects; and we further quantified the plant phytomass by weighing species in subquadrats of m² quadrats (for details see Camps and Linder 989). We also measured four times daily (at 0800, 200, 600, and 2000 hours) the minimum and maximum temperatures; direction and strength of the wind; and insect abundance. We quantified the abundance of mosquitoes (Culicidae), black flies (Simulium spp.), and tabanids (Chrysops spp., Tabanus spp., and Hybomitra

354 | TH E R E T U R N O F C A R I BO U TO U N G AVA

24 9 3 3 16 11 10 6 8 4 17 3 7 3 3 5 17 11 25 18 4 6 15 19 8 19 8 26 14 8 13 11 12 14 16 4 15 9 16 20 19 22 24 5 18 26 16 12 15 19 18 14 23 24 14 17 25 27 24 12 15 17 19 18 22 19 23 16 15 11 11 21 18 14 17 14 12 11 12 14 24 25 22 19 10 38 18 24 10 6 1 15 18 23 11 23 0 19 15 12 2 11 9 16 17 12 10 7 31 12 2 7 25 20 5 17 9 14 4 9 8 8 7

9 14 16 23 11 24 24 21 21 22

6 10 13 10 11 7 13 14 3 34 16 13 23 10 10 26 24 17 17 15 18 24 14 17 16 16 5 17 28 28 18 12 9 10 17 19 25 16 11 8 24 21 22 14 19 8 20 21 20 20 14 11 17 16 21 20 7 3 10 11 14 6 9 0 13 0

20 km

50

100 KILOMETRES 50

100 MILES

Fig. 13.1 (above) The mean speed (km/day, 1986 to 1992) that the satellite females travelled in spacing across their range, tabulated on the basis of the long. x lat. grid system. The greatest speeds were in the central interior where animals generally moved between the taiga and tundra in the non-insect season and where their lichen forage had been degraded 30–50% by the high animal numbers in the 1980s (see fig. 7.5). The outlying grids with speeds > 20 km/day were usually single animals that had been localized and first initiated major movements. Fig. 13.2 (facing page) The annual mobility cycle of the satellite females in the seven years of satellite monitoring is shown for comparison of the timing of the pauses between years. The mean number of animals monitored each year is shown, as well as the total number of locations secured at three- or four-day intervals. The annual reduced travel rates (termed pauses) are evident: September, fall breeding, winter, and May in some years. The June pause was difficult to monitor since animals were generally captured in June and collars removed or upgraded.

spp.) by net sweeps both upwind and downwind; crossover tests (insects flying across a white grid paper in one minute); and bites per minute on an exposed arm without repellent. The abundance of oestrids (Cephenemyia trompe and Hypoderma [Oedmagena] tarandi) seen per km of travel was quantified and both oestrids and tabanids were captured in traps in 992 (Camps and Linders 989). We tabulated the harassment effect of insects in relation to caribou move-

30

ˉxn = 4.0 ± 0.04 n = 120

20 10

86–87 0

ˉxn = 3.8 ± 0.15

20

n = 117 10

87–88 0 20

ˉxn = 4.6 ± 0.16

KILOMETRES PER DAY

n = 90 10

88–89 0

ˉxn = 3.9 ± 0.10

20

n = 87 10

89–90 0 30

ˉxn = 5.1 ± 0.16

20

n = 114 10

90–91 0 20

ˉxn = 9.5 ± 0.36 n = 122

10

91–92 0 20

ˉxn = 7.8 ± 0.15 n = 91

10

92–93 0

J

J

A

S

O

N D J MONTHS

F

M

A

M

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Table 13.1

Kilometres travelled per day by satellite caribou June 1986 to June 1993

Month

1986–87

1987–88

1988–89

June July August September October November December January February March April May

5.7 ± 0.88 (30) 18.1 ± 1.91 (43) 18.6 ± 1.54 (44) 10.5 ± 1.25 (40) 19.0 ± 1.95 (40) 20.2 ± 2.10 (40) 12.0 ± 2.41 (40) 13.4 ± 1.45 (44) 8.9 ± 1.02 (36) 6.1 ± 0.85 (40) 14.3 ± 2.16 (40) 10.1 ± 1.50 (44)

17.6 ± 1.25 (40) 16.5 ± 1.21 (68) 15.6 ± 1.14 (61) 12.7 ± 1.28 (33) 17.7 ± 1.86 (40) 18.2 ± 1.89 (37) 8.2 ± 1.41 (40) 8.5 ± 1.24 (30) 5.8 ± 1.91 (26) 7.9 ± 1.69 (24) 11.5 ± 2.75 (30) 15.5 ± 2.32 (28)

8.6 ± 2.68 (15) 14.2 ± 1.29 (32) 21.7 ± 2.20 (30) 16.7 ± 2.1 (30) 16.5 ± 1.28 (40) 17.3 ± 1.86 (28) 9.5 ± 1.32 (33) 5.7 ± 1.09 (26) 5.0 ± 0.72 (28) 10.6 ± 2.06 (27) 9.3 ± 1.63 (27) 18.8 ± 2.13 (32)

Total Km/Yr Mean

157.0 4787 13.1 ± 1.46 (12)

155.7 4746 13.0 ± 1.29 (12)

153.6 4704 12.8 ± 1.56 (12)

MIGRATORY ECOTYPE C CALVING

GEORGE RIVER (OVERGRAZED)

30

PORCUPINE (NOT OVERGRAZED)

MIGRATORY TO CALVING

CARIBOU IN TORNGAT MTS.

FALL EXTENSION

SEDENTARY ECOTYPE NOV.

25

RED WINE HERD NOV.

AUG.

KILOMETRES PER DAY

AUG.

AUG.

NOV. NOV.

20

C

15

C

10

5

C

C C

C

C

C

0 JUNE

JUNE

JUNE

ANNUAL MOBILITY CYCLE OF CARIBOU

JUNE

Environmental Factors in Distribution and Movement | 357

1989–90

1990–91

1991–92

1992–93

10.8 ± 1.61 (25) 17.9 ± 1.83 (40) 23.4 ± 1.87 (39) 21.7 ± 1.55 (24) 18.0 ± 1.98 (27 18.5 ± 1.63 (35) 13.3 ± 1.66 (37) 4.4 ± 0.70 (31) 4.1 ± 0.86 (24) 6.1 ± 1.24 (22) 6.3 ± 0.98 (18) 21.0 ± 4.86 (15)

5.1 ± 1.09 (19) 8.8 ± 1.31 (21) 19.6 ± 1.48 (45) 16.4 ± 1.79 (41) 20.8 ± 1.96 (42 ) 20.6 ± 1.98 (58) 15.3 ± 1.93 (37) 4.9 ± 0.52 (58) 3.4 ± 0.39 (55) 3.7 ± 0/46 (47) 8.5 ± 1.10 (66) 13.7 ± 1.57 (61)

9.0 ± 0.94 (82) 12.2 ± 0.77 (130) 15.9 ± 0.90 (119) 10.6 ± 0.83 (105) 17.5 ± 1.0 (131) 17.3 ± 0.96 (117) 8.4 ± 0.91 (48) 8.8 ± 0.82 (78) 6.3 ± 1.31 (53) 3.8 ± 0.51 (77) 5.8 ± 0.67 (8) 13.8 ± 1.39 (87)

8.8 ± 1.16 (65) 14.1 ± 1.06 (79) 15.9 ± 0.91 (75) 14.1 ± 11.20 (43) 16.1 ± 1.26 (55) 11.4 ± 1.07 (55) 8.4 ± 0.91 (48) 9.0 ± 1.02 (59) 3.5 ± 0.50 (53) 3.6 ± 0.42 (62) 6.1 ± 0.88 (56) 10.5 ± 1.00 (64)

165.5 5061 13.8 ± 2.08 (12)

149.8 4304 11.7 ± 1.96 (12)

124.4 3950 10.8 ± 1.32 (12)

121.5 3719 10.1 ± 1.26 (12)

Mean

9.4 ± 1.56 14.5 ± 1.26 18.6 ± 1.17 14.7 ± 1.50 18.1 ± 0.65 17.6 ± 1.15 10.7 ± 1.07 7.8 ± 1.18 5.3 ± 0.71 6.0 ± 0.98 8.8 ± 1.20 14.8 ± 1.53

ments in the one- or five-minute tests as to number of head shakes, body shakes, body bites, and leg stomps per caribou minute of observation. Activity budgets (lying, walking, standing, running, and feeding) were based on horizon scans as part of the monitoring program and were conducted four times a day coincident with weather parameters and measurements of insect abundance. The scans recognized complete counts – all caribou seen were included – and active caribou only, i.e., that excluded caribou lying down (for more detail see Camps and Linders 989). Travel rates for caribou were expressed as km/day based on satellite-collared caribou monitored from June 986 to June 993. The distances between locations at 3–4 day intervals were corrected based on a correction factor of .3 (determined from a few caribou in 988 with transmitters that provided fixes on a 24hour basis). We quantified these rates as to life-history events (mosquito season,

Fig. 13.3 (facing page) The relative mobility of the caribou in Ungava compared between the migratory caribou (George River) when in the Torngat Mountains (1986–92, broken) and outside the mountains, 1986 to 1989. For comparison the mobility rates of the Porcupine herd in Alaska are shown 1985–87 (Whitten and Fancy 1990) and the sedentary Red Wine herd 1982–85 (adapted from Brown 1986). The area labelled fall extension for the George River compared to the Porcupine resulted from the overgrazed fall range in Eastern Ungava with the animals continuing to travel faster and further, whereas the Porcupine herd, which had not overgrazed its late summer and fall range, had reduced mobility rates (Russell et al. 1993).

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August dispersal, and calendar months), calculating the speeds at which caribou crossed through the longitude-latitude grid system that we used as the basis of our range survey (chapter 7). We also recorded the time the animals spent in each of the grids based on the 3–4 day reporting schedule (fig. 2.7). We used snow depth statistics recorded at weekly intervals at Schefferville at the McGill Research Station 973–74 to 99–92 (no data 992–93), the same ones we used to assess the annual changes in travel rates (see earlier chapters). Special Satellite Comments

In June 988, satellite collars on four female caribou transmitted information every fourth day from 0600–500 hours (GMT). For June we also used data from previously (987) collared caribou transmitted every third day (n = 8) and every day (n = 2). These collars had activity recorders that included the long-term activity index (LTA) and the short-term activity index (STA). The STA , being the number of active seconds per minute during satellite overpass time, are expressed in counts (the number of times a mercury switch is activated by caribou movement, 0–60 per minute). Regelin and Whitten (986) and Fancy et al. (989) noted that the 60-second activity counts showed good correlations with the behaviour of caribou. Observing captive caribou, they divided the STA into 6 behaviour classes, determining a mean number of counts per behaviour by averaging counts per minute during prolonged display of certain behaviour: lying down =  (count per min.); grazing = 4.5; standing = 0; browsing = 6; walking = 27; and running = 55. The LTA indicates the activity during the preceding day prior to satellite overpass. Since this index is the result of the constant accumulation of the STA index, the LTA accounts for the total period of caribou activity. For instance, if a caribou grazes for 60 minutes, the LTA registers a net mean value of 270 counts (60 x 4.5). Since counts are equal to seconds (60 counts per minute), the net grazing activity accounts for only 0.3 hour (270 seconds), whereas an observation of the same animal in the field would be counted as  hour of “feeding activity.” The LTA is therefore an absolute index ratio rather than an interpretation of the actual field-observed activity per 24 hours. Seasonal Changes in Mobility We segregated the annual monthly movement cycle (table 3.) into 2 divisions based on the satellite monitoring of cows 986–93 (table 3.2). The cycle included five pauses or dates of low mobility subtended by decelerating and accelerating trends. The pauses or slowdowns included: one at calving; one in September; another during fall breeding; one during mid-winter, and one in May before moving to calving areas (figs. 2.3, 3.2). These pauses were not nearly as evident when the animals were in the Torngat Mountains; nor were they representa-

Environmental Factors in Distribution and Movement | 359

Table 13.2 Annual cycle of acceleration and deceleration 1986–87 to 1992–93 (females with UHF radio transmitters) Seasonal Period

Calving Pause Post-calving Shift Mosquito Season August Dispersal September Pause Fall Acceleration Breeding Pause Early Winter Shift Winter Pause Spring Acceleration May Pause Pre-calving Shift

Approximate Dates or Mean Date of Pause ( CV %)

14.3 June ± 1.47 (27) 22 June–7 July 8–31 July 1–21 August 5.2 Sept. ± 1.78 (83) 10 Sept.–18 Oct. 22.1 October ± 1.20 (14) 1 Nov.–31 Dec. 12.3 Feb. ± 3.61 (68) 14 Mar.–30 April 21.6 May ± 2.69 (28) 20 May–7 June

Kilometres per Day ( CV %)

2.4 ± 0.52 (57) 7.6 ± 0.82 (29) 16.7 ± 1.80 (25) 21.2 ± 1.69 (21) 5.4 ± 1.69 (74) 17.4 ± 0.76 (12) 9.7 ± 1.06 (29) 13.6 ± 1.25 (24) 2.9 ± 0.25 (32) 7.7 ± 0.91 (31) 6.2 ± 1.25 (50) 14.8 ± 0.54 (34)

Major Social/ Environment Proximate Factors

birth/calf bonding seeking greens insects, plant cover oestrids and greens optimum foraging decline food quality breeding > snow/ice, numbers shallow snow low risk return tundra, numbers seeking early greens to calving region

tive of the movements of the sedentary Red Wine herd (Brown 986) east of the Smallwood Reservoir (figs. 2.3, 3.3; Bergerud 2000). In Alaska an additional pause occurs in July which we did not observe. Skoog (968) recognized this pause for the Nelchina herd in Alaska, which occurred when caribou sought discrete upland habitats for mosquito-relief. The caribou of Newfoundland also had reduced mobility during the mosquito season if forested habitat or treeless uplands were available to provide wind relief from insect attacks. However, if the terrain was homogeneous and lacked sites for respite, the Newfoundland animals banded together and continued to move when bothered by insects (Bergerud 974b). The George River herd did not make this July pause, contrary to some of the herds in Newfoundland and the large migratory herds in Alaska and NWT. The George remained on the tundra east of the George River in July in generally elevated habitat (600–800 m) that lacks physiographic relief features. The caribou aggregated as a relief mechanism – sharing their tormentors and creating updrafts in CO ₂ to reduce attacks. When high winds or inclement weather abated daily insect attacks, the animals decelerated their travel and aggregations dispersed (Camp and Linders 989). June Pause

The first pause in the biological year ( June to 3 May) occurred during calving when the females reduced mobility. The mean day of least movement between years was 4 June, when females moved only an average of 2.4 km/day, the least movement of the year (table 3.2). Other authors have noted reduced movement

METRES PER MINUTE WALKING WHILE FEEDING

6

1989 1990 1991 1992

5

4

3

Y = 5.072  0.034X r = 0.816 n = 14

2

TOTAL SAMPLE n = 814

1

0 0

10

20

30

40

50

60

70

80

90

100

PERCENTAGE PLANT COVER 6

GRAMINOIDS (n = 307) BIRCH (n = 194) TUNDRA SHRUBS (n = 29) BIRCH + TUNDRA SHRUBS (n = 10) GRAMINOIDS + TUNDRA SHRUBS (n = 51) GRAMINOIDS + BIRCH (n = 10)

METRES PER MINUTE WALKING WHILE FEEDING

OVERGRAZED

5

4

G RA MINO

3

IDS

BIRC H

Y = 4.744  0.026X r = 0.968 Y = 3.944  0.031X n=4 r = 0.973 n=4

2

1

0 0

10

20

30

40

50

60

70

PERCENTAGE PLANT COVER

80

90

100

Fig. 13.4 Mobility compared to plant cover. (above) The animals fed slower in the summer where plant cover was more abundant; (below) Additionally animals had to pause to strip birch leaves. This reduced their pace as compared to the continual moving forward with monocot graminoids. Tundra shrubs were considered overgrazed if they represented 30% or less of the cover.

Environmental Factors in Distribution and Movement | 36

of cows at parturition (Lent 964; Skoog 968; Fancy and Whitten 99), a necessary respite for completing parturition and developing the maternal/filial bond (Pruitt 960; Lent 974). Post-calving Shift

Within days of birth in mid-June the cows were again on the move with rates three times that noted during the calving pause (table 3.2). The interval after calving and before insect harassment was especially important, allowing animals to secure the early greens necessary for high lactation demands when the emerging vegetation – especially early sedges – was abundant and high in protein. They moved slowly in this interval prior to insect harassment (7.6 km/day, table 3.2), feeding more slowly in graminoid stands than in birch where they had to strip the leaves (fig. 3.4). The animals moved more quickly when foraging on prostrate tundra shrubs where ground coverage had been reduced by grazing and trampling (fig. 3.4). These travel speeds in June prior to the arrival of mosquitoes appeared to be largely free of group-size effects (social facilitation or interference). A GLM analysis of the impact of group size and plant cover indicated that group size was not significant: P = 0.498. Plant cover, on the other hand, was highly significant: P = 0.000 (n = 797 one-minute tests of 95 groups where travel rates, ground cover, and group size [2–500+ animals, minimum and maximum] were simultaneously recorded). The multiple regression for the 797 tests was Y = 5.965 - 0.00062 X (group size) - 0.0435 X² (plant cover). Very large groups may have fed slightly slower, but this could have been a cover effect; the correlations were speed vs cover: r = -0.42, P = 0.000 (n = 797); speed vs group size: r = -0.08, P = 0.022 (n = 78); and group size vs cover: r = 0.26, P = 0.00 (n = 673). The mean speed of these feeding animals was 2.4 m/min. (n = 76). In another test we segregated 74 additional groups in three years into 9 subgroups where we had no knowledge of the plant communities the animals were moving through. These animals travelled at a mean speed of 0.4 m/min. and the correlation between group size and speed was r = 0.206 (n = 3 years x 9). In general we found that the speed of animals moving (988–92) prior to insect emergence in June (fig. 3.5) was not affected by group size (fig. 3.6: few insects present). However, it was often difficult to distinguish where one group ended and the other began with these migratory caribou, especially for the larger herds, where there was less synchrony in the dominant activity (table 2.2). Mosquito Season and August Dispersal

With the arrival of the mosquito season in July (fig. 3.5; table 3.3), movements accelerated (table 3.2; figs. 3.6, 3.7), owing to a (rather abrupt) decline in feeding – caused by the arrival of biting female mosquitoes and, in some years, black flies as well – and an increase in walking (fig. 3.8). Figure 3.7 graphs bites (to

1988

58' 30° / 65' 24°

25

58' 44° / 65' 53°

56' 43° / 64' 53°

COOLER COAST

20 MOSQ BITE

15

OESTRIDS

BLACK FLIES

10

TABANIDS

5 0

1989

56' 43° 64' 53°

35

58' 17° 66' 27°

57' 43° 66' 12°

57' 11° 62' 21°

56' 00° 67' 00°

MINIMUM AND MAXIMUM DAILY TEMPERATURE (C)

30 25 MOSQ BITE

20

BLACK FLIES

15 10

TABANIDS & OESTRIDS

5 0

IN TRANSPORT

-5

1990

57' 11° 63' 54°

57' 46° 66' 12°

58' 14° 68' 28°

25 20 15

MOSQ BITE

10

OESTRIDS BLACK FLIES

5 0 30

TABANIDS

1991

56' 43° 64' 53°

57' 55° 65' 12°

56' 43° 64' 53°

25 20 15 10

BLACK FLIES

5

MOSQ BITE

TABANIDS

OESTRIDS

0 15

20

25

JUNE

30

5

10

15

JULY

20

25

30

5

AUG

5

GROUND OBSERVATIONS FEW INSECTS PRESENT MOSQUITOES PRESENT MOSTLY OESTRIDS PRESENT

KILOMETRES TRAVELLED PER HOUR

4

(6) MEAN GROUP SIZE

(87)

(7)

AERIAL OBSERVATIONS OF LARGE GROUPS IN JULY

[5] DAYS BETWEEN LOCATIONS OF RADIO-COLLARED

(83)

3 (162)

(47) 2

(24)

(3) (6)

(40k)[5]

(4)

(10k)[8]

(17)

1 (44)

(100k)[6]

(173)

(6)

(31)

(10k)[8]

(41) (21) (150k)[8]

52

58

76

113

36

1988

1989

1990

1991

1992

HOURS WATCHED

1993

1994

1995

Fig. 13.5 (facing page) The phenology of insects. There was considerable variation between years in the emergence of black flies, mosquitoes, tabanids, and oestrids. Additionally the results were affected because of changing camp locations within and between years. The most consistent camp site was at the “running-out” of the George River from Indian House Lake (56º43' N, 64º53' W) visited in 1988, 1989, and 1991 and where mosquitoes were especially abundant. Fig. 13.6 (above) Travel rates were less in the pre-insect season (primarily June) in comparison to those during the mosquito and oestrid seasons. We did not detect a social facilitation response between increased mobility and larger groups sizes. The mobility rate of the large herds monitored from the air is not directly comparable to the ground observation rates since there were several days between the aerial sighting that included long intervals of standing and lying. The large herds seen from the air in July were relocated based on core radio-collared animals as monitored by John Russell, a biologist under contract to Renewable Resources of Sidney, BC .

30

5

km / h : n = 52 hrs

25

KILOMETRES PER HOUR BITES PER MINUTE

4

20 FIRST OESTRIDS

3

15 10

2

BITES NOT RECORDED NO DATA

1

5 0

0

5

25

km / h : n = 57 hrs

20

4 FIRST OESTRIDS

3

15 10

2 NO DATA

1

5

NONE

0

KILOMETRES PER HOUR

30

1989

6

1990

5

km / h : n = 76 hrs

BITES PER MINUTE

KILOMETRES PER HOUR

6

0 30 25

4

20

OESTRIDS COMMON

3

15

2

10 NO DATA

1 0

BITES PER MINUTE

1988

5

BITES PER MINUTE

KILOMETRES PER HOUR

6

0 10

15

JUNE

20

25

30

5

10

15

JULY

20

25

30

Fig. 13.7 Mobility rates and activity budgets were altered by insect harassment. The most severe reactions were to a combination of mosquito and oestrid attacks in the last week of July. When under attack by mosquitoes, the animals bunched and commonly walked, whereas when the harassment was primarily by oestrids the animals often stood with head hanging low, listening and waiting for the sound of warble flights and tactile landings resulting in body shakes, sometimes followed by the animals taking flight.

90 80

MOSQUITOES APPEAR

60

MEAN MINUTES PER DAY 139 ± 18 n = 48

50

4

OESTRIDS

WALKING

70

3

2

40 30

1

WALKING

ACTS

ED

10

ING

20

0 10 100

15

20

25

30

5

10

15

20

25

0 30

MEAN MINUTES PER DAY 143 ± 17 n = 34

90

5

10

15

1989

FEED / WALK r = −0.639 n = 31

5

4

50 40 30

ED

OESTRIDS 3

WALKING

2

ACTS

ACTS PER MINUTE

60

FE

70

IN

G

80

ACTS PER MINUTE

PERCENTAGE FEEDING OR WALKING

FEED / WALK r = −0.804 n = 48

ACTS

FEEDING

5

ACTS PER MINUTE

1988

FE

PERCENTAGE FEEDING OR WALKING

100

1

20 10

ACTS 0

0 10

15

20 25 JUNE

30

5

10

15 20 JULY

25

30

5

10 15 AUGUST

Fig. 13.8 In July each year the rate of feeding declined and walking increased with the appearance of large numbers of biting mosquitoes that interrupted feeding and searching with frequent shaking and leg stamping. The large massed herds that formed had high rates of travel with little foraging.

366 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 13.3 Parameters

The abundance of insect pests 1988 to 1991 1988

First Warble Fly Seen 17–25 July¹ First Black Fly Seen 27 June First Mosquito Bite 27 June First Deer/Horse Fly 18 July Peak Abundance Peak Mosquitoes 22–29 July Dates Mostly Gone 29 July Peak Mosq. Bites/Min. 4.5 ± 1.17 Peak Warble Flies 9 August Peak Black Flies 25–28 July Peak Black Fly Bites/Min. 2.6 ± 1.41 Mosquito Abundance July Only No./Sweep Downwind 20.9 ± 3.25 No./Sweep Upwind 6.1 ± 1.49 Bites/Min. 1.3 ± 0.50 Landings/Min. no data Across Paper/Min. 9.2 ± 2.74 Relief Act/Min. 1.2 ± 0.18 (18)³

1989

1990

1991

11 July 23 June 25 June 11 July

7 July 8 July 4 July 4 July

22 July 4 July 9 July 15 July

7–11 July 24 July 7.7 ± 3.57 30 July 23 July 4.3 (n=1)

12–15 July 21 July² 3.5 ± 1.60 16 (?) July no data no data

25 July–3 Aug. 3 August 8.8 ± 1.85 30 July 29 July–3 Aug. 7.3 ± 1.95

5.2 ± 2.17 1.1 ± 0.34 1.9 ± 0.80 0.9 ± 0.52 5.1 ± 2.54 0.5 ± 0.16 (16)

4.6 ± 1.26 1.7 ± 0.59 1.2 ± 0.43 1.0 ± 0.29 7.3 ± 2.23 0.6 ± 0.14 (12)

4.7 ± 1.59 0.9 ± 0.30 2.0 ± 0.77 0.7 ± 0.33 4.0 ± 1.30 0.2 ± 0.11 (21)

¹ Some confusion in first recognizing a warble fly until 25 July ² Left the field 2 July, see fig. 3.4 for dates and locations ³ Total days observations made Note: Mosquito species recorded at Schefferville are Culiseta alaskensis, Culiseta impatiens (peak st wk June), Aedes nigripes, Aedes communis (3rd wk of June), Aedes hexodontus (3rd wk of June), Aedes punctor (4th wk of July), Aedes excrusians (st wk of August). A. punctor is the dominant species (Lewis and Weber 984) and the species that bothers caribou the most.

an arm) per minute; figure 3.8 indexes the frequency of caribou relief actions. The animals also massed in mid- to late July as the mosquitoes came on (fig. 3.9). With the arrival of oestrids and tabanids in late July (table 3.3), the animals reached their greatest travel rate in the season, 2.2 km/day (table 3.2). The oestrids bothered the caribou more than did mosquitoes (fig. 3.0; table 3.4), at times making the caribou run (table 3.5). If mosquitoes were still present when the oestrids emerged, relief actions were compounded (table 3.4). When under attack, caribou stopped feeding and often stood for long minutes in what we call the “oestrid position” with their heads down, listening for the flies. Relief actions increased in proportion to the abundance of these parasitic insects (table 3.4) and were especially bad when lone animals were unable to share their attackers with other caribou (table 3.5). The size of the aggregation decreased in August when only oestrids/tabanids were on the wing (fig. 3.9), especially when individual animals were attacked

250 100

3000

1989

1988

n = 384 GROUPS MEAN 42.0 MEAN GROUP SIZE

90

MEAN GROUP SIZE

80 70 60 50

MOSTLY OESTRIDS

20

n = 106 GROUPS

10

0

10 5 AUGUST

40

15

OESTRIDS PRESENT MOSQUITOES GONE

30 20

MOSQUITOES PEAK

10 0 10

100

15

20

25

30

5

10

15

270

490

20

25

30

5

30

5 AUG

1990

n = 575 GROUPS MEAN 21.1

90

MEAN GROUP SIZE

80 70 60 50 40 30 20

MOSQUITOES PEAK

10 0 10

15

20 JUNE

25

30

5

10

15 JULY

20

25

Fig. 13.9 When the caribou were under heavy mosquito attacks they aggregated, an anti-mosquito tactic well documented in the caribou literature. Mosquito harassment is the primary stimulus for the formation of the large post-calving herds that are photographed and counted as a census technique. Note the close correlation of group size and peak mosquito abundance in 1989 7–11 July and 1990 12–15 July. In August, when the mosquitoes cease, the herds splinter into groups and disperse across the tree line going south or west, still in the continued presence of insect harassment by oestrids, tabanids, and black flies.

368 | TH E R E T U R N O F C A R I BO U TO U N G AVA

30

AUGUST

KILOMETRES TRAVELLED PER DAY

25

OESTRIDS 20

Y=

15

29.370X X + 0.629 r2 = 0.929

10

1988 1989 1991

5

0

0

1

2

3

4

5

6

Fig. 13.10 Oestrids disturbed the caribou more than mosquitoes, resulting in increased mobility rates.

MEAN RELIEF ACTS PER MINUTE WEEKLY INTERVALS JULY & AUGUST

by more than one oestrid. These smaller groups stood more and fed less (table 3.5), and in these cases would have decreased mobility. On the one hand it was every animal for itself; on the other hand an animal often ran to another, warble flies in tow, redistributing its tormentors in a legitimate example of facilitation/ interference. Caribou biologists concerned about the impact of low-level aircraft on caribou could put things in perspective by spending a day on the tundra in August when these animals are truly stressed by oestrid flies. Figure 3. provides a summary of the caribou’s activity budgets and mobility rates and compares them with severity of insect harassment. The travel rates (km/hr) increased as insect harassment increased; feeding declined with harassment. The George River females travelled longer distances in August than in July (table 3.), as did the Central Arctic herd in Alaska: 2 vs 9 km/day (Roby 978), but the Porcupine herd travelled further in July (Whitten and Fancy 990). The mean monthly rates for the satellite-collared animals in 7 years were 8.6 km ± .7 km/day in August; and 4.5 km ± .26 km/day in July – higher rates than

Environmental Factors in Distribution and Movement | 369

Table 13.4 Insect-related activity of active caribou (not lying) during different levels of harassment

Caribou Actions

Mild Mosquitoes

Acts per minute Mosquitoes Oestrids and Oestrids None Mild Moderate Severe

Head Shake Body Shake Leg Stamp Bite Body

0.77 0.10 0.00 0.00

1.87 1.57 0.71 0.09

0.06 0.04 0.00 0.01

0.35 0.24 0.07 0.05

0.78 0.60 0.16 0.13

1.14 0.74 0.55 0.17

Means

0.22

1.06

0.03

0.18

0.42

0.65

Min/Sec Observed

85:58

190:49

607:53

524:48

650:48

777:15

Activity Budgets (Not Lying) Feeding Walking Standing Running

32.3 59.3 0.9 6.6

4.1 27.1 64.5 4.3

58.8 35.1 6.0 0.2

31.3 32.2 34.1 2.5

15.9 17.5 65.5 1.1

6.5 15.8 75.4 2.3

Minutes Watched

86

191

608

525

651

777

Table 13.5 Activity budgets and frequency of insect-related activity during attack of different numbers of oestrids Number of Oestrids per Caribou 2 3

Parameters

1

% Activity Feeding Walking Standing Running

23.1 9.6 66.0 1.3

0.2 18.6 75.4 5.9

1.8 5.0 93.2 0

0 1.4 98.6 0

Frequency of Activity (min-¹) Head Shake Body Shake Leg Stamp Bite Body Means

3.0 1.8 1.2 0.3 1.6

3.0 2.6 1.4 0.6 1.9

2.1 1.1 1.0 0.4 1.2

10.1 6.9 4.8 0.9 5.7

81:00 3.05 ± 0.77 20

63:27 1.82 ± 0.56 17

55:48 1.0 6

8:32 1.0 3

Minutes:Seconds Observed Mean Group Size Number of Groups

≥4

STANDING (%)

50

Y = 68.457 + 14.429X r = 0.800 n=9

92,925 CARIBOU

NO TREND MEAN 2.0 ± 0.30

0

FEEDING (%)

80

Y = 64.244  6.511X r = 0.817 n = 23

50

WALKING (%)

0

Y = 21.982Xe 0.230X r2 = 0.511 n = 22

50

0

KILOMETRES PER HOUR

8

Y = 0.275 + 0.532X r = 0.727 n = 21

5

290 HOURS

0 1988 1989 1990 1991

Y = 0.0065X 2.874 r2 = 0.855 n = 24

3 2 1

341 HOURS

2

3

4

5

6

MILD MOSQ.

MILD MOSQ. AND TAB.

MILD MOSQ. AND B.F.

MILD

7

8

MED. SEVERE

OESTRIDS, BLACK FLIES, & TABANIDS

9 SEVERE OESTRIDS & MOSQ.

1

NO INSECTS

0 PRE INSECTS

RELIEF ACTS PER MINUTE

4

Environmental Factors in Distribution and Movement | 37

those in Alaska and possibly related to the reduced plant cover in Labrador (the Central and Porcupine ranges in Alaska were not overgrazed). Rates in August exceeded or equalled those in October–November, the months of the classical fall migration when caribou are expected to make long movements to winter pastures. Our ground observations overestimated mobility rates since we excluded caribou lying-down and since more observations were made on warm, sunny days (when insects are especially evident) than on cold, windy days when caribou spent more time feeding and lying down. Furthermore, the mean summer latitude of the George River herd is 57° N, where there are more hours of darkness than caribou living at higher latitudes experience, and correspondingly longer periods when cooler temperatures limit mosquito activity. In the insect season feeding was heaviest when mosquitoes and oestrids were least active. Between 0600–0800 hours, 70% of the animals we observed were feeding; between 2002200 hours and 0500, 6% of the animals were feeding. July–August is the season of maximum green phytomass, rich in nutrients. Animals should travel slower when feeding rather than faster. The high mobility did not seem to be a density-dependent race to unutilized green patches. Rather, a common sequence was this: Aggregation sizes grew daily during the warm hours if winds were light, in response to the abundance of mosquitoes. When insect attacks slackened the animals dispersed feeding, not in a race to reach a high phytomass but rather to crop nearby forage with reduced walking and searching. The increase in movement took place when the animals were again on the move, walking and/or running to escape insects. September Pause

From mid-August until early September the animals decelerated, reaching a pace of only 5.4 km/day ± .62 km/day on a mean date of 5.2 September ± .78 days (table 3.2; fig. 3.2). The oestrids were most severe in 988 and 989 in the first two weeks of August; as they gradually disappeared the pace slowed and the animals improved their energy balance with an increased intake of dry matter (fig. 7.2, also see Appendix), less expenditure in travelling and evasive body movements. This respite – a time when green plants are still nutritious – falls approximately 0 days before the end of the growing season (fig. .5) and prior to the first frosts and leaf drop.

Fig. 13.11 (facing page) A summary of activity budget and mobility rates plotted against the increasing severity of insect disturbance. As the harassment of insects increased the animals fed less and walked more, and kilometres travelled per hour increased. If the oestrid attacks were severe the caribou spent more time standing.

372 | TH E R E T U R N O F C A R I BO U TO U N G AVA

KILOMETRES TRAVELLED BETWEEN 3 OR 4 DAYS

100 90 1988

80 70

SEPTEMBER PAUSE

60

1989 1992 FEW

OESTRIDS

LEAST PAUSE

50

1990

3 DAY

40

1986 1991

30

1987

20 1990

10 0

4 DAY

10

20 AUGUST

30

10

20 SEPTEMBER

Fig. 13.12 When the oestrids ceased in late August the animals immediately slowed down and spent long periods feeding on vegetation that was still green. As the growing season ended mobility increased as green foods were replaced with lichens. The pause in 1992 was less than in other years: 1992 was the summer of the coldest weather and the fewest oestrids in our study.

Fall Acceleration and Breeding Pause

The rate of travel generally accelerated after the September slowdown as animals aggregated and densities increased (fig. 3.2). The animals dispersed in several different directions in these years but were generally in the taiga, where the growing season commonly ended between 0–20 September, at least a week later than on the tundra they had vacated. With the rapid decline in forage quality at this season, the animals may have travelled faster, searching for more discrete patches of the remaining green forage. The animals again slowed their movements in October when breeding occurred (fig. 9.6, table 3.2), a pause noted for caribou in Alaska as well (Skoog 968). Following the rut the mobility of the herd commonly increased (the early winter shift) until snow became general in November (table 3.2). As the snow cover built up in November and December, the animals spent more time searching through snow cover and digging craters and the rates again declined (the winter pause) (fig. 3.3).

KILOMETRES IN 3 DAYS OR SNOW DEPTH (cm)

120

120

1986–87 MAR. 23

100

100

NOV. 2

80

SNOW

80 SNOW

60

r = 0.525 n = 20

60

r = 0.730 n = 20

40

40 NOV. 1

20

20 SPEED

0

O

N

D

J

F

M

A

M

J

0

SPEED O

N

D

J

MONTHS

KILOMETRES IN 3 DAYS OR SNOW DEPTH (cm)

120

1988–89

M

A

M

J

APR. 23

120

APR. 9

1989–90

100

80

HEAVY SNOW

80 NOV. 1

SNOW

60

20

N

D

20

J

F

M

r = 0.752 n = 23

40

SPEED O

SNOW

NOV. 5

60

r = 0.432 n = 22

40

A

M

J

0

SPEED O

N

D

J

MONTHS 120

F

M

MONTHS 120

APR. 12

1990–91

100

A

M

J

M

J

APR. 6

1991–92

100 NOV. 1

SNOW

80 60

80 60

r = 0.826 n = 18

40

SNOW NOV. 3

r = 0.837 n = 15

40

20 0

F

MONTHS

100

0

KILOMETRES IN 3 DAYS OR SNOW DEPTH (cm)

MAR. 23

1987–88

20

SPEED O

N

D

J

F

M

MONTHS

A

M

J

0

SPEED O

N

D

J

F

M

A

MONTHS

Fig. 13.13 Caribou continued to move rapidly in November in the absence of deep snows but rates gradually declined in December as snow profiles built past 40 cm. Snow depths far exceeded the limits of 60 cm suggested by Pruitt (1959) and Henshaw (1964). However the animals did seek areas of reduced snow cover in habitats that have both lichens and good visibility. Generally in late March or in April mobility again increased even though snow cover was still increasing. The increased mobility headed the animals back in the direction of the Labrador tundra and Caribou House. Snow depths in this fig. were based on a snow-station course centrally located at Schefferville and monitored by McGill university students at approximately weekly intervals. The correlation coefficients between mobility and snow depths covered the period of snow build-up only until the dates of maximum accumulation with mobility regressed on snow depths.

374 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 13.6 Biological Year

The winter pause based on UHF radio-collared females No. of Animals

1986–87 1987–88 1988–89 1989–90 1990–91 1991–92 1992–93 Means

4 6 4 4 6 10 9 6.1 ± 0.94

Dates of Pause

Total Days

Mean Km Travelled Mean Km in Pause Travelled/Day

17 Dec.–12 Feb 18 Dec.–13 Feb. 17 Dec.–11 Feb. 20 Dec.–10 Feb. 20 Dec.–11 Feb. 17 Dec.–12 Feb. 16 Dec.–25 Jan.

57 57 56 52 53 57 40

331 ± 47 49 ± 12 62 ± 13 90 ± 14 207 ± 48 271 ± 58 99 ± 22

5.8 ± 0.81 1.0 ± 0.21 1.0 ± 0.33 1.7 ± 0.26 3.9 ± 0.91 4.7 ± 1.02 2.4 ± 0.53

53.1 ± 2.32

158.4 ± 42.06

2.9 ± 0.72

Winter Pause

An extended winter pause (2.9 km/day) occurred in late December to the middle of February, when sinking depths were greatest in new, unsettled snow (table 3.6). This period of reduced mobility had been documented for migratory caribou in the Northwest Territories and Alaska (Kelsall 968; Skoog 968). We discuss in chapter 4 our belief that this reduced mobility is primarily a strategy to reduce predation risk by seeking and compacting the snow profile, rather than the classical view that it is to reduce energy expenditure in cratering (Thing 977). Since the animals had selected lichen ranges of relatively low snow profiles (habitats we refer to as the optimum range as opposed to the critical range), to go elsewhere would only increase energy expenditure without the compensation of increased forage (Bergerud 974c). It would also increase predation risk, since deep, undisturbed snow cover favours increased predation (Mech et al. 995). Spring Acceleration

Commencing in mid-March the animals commonly left the optimum snow ranges and accelerated their rate of travel (fig. 3.3). When the animals had wintered west of 7° W and north of 55° N they followed the tree line northeast. This acceleration in early spring occurred despite the fact that snow depths in central Ungava increased in March and April (figs. .7, 3.3). However, snow cover was relatively shallow along the tree line and reduced sinking depths enhanced mobility. The appearance of brown substrates on windswept ridges may have contributed to the increased rates of travel. We feel the forage procurement equation had changed from mid-winter: the animals could increase their forage by generally travelling faster, searching for the more exposed but more widely dispersed flora on the tundra. We will discuss later whether or not they have a builtin clock (and map) that coordinates distances with the amount of time available for returning to the calving ground before parturition.

Environmental Factors in Distribution and Movement | 375

Table 13.7 The phenological dates associated with the May pause of females with UHF radio collars in seeking early greens Dates in May or June¹ Date Max. Date Rate Pause

Year

Date Ice Out of Knob Lake

Date Crossed Tree Line East

1987 1988 1989 1990 1991 1992 1993

4 June 14 June 6 June 17 June 20 June 29 June 6 June

3 May (3)³ 12 May (2) 19 May (3) 12 May (1) 8 May (4) 18 May (3) animals east

1 May 5 May 9 May 17 May 4 May 10 May 21 May

15 May 15 May 30 May ??⁴ 21 May 25 May none⁵

28 May (2) 21 May (4) 18 May (2) ??⁴ 20 May (4) 17 May (3) unknown

10 9 unknown

13.7 June

12.0 May

9.6 May

21.2 May

20.8 May

8.6

Means ¹ ² ³ ⁴ ⁵

Date Moving Days of Towards Calving² Pause

13 4 7

Dates are approximate due to 3-day reporting schedule Based on azimuths leading towards locations of least movement and not mobility rate Sample size Only one animal, data not adequate Early phenology year with no pause. Caribou may have been eating greens in the last weeks of May

The spring acceleration in travel rates reached a peak in the 7 years of UHF tracking on 9.6 May ± 2.72 days (extremes  May to 2 May) (table 3.7). The mean date that animals crossed the tree line going east was 2.0 May ± 2.46 days (6 years only: in 992–93 they stayed east). By this date they were decelerating (table 3.7). May Pause

Several of the UHF animals nearly paused (4.5 ± 0.75 km/day) near the tree line in mid-May (fig. 3.4); there may have been early greens at this interface and further penetration would have taken them to the overgrazed June–July ranges east of the George River. After this pause a last-minute spurt took cows to the heavily-overgrazed calving ground (table 3.2; see also Otto et al. 2006). A similar sequence occurred in British Columbia where expectant cows remained at low elevations feeding on early greens until parturition was imminent; they then went uphill to calve at high elevations away from travelling wolves but where the phenology was late and the phytomass low (Bergerud et al. 984). Annual Dispersion and Fidelity in Distributions We evaluated the distributional spread of the radio-collared females by months for the years 986–9 when the herd numbered greater than 600,000 animals.

30

1987

20 EARLY GREENS

ICE OUT CALVING

10

0 30

n=2−7

1988 EARLY GREENS

20

ICE OUT CALVING

KILOMETRES TRAVELLED PER DAY

10

0

n=1−4

30

1989

20

EARLY GREENS

ICE OUT

CALVING 10

0

n=3−4

30

1991 EARLY GREENS

20

ICE OUT

CALVING

10

0 30

n = 5 − 10

1992 EARLY GREENS

20

CALVING

10

0

ICE OUT

n = 3 − 11 5

10

15

20

MAY

25

30

5

10

15

20

JUNE

25

30

JUNE

JULY

n = 21 5 YEARS

AUGUST n = 37 7 YEARS

n = 50 8 YEARS

0

100 KILOMETRES

0

100 MILES

TREELINE CALVING CENTRE

SEPTEMBER n = 42 7 YEARS

MONTHLY CENTRE SETTLEMENT

1986 1987 OCTOBER n = 42 7 YEARS

1988 1989

NOVEMBER n = 42 7 YEARS

1990 1991 1992 1993

Fig. 13.14 (facing page) The females with UHF radio transmitters commonly reduced daily mobility rates after crossing the tree line in May and foraged on newly emerging graminoids prior to moving again to the general area Caribou House where they would give birth. The dates of “ice-out” were the dates that McGill research students quantified the break-up of winter ice on Knob Lake, Schefferville. The calving dates are based on table 9.3, which in turn is based on the analysis shown in fig. 9.1. Fig. 13.15 (above) The monthly distributions June to November of the UHF radio-collared females. The Monthly Centre is the estimated mean centre of each month’s distribution in 5 to 8 years of monitoring. The monthly “Herd Dispersion” indices in fig. 13.17 were measured from this monthly overall centre in 7 years to the centre for that month in one year (i.e. the October dispersion index for 1987 is about 125 km from the overall October centre in 7 years [the square symbol divided into quarters]). The distribution of the females in October 1987 is quite distinct (see the area enclosed with a dashed line ---). The annual distributions in June and July are closely overlapping (a low dispersion index) since the animals remain on the Labrador tundra, in contrast to the wide distributions in December (high dispersion index) as the animals sought new ranges between years in response to annual changes in the snow cover, seeking low-risk habitats with reduced snow cover.

378 | TH E R E T U R N O F C A R I BO U TO U N G AVA

DECEMBER

JANUARY

n = 40 7 YEARS

n = 39 7 YEARS

0

100 KILOMETRES

0

100 MILES

TREELINE FEBRUARY n = 35 7 YEARS

CALVING CENTRE MONTHLY CENTRE SETTLEMENT

MARCH n = 39 7 YEARS

1986 1987 APRIL

n = 34 7 YEARS

1988 1989

MAY

n = 35 7 YEARS

1990 1991 1992 1993

Fig. 13.16 The monthly distributions December to May of the females with UHF radio collars. Some small distributions were based on only one radio-collared female. These restricted distributions are the result of localization in fragmented sites that most likely had reduced snow profiles compared to areas adjacent.

The distance between females as the herd expanded its range should be an index to the uniqueness of the habitat in meeting the requirements of the animals. If the animals were concentrated in the same area each month between years, it signifies a discrete limited requisite; if the females in their monthly distributions were widely distributed between years, we felt the animals’ needs could be met by a wider variety of habitats. To measure dispersion we first estimated the overall monthly geographical centre for each of the 2 calendar months by overlapping the monthly distributions secured in 5–8 years (figs. 3.5, 3.6). Twelve polygons were constructed each year, one for each month, by connecting the peripheral locations for all the satellite locations for that month. Our monthly cohesive index was the mean dis-

Environmental Factors in Distribution and Movement | 379

Table 13.8 Total range size (1,000s) in 6 years of satellite females when the population reached peak numbers (additional monthly distributions shown figs. 13.15 and 13.16) Month

1986

Size of Range (x 1,000 km²) and Number of Animals 1987 1988 1989 1990 1991

June¹ July August September October November December January February March April May

15/4² 45/4 39/4 29/4 84/4 30/4 13/4 – – – – –

39/6 44/7 53/6 57/8 84/7 87/7 30/8 25/5 16/4 13/4 18/4 14/4

31/6 32/4 51/4 54/4 54/4 65/6 33/4 18/4 4/2 2/2 15/2 27/2

25/7 55/5 73/5 116/5 96/8 54/5 29/4 19/4 12/4 27/4 20/4 36/4

10/3 8/2 12/2 20/5 55/7 74/6 50/7 9/4 28/4 20/4 16/4 35/3

– – – – – – – 10/4 13/5 23/5 19/5 38/7

Mean

24.0 ± 5.25 36.8 ± 12.76 45.6 ± 10.01 55.2 ± 16.77 74.6 ± 8.49 62.0 ± 9.65 31.0 ± 5.89 16.2 ± 2.99 14.6 ± 3.89 17.0 ± 4.39 17.6 ± 0.93 30.0 ± 4.42

¹ Mean calving ground 986–93, 24.7 ± 2. x ,000 km² ² Number of satellite females

tance between the centres of these monthly polygons and the overall centre for that month based on the distributions in all 6 years (table 3.8). An index of range fidelity for individuals was based on four satellite-collared females monitored for three consecutive years June 986 to June 988 (Harrington and Luttich 99). The fidelity index was the mean kilometres between locations obtained on the same date 365 ± 2 days apart for each individual in the three consecutive years. Dispersion Index

The herd dispersion index indicated merging philopatric distributions of females in June and July in the years of high numbers. After the animals crossed the tree line in August going west (fig. 3.7), the animals began to scatter. With the general arrival of snow in November, animals became further separated as movement reached maximum rates (figs. 3.2, 3.3). From January to April the animals localized and the mean size of the individual ranges varied between 6,000–8,000 km² (table 3.8). In these months the individual satellite-collared females were widely spaced (fig. 3.6) with reduced overlap, averaging over 300 km from the overall geographical centres for these months (fig. 3.7) After the animals began to move east the paths of the individuals converged and dispersion declined as their monthly ranges commenced to overlap. In earlier years the dispersion of the herd would have been less when numbers were low and the herd was restricted to the centre of habitation. The centre of the

500

FIDELITY DISPERSION 400

300 INDIVIDUAL FIDELITY

200 CALVING

HERD DISPERSION OR FIDELITY INDEX (km)

380 | TH E R E T U R N O F C A R I BO U TO U N G AVA

HERD DISPERSION DISPERSION APRIL 1954 & 58

100

MEAN AREA (km²)

J

J

A

S

O

N

D

J

F

M

A

M

BIOLOGICAL YEAR Fig. 13.17 The herd dispersion and individual fidelity indices (discussed in fig. 13.15) plotted by months. Individual fidelity is the mean distance between locations of the same single animal obtained on approximate matching dates in three consecutive years (1986 to 1988) and is adapted from Harrington and Luttich (1991). This “Loop of Life” confirms the wide ranging of the animals in the winter as snow conditions vary and the essential core of June with the homing to the calving ground located in the centre of the Labrador Peninsula tundra. Also shown is mean area (km²) in six years, table 13.8.

herd in April 954 was 00 km apart from that of 958, whereas from 987-92 the mean approximate distance of the April ranges from the overall monthly centre was 290 km (fig. 3.7; Banfield and Tener 958; Bergerud 958, 967). The population in the 950s was only 2% of the numbers in the 980s yet the dispersion of the April range in those early years represented 34% of the spacing used by the herd in April 987–92 (fig. 3.7). Thus the extent of the range occupied did not increase in correspondence to the herd’s increase in numbers. Fidelity Index

The fidelity index mirrored the dispersion index. In the winter the four satellite females had an average dispersion of 350 km from their location one year previous. The distance between consecutive year locations declined in May as the females converged on the Labrador tundra to calve and the index remained down in the summer months while the females resided on the limited tundra

Environmental Factors in Distribution and Movement | 38

in Labrador. In actual fact, the animals showed no fidelity to prior locations even at calving. Cows did not return to previous calving locations. The index was greater when the animals were more widely spread with non-specific space requirements; the index is smaller when they move to the tundra east of the George River and space requirements are quite specific: reducing predation risk. However both indexes demonstrated convergence at the calving habitat in June. Both its restriction and its central location in the tundra east of the George River makes the calving ground the hub of the rotating wheel in the animal’s annual distribution cycle. Environmental Influences on Seasonal Distributions Skoog (968, 445) said, “Eventually the continued movement of caribou, guided by a multitude of environmental factors, evolves into a conventional pattern, both temporal and spatial … a definite regularity develops. Certain areas of range are favoured at certain times of the year, passage to and from these areas follows specific routes, as directed by terrain features and by the ‘force’ of previous experience, the timing of major movements is governed by seasonally recurring physiological drives and external environment cues.” Kelsall (968, 06) stated “During the balance of the year (other than migratory periods) the animals are nomadic. They move constantly in response to frequently changing environmental pressures and often in unpredictable directions.” In the 950s and 960s when Skoog, Kelsall, and Bergerud followed the caribou, there were no unsightly radio packages adorning their manes. Dauphiné et al. (975) installed the first radios on the Ungava Pensinsula from June–October 973, which allowed us to monitor distributions, rates of travel, and travel routes, and to ascertain more precisely what the “multitude of environmental factors” were that guided caribou in maximizing energy intake, minimizing predation risks. The gregarious social structure of caribou and their high numbers in the 980s required the caribou to be on the move, constantly changing their distribution. But the directions they took still needed explanation. The satellite monitoring not only told us how fast they were going but when they changed directions. Based on the monitor schedule of receiving radio-fixes at 3–4 day intervals we estimated the date that the animals changed compass headings by ≥ 30°. We then looked for environmental factors that might explain the rerouting at locations where routes had changed. We took special note that several satellite females who were separated by > 20 km changed direction within a matter of days, and we considered this simultaneous movement evidence of a common environmental influence. We considered three major hypotheses: () the animals selected routes based on energy considerations (topographic funnelling), travelling down valleys and

382 | TH E R E T U R N O F C A R I BO U TO U N G AVA

along eskers, skirting open water; (2) the animals moved along environmental gradients, walking into the wind to reduce insect harassment, for example, or following snow gradients or an incline in phytomass abundance; and (3) the animals were goal-oriented in the directions they chose to move, returning to traditional areas either because they recognized landmarks and topography or had intrinsic orientation compasses. Kelsall (968) noted how barren-ground animals out of sight of the shoreline maintained directional azimuths when crossing large frozen lakes in the spring. Post Calving

Following calving, most of the satellite females moved from their calving sites to the northwest (69%, n = 20, fig. 3.8). A few cows moved towards the coast. In 993 when the herd calved north of Caribou House adjacent to the Ungava Coast, they moved mostly southwest although some went east (fig. 3.9). Initially we thought all post-calving movements were goal-oriented to insect relief habitat adjacent to Ungava Bay or the Labrador coast. But in 988 we found that insect relief occurred only within 3 km of the coast (also Dau 986). Only 3 of the 20 satellite females actually reached the coast; the others turned back south in early July before they had benefited from the cooling ocean influence on mosquito emergence. All 20 animals turned and retraced their routes south on the Labrador tundra (fig. 3.8). The initial movements north and east post calving also kept the animals on the tundra, away from forested habitat where wolves might have been more common, although bears were more common along the Labrador coast than on the calving grounds. Additionally, large numbers of calves drowned in some years on the northwestern route when they crossed several tributaries that flowed west to the George River. Hence the post-calving movements did not appear to enhance early calf survival. In the NWT, the traditional post-calving movements of the Bathurst and Beverly herds do not appear to reduce the risk of predation to young calves. The Bathurst post-calving movement south and southwest from the Arctic coast in some years crosses the end of Bathurst Inlet (Heard et al. 996), where there is a flush of green vegetation and where wolves and alternative prey are more plentiful than further north. The Beverly herd as well generally moves south from the calving ground – even though space is available farther north (Fleck and Gunn 982) – to the vegetative oasis adjacent to the Thelon River where wolves and alternative prey are much more common than to the north (Kuyt 962; Fleck and Gunn 982; Heard and Williams 992). The Porcupine herd in Alaska commonly shifted more into the foothills in late spring (Russell et al. 992, 993), where wolves and bear were more common (Garner and Reynolds 986; Whitten et al. 992; Young and McCabe 998). Again it appeared that early green food was the drawing card (Russell et al. 993).

Environmental Factors in Distribution and Movement | 383 69

N

32 21 7

10

3 3

3

9

3

7

POST-CALVING TO LATE PHENOLOGY n = 26

9

9

JULY MOSQUITO SEASON STAY TUNDRA n = 33

AUGUST AWAY FROM TUNDRA n = 34

15

39 53

14

13

5

3 6

8

8

8

8

SEPT. /OCT. MANY TURNS n = 36

29

3 5

11

TO WINTER PAUSE AND LOW SNOW n = 37

13

70

16

11

13

19 33

24

16

19

11

3

3

NOVEMBER FROM RUT PAUSE n = 38

43 26 9

7

4 26

11 4

7

MARCH FROM WINTER PAUSE n = 35

APRIL TO TUNDRA n = 23

26

4 4

9 9

NO 1993 SAMPLE

LATE MAY TURN TOWARDS CALVING SITES n = 23

39

Fig. 13.18 The azimuths (rounded to eight compass points) that the UHF females were travelling during the seven years we plotted their courses (figs. 12.15 and 12.16). The percentage of animals that followed each azimuth is shown at the end of each arrow. These azimuths do not provide information on males. For example, a major post-calving movement of males is to the coast at the start of the growing season (20–30 June) where there are early greens and insect emergence is delayed.

In the 970s when the George numbered less than 200,000, the cows calved along the Labrador-Quebec border on high windswept terrain with a late phenology and both > 40% snow cover and low phytomass at calving. With high numbers in the 980s the calving ground shifted both west and south to lower elevations with less snow cover and an earlier phenology. The direction of trail systems adjacent to the calving ground (fig. 2.9) indicated that caribou have

384 | TH E R E T U R N O F C A R I BO U TO U N G AVA

65o

70o

SETTLEMENT GROUPS ≥ 2,500 CARIBOU GROUPS < 2,500 CARIBOU SATELLITE PRESENT

60o

60o 0

CALVING AREA 1993

0

50

100 KILOMETR ES 50

100 MILE S

CARIBOU HOUSE

K O RO

KUUJJUAQ

51k

FORMERLY HEBRON

14k

R.

49k

TUNULIK

56k

ORGE R. GE

11k 66k

R.

12k 16k

17k

R.

AK SO KOK

28k

C R.

FA L C

O

Z

INDIAN HOUSE LAKE

F RA SER R.

NAIN

TREE L I N E

CA

R. R.

N

AU ISC I AP

S PA DE

55o

SCHEFFERVILLE 65o

Fig. 13.19 The calving area in June 1993 was farther north than in the previous 20 springs. The spring phenology was extremely early in 1993, with the ice leaving Knob Lake 6 June compared to a 37-year mean of 13 June. Mosquitoes appeared during calving and the animals moved north of Caribou House. The July dispersal of the aggregations from this most northern calving ground in 1993 was to move to Indian House Lake, > 150 km, and also included an atypical 200-km movement east into the Torngat Mountains. The estimated size of several of the post-calving aggregations, from 4–23 July, is listed. These counts are based on photographs taken by John Russell (analysis based on data from Couturier et al. 1996 and Russell et al. 1996).

historically gone northwest and downslope after calving, crossing (rather than following) the topography and the esker systems. In earlier years before overgrazing they had descended to lower elevations where birch had been plentiful. The maximum stands of birch that we measured in our range studies were at Gordon

Environmental Factors in Distribution and Movement | 385

Table 13.9 The spacing of individual caribou within groups of various size as affected by mosquito harassment, 1988 Dates and Insects

Group Size

Caribou Lengths between Animals

Number of Groups

No Mosquitoes (17–28 June) Acts/Min. none, Bites/Min. none

1–10 animals 11–20 animals ≥ 21 animals Mean

8.7 ± 4.5 10.0 ± 6.4 14.0 ± 10.8 10.9

36 10 13

Moderate Mosquitoes (29 June–11 July) Acts/Min. 0.439 ± 0.337, Bites/Min. 0.406 ± 0.24

1–10 animals 11–20 animals ≥ 21 animals Mean

3.9 ± 2.3 6.9 ± 2.9 7.6 ± 3.8 6.1

19 16 14

Severe Mosquitoes (12–21 July) Acts/Min. 0.707 ± 0.187, Bites/Min. 1.98 ± 0.39

1–10 animals 11–20 animals ≥ 21 animals Mean

2.5 ± 0.7 3.3 ± 0.7 4.5 ± 1.8 3.4

3 5 9

(58°7' N, 66°27' W) and Tunulic (57°43' N, 66°2' W). Thus the movements in the 980s, which seemed maladapted because of overgrazed birch and alpine shrubs, likely originated in previous decades when the lowland stands of birch along the George, Tunulic, and lower Ford Rivers provided a positive energy balance in late June – a balance that no longer existed in the 980s. We believe that the postcalving movements of the George River herd followed a green phytomass gradient consistent with the findings in Alaska and the NWT. Mosquito Season

The large aggregations that form in mid- to late July north of tree line in North America, including the George River herd, congregate to reduce mosquito harassment (Kelsall 968; Skoog 968; Roby 978). Animals in the centre of the large masses are able to reduce harassment (Russell et al. 993); furthermore, aggregations warm the air so that updrafts carry away the CO ₂ that attracts host-seeking diptera (Anderson and Olkowski 968; Anderson and Hoy 974). By being massed at one small location they may also swamp the local mosquito population. Our limited data also showed the animals in tighter groups when they were being harassed by mosquitoes (table 3.9). The bites/min. in the period 29 June–  July 989 averaged 0.406, but increased five times to .98 by 2–2 July; but the relief acts/min. were only 6% higher between the two periods – similar to a reduction in space between animals (29 June–2 July and –2 July), when an initial distance between caribou of 6. caribou lengths was reduced to 3.4 lengths, a compression of 44% (table 3.9).

386 | TH E R E T U R N O F C A R I BO U TO U N G AVA

In July the females near the coast reversed their direction, moving southeast (fig. 3.8). The mean date of turning was 6 July (Julian 96.5 ± 3.02), almost two weeks after mosquitoes had become bothersome along the George River. These females north of 58° N may have stayed north because mosquitoes emerged later at higher elevations. For example, mosquitoes were almost nonexistent at our Ford Lake camp (57°55' N, 65°2' W, 750 m) –23 July 99, but were extremely abundant along the George River on 25 July. The animals continued moving south and southeast throughout most of July and large post-calving aggregations commonly formed in the vicinity of Indian House Lake 988–95 (fig. 3.20) near where Mrs Hubbard (908) had seen the herd in August 905 (fig. 3.20, lower left). However, other post-calving aggregations remained on the tundra, but north of 57° N and mostly east of 66° W (fig. 3.2). These movements south on the tundra in July were again against the topography – crossing eskers and fording streams draining west into the George River. In addition, retracing their steps took the caribou back to ranges that had been heavily grazed when they moved north previously. The animals need to remain in large groups on the tundra to reduce mosquito harassment. To remain in windswept vistas with low vegetation, the animals near the coast had to go south, staying more to high ground and avoiding heavy vegetation when mosquitoes were most abundant. But although wind and temperature certainly affected the abundance of mosquitoes (fig. 3.22), the movement south cannot be explained by the hypothesis that caribou walk into the wind to reduce mosquito harassment (table 3.0; fig. 3.23). This hypothesis has existed since the first naturalists observed the immense herds’ agitation to insects, and it seems a reasonable theory, inasmuch as facing into the wind provides relief to us and our unprotected faces. But the hypothesis survives anecdotally without having been tested. For this reason we recorded the

Fig. 13.20 (facing page) A common movement route of the post-calving aggregations in late July in several years was to enter the taiga near Indian House Lake where the Naskapi used to wait (fig. 5.1). The approximate location of the herd is shown for August 1905 at the location where Mrs Hubbard encountered the August dispersal on her trip down the George River (Hubbard 1908). Note the variations in the space occupied by a herd of 100k± on 22 July 1990 (to the west of the “running-out” of Indian House Lake). Under severe mosquito/fly attack this herd compressed itself into three small masses on 24 July and then spaced even closer together 25 July. Lo Camps encountered this aggregation on the ground on the 27th and reported that the animals were under attack by warble flies/tabanids. Then later in the day as insects abated the herd separated into 2+ sections. Camps was also on the ground 25 July 1988 with the herd of 100,000 shown on the fig. in red. Initially the pilot couldn’t land to put Camps ashore: the nearest lake, 4 km in length and at right angles to the line of march, was completely inundated with swimming caribou. After landing, the animals were moving so fast Camps couldn’t maintain contact even by

TREE LINE 1988 1990

66o

65o

64o

G

EO RGE R.

1991 1994 1995

CARIBOU HOUSE

20/7 50k

50k 50k ADULTS 20/7 20 JULY 8 AUG. 1905

FA L

150k

C

. OZ R

19/7

21/7 57o

57o

22/7 100k 23/7

25/7/88 100k

LE

WHEELER R.

HA W

40k

BAD INSECTS 24/7 & 25/7

R. 24/7

23/7 27/7 100k 27/7

26/7

56

o

LAC CHAMPDORE

10k

18/7 10k

INDIAN LAKE HOUSE 100k

28/7

26/7

25/7

27/7

MISTINIBI LAKE

19/7

40k

25/7

23/7 2k

RG E R .

10k 21/7

GEO

D E P AS R .

26/7

E APPROX. TREE LIN 56o

MISTASTIN LAKE

GORLANDS LAKE

RESOLUTION LAKE

26/7 55o

55o 0 0

67o

10

20 KILOMETRES 10

“LA FOULE” 8 AUG. 1905

20 MILES

66o

65o

64o

running. Bergerud had seen this herd from the air earlier that day while 20+ km distant and initially thought it was a dust storm. (Most of the data in this fig. was gathered by Renewable Resources and is on file with Department of National Defense and was based on repeated identifications of the locations of radio-collared animals.)

12–15 JUNE 17–18 JULY 17–18 JULY 15–25 AUGUST

1992 UNGAVA BAY GEORGE RIVER

HEBRON

KUUJJUAQ MALES JULY

NAIN

A

CALVING

U

G

U

S

JUNE

T

D

IS

PE

RS

0

AL

50

0

100 KILOMETRES 50

SCHEFFERVILLE

100 MILES

26 JUNE 4 AUGUST AUGUST DISPERSAL POST CALVING

1995 UNGAVA BAY GEORGE RIVER

HEBRON

KUUJJUAQ

CALVING JUNE 10–12

A

U

G

US

T D ISP ERSA

NAIN

L

SCHEFFERVILLE

Fig. 13.21 The major direction of the August dispersal in 1992 and 1995 (adapted from Renewable Resources reports prepared for the Department of National Defense). The individual plots are the locations of satellite females.

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(n = 113) (n = 94) (n = 69) (n = 118) 1991 LATE YEAR

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Fig. 13.22 (above) Variation in the abundance of mosquitoes between the years with the peak abundance, 1988 at temperatures of 10/11°C and 1991 at temperatures of 22/23°C. Mosquitoes were generally not on the wing when temperatures fell below 6 or 7°C and not active with winds ≥ 6 m/sec. Mosquitoes were more active in the morning and evening when there were generally cooler temperatures but less wind.

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0%

10%

20%

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E

E E LI N

WIND DIRECTION (COMING FROM) n = 403

CARIBOU DIRECTION (GOING TO) n = 42,687

Fig. 13.23 The wind directions (1988–92) recorded four times a day at our June/July field camps compared to the direction the majority of the animals were moving by our camps. These comparisons of wind directions and caribou orientation do not support the hypothesis that animals were travelling into the wind to reduce mosquito harassment. Statements in the literature that caribou travel into the wind for insect relief are generally based on anecdotal observations.

direction the animals were going as well as the direction the wind was coming from at all our ground stations (table 3.0; fig. 3.23): There was no consistent correlation, only random chance. The wind was occasionally strong from 8 of the 6 compass directions. If the caribou always tried to face into the wind how could they ever get anywhere? And yet this belief will probably live on. We stress again the momentum of large herds, a momentum that maximizes in July because the animals are massed in huge groups, walking more, feeding less. We feel mosquitoes, not forage, set distribution and pace in July. The best evidence for this is that with the cessation of mosquitoes in early August the animals made abrupt and major changes in direction of travel and group size (the latter were reduced), and aggregations headed generally west into more forested

Environmental Factors in Distribution and Movement | 39

Table 13.10 Comparison of the direction caribou were travelling relative to wind direction from the ground observations July 1988 to 1991 when mosquitoes were active Wind Direction (%)/Direction Caribou Moving (%)

Station Location 59° N 57° N 58° N 57° N 56° N 58° N 57N 58° N 57° N Lat./Long. 62° W 65° W 66° W 62° W 66° W 66° W 65° W 65° W 65° W Median Date Counted 7/11 7/20 7/5 7/18 7/10 7/17 7/1 7/18 7/30 Caribou Tabulated 1,553 8,000 7,271 6,342 3,641 4,468 5,947 5,581 784 Mosquito Abundance in 25 Sweeps 22.3 20.8 12.7 1.27 6.6 2.6 1.9 1.5 14.9 Bites/Minute 0.05 2.6 4.1 0.63 0.39 1.9 0.02 0.12 9.4 Wind Direction¹ major direction 2/5² 0/0 North¹ NNE 27/0 23/0 NE 3/0 5.0 ENE 0/0 9/0 East 0/0 0/0 ESE 2/0 0/0 SE 21/0 0/0 SSE 3/0 14/0 South 5/8 0/6 SSW 2/0 2/0 3/10 5/100 SW¹ WSW 2/0 0/0 West 0/0 2/0 WNW 2/0 11/0 11/7 7/0 NW¹ NNW 18/0 23/0 no direction 0/0 0/0

13/2 3/4 0/6 0/0 0/2 10/0 0/26 3/0 10/0 8/0 3/0 18/0 18/0 0/6 10/31 8/5 0/18

16/9 5/0 2/0 0/0 9/0 0/0 11/0 0/54 0/0 2/0 2/0 0/0 21/5 5/0 23/31 5/0 0/0

18/1 18/0 5/0 5/0 0/0 5/0 11/1 0/0 18/0 0/0 2/0 0/0 0/0 2/37 9/55 7/7 5/0

10/98 3/0 8/0 0/0 3/0 3/0 5/0 26/0 3/1 5/0 3/0 3/0 0/0 0/0 18/0 10/0 0/0

7/0 12/0 2/7 0/3 2/2 0/0 29/0 10/0 5/0 2/0 2/1 0/0 0/44 0/0 5/39 5/0 7/3

11/0 0/0 6/3 6/0 15/8 0/0 11/0 6/1 0/0 0/1 0/18 6/0 17/49 0/0 11/1 9/0 2/17

19/0 11/0 0/0 0/0 0/0 0/0 0/0 4/0 4/0 11/8 0/92 26/0 0/0 0/0 19/0 7/0 1/0

¹ Major directions caribou moving ² Wind from the north 2% of the time, 5% of the caribou walking north into north wind

landscapes (fig. 3.8). Note that these are habitats with less wind relief and lower, less varied topography – habitats, in other words, where the strong flying oestrids and tabanids could operate more effectively. Furthermore, horse flies (Hybomitra spp.) and deer flies (Chrysops spp.) were much more common below tree line, especially in the peat land habitats they favour for pupation (McElligott 992; McElligott and Lewis 996) and through which the caribou move in August. August Dispersal

The caribou in the large migratory herds in North America make amazing changes in aggregating behaviour and the amount of space occupied between the

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end of July and early August. The huge July aggregations splinter and disperse across the landscape. The most striking example is the Porcupine herd in Alaska, which in some years may coalesce into a single aggregation on the coastal plain. By mid-August, however, animals are scattered as far south as the Porcupine River. The mean area occupied when aggregated was ,330 km² ± 240 km² (2 years); on 8 July 977 there were 05,000 animals in only 32 km², a density of 800/km². After dispersal in August, the herd occupied a minimum area of 5,76 km² ± 3,573 km² (7 years) and densities ranged from 4–8/km² (data from Russell et al. 992). Kelsall (968) called this break-up the August dispersal and it was very pronounced for George River animals in the 8 years in August 988–95 that either we or Renewable Resources observed aggregations (figs. 3.20, 3.2; Renewable Resources 99, 993, 994, and 995; Russell et al. 996). One hypothesis for explaining the August dispersal suggests that animals scatter in response to the oestrid attacks that commonly commence at the end of July (Curatolo 975; Roby 978). However, we noted annual differences in the arrival of oestrids, as did Toupin et al. (996) and these were not synchronous with August dispersal. We saw the first warbles in 989 and 990 on 7 and  July respectively (table 3.3). Emergence was later in 988 (25 July), and in 99 (22 July). Toupin et al. saw their first in 993 on 9 July and never saw any in 992 – a record cold summer. Clearly these annual variations in the phenology of oestrids are relevant to evaluating the hypothesis that oestrids are the cause of the August dispersal. Oestrid emergence might vary between years based on differences in the length of the pupation interval on the ground; or annual variations could arise because there were different egg-laying schedules the previous season inasmuch as temperatures and winds affect the searching activities of the flies. The warble fly cycle has been researched by many biologists, especially in countries with domestic reindeer, and can be summarized as () the egg stage, 6 days; (2) larvae stage, 0– months; (3) pupa stage, 3–8 weeks; and (4) the fly stage, 6–8 days (review by Camps and Linders 989). In northern Ungava the larvae leave the caribou in early June. Forty-seven females we examined 6–29 April (974–84) had a mean of 47 ± 4.8 larvae and seven females collected 9–26 May still had a similar number, 45 ± .8. However, in the interval 6– June, nine females had a mean of only 0 ± 5.3 larvae remaining and many fresh departure holes. If the larvae emerged in May, many would fall on snow and fail to survive. Snow was still general the first of June in the years 98, 982, 988, and 992, and we found a few intact pupal cases that may have fallen on snow. If we consider  June as the date of larval emergence, then for the three earlyfly years (989, 990, and 993) pupation length would have been 5 weeks. For the three late-fly years (988, 99, and 992) the interval in the substrate would have approximated 7 weeks. Both intervals are consistent with pupation times in

1990 3 1991 8 1992 8 91

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Fig. 13.24 The movement of the satellite females in August again illustrated their southern movement on the Labrador tundra and the common passage into the taiga across Indian House Lake. The fig. illustrates what appears to be some synchronous turning of widely spaced satellite females, in the same year, suggesting a common environmental stimulus.

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the literature. The mean June temperature recorded at Schefferville for the three early-fly years was 9.6°C ± .0° and for the three late-fly years 6.8°C ± 0.60°. This is a significant difference, which agrees with the hypothesis that variability in emergence chronologies are moderated by substrate temperatures during pupation. Still, the major warble flights in all years (early and late) were in the latter days of July; given the short lifespan of the adults, most emerged following a pupation stage longer than 5 weeks. The second theory for the difference in emergence dates respective to different egg laying schedules is consistent with Solopov’s (989) data that showed the emergence of O. tarandi larvae were not normally distributed and occurred in a series of pulses and in agreement with Nilssen and Haugerud (994). The latter authors noted that temperature during larval departure had only a slight effect on the dropping rate and postulated that temperature during the preceding summer was therefore the probable explanation of an uneven drop (or emergence). Our data in 988 showed three peaks of oestrid activity 25–30 July, 6–3 August, and 22–25 August (fig. 3.25). In these intervals both temperatures and wind conditions were favourable for warble flights and egg laying (fig. 3.25). This supports the theory that periods of infection must coincide with wind and temperature conditions that are suitable for seeking hosts; hence egg-laying chronologies vary within and between years. In the case of the George River herd, which is distributed further south than the other migratory herds, oestrids were on the wing in the latter half of July in some years when mosquitoes were still abundant. Faced with both biting and parasitic insects, the large herds remained intact. In fact, the largest herds we saw were in the last week of July 988, 989, and 990, when mosquitoes, tabanids, and oestrids were all on the attack. In 988 warble flies appeared 25 July and biting by mosquitoes was greatly reduced by the last of July (fig. 3.25). The last warble fly was seen 3 August in 988, 37 days after the first fly. Dau (986) also found simultaneous attacks of both mosquitoes and warble flies on the postcalving aggregations of the Central Arctic herd in 982 and 983. Warble flies in the presence of mosquitoes do not result in the August dispersal.

Fig. 13.25 (right) In 1988 male mosquitoes were common in the beginning of July prior to the biting female mosquitoes. Black flies and oestrids (primarily warble flies) first bothered caribou in the last week of July. There were three peaks of warble fly abundance in 1988 that were correlated primarily with warm temperatures ≥ 13°C. These warm days commonly had periods of reduced wind speeds favourable for oestrid flights. The lower temperature limit for oestrids has been placed at 10°C by Mörschel (1999) and Anderson et al. (1994); 13°C by White et al. (1975); 13–15°C by Kelsall (1975); and 13–17°C by Helle and Tarvainen (1984). Maximum wind speeds for oestrid activity from the literature are 6–8 m/sec. by Anderson et al. (1994) and 8–9 m/sec. by Kelsall (1975).

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396 | TH E R E T U R N O F C A R I BO U TO U N G AVA

We favour Kelsall’s (968) hypothesis that this remarkable dispersal occurs because the caribou are “released” from mosquitoes. The confusion has come about because in some years mosquitoes disappear at about the same time that warble flies become bothersome. Kelsall recounted an amazing observation of the Beverly herd (NWT) on  August 958: A huge post-calving aggregation of approximately 64,000 approached the Thelon River en masse, hesitated, then plunged in. But as the animals emerged on the farther side, the herd virtually “flew apart,” with animals streaming off in several directions. The August dispersal had commenced at a single moment. Swimming the river would have both cooled the animals and released them from mosquito attacks. We have observed George River animals emerge from cold swims on hot mosquito days to run and even buck. One caveat is that warble flies are present at water crossings, where they may be more successful laying eggs on wet fur, but we noted that animals often turn back when they encounter such ambushes. Furthermore, a large herd like the one Kelsall saw would swamp the few waiting flies. Our most telling observation was of the severe harrassment of a herd of 00,000 animals (0 females had radio monitors) by mosquitoes, oestrids, and tabanids on 28 July 990. From 29–3 July the weather turned cold, with high winds and rain. On  August we resurveyed the range from the air and located some of the same radio-collared animals. The herd had disbanded and was scattering. But it could not have been the oestrid flies that caused the break-up: The inclement weather prevented their activity just as much as it had that of the mosquitoes. According to Kelsall (968, 3), the August dispersal “appears to coincide with the release from harassment by black flies and mosquitoes. When release occurs, caribou activity is naturally and necessarily directed towards the individual pursuits of eating and resting. Any advantages to be gained by maintaining close herd formation are outweighed by the advantage to the individual in not having to compete for food.” Heard et al. (996) make the same argument. However, caribou can still reduce oestrid attacks by aggregating in small groups (Dau 986). In Newfoundland caribou aggregated and stood on windy hills where they could share both wind and warble flies with their “dear neighbours.” Caribou in the mountains commonly group on snow fields in late summer, as do George River animals in the Torngats. The snow prevents warble flies from approaching quietly on the ground; and by holding their muzzles low, caribou can prevent oviposition by nose bots by blocking their nostrils with snow. Anderson and Nilssen (998) feel that the primary reason caribou stand on snow patches is to thermoregulate, not to reduce insect harassment. We argue that if the animals’ presence on snow packs is primarily for temperature relief, they would recline on the cold snow (indeed some naïve calves do, see fig. 5 in Anderson and Nilssen 998). Instead the adults stand in anti-oestrid stance, listening for the flight sounds of parasitic flies. Anderson and Nilssen showed in their study area that a height of one metre above the snow pack produced a tem-

Environmental Factors in Distribution and Movement | 397

perature advantage only one degree cooler than the temperature measured one metre above bare ground. In the herds we studied, we have not observed animals standing on snow fields prior to shedding and to the emergence of mosquitoes and black flies in June, despite the often high June temperatures (fig. 3.5). This should be the crucial experiment: The Arctic North is covered with shallow cold lakes. Since caribou legs are important thermo-regulatory conveyors, why don’t they stand in the cold water on hot days if there are no snow fields present to moderate body heat? It doesn’t happen. Conclusion: supposed cause (hot temperatures) present; supposed effect (caribou cooling off in the water), absent; i.e., cause not sufficient (Hempel 966). However, we have observed caribou on hot windless days in shallow ocean water on tide flats. In these cases they were initially bothered by oestrids and ran up and down the beaches, dashing into the ocean. They were less bothered in the ocean and received additional relief from afternoon, on-shore ocean winds. The severe attacks of oestrids and tabanids do splinter social bonds (Roby 978). Roby recorded a distance of 8.7 m between animals in August not bothered and 70.7 m for groups under attack. Although Ungava animals usually stood when bothered, they also ran – possibly to leave the oestrids behind or to locate a refuge – and these increases in gait should contribute to their high travel rate in August. In August the herd dispersed across the tree line (fig. 3.20) and continued to move rapidly. Females with UHF radios – even many kilometres apart – commonly followed similar azimuths and made synchronous turns (fig. 3.20, 3.2, 3.24). The taiga they entered had fewer shrubs and the most extensive trail system in Ungava; both factors may have contributed to maintaining rapid travel. The also entered the area where the males had shed their warble larvae in late May (males had 2 times more larvae than females [fig. .3; Kelsall 975; Thomas and Kiliaan 990]) and where tabanids had pupated in the extensive fens (McElligott 992). Furtheremore, since warble flies are capable of travelling several hundred kilometres, those that originated from the larvae dropped from females on the tundra should have been able to reach the animals (Nilssen and Anderson 995). Parasite avoidance, as has been suggested by Folstad et al. (99), does thus not explain this August movement. Our data shows that high winds, not cooler temperatures, provided the most relief from mosquitoes and black flies (figs. 3.22, 3.25). The herds remained on the tundra in July for this relief and turned towards the tree line (and its reduced wind action) only when the mosquitoes abated. This release allowed them to seek less heavily-grazed habitats prior to the end of the growing season. Figure 3.26 presents the three indices we have used in discussing the impact of insect harassment on distribution and movement: () mobility rates; (2) insect relief actions (i.e. body shaking); and (3) group size. The biting of mosquitoes

398 | TH E R E T U R N O F C A R I BO U TO U N G AVA 187 100

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MEAN INSECT ACTS PER MINUTE (2 WEEK PERIODS)

Fig. 13.26 The harassment of insects in the summer influenced group size and travel speeds of the caribou we monitored passing by our camps from 1988 to 1992 (also fig. 13.6). Caribou in the pre-insect season travelled in moderate size groups (5 to 30) at speeds of only 0.4 to 0.9 km/hr. With the arrival of mosquitoes the animals aggregated in mean group sizes from 70 to 190 animals and mobility increased 0.8 to 2.4 km/hr. When oestrids joined the mosquitoes the group size was reduced (10–50 per group) but travel rates increased to 3 km/hr. After the mosquito season the August dispersal occurred, resulting in the smallest group sizes (less than 5 animals) travelling at the greatest speeds of 4 to 11 km/hr; these are the animals most bothered by insects. This August dispersal in the presence of oestrids does not coincide with a change in plant quality or fecal nitrogen (fig. 7.4, table 7.2). Animals in small groups would have had less forage competition and might have been expected to travel more slowly if forage was the primary consideration.

which commenced in early July resulted in an increase in travel rates from the pre-insect season rate of 7.6 km/day to 6.7 km/day in July (table 3.2). Group size increased to lessen the impacts. The animals remained on the tundra despite a shortage of food. With the end of the mosquito season, group size went from thousands to as few as –5 animals, and these small groups scattered, moved west, and crossed the tree line. At this point they were attacked by oestrids and tabanids and their rate of travel reached its maximum for the year at an average of 2 km/day (table 3.2). While under attack they often stood; but they also ran and reacted much more vigourously than they had with mosquitoes (fig.

Environmental Factors in Distribution and Movement | 399

3.26). Clearly they were extremely stressed. Biologists should see these so-called “crazy” carbiou before they get concerned with discussions about the disturbances caused by major human impacts – roads, hydro lines, pipe lines, sonic booms, and all the rest. Caribou are a gregarious species, and although they may trample lichen supplies, in many situations their foraging appears to benefit from observing – and often joining – other feeding animals. But individual evasive action to oestrid harassment, which splinters social bonds (Roby 978), is also a factor in the small group size in August. The rapid pace declined to only 5.4 km/day in the first week of September – the so-called the September pause (table 3.2; fig. 3.2), and the reduction coincided closely with the end of oestrid attacks. Oestrids are only on the wing for 6–8 days (Espmark 96, 968; Skjenneberg and Slagvoid 968; Washburn et al. 980), and the presence of these insects – perhaps augmented by a reduced forage biomass – primarily explains the rapid August travel. The George River animals travelled faster in August than the animals in the Porcupine herd in Alaska where the range was not overgrazed, but as they slowed to feed they again formed larger aggregations. This does support the hypothesis that the August dispersal was to reduce food competition; but there was no evidence of a major change in food quality coincident with either the August dispersal or the September pause (table 7.2). September–October Movements

Following leaf fall and freezing temperatures in late September and continuing into November, the animals travelled in a variety of directions below tree line (fig. 3.8). These directions were not consistent with topographical gradients or goal-oriented shifts. In several years satellite-collared animals crisscrossed their own previous trails (figs. 2.5, 2.6; Vandal et al. 989). The changes in azimuths on the part of the satellite animals – even those dozens of kilometres apart – displayed widespread synchrony. We recognized three temporal sequences in changing directions: the fourth week of September; the fourth week of October or first week of November; and the last week of November (fig. 3.27). For example: on 23 September 989, 4 satellite animals all turned and again on 27 September; in 99, 2 females made major turns approximately 23 November and 5 females turned the next day, 24 November. Although we cannot specify exact dates because signals were received only at 3-day intervals, there was clear synchrony in directional shifts between widely-spaced animals that cannot be explained by social facilitation. Nor were the aggregations packed closely enough to induce a ripple effect. We attribute the directional change in late September to the change in forage quality that coincides with the end of the growing season about 5 September and with the first hard frosts that commonly occur towards the end of September.

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Fig. 13.27 There were several periods between the September pause and reduced mobility in winter when the satellite animals made major changes in azimuths of 30 degrees or greater. Many females turned in the last week of September, probably searching for the last supplies of green foods. In mid-October turning again increased coincident with the formation of lake ice facilitating rapid movement in different directions. There was more turning in the last week of November as animals moved to lower snow profiles.

Some animals that had gone north turned in a more southerly direction in 986 and 988; others that were moving southeast or southwest turned more northerly in 989 and 990. Our analysis did not include an evaluation of changes in elevation, which may have played a role. The next major directional change occurred in late October and early November during or just after fall breeding. Again there was no consistent directional

Environmental Factors in Distribution and Movement | 40

orientation. The mean date of the freeze-up of Knob Lake at Schefferville in 3 years was 29 October (Julian 30.7 ± .97), with extremes 3 October 955 and 4 November 970. The rapid appearance of the frozen lake highway would have changed mobility and feeding/bedding cycles. The reduced snow level and unobstructed visibility on frozen lakes would greatly enhance antipredator tactics of herding and could channel animals in new directions. In 986 the lakes froze about 6 October and the mean date that four animals turned was 6.5 October. The next fall the ice formed 6 November and two animals north of Knob Lake made major directional changes 5 and 6 November. Central Ungava is laced with lakes; the mean percentage water/ice tabulated from topographical maps was 6% ± .22% in 54 of the long. x 0.5 lat. grids between 55° N and 58° N and 66° W and 75° W, but the percentage water/ice in the 2 grids where caribou turned in late October was 2% ± .66% (t = 2.249, P < 0.05). The last major turns before the mid-winter pause commonly occurred in late November as snow cover reached > 46 cm (fig. .7). Widely-spaced individuals in central Ungava would have contacted local snow gradients that led in different directions. With the low snow cover in October the herd moved rapidly, but slowed down in November as snow cover built (fig. 3.3) and there were fewer areas with lower snow profiles to follow as gradients. Mid-Winter Pause

A mid-winter pause is characteristic of caribou populations in North America (Bergerud 974c; Eastland 99). Satellite animals in Ungava travelled a variety of directions after the breeding season until they localized in areas of reduced snow cover (table 3.6). In this season animals sought low snow cover to conserve energy and/or to reduce predation risk. By aggregating and pausing they modified the snow cover, cratering and compacting snow in their network of trails. In a sense, this is similar to the yarding of white-tailed deer (Odocoileus virginianus) in cedar swamps. The modified snow cover would aid mobility in encounters with wolves since wolves are more successful in deep snows (Dale et al. 995; Mech et al. 998). This winter pause results because animals are in optimum areas (Bergerud 974c) – “islands of least snow.” There are no gradients of reduced snow to facilitate dispersal since the animals are already in them. But if a new snowfall alters the gradients, they could become mobile once more (Bergerud 963). Some females were more sedentary than others during this pause (figs. 2.5, 2.6, 3.6); the variation between animals in different locations was in response to local snow conditions. March/April Movements

If the animals had spent the winter pause west of 70° W, the aggregations generally migrated northeast in March, following the trails along tree line across the

402 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Ungava Peninsula in the vicinity of the Koksoak River (fig. 2.9). Their route followed the esker topography and a substantial string of previous trails, a route that Low had noted (898) a century earlier. Several of the satellite animals paused in these months and localized west of Kuujjuaq. A second route followed by animals that had localized for the winter east in Labrador went north or northeast. Both routes moved the herd to tundra areas with reduced snow cover and where windswept upland slopes meant vegetation would be exposed earlier than in the taiga. The general movement abreast of the tree line in March and April towards the Ungava Bay coast and Kuujjuaq – an area of low snow cover – is not in the direction of the calving ground. Several herds in the NWT travel routes in March and April on bearings that appear to be on a direct line with their calving grounds (Kelsall 968, Map 22). These straight-line courses that finish on the calving ground give the impression of a goal-oriented movement originating as early as mid-March – over three months before parturition. Several of these direct routes are at right angles to the tree line and one could argue that the animals are following a retreating snow line, a forage gradient north, or even magnetic lines of force (ibid.). But the treks of the George River herd in March and for much of April are not pointed at their calving ground; in fact, when the Leaf River herd calved further south near the Leaf River in the 970s (Le Henaff 975), the route they followed along tree line took the most northern columns through the calving ground. Our argument for the George and the Leaf River herds in these months – as well as for the NWT herds – is that females follow routes with reduced snow levels or reduced sinking depths (resulting from spring crusting) to reach their goal of their calving ground (more later). Bergerud (2000) has hypothesized that calving grounds develop historically at those locations where routes determined by snow and forage come up against a water/ice barrier – as in the case of the Bathurst herd in the NWT – or against a snow barrier – as in the case of the George River herd in Labrador and the Beverly and Kaminuriak herds in the NWT (see Fleck and Gunn 982). By mid- to late April most females in the George River herd were moving in the direction of the Labrador tundra and the calving grounds. The major route was southeast from Ungava Bay. However, if the animals had wintered in the central interior south of 56° N (as in 987–88), they took a shortcut that moved them northeast from their winter locations rather than north to the tree line and then northeast (figs. 2.5, 2.6, 3.28). If the animals had wintered south in Labrador (as in 992–93), they moved northwest in April. A number of the satellite-collared animals returned on azimuths that led to grounds where they would calve in June (fig. 3.8), but these straight routes were not directed to the locations where they had calved the previous year (figs. 2.5, 2.6). The environmental stimuli that led the George River herd across Ungava in the 980s when the George River herd was the largest in the world resulted in

Environmental Factors in Distribution and Movement | 403

WP

REDUCED RISK HIGH SNOW WINTERS

DD TA IG D OM SD E N NT F R

PL DIS

CH EN S

LL

TREE L

INE

WP

REDUCED RISK LOW SNOW WINTERS

CP SP RP WP MP

CALVING PAUSE SEPTEMBER PAUSE RUTTING PAUSE WINTER PAUSE MAY PAUSE CARIBOU HOUSE

GREENS LICHENS DD

RP

T UN DR A LIC HE NS D D

H LIC ACEME

A

DD

SP

GREENS INDIAN HOUSE LAKE

GREENS LATE JUNE

CP

JULY MOSQUITO RELIEF

MP GREENS

0 50 DRIVEN DISPLACEMENT FROM TAIGA (TRUE MIGRATION) 0 DRIVEN ENVIRONMENT FACTORS SEEKING GREENS SEEKING LICHENS MOBILITY SPEED DENSITY DEPENDENT

100 KILOMETRES 50

Fig. 13.28 A summary of the major movements and possible environmental factors. The Loop of Life. The spring movements of females to the tundra and calving sites (open arrows) is the only response that entails orientation/fidelity not driven by current present casual factors and qualifies as a true migration. In chapter 15 we discuss our belief that this spring migration to the tundra evolved as a displacement from the taiga that was less favourable for calf survival rather than as a goal-seeking response to reach a favourable foraging habitat in the tundra.

rapid travel rates. This took place in a largely pristine world at a time when global warming had not reached Labrador. Although the exact patterns may not have been repeated, the historical records indicate similar movements when Europeans first reached Ungava 200 years ago. Only one movement pattern qualifies as a true migration involving destination-orientation and fidelity: the annual return in the spring to the Labrador tundra and their “Caribou House” (fig. 3.28). The same driving variables – snow, forage, predation risk, and insect relief – can be expected to apply to the other large migratory herds in North America. The Loop of Life always takes them back to their “caribou house,” the Labrador Tundra.

100 MILES

CHAPTER FOURTEEN

Optimal Foraging and Predation Risk in the Winter and Growing Season

There is a growing concern among caribou biologists about the impact of global warming on caribou. But the concerns voiced (Russell 993; Griffith et al. 998; Gunn 2000b; Weladji et al. 2002; Heggberget et al. 2002) relate solely to optimal foraging considerations and exclude how predation risk will alter as temperatures increase in the Arctic. Certainly the latter will be affected by climate change, and we feel that predation impacts will be the primary means by which survival rates will alter in North America. Belovsky (99) held that insect and predator avoidance will “constrain” optimal foraging. Lima and Dill (990), however, insist that there is nothing constraining about a free choice between two options; neither is more fundamental. They say (990, 630): “The behavioural options open to feeding animals lie on a continuum between energy maximization (at the complete expense of predator avoidance) and minimization of risk (at the complete expense of feeding). Clearly, neither option is desirable and optimal behaviour will lie somewhere between; however, there is nothing ‘constraining’ the animals from choosing one of the extremes.” Animals are free to choose, and their choice may affect their survival and reproductive fitness (fig. 4.). Distribution Strategy in Winter The large migratory herds in Alaska, the Northwest Territories, and Newfoundland generally select winter ranges of low snow depths below tree line (fig. 4.2), similar to the George River herd. Skoog (968, 446) observed that “activity during the season (January–March) hinges to a certain extent upon snow depth; i.e., deep snows tend to inhibit extensive movements, whereas an open

Optimal Foraging and Predation Risk in the Winter and Growing Seasons | 405 PREDATOR ABUNDANCE

CHOICE

FORAGE OPTIMAL BUT MORE PREDATION RISK

FORAGE LESS THAN OPTIMAL BUT LESS PREDATION RISK

CARIBOU SURVIVAL LESS

DECREASE CONDITION

CARIBOU REPRODUCTIVE SUCCESS LESS

EITHER SIDE CAN LEAD TO POPULATION GROWTH OR POPULATION DECLINE DEPENDING ON THE DEGREE OF COMPROMISE

Fig. 14.1 The options of optimal foraging vs predation risk at calving. Females can choose areas with more optimal foraging conditions but the trade-off is more risk for their neonates. Alternately they can choose areas with less risk but where the trade-off is reduced physical condition that may affect the viability of the neonate and possibly reduce the chance of reaching estrus in the coming breeding season.

winter does the opposite.” This was also true for the migratory caribou in Newfoundland (Bergerud 963, 974a). Kelsall (968, 65), in speaking of herds that wintered on the tundra in the NWT, wrote that “generally the caribou winter on the most snow-free sections of upland country.” Russell et al. (993) showed that the Porcupine herd normally wintered in regions of low snowfalls (Ogilvie and Hart Mountains) largely dictated by the regional snow patterns. Two contrasting hypotheses for explaining the strategy of wintering in low snow cover in North America are () caribou select areas of low snowfall to maximize forage intake; and (2) habitats with reduced snow depths are selected to reduce predation risk. The major winter foods of caribou are the Cladina lichens which dominate the ground layers on the winter ranges that the North American migratory herds occupy in the winter. Prior to the growth of the George River herd the lichen biomass in the lichen woodlands of Ungava were especially abundant (Hustich 95), and large supplies still existed in the 980s (chapter 7, Crête et al. 990b). These

406 | TH E R E T U R N O F C A R I BO U TO U N G AVA 18

ABOVE TREE LINE

KAMINURIAK ( > 1966 )

BEVERLY ( > 1970 )

TOTAL

14 12 10 8 6 4 2 JAN FEB

MAR APR MAY JUN JUL

AUG SEP

OCT NOV DEC

2 4

BELOW TREE LINE

NUMBER OF RETURNS

16

6 8

WOLVES HAVE YOUNG

10 12 14 16 18

Fig. 14.2 The monthly distributions of hunter returns of tagged animals in two herds in the NW T show the typical pattern of the migratory ecotype of moving to the tundra to calve and remaining there during the insect seasons, partially spaced away from the wolves further south who are involved in denning. But what is also interesting is that this distribution pattern came from a unique data source based on the locations where native hunters harvested their animals and indicates animals were taken in all months of the year (data adapted from Parker 1972b). These animals had been tagged by wildlife crews at water crossings to study movements prior to the widespread use of radio tracking.

reindeer lichens reach maximum potential in open canopies where precipitation is high and deep snow cover protects them against abrasive snow/wind action (Ahti 959; Bergerud 97a; Crête et al. 990b; Thomas et al. 996). The assumption has been that caribou did not select the maximum lichen stands under deep snow for reasons to do with expenditure of energy. They selected ranges of low snow cover because they could secure more lichens/effort (relative abundance) than they could digging through deeper snows to reach a greater phytomass (absolute abundance, see Bergerud 974c; also Skogland 978). Until recently the conventional wisdom held that escape opportunities of caribou fleeing from wolves improved with deeper snow cover. Although wolves have a similar weight load on-track (foot loadings) to caribou (Nasimovich 955),

Optimal Foraging and Predation Risk in the Winter and Growing Seasons | 407

this is thought to be offset by the wolves’ shorter legs, making pursuit impossible if wolves sink to chest level (Kelsall 968). But the empirical evidence (based on radio tracking wolves) shows otherwise. Wolves are more successful in deeper snows and can even make multiple kills (Mech et al. 998). The regression of moose killed/caribou killed regressed against total snowfall in Alaska was Y = 6.076 - 0.07X, r = -0.883, n = 7 seasons (calculated from Mech et al. 994). Wolves were switching from long-legged moose to caribou as snow levels built. Dale et al. (994 and 995) radio-tracked wolves in the Gates of the Arctic National Park – further north than Mech. They stated that caribou appear vulnerable to predation due to the combination of deep snow and mountainous, rough terrain. Caribou groups were generally observed on or near ridges that were windblown and either had little snow or snow that was hard packed, and the wolves chased caribou from these ridges into deeper snow. These workers also noted multiple kills. The mortality rates (prior to radio collaring females) in the 40-Mile herd in Alaska were correlated with winter severity in 8 years, r = 0.792 and in the Delta herd in 7 years, r = 0.634. Most deaths resulted from wolf predation rather than scavenging, since marrow fat percentages indicated the females had not starved (calculations from Boertje et al. 995; Boertje et al. 996; Valkenburg et al. 996a; Valkenburg 997). These findings indicate that caribou may be seeking low snow cover in the winter to reduce predation risk. Mortality rates of radio-collared adult cows in the George River herd were also higher in years of greater snow. The correlation in annual death rates presented by Hearn et al. (990) and Crête et al. (996) for the years 984–95 to 99-92 and our index of snow depths was 0.824, n = 8. The percentage of marrow fat in April for pregnant females in 0 winters during our study was high at 87.0% ± 0.83% with little variation (CV = 3%) (fig. .) and was not correlated with winter severity, r = 0.23 (mean number of females measured per year was 05). In Alaska the vulnerability of caribou to wolf predation in deep snows might relate to prey switchover, i.e., the increased predation of caribou in deep snow was not simply a mobility question. Rather, wolves found moose more difficult to take in deep snows and thus devoted more effort to hunting caribou. This argument would not apply in Ungava since moose numbers were less than 0./km² (Chubbs and Schaefer 997). Wolf predation was the major limiting factor in mortality for adult females in Ungava and was exacerbated by heavy snow cover. Snow depths should also affect the over-winter predation rates of calves between 5 and 0–2 months of age prior to growth in their second summer. Some studies in North America have shown that calves had higher death rates over winter from predation than did adults (Miller 975; Fancy et al. 994; Valkenburg et al. 996a), but others have found no difference in mortality rates (Davis and Valkenburg 99; Mech et al. 998). Our index of over-winter mortality of calves (the decline in the calves/00 females over winter) showed that there was little difference in over-winter mortality between calves and adult females for the three cohorts born when wolf numbers were low (due to rabies outbreaks in

408 | TH E R E T U R N O F C A R I BO U TO U N G AVA

976, 982, and 992) (fig. .5). Additionally, the over-winter loss of calves born prior to 984 showed no consistent trend when regressed against winter severity. However, calves born after 984 had increased mortality rates in winters of deep snows. The percentage of marrow fat in all the cohorts sampled in 8 years between 980–9 was sufficient (a mean of 74%) to stave off starvation. However, vulnerability increased when the calves were smaller in body size, and after 983 the size of winter calves decreased. The mean mandible size of 7 cohorts between 973–83 was 260.5 mm ± .75 mm and for 6 cohorts in the interval 984–90 it was 252. mm ± .93 mm (t = 3.26, P < 0.0). Our bimodal vulnerability to wolf predation based on body size is consistent with the divergent views reported in the literature. The calves in the Delta and Denali herds that died over winter at rates similar to adults were large and in good physical condition (Davis et al. 99; Mech et al. 998). The calves in the Kaminuriak and Porcupine herds with higher mortality rates than adults over winter were smaller-bodied animals. In the Porcupine herd, body condition had declined (Gerhart et al. 996), and possibly this applies to the Kaminuriak herd as well (Dauphiné 976). We believe the smaller calves born after 983 in Ungava died over winter primarily from wolf predation exacerbated by reduced mobility in deep snows. It would have been a selective advantage for cows to choose winter ranges of reduced snow cover to improve survival chances for themselves and their progeny. The first hypothesis suggests that low snow profiles are selected for considerations to do with energy expenditure, but if animals are selecting low snow profiles to enhance winter foraging, we would expect them to be in superior condition to their counterparts feeding in deeper snows – a greater abundance of lichens notwithstanding. Thomas and Kiliaan (998) collected animals from the Beverly herd in 8 winters for condition studies. In March 984 they collected animals at both Sifton Lake, 30 km north of tree line and at Porter Lake, 60 km south of the tree line. The taiga animals feeding in deeper snows had higher weights and fat reserves than the tundra animals feeding in a lower snow profile (fig. 4.3). Also these authors collected and examined animals at the tree line in two other years (983 and 987) which were in poorer condition than animals harvested south of the tree line in five years (fig. 4.3). The ranges south of tree line in the NWT can be expected to have three times more lichens than those north of the tree line (Kelsall 968; Thomas et al. 996). Lichen supplies are much more abundant in the taiga of Ungava than on the tundra (fig. 7.5) and females collected from the taiga ranges were heavier than those at or north of the tree line where snow cover was less (fig. 4.4). In 980 Parker (98) collected females both from Nain (below or at tree line) and from Hebron (north of trees and where snow levels were shallower). The Nain animals were in superior condition (table 4.). This does not support the hypothesis that caribou select low snow profiles to enhance energy balances.

PORTER LAKE

60

EY

20

T

15

FA

80

25

SIFTON LAKE

10

BA CK

100

30

SIFTON LAKE

5

BODY WEIGHT (kg) OF > 3 YEARS

0 PORTER LAKE

88 87 86 85 84 83 82 81 80 79 78

ABOVE TREE LINE

70

ABOVE TREE LINE

SIFTON LAKE

SNOW DEPTH (cm)

60 50 40

170 km BELOW

100 km BELOW

110 km BELOW

10 km ABOVE

PORTER 60 km BELOW SIFTON 130 ABOVE

1980

1981

1982

1983

1984

30 20

WHERE ANIMALS COLLECTED RANGE WIDE 40 km BELOW

75 km BELOW

25 km ABOVE

1985

1986

1987

Fig. 14.3 Physical condition in winter of animals in the Beverly herd, NW T. Thomas and Kiliaan (1998) collected and autopsied caribou from the Beverly herd in the NW T in eight winter seasons (1980–87) to quantify the winter fat and physical condition of the animals in the winter. The Beverly herd was selected for this study partly because it had the greatest percentage of its winter lichen range burned by fires in comparison with other herds in the NW T. The animals they examined were in good condition and superior to the adjacent Kaminuriak herd studied 20 years earlier by Dauphiné (1976), despite the fact that there had been less lichen destruction by fire on the winter range of the Kaminuriak. The winter condition of the Beverly did vary between winters from 1980 to 1987. In general the animals were in their best condition when they had wintered well south of the tree line in the taiga rather than when they wintered north of trees.

BACK FAT DEPTH (mm)

120

FA T

PORTER LAKE

KI DN

KIDNEY FAT MASS (g) > 3 YEARS

140

WEIGHT OF ADULT

(kg)

40 | TH E R E T U R N O F C A R I BO U TO U N G AVA 105 100 95

1988 (16) 1976 (21) 1982 (36)

1993 (20)

1987 (11)

90 85

1983 (5)

Y = 101.240  0.137X

1986 (12)

r = 0.837

1984 (11)

80 IN SAMPLE 150

100 BELOW

50

0

50

KILOMETRES FROM TREE LINE

100 ABOVE

150

Fig. 14.4 Animals in this study in March and April had higher mass when harvested south of the tree line than on the tundra, similar to the Beverly herd (fig. 14.3). When populations are at high densities the animals maintain their overwinter condition in the taiga with the larger supply of lichens. However when numbers are low the tundra may be more optimum in the winter, especially in years of heavy snow in the taiga. (x axis coded)

In March and April the George River animals left the areas where they had paused in mid-winter and generally moved northeast, flanking the tree line. Caribou in Alaska, the Northwest Territories, and Newfoundland also leave their wintering areas in these months and all move to areas of shallower snow. In the case of the interior herds in Alaska the snow pack peaks in January (Skoog 968); one might argue that these movements 6–8 weeks later are stimulated by the appearance of brown substrates and low snow profiles for locating forage. However, in the Northwest Territories and Ungava these early spring movements occur simultaneous to peak snow cover (fig. 3.3) (Russell et al. 993; Thomas and Kiliaan 998). Nor are winter greens more common on the tundra than the taiga in these months. Common to all ranges in late March and April is the settling of snow and sun crusting, both of which increase the density of the snow and reduce the sinking depths of caribou. We theorize that the migrating George River caribou are travelling on gradients of sinking depths that generally decrease moving northeast. This would enhance mobility, thus reducing predation risk, but it comes with the price of less phytomass. The animals in these movements north take advantage of frozen lake surfaces with reduced snow cover. Caribou in the Northwest Territories and Ungava are most often killed by wolves on frozen lakes in the winter and spring (Miller 975). Yet they spend much of their time feeding inland off shorelines. Animals in the Porcupine herd spent 75% of their activity budget in April feeding while shifting

Optimal Foraging and Predation Risk in the Winter and Growing Seasons | 4

Table 14.1 Condition of females in April 1980¹ compared to caribou that wintered on the tundra (Hebron) and returned from taiga (Nain) Age of Animals Condition Indices

Hebron 3 and 4 April 3

Nain 5–15 April

Probability of of a Difference

10 Months of Age Mean Back Fat (mm) Mean Kidney Fat (g) Mean Femoral Fat (%) Mean Body Weight (kg) Mean Total Warbles

0.0 ± 0 (3) 20.1 ± 7.80 (3) 52.3 ± 9.61 (3) 42.1 ± 1.40 (3) 119.7 ± 48.72 (3)

0.2 ± 0.15 (13) 22.1 ± 1.69 (13) 57.8 ± 3.84 (13) 45.1 ± 1.04 (13) 59.0 ± 8.91 (13)

0.337 0.839 0.585 0.094 0.340

22 Months of Age Mean Back Fat (mm) Mean Kidney Fat (g) Mean Femoral Fat (%) Mean Body Weight (kg) Mean Total Warbles

0.0 ± 0 (4) 22.9 ± 8.32 (4) 55.5 ± 17.89 (4) 64.1 ± 3.54 (4) 146.0 ± 21.30 (4)

3.6 ± 1.18 (14) 40.8 ± 5.04 (13) 88.6 ± 0.86 (16) 73.3 ± 1.88 (15) 53.7 ± 10.17 (15)

0.010 0.121 0.161 0.071 0.015

≥ 34 Months of Age Mean Back Fat (mm) Mean Kidney Fat (g) Mean Femoral Fat (%) Mean Body Weight (kg) Mean Total Warbles

0.0 ± 0 (10) 39.6 ± 5.75 (8) 73.1 ± 6.13 (10) 88.5 ± 2.33 (10) 50.3 ± 15.68 (7)

6.0 ± 0.72 (87) 84.8 ± 3.24 (71) 90.1 ± 0.42 (88) 93.7 ± 0.82 (91) 39.1 ± 3.98 (88)

0.0001 0.0001 0.214 0.060 0.512

¹ Data collected by Parker 98 and raw data sheets provided to the authors

north (Russell et al. 993). When caribou are feeding inland from frozen lake shores they flush from these lichen woodlands and flee to frozen lake surfaces if they are surprised by wolves. The animals are killed most often on frozen lakes – not because they are more vulnerable there, but because this is where the chase leads them as they seek open vistas, shallower snow, and better traction. The behaviour of caribou bedding on frozen lakes at some distance from the shoreline has been considered an antipredator tactic since the 950s (Banfield 954; Kelsall 968). Caribou are the most cursorial of the surviving deer species (Geist 998). Their rapid escape rate is maximized with minimum leg and hoof lift on windswept frozen lake surfaces. Even a few centimetres of snow increase the cost of locomotion and reduce their high-speed advantage over wolves. We noted for the George River herd that they increased their use of frozenlake surfaces from October to March as snow cover accumulated. The percentage of lake surfaces occupied over winter in the mapped grids increased slightly ( December, 8.7%;  January, 8.6%;  February, 20.0%;  March, 20.8%; and  April, 20.9%). These shifts to ice reduced the extent of terrestrial lichens in the daily home ranges but the openness facilitates early detection of predators and the shallow snows on lake surfaces enhance escape.

42 | TH E R E T U R N O F C A R I BO U TO U N G AVA

During the snow season adult males in Ungava commonly segregated from females in the taiga, and frequented ranges at lower latitudes (Bergerud 967; Vandal et al. 989). In such locations the males commonly ranged habitats that had both more lichens and snow cover than where females wintered. This sequence has been well documented for the migratory herds in the Northwest Territories. In both the NWT and Ungava, the males are generally in smaller, dispersed groups and thus don’t compact snow as much as the large aggregations of females with progeny do. Included with the male groups are three-year-old males (Miller 974), similar in size to adult females, so the segregation in not explained simply by the ability of larger bodies to navigate deeper snow profiles (Klein et al. 987). Our view is that males reduce their predation risk in the winter by separating from the large cow/calf herds. The high concentrations of wolves that have been recorded in the NWT were all with these large, noisy, conspicuous female/calf aggregations (Miller 975; Parker 973; Fleck and Gunn 982; Heard unpublished). By dispersing away from wolves in vast space and deeper snows, travel routes for males would be harder to locate. A natural wolf/caribou experiment on the Slate Islands (36 km²), in Lake Superior in Ontario supported the hypothesis that sexual segregation in mid-winter for migratory herds reduces predation risk for males. The Slate Islands caribou population has been monitored 974–200 (Bergerud 200; Bergerud et al. 2007). From 974 to 994 there were no wolves present and the mean density of caribou was 7.3 ± 0.80 caribou/km² – the highest density in North America (Bergerud 996, 2000), yet these caribou in winter seldom ventured out on the many frozen lakes on the Islands (Euler et al. 976; Bergerud 200). Bergerud also monitored the caribou in Pukaskwa National Park on the mainland, only 50 km distance from the island archipelago; these caribou were regulated by wolf predation and averaged only 0.06/km² animals over the same timespan (Bergerud 996). These caribou did visit frozen lakes. In 994 two wolves from the mainland crossed to the Islands. An aerial search in March 995 indicated they were hunting caribou, but the caribou were not using the shallow snow cover on the lakes. At the time the snow was extremely dense, so much so that our snowshoes were not necessary. The animals were dispersed under tree cover and travelled easily on the crusted snow. The many conifer blow-downs in those forests would have further hindered wolves in pursuit. The next winter the two wolves continued to hunt caribou. On 2 February, an aerial census showed 29 caribou, both males and females, together, on the frozen lakes (68% of the population). The snow then was extremely deep and when caribou left the lake ice they sank to brisket height. The escape strategy was to flee to the frozen lake and also to escape on ice between lakes as Carruthers et al. (986) noted for caribou in the NWT. The wolves were selectively killing the smaller females over the males; the observed ratio of males to females before the wolf arrival in 994 was 43% males, but by 995 and 996 the percentage of male

Optimal Foraging and Predation Risk in the Winter and Growing Seasons | 43

adults had increased to 54% (we were familiar with a large proportion of the population). The annual survival of tagged animals in these two years with predation was 89% for males (n = 95) and 75% for females (n = 60); the mean survival over 6 prior years had been 82% for both sexes. In a closed island system the males could not segregate themselves from the more vulnerable, smaller females and progeny. In Ungava, unlike the Slate Islands, the males are able to avoid the large female/calf groups that attract wolves; thus these males should reduce their predation risk until early spring when the females migrate north and leave them behind, nearer to wolves denning near tree line (chapter 6). In Ungava caribou select areas of low snow as low-risk habitats – regardless of lichen abundance – where they can use their cursorial advantage in predator escape (figs. 2., 2.2). Moving about on compacted snow and digging craters may entail increased energy expenditure, but predation risk is the first order in the winter season when only maintenance nutrition is necessary. Both the highenergy lichen forage and the compacting of the snow where they localize contribute to escape flight. Spacing Strategy in the Growing Season With the return of the growing season the North American caribou need to optimize nutrient intake to enhance their reproductive potential. The problem of predation risk is now paramount, especially after the vulnerable new generation arrives. Additionally, the animals must employ strategies to minimize the detrimental effects of insect harassment on nutrient intake. To minimize insect and predation problems, the migratory caribou in North America return to the tundra in the spring. When the George River herd reached high numbers, this spring migration resulted in the serious reduction of forage above tree line (chapter 7), providing us with an opportunity to evaluate the priorities of risk and harassment in the context of a nutrient shortfall. The females and males became segregated during this spring migration relative to reproductive fitness. The females moved farther from the males in April, following a receding snow gradient that took them northeast to the tree line and beyond (figs. 2.5, 2.6) and to habitats with a reduced phytomass and later phenology where there were fewer wolves. The males lagged behind in less safe habitats at lower latitudes and elevations, awaiting the start of the growing season and seeking nutritional green forage. In the spring of 982 we followed the course of the spring migration and examined wolf-killed animals. We located 34 males and 36 females killed by wolves; many of the males died on the ranges vacated by the females in the spring. These mortalities indicated significantly higher mortality rates for males left behind than for females since the sex ratio of the living was  male:2 females. This was a conservative test, since only females had radio collars with mortality sensors.

44 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 14.2 Travel speeds (km/hour) of caribou active (not lying) in the pre-insect season in June between different size groups Group Size

1–5 Animals 6–10 Animals 11–15 Animals 16–20 Animals 21–30 Animals 31–45 Animals 46–70 Animals 71–150 Animals > 150 Animals Means ± S.E. Rank correlations:

Rank

1988 Mean (n)

Kilometres per Hour 1990 Mean (n)

1991 Mean (n)

(1) (2) (3) (4) (5) (6) (7) (8) (9)

0.46 (13) 0.24 (11) 0.29 (42) 0.38 (41) 0.57 (22) 0.10 (6) 1.13 (16) 0.80 (21) 0.58 (16) 0.5 1 ± 0.105 (188) r = 0.519

0.85 (114) 0.65 (74) 0.42 (24) 0.64 (15) 0.34 (27) 0.21 (8) 0.29 (9) 0.39 (5) – 0.47 ± 0.077 (276) r = -0.797

0.69 (58) 0.56 (75) 0.53 (39) 0.86 (28) 0.74 (25) 0.28 (26) 0.74 (11) 1.17 (7) 2.06 (4) 0.85 ± 0.172 (273) r = 0.633

The females crossed the tree line in the spring, generally in late May. Coincident with this, travel rates increased as they encountered the overgrazed and trampled tundra. If the animals came from the west, they generally turned south on the Labrador tundra and decelerated when they neared the tree line at lower latitudes. We attribute this pause to seeking early green graminoids while remaining in habitats with open vistas and low snow cover. An aerial survey in May 995 found 40% of the animals observed (7,706) in the herb-sedge biotype near 56° N; the availability of this biotype was 9%, which shows that it was selected (Renewable 995). After calving the females generally went north from the calving ground, staying on the tundra. This movement took them to higher elevations and latitudes where they tracked the green phenology and selected habitats with a greater biomass than in plots we selected randomly. The emergence of mosquitoes was delayed in these habitats and the animals maximized their distance from the tree line where wolves were more common. This post-calving period before mosquitoes was one of searching for forage; travel rates slowed when phytomass increased and was not seriously affected by group size (table 4.2). During this pre-insect season in late June and early July, dry matter intake was low (chapter 7) even though the animals were feeding 60% of the time – 0% more than other herds in North America (table 7.8; fig. 4.5). However, it still resulted in low energy intake and energy budgets that were generally negative 988–9 (fig. 4.6). If the phytomass had not been overgrazed their energy budgets would have been positive, similar to other herds. We were concerned that we had biased our calculations of energy budgets by recording observations only during the day. To evaluate this, Camps conducted

Optimal Foraging and Predation Risk in the Winter and Growing Seasons | 45 100

STANDING

PERCENTAGE OF ACTIVITY

LYING

100

18% 2%

WALKING

20%

50

FEEDING

0

PRE-INSECT SEASON

60%

43,515 CARIBOU 12%

LYING

PERCENTAGE OF ACTIVITY

10% STANDING

37% WALKING

50

41%

FEEDING 0 6–8

INSECT SEASON 8–10

49,410 CARIBOU 10–12

12–14

14–16

DAYLIGHT HOURS

16–18

18–20

20–22

MEAN

Fig. 14.5 The activity budgets of the caribou compared between the pre-insect season in June and early July and the insect season in July and August, 1988 to 1991. More time was spent feeding and less walking prior to arrival of mosquitoes in July than later when bothered by mosquitoes and black flies.

horizon scans on an hourly basis through the night of 22–23 June and shadowed one lone female for 8.7 hours. The nocturnal activity of 54 groups (460 animals) was 62% of the time feeding, 3% lying, and only 5% walking. Feeding rates were the same as in daylight hours, but animals walked less and reclined more. The lone female foraged 57% of the night with long periods – 42% – spent lying down.

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ENERGY ( thousands of kJ)

1988

1989

60

60

50

50

40

40

30

30

20

20

10

10

0 152

162

172

182

192

202

212

1990

232

242

INTAKE EXPENDITURE

50

ENERGY ( thousands of kJ)

222

0 152

30

30

20

20

10

10

172

182

192

202

212

JULIAN DATE

222

232

242

182

172

182

192

202

212

222

232

242

192

202

212

222

232

242

1991 40

162

172

50

40

0 152

162

0 152

162

JULIAN DATE

Fig. 14.6 The daily energy budgets, 1988–91, of caribou in the pre-insect season (late June, early July) and the insect seasons, primarily July but some observations in August 1988. Positive energy budgets are not achieved until August (1 August Julian day 213) after the mosquitoes abate. This return to a positive energy in August is hard to explain since the caribou travel further in August than any other month (figs. 12.22, 13.3) and are bothered on some days more by oestrids in August than by mosquitoes in July (fig. 13.26). Further, the forage is less nutritious in August than earlier in the growing season (fig. 7.4). On the positive side, the movement across the tree line in August to more lightly trampled forage and the smaller foraging group size did result in an increase in dry matter intake in 1988 and 1989 (fig. 7.12). Further oestrids are only active in daytime.

Next we expanded the budget statistics based only on daylight tallies to 24 hours in order to compare them with LTA data from satellite-collared animals that spanned an entire 24-hour day. The expanded scan data was quite similar to the long-term satellite data following calving and prior to the insect season: 2.47 active hours from satellite observation in 24 hours vs 3.6 active hours from daytime observations expanded to a 24-hr day (table 4.3). This was the season when the females needed abundant forage for lactation before the insects emerged. In

Optimal Foraging and Predation Risk in the Winter and Growing Seasons | 47

Table 14.3 The hours that caribou were active per day based on the Long-term Activity Index ( LTA – 24-hour schedule, satellite collars) and field observations during daylight hours expanded to a 24-hour basis for comparison to the satellite schedule (June, July, August 1988)¹ Dates and Activity

17–26 June Post-calving 1–11 July Moving North 13–25 July Mosquitoes 28 July–16 August Oestrids/Tabanids

Hours Active/Day Long-term ( LTA )

Hours Active/Day – Horizon Scans, Expanded to 24-hr day

Difference

2.47 ± 0.22 (7) walking less and lying more

3.16 ± 0.57 (9) more active

+0.69

5.60 ± 1.22 (3) walking more

2.73 ± 0.15 (9) feeding/lying more

-2.87

7.87 ± 0.24 (3) feeding and lying more

11.6 ± 2.80 (2)² walking more

+3.73

7.77 ± 0.27 (7) feeding more

8.47 ± 0.50 (17) moving more

+0.70

LTA -Horizon

¹ See Appendix on how scans were converted to 24-hour basis ² Only recorded on 2 days but caribou bothered on both days and walking in mass, believed to be much higher than satellite (LTA) that included cold nights and no mosquito activity

spite of their efforts to increase foraging (compared to other herds, table 7.8), their energy budgets were generally negative and their body mass and fat reserves reached the nadir for the year (figs. 8.9, 9.3). A general movement sequence of migratory herds in North America is to vacate the heavily-grazed calving grounds after socialization with the neonates is accomplished. In chapter 3 we concluded that the George River animals post calving were tracking the green phenology to higher elevations. One consequence of this movement is that early hatches of mosquitoes are reduced. In an evolutionary sense, this movement also prevents wolves from denning on calving grounds: Their altricial pups would be unable to keep up with the caribou once they move on; nor does the inhospitable habitat of the calving ground present the wolves with alternative prey. The movement period – July (table 4.3) entailed extensive feeding during the daylight hours. The satellite LTA readings were higher than the expanded daylight scans (table 4.3, – July: LTA 5.60 vs 2.73). The only activity that could have raised these scores in relation to the expanded daylight scans is walking (note that activity scores/minute are:  for lying down; 4.5 for grazing; and 25 for walking). The caribou must have been travelling in the hours when we were not active – possibly in the early morning – as we recorded on 6 July (table 4.4). When the mosquitoes emerged in mid-July the animals remained mostly on the tundra (fig. 4.7). They aggregated to reduce harassment, walked more and

TREE LINE

OUTSIDE INSECT SEASON DURING INSECT SEASON 1,037 LOCATIONS 0 0

50

100 KILOMETRES 50

100 MILES

Fig. 14.7 (above) Satellite animals in the herd in 1997 were distributed well west into the taiga in the latter stages of the insect season. This is another reminder that it is the mosquitoes and not the oestrids and tabanids that keep the caribou on the tundra in July even when it is overgrazed. The distribution of the herd in 1997 showed a major retraction in range from the 1980s (see figs. 12.2 and 12.3), with the area in 1997. Data provided by the Department of National Defense. Fig. 14.8 (facing page, above) During the insect season in July and August energy budgets depend both on the abundance of the insect species and whether the weather is favourable for insects or unfavourable. The negative/postive switching often occurs on adjacent days as temperatures and wind speeds are favourable and then negative for mosquitoes and oestrids. Successful feeding also increases expenditures for maintenance. Fig. 14.9 (facing page, below) A comparison of the time spent walking and feeding and travel speeds in the growing season in daylight hours. The animals were more mobile in August when bothered by oestrids than in July when mosquitoes were the problem. The pre-insect season in June and early July was the most favourable for time spent feeding with reduced mobility rates.

ENERGY ( ×1000kJ)

50

50

40

40

MOSQUITOES

30 20

20

10

10

0

NO MOSQUITOES

30

14/7/88 12/7/88 13/7/90 13/7/88 28/7/88

0

29/7/89 30/7/88 31/7/88

ENERGY EXPENDITURE

ENERGY ( ×1000kJ)

ENERGY INTAKE 50

50

40

40

WARBLE FLIES

30 20

20

10

10

0

11/7/89 8/8/88

4/8/88

NO WARBLE FLIES

30

1/8/88 13/7/89

0

24/8/88 7/8/88

3/8/88

MEAN KILOMETRES PER HOUR PER WEEK

6

JUNE JULY AUGUST

5 88

88

4

LAST WEEK OF JULY

Y = 0.062 + 0.071X r = 0.721 n = 26

3

Y = 4.655  0.044X 89

89

r = 0.738 n = 26

2

1

0 0

10

20

30

40

50

60 0

TIME SPENT WALKING ( % )

10

20

30

40

50

60

70

TIME SPENT FEEDING ( %)

WEEKLY MEANS (1988–91)

80

90 100

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Table 14.4 The activity budget of George River caribou at night compared to the abundance of mosquitoes and the temperature (16 July 1990, 9 PM [2100] to 5 AM [0500]) Time

9 PM (2100) 10 PM (2200) 11 PM (2300) 12 am (2400) 1 am (0100) 2 am (0200) 3 am (0300) 4 am (0400) 5 am (0500) Means and Totals

Temp Total Caribou °C Insects¹ Seen

14 14 12 11 10 8 7 8 8²

86 77 34 13 0 0 0 0 0

43 20 none 112 15 15 47 22 21 295

Group Size

Feeding

Percentage of Time Walking Lying Standing

11.0 (3) 56 35 7 2 10.0 (2) 75 2 15 – none – – – – 37.3 (3) 76 3 20 – 15.0 (1) 67 27 7 – 7.5 (2) 100 – – – 23.5 (2) 49 9 43 – 5.5 (4) 18 82 – – 10.5 (2) 14 86 – – 15.0 (19) 61.4 (181) 21.7 (64) 16.6 (49) 0.3 (1)

¹ Total insects include those captured in 25 downwind sweeps plus those captured in 25 upwind sweeps plus those that crossed the paper in one minute and the total bites per minute. ² At 8 AM the total insects were 4 and the temperature 9°C

fed less (fig. 4.5), increasing the ratio of energy expenditure to energy intake while harassed by insects (fig. 4.8). Travel rates accelerated (fig. 4.9) when the animals were bothered; the overgrazed range would have accelerated mobility (fig. 3.4). In the mosquito season, we again wondered if the daily activity budget was representative of the schedule at night. Camps monitored the herd on the night of 2 July 990, observing 9 groups (295 animals). They fed 6% of the time compared to 4% in the day scans; and they walked 22% of the time compared to 37% in daylight hours and reclined 7% (table 4.4). Mosquitoes ceased at 000 when the temperature dropped to 0°C (table 4.4). It is interesting that most of the animals continued to feed through the night from 200 to 0300. Then at 0400 the groups commenced to travel, even though the mosquitoes were still not active (table 4.4). If lying down is not considered, the active animals fed 74% of the night and walked 26% (table 4.5). These night percentages were similar to the daylight percentages for the Central Arctic herd with few mosquitoes and the 40Mile herd in the post-calving period, also with few mosquitoes (table 4.5). The cool – even cold – nights in the subarctic in July provide a forage make-up period; the forage is not as nutritious as in the pre-insect interval (fig. 7.4) but the phytomass is greater, as is the bite size. The mean temperature during July at the 0800 readings were: 988: 9.5°C ± 0.79°; 989: 8.°C ± 0.74°; 990: 9.3°C ± 4.2°; and 99: 9.8°C ± 0.57° (overnight minimum 5.3°C ± 0.5°). The minimum percentage of the nights in July with temperatures below 0°C was 58% in 988;

Optimal Foraging and Predation Risk in the Winter and Growing Seasons | 42

Table 14.5 Activity budgets of active caribou (not lying) during times of insect harassment, primarily by mosquitoes in the summer Herd Name

George River Daytime (1988) Nighttime (1990) Central Arctic (Alaska)¹ Mild Insects Moderate Insects Severe Insects Central Arctic (Alaska)² Central Arctic (Alaska)³ 40-Mile Herd (Alaska)⁴ Porcupine Herd (Alaska/Yukon)⁵ Mosquitoes + Oestrids

Feeding

Activity Budget (%) Walking Standing

Running

33.2 73.6

59.2 26.0

0.9 6.6

trace 0.0

70.0 62.8 38.6 51.3 59.0 70.2

17.9 17.9 20.1 15.0 41.0 15.6

8.8 12.9 19.1 13.8 0.0 5.1

3.4 6.3 22.0 2.0 0.0 9.2

37

19

37

8

References: ¹ Roby 978; ² Murray and Curatolo 986; ³ Dau 986, Dau combined walking and running; ⁴ Curatolo 975; ⁵ Russell et al. 993 (data from others converted to active caribou (lying caribou not included ) before calculating activity budgets.

62% in 989; 54% in 990; and 85% in 99. There were not many nights on the Labrador tundra when mosquitoes were active all night, but this should change when global warming reaches Ungava. When the daylight scans in the mosquito season were extrapolated to the 24hour schedule for comparison with satellite-collared animals, the daylight active hours far exceeded the long-term active hours (.6 to 7.9, as shown in table 4.3). During the night the animals fed and rested more and walked less than they did in daylight hours when bothered by mosquitoes. This increase in feeding at night compensated in part for the increased energy expenditure during the day when harassment reduced energy intake and animals walked en masse in the anti-mosquito aggregations typical of July (fig. 4.9). The abrupt cessation of mosquito abundance in the last week of July resulted in the splintering of the large post-calving aggregations (chapter 5) and triggered the August dispersal, well-recognized in the caribou literature. This dispersal did not coincide with a change in the food quality. Daily fecal nitrogen readings in July and August 989 mirrored closely the nitrogen percentages in willow and birch – the dominant forage in these months. All three indices of food quality declined gradually during August (fig. 7.4). In eight years of our monitoring, the herd left the tundra in August and crossed the tree line going west. This movement took them farther from the warble pupation sites located in the vicinity of the calving grounds, but at the same time it increased their prox-

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imity to the pupation sites where the males had shed their larvae. These movements also increased their exposure to deer flies (Chrysops spp.) and horse flies (Hybomitra spp.) that generally laid their eggs in muskeg habitats (McElligott 992). The caribou showed strong avoidance behaviour to all of these large dipterans’ attacks, reducing feeding and dry matter intake. This generalized avoidance response is consistent with Karter and Folstad’s (989) view that caribou may have difficulty distinguishing between species, or caribou may show a generalized shaking response to tactile stimulation. August was the month of greatest mobility for the herd, partially explained by oestrid and tabanid harassment which increased walking and running. A decline in oestrids in the latter half of the month was mirrored in reduced mobility (fig. 3.2). Additionally, animals were still above tree line at the beginning of the month on the overgrazed June/July range. They may have travelled faster feeding on the reduced phytomass. With the appearance of the large flying dipterans in August, the animals tend to run-off and disperse, but when they’re feeding, they move more rapidly than when they are bothered by mosquitoes. These large flies are more restricted by cooler temperatures than are mosquitoes (Dau 986; Russell et al. 993) and they are not active at night. In August there were larger time spans for individual animals to seek their own best pastures. The energy budgets did fluctuate daily on the basis of the harassment, but were more frequently positive in August than in July (fig. 4.5). During the oestrid season, the number of active hours based on the daylight scans was only marginally higher than the satellite 24-hour schedule (table 4.3: 8.47 vs 7.77). With the oestrids the animals sometimes run (a score of 55 out of 60), but they also stand for long periods (score of 2), though shaking may add to the activity score. The closeness of these two indexes in active hours may imply that our horizon scans are biased high towards conspicuously disturbed animals. Obviously the warm, quiet days that both observers and oestrids prefer creates a well-acknowledged bias. The pattern that distinguishes the activity budgets of the George River from other herds in North America was the increase in walking rather than feeding time in July and August during the insect season (figs. 4.5 and 4.9) (Curatolo 975; Roby 978; Boertje 985; Murphy and Curatolo 986; Dau 986; Downes et al. 986; Fancy 986; Russell et al. 993). Two additional factors that may have contributed to the rapid rates in August were the reduced abundance of deciduous shrubs below tree line and the extensive trail system. As the animals went west into the taiga the ranges were less heavily grazed, but the dominant forage group of shrubs was far less common than on the overgrazed tundra. The mean percentage of shrubs on the June/July tundra ranges was 36% ± 3.92% at 23 stations (long. x 0.5 lat. grids) and only 3% ± 0.9% at 53 sites on the taiga. Also, the trail system was heavy below tree line;

Optimal Foraging and Predation Risk in the Winter and Growing Seasons | 423

the animals moving through the taiga in August followed the heavily-developed trail systems in searching for the more widely-spaced but less heavily-grazed birch and willow stands. Animals travelled faster when plant cover was less. Animals must constantly balance the advantages and disadvantages of the space they occupy in the summer. July is the month in the Arctic of maximum forage quality and phytomass, although it is also the month of major insect harassment and the period that calves remain susceptible to predation. The fact that the males reach the tundra locations of the females in July substantiates this assessment of the quality, since males track optimal forage habitats (Whitten and Cameron 980). By staying in the tundra in July, cows of the migratory herds in Ungava – as well as in the Northwest Territories and Alaska – have the best options: quality forage, insect relief, and reduced risk. Late August and September were the months to make the fat/weight gains for reaching estrus thresholds. The body weights and fat reserves of females increased rapidly in these months and exceeded gains made by the Kaminuriak herd, NWT, in the 960s. This increase occurred despite the overgrazed range above tree line because the females were prepared to increase predation risk and shift their range below tree line to less overgrazed habitats; however, if they had had sufficient phytomass above the tree line, they would have remained longer there and in the centre of habitation as they had in the 970s. With the denuded range most of the cows still needed an additional week in October to reach estrus. In contrast to the George River females, the Porcupine herd in Alaska received its energy boost and accumulated fat reserves in June and July from rapidly greening forage high in protein, but their reserves declined in mid- and late summer with the quality of the vegetation (Russell et al. 993). This sequence was the reverse of that for the George River females on their more denuded summer range; the latter got their quality boost in late August and early September. Thus caribou appear to have some flexibility in the sequence of weight and fat accumulations prior to the fall breeding season. The movements of the females in the George River herd from August until October prior to snow cover was the density-dependent factor that resulted in range expansion from the centre of habitation and the maintenance of a rather constant annual density of approximately .5 /km², despite an estimated increase of 460,000 animals from 973–74 to 986–88. The limited extent of the summer range which led to the overgrazing provided the impetus to push distribution outward in order to meet fitness needs for reaching body conditions sufficient for breeding in October. Most of the other large herds in North America have summer tundra ranges greater than those available to the George River and summer forage problems have not been reported for these herds. However, the Nelchina herd in Alaska did apparently overgraze its summer range at densities approximately 8–9 ani-

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mals/km²; this reduced body size and possibly affected demography (Skoog 968; Valkenburg et al. 99). Because of its unique 30-year increase within a restricted range above tree line, the George River herd provides a complete panorama of how caribou use space in conditions that range from an accumulated phytomass to a seriously reduced phytomass. Although the tundra was their preferred range, they were prepared to leave it earlier and to seek lichens; thus the range expansion was an individual response to forage scarcity and not the result of a “social stimulus” in the sense of Skoog. Toupin et al. and Manseau studied insect harassment of the George River herd in 992 and 993 (Toupin et al. 996; Manseau 996), concluding that “its contribution to the negative energy balance during the first month of lactation seems negligible” (Toupin et al. 996, 375). But this statement is not applicable here, because they studied the harassment in the pre-insect season, and they didn’t even see an oestrid in 992 – the coldest season on record. Oestrids were on the wing in August 992, however, since in April 993 we found a mean of 4 ± .2 warble larvae per caribou (n = 28 females); one female even had 327 larvae – the highest number we found in counting larva. They also picked a study area near the coast, an atypical location where the females calved in 993 30 km farther north than the geographical centre of calving in 2 other years (fig. 2.3). In 988 we found that mosquito emergence was 2–3 weeks later near the coast than along the upper George River where the large July aggregations formed in most years. This area, which is in the vicinity of Indian House Lake, generally had hordes of mosquitoes after mid-July, and this low river valley was a major highway as the animals moved south seeking birch and willow growth. Caribou in the George River herd are massively infected with warble larvae. Parker (98) as well as Huot and Beaulieu (985) reported 00% infection rate, and all 28 females we examined in April 993 were infected. The mean annual larvae counted per autopsied animals in April between 980–93 was 75 ± 3.7 larvae per male (n = 9 animals); and 5 ± 3.6 for adult females 979–93 (n = ,245 females). These frequencies are similar to the larval loads of the migratory herds on the mainland in the NWT (Kelsall 968, 975; Thomas and Kiliaan 990). These authors felt that harassment seriously affected activity budgets: It has even resulted in the death of animals in Alaska and northern Canada (Kelsall 968; Davis and Valkenburg 979; Heard 99, pers. comm.). The George River herd has an even heaver insect problem than more northern herds because it inhabits latitudes where black flies, deer flies, and horse flies add to the burden. These insects seriously negate energy intake (fig. 4.9). Competitive Interference at High Densities Manseau (996) in 992 and 993 also studied the foraging efficiency of the George River herd prior to insect emergence. She counted animals by horizon scans (.2

Optimal Foraging and Predation Risk in the Winter and Growing Seasons | 425

to .8 km²) and compared these densities with the percentages of animals feeding, the length of feeding bout, and the proportions of animals feeding in different habitats. She hypothesized that at high densities (as high as 2,500/km²) competitive interference (interactions) between animals reduced searching efficiency, concluding that those caribou that joined a group did so at a potential loss in foraging efficiency. We also studied this, but instead of measuring densities we quantified aggregation effects by recording activity budgets and travel rates between the differentlysized groups that passed by our stations prior to insect emergence in late June and early July. We also measured competitive interactions by group size in June 978 vs June 988, a period in which the density of the herd had increased 3.5 times (table 2.3). The caribou in 988 had fewer interactions than in 978, but in 988 densities were higher and biomass had been reduced. Manseau didn’t measure interactions, but she concluded that competitive interference was reducing foraging and searching efficiency since the percentage of animals feeding declined at high densities. She also showed that walking increased at high densities, but reduced feeding could have resulted because large travelling aggregations had entered her viewing area and not because animals were moving from feeding sites due to competitive interference. She presented a photograph of 400 animals feeding and lying down; these animals showed a uniform repulsed distribution with nearly all the adults spaced away from each other, a finding we agree with. We were unable to show a significant effect of group size on feeding efficiency or travel speeds. Animals travelled faster feeding when plant cover was reduced. In 988 larger groups actually fed at slower speeds. Animals may have oriented on the greater cover and/or on the locations of other feeding animals. The mean percentage of animals feeding per group and the mean size of groups were not correlated based on daily means in June and early July (988, r = 0.075, n = 23 days; 989, r = 0.078, n = 5 days; 990, r = -0.06, n = 9; and 99, r = -0.28, n = 3). Travel speed and mean group size were not correlated in the aggregations passing our camp in 5 years (fig. 3.6). Our major finding was that animals – regardless of group size – fed slower when they encountered a greater phytomass and when they fed in the absence of insect attacks. This agrees with Manseau’s observation that the proportion of animals feeding in high-density birch phytomass increased with higher densities but decreased with high densities in a shrub tundra habitat of low phytomass. Caribou have evolved a foraging strategy in the growing season that improves their feeding efficiency in a social setting, using the open visibility and efficient mobility provided by the tundra space. If the food supply is patchy and of high quality, dominants may move to where other animals are feeding. But in our observations in 978 this resulted in only minor displacements; target animals continued to feed and all animals were able to use the patch. If the phytomass is

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naturally sparse or overgrazed (as it was 988 and when Manseau watched animals in 992 and 993), the animals will be more spaced in searching for their own patch, and will move faster with smaller bites and longer feeding bouts. Observing the behaviours of other feeding animals facilitates efficiency but does not necessarily lead to competitive interference. Caribou are of two minds: to join or to leave. Joining a small group facilitates foraging; leaving a group bothered by oestrids facilitates relief; moving to a large massed herd facilitates mosquito relief but interferes with foraging. Aggregating improves use of information (Lent 964; Lott 99), both in detecting and avoiding predators and insects and in searching for a restricted food supply in the open landscape. Russell et al. (993) felt that caribou, in order to optimize nutrient intake, employed strategies to minimize detrimental effects of insect harassment. The ideal for caribou in July and August is insect relief habitat, such as exposed ridges in close juxtaposition to abundant shrub supplies, especially dwarf birch. The Porcupine herd, which spends July in the British, Barn, and Richardson Mountains, has just this: The animals remain on the exposed ridges when insects are on the wing but descend to nearby shrub communities when the insects abate in the cooler hours. The undulating tundra habitat east of the George River is less mountainous than that in the Yukon and Alaska. Elevations generally vary only a few hundred metres (400–800 m) and the few snow patches remaining in mid-summer are in the rugged Torngat Mountains. Still, there are low ridges that provide greater relief than what we noted for the Leaf River herd in Ungava summering west of 7° W and north of 58° N. It seemed paradoxical that many of the George herd’s July movements – especially the major route south – paralleled the valley of the George River where mosquitoes were especially abundant. However, this river system in the tundra had major supplies of dwarf birch and willow – the herd’s major summer foods, albeit heavily-grazed. And there was time to feed when nightly temperatures declined below the threshold for mosquitoes. The percentage of caribou that we noted feeding in July between 0600–0800 hours was 68% (n = ,205, fig. 4.5), actually higher than the percentage of animals feeding from 0800–2200 in the pre-insect season in June and early July, which was 60% (fig. 4.5). If the animals in July had moved into the taiga prior to their release from mosquitoes, the tree cover would have reduced the effectiveness of forming tight compact herds for relief. There would also have been less wind relief and the taller shrubs would have increased the cover for mosquitoes. Although the forage on the George River tundra was less in the 980s than in the 970s, it still may have provided the best habitat mix for insect relief and forage. A summary of the spacing and gregarious behaviour of the herd in the growing season is available from Renewable Resources’ studies 99–95 (table 4.6), the object of which was to determine actual densities of animals during the growing season in the Low Level Training Area for jet aircraft at Goose Bay in Labrador.

Optimal Foraging and Predation Risk in the Winter and Growing Seasons | 427

Table 14.6 The use of space by caribou during the non-snow season 1991–95, primarily south of 57° N and east of 66° W. Animals generally counted in blocks 465 km² (all the data was collected by Renewable Resources, Sidney, BC , under contract to the Department of National Defense) Spacing Season

Census Blocks¹

Pre-calving (Early Greens) 25–31 May 1992 10 25–30 May 1994 8 21–27 May 1995 10 Means 9 ± 0.6 Calving (Pre-insect) 23–25 June 1991 Mosquito Season 22–28 July 1990 21–27 July 1991 4–23 July 1993⁴ Means

8 – 8 13 11 ± 2.5

August Dispersal (Oestrids) 20–25 August 1992 9 6 4–23 August 1993⁵ 17–23 August 1994 8 18–25 August 1995 10 Means 8.3 ± 0.9

Radios Located Total % of Total²

Caribou per Collar/ 465 km²

km²/ Radio Caribou

Caribou/ km²

17 15 18 17 ± 0.9

17–223 14 18 18 ± 2.3

1,690 4,220 2,558 2,823

306 217 258 260 ± 25

5.9 ± 1.16 17.9 ± 4.25 9.01 ± 1.42 10.9 ± 3.60

16

21

3,120

200

23.6 ± 4.87

17 32 23 30 58 62 33 ± 1.3 41 ± 1.03

7,240 7,420 6,010 6,890

– 139 104 122

– 48.8 ± 11.09 56.5 ± 12.79 52.7 ± 3.85

9 9 10 16 11 ± 1.7

9–12 10 9 16 11 ± 0.7

1,770 – 3,280 4,172 3,074

470 310 372 290 361 ± 40

4.5 ± 2.20 1.7 7.4 ± 3.53 13.6 ± 4.36 6.8 ± 2.57

September (Pre-rut) 18–26 Sept. 1992 18–25 Sept. 1994 20–27 Sept. 1995 Means

10 9 10 9.7 ± 0.3

18 28 18 21 ± 3

18–24 25 18 22 ± 0.9

830 2,210 6,297 3,112

261 149 258 223 ± 37

2.9 ± 0.60 12.5 ± 4.42 22.8 ± 5.76 12.7 ± 5.75

Rutting Season 23 October 1991

4

5

6

2,110

320

10.0 ± 5.47

¹ Census blocks are 465 km² ² Based on total radios available: 990 – 53, 99 – 7, 992 – 76 to 98, 993 – 93, 994 – 0, 995 – 0 ³ 7 to 22% ⁴ 3 large aggregations with at least one radio collar (mean size 26k ± 6), assume all caribou in photographs included in area of 465 km² ⁵ Based on aerial transects rather than block counts

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Data (such as this) on summer densities of migratory caribou in North America are nearly nonexistent in the literature, except for that tabulated on calving grounds. In four years these researchers located radio-collared animals and then counted the animals in an adjacent block (465 km²). By extrapolating the results to the known collared adults alive in the population (bottom of table), it is possible to estimate the total size of the George River herd in the early 990s. Such census extrapolations are consistent with a major decline which occurred subsequent to the maximum counts in the 984 and 988 surveys. The summer densities of the herd from this data indicate that the population was 8 times denser in the mosquito season than the oestrid season and 5 times denser than in the pre-calvng and pre-rut periods. Since these two months (July and August) provide the greatest abundance of summer forage at a critical point in the animals’ recovering physical condition, this data shows to what extremes they are prepared to compromise optimal foraging in exchange for relief from two different insect groups with very different life cycles. Global Warming and Optimal Foraging/Predation Risk Conference proceedings on climatic change make it evident that caribou researchers have been focusing on forage/energy considerations without discussing changes that warmer temperatures might bring to bear upon the interactions of wolves and caribou. During our study there was no evidence of warming temperatures in Ungava. Therefore one can use the George River data as a control in comparisons with recent findings in Alaska and the Yukon, where global warming is already affecting caribou (Griffith et al. 998). Our conclusions above were that avoiding predation risk outweighed optimal foraging during the deep snow season (December through March). Forage considerations dominated, however, from the end of the mosquito season ( August) until snows generally exceeded 40 cm. One major concern in the literature about Arctic warming is that there will be a reduction in the abundance of terrestrial lichens due to an increase in forest fires. Additionally, a predicted increase in snow depths would require more energy from animals who must dig feeding craters. Studies of lichen abundance have been legion over the past 40 years – some of us have spent endless field days looking in feeding craters and measuring lichen abundance (Bergerud 97a, 974c, 988; Miller 976a, 980; Russell et al. 993; Thomas et al. 996): All in vain, however. Arseneault et al. (997) stated (p. 66) “Density-dependent limitation of winter forage … has not yet been described for large, lichen dominated, continental ranges of wild caribou.” Their lichens studies for the George River encompassed Landsat imagery 989 vs 992. For the George River herd the range has historically been heavily and repeatedly burned (Hare 959; Payette et al. 989, 992;

Optimal Foraging and Predation Risk in the Winter and Growing Seasons | 429

Couturier and Marten 990). Indeed there was so much ablaze in July 988 that we could not fly west of 72° W for range studies. The George River herd has had the highest number of caribou of any major herd in North America and these animals have had to crater in the deepest snows of any migratory herd. Even with an overgrazed summer range, fat reserves of pregnant females in March 982, 986, and 987 averaged .7 kg ± 0.63 kg. of fat (986 and 987 from Couturier et al. 989). These fat reserves are similar to those projected for the Porcupine herd (Russell et al. 993), and were greater than that for the Kaminuriak (Dauphiné 976). Thomas and Kiliaan (998) showed that the condition of the Beverly herd in March over 8 years 980–87 was superior to the condition of caribou in the Kaminuriak herd in early April in 3 years (966–68) despite reduced lichen supplies for the Beverly herd in both the 960s and 980s due to forest fires, and despite the fact that Beverly herd densities were 3–4 times greater in the 980s than densities for the Kaminuriak herd in the 960s (Parker 972a; Miller 976a, b; Thomas et al. 996; Thomas and Kiliaan 998). Thomas and Kiliaan (998, 26) reported that “those data all indicate that the Beverly herd experienced better winter range conditions 980–87 than did the Kaminuriak herd 966–68. Therefore, there was no evidence that winter range of the Beverly herd was inadequate for the population of caribou in spite of vast areas burned since 969 in the western and southern portions of the historical winter range.” We can rank these four major herds (Porcupine – 980s; George River – 980s; Kaminuriak – 960s; Beverly – 980s) according to late-winter body condition as follows: Snow Depths: George > Kaminuriak > Beverly > Porcupine Densities: George > Beverly > Porcupine > Kaminuriak Lichens: George > or = Kaminuriak > Beverly > Porcupine Body Condition: Porcupine > or = Beverly > Kaminuriak > George Recent Range Destruction from Fires: Beverly > George = Kaminuriak > Porcupine There is no obvious relationship between snow cover, lichen abundance, animal densities, physical condition, or fire occurrence. The highest persistent density of caribou in North America (6–4/km², 974–99) has been on the Slate Islands in Lake Superior (Bergerud 996). These islands have a history of logging and forest fires; there are no terrestrial lichens; and there are no arboreal lichens within reach of the animals except on blow-downs. We do not believe that changes in lichen abundance and winter energy budgets should be given priority in evaluating the potential impacts of climate change. Caribou biologists have also voiced concern that climatic change could impact caribou in altering their summer foraging regime and energy budgets. The most persuasive arguments are those of Russell (993), who raised a red flag about pos-

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sible foraging problems based on the following predictions made in a 986 conference: () a 2–4 week earlier snow melt; and (2) a 2–4°C increase in summer temperatures. Russell reasoned that mosquito harassment might decrease foraging budgets, and that plant phenology and senescence could occur earlier in the growing season, thus affecting the availability of nutritious forage when lactation demands were high. How mosquitoes will react to warming temperatures cannot be predicted. Each mosquito species has evolved its own life-history schedule. At Indian House Lake during our summer energy budget studies we noted major differences in mosquito harassment between years (988–92), both in numbers and annual chronologies. Peak abundance occurred in 988 at 0–°C and in 99 at 22°C and 23°C. On 23 June 989 the temperature reached 33°C at Indian House Lake (44°C in the sun) and the entomologist operating from Schefferville (E.K. McElligott) felt that larvae might die from physiological stress in the warm waters; and indeed there were far fewer mosquitoes in 989 than in 988. We view the early growing season predicted with climate warming as a plus for caribou. Cows will be in better condition at parturition and birth weights will increase. The body size of caribou is determined by the length of the growing season (fig. 2.2). With warming we may have larger caribou. Klein (970) has argued that the flora of the arctic is of higher quality than that foraged by woodland caribou, but it is the number of days available to forage on growing vegetation that drives growth. In time, with climatic warming, calving dates may also advance, which in turn might advance lactation demands to keep abreast with the earlier phenology. The dates of calving also vary with the length of the growing season. The correlation between the Julian Date of peak calving in 23 herds in North America had a high coefficient of determination r² = 0.99. We believe caribou should benefit nutritionally with warming spring and summer temperatures. Wolf predation is now accepted as the major limiting factor for moose and caribou in North America (see 24 references in Bergerud and Elliott 998). With global warming we can expect wolf numbers (and their impacts) to increase. We suggest four sequences of concern (although other workers would list other predation consequences). First, a warming Arctic could result in a decline in the tundra and with it the abundance of lemmings and arctic foxes. Wolves inhabiting ranges overlapping arctic foxes are exposed to the Arctic fox rabies vector (MacInnes 987) and there have been serious outbreaks in Alaska (Weiler and Garner 987; Ballard and Krausman 997) and in Ungava. Rabies outbreaks in Labrador are documented back to the early 800s (Elton 942). The George River herd exceeded the carrying capacity of its summer range in about 982 after the wolf population crashed; based on the mean pack size, the decline was 6%; or, based on harvest statistics, 8% (Bergerud 988a). In the absence of this disease wolf populations in the Arctic would be limited by the prey biomass (Fuller 989)

Optimal Foraging and Predation Risk in the Winter and Growing Seasons | 43

and might frequently exceed 7 wolves/000 km². This could result in caribou declines (Bergerud and Elliot 986). Second, with warmer winters we could expect greater snowfalls and depths. Caribou are more vulnerable to predation in deep snows, at times resulting in surplus killing (Mech et al. 998). With excessive snow, caribou might not reach the increased safety of their calving grounds. This happened in the case of the Nelchina herd in 964, 965, and 966 (Bergerud and Ballard 988) and more recently for the Porcupine herd, resulting in major mortality. It is not that caribou cannot cross deep snow cover lacking brown substrates: In the mountains of British Columbia animals commonly move over extensive snow fields when brown substrates are available elsewhere. In the Arctic, however, extensive snow at lower latitudes may signal that calving grounds are still covered and thus lack brown substrates for crypsis of newborns. Thirdly, the caribou in the NWT and Ungava winter in relatively level topographies that use the frozen lake surfaces of the Canadian Shield to mitigate predation risk and enhance escape possibilities. They don’t have the advantage of the reduced snow and open vistas (for spotting approaching predators) in the mountains as does the Porcupine herd. If climate change reduces the extent and duration of the frozen lake period, this – coupled with deeper snows in the forest – would greatly enhance the effectiveness of wolf predation. As a result, caribou would spend more time on the tundra in diminished physical condition. Our fourth concern is the most serious. With increased warming and the advance of the tree line we can expect moose to extend their range north. Moose have been pushing north for decades, increasing the prey base for predators and thus the abundance of wolves. With the advance of the tree line this movement will be accelerated. This enhanced abundance of wolves, coupled with the loss of habitat that has reduced the spacing-out advantages of woodland caribou, has resulted in an alarming rate of extinction in local populations on the southern edge of their range (Bergerud 2000). When caribou returned to Ungava during the Holocene they were not followed by moose, but now moose are at the door: It takes only 0.0 moose/km² for wolves to reach 7/,000 km², a number too high to maintain caribou numbers. We should shift our concerns relative to global warming from forage to predation; the most pressing problem will arise as a result of more moose, more wolves, and fewer arctic foxes – from, in other words, species-diversity problems. The southern limit of caribou in Canada and the United States is not based on forage abundance or temperature tolerance but on mammalian diversity and its implications on mortality rates. If caribou are to persist, wolf management will be necessary.

CHAPTER FIFTEEN

Spacing Theory of Calving and Migration

The spectacular spring migrations of caribou/reindeer in the Arctic and the return of females to particular calving areas (fig. 5.) have long intrigued laymen and scientists alike, but they have not been adequately explained from a theoretical perspective (Baker 978). The only movement that the George River herd undertakes that qualifies as a true migration is the spring return of preparturient females to the calving ground on the Labrador tundra (fig. 3.28). Dingle (996) defines true migration as undistracted movement, not directly responsive to resources, where cessation is primed by the movement itself. Based on Naskapi lore and the ages of ancient tent rings along Indian House Lake where the Naskapi and other native peoples awaited the caribou’s fall movement west to the taiga, this return to Indian House Lake in Labrador dates back over 4,000 years (fig. 5.) (Cabot 92, 920; Taylor 969; Jordan 978; Samson 978). During our monitoring in the 970s and 980s, the George River pre-parturient females commonly migrated 300–600 km from March through May in their return from winter ranges to the Labrador tundra for calving (fig. 2.5, 2.6). Migration Hypotheses The primary dyad of hypotheses (Jacobi 93) to account for the evolutionary origins for these spring migrations are () this movement response is destinationoriented: the animals are seeking a specific requisite provided only in arctic habitats and at particular locations; or (2) these migrations were selected as displacement responses and the animals are shifting to avoid a less favourable environment in the taiga. If calving locations provide a necessary requisite, the alienation of these habitats by economic disruption or climatic change could

T

Spacing Theory of Calving and Migration | 433

INE EL RE ALPINE

CALVING GROUNDS

75 % S JUN NOW E1

0 0

TR

MOUNTAIN

EE

250

500 KILOMETRES 250

500 MILES

LIN E

LAKES E ICE-FRE1 JUNE

MUSKEG ISLAND CALVING GROUND CALVING GROUND SHIFT SPRING MIGRATION DISPLACEMENT DISTANCE

Fig. 15.1 Strategies used by sedentary and migratory ecotypes to reduce predation risk at calving. Females of sedentary caribou have options of “spacing out” at calving to mountain tops, muskegs, or lake shores and islands. Females of migratory herds “space away” from predators (mostly wolves) by migrating to calving grounds that are displaced as far as possible from the tree line consistent with having brown substrates for crypsis of newborn calves. (See also fig. 2.3)

affect the demography and size of populations. But if the migratory response is to “space away” (Bergerud and Page 987) from a less favourable taiga environment, the alienation of only the end-point of the migration might have less serious consequences. Kelsall told us long ago (968) that the calving grounds to which the migratory NWT herds journeyed were inhospitable areas with extensive snow cover; elevated, cold, windswept topography; sparse vegetation, and a delayed growing season. Truett et al. (989) reviewed the characteristics of calving habitats for both sedentary and migratory ecotypes by comparing whether such calving sites had earlier snow melt and green-up than the areas vacated, as well as whether they had better forage, fewer predators, and a more diverse topography. The

434 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Table 15.1 Characteristics of calving locations for caribou compared to elsewhere in the herds’ range (Truett et al. 1989) Environmental Factors Considered

Time of Snow Melt Calving Area Earlier Calving Area Later Time of Green-Up Calving Area Earlier Calving Area Later Forage Quality/Quantity Calving Area Greater Calving Area Later Topography Calving Area Greater Calving Area Less Presence of Predators Calving Area Greater Calving Area Less

Number of Caribou Herds¹ Sedentary Ecotype Migratory Ecotype Yes² Probable Yes Probable

Grand Total %

3 11

1 1

3 15

1 7

19 81

6 7

1 3

2 22

0 1

21 79

4 5

0 1

0 18

0 4

13 88

7 4

3 0

10 8

4 1

65 35

1 8

0 5

3 17

0 0

12 88

¹ Sedentary includes 20 herds, 9 of which were visited by Bergerud (45%). Migratory includes 27 herds, 5 of which were visited by Bergerud (56%). ² Yes means data available or visited. Probable means not visited, a judgment call.

destination-oriented hypothesis shows that the majority of the animals are going to habitats with late snow melt, late green-up, reduced forage, diverse topography, and fewer predators (table 5.). Conversely, the displacement view shows that the females are leaving areas with reduced snow, more early greens and forage, and more level topography, and more predators. Nutrition Destination Hypothesis The “destination-oriented” theory has been the dominant view in recent decades. It has been argued that arctic ranges provide highly nutritious foods for growth and reproduction (Klein 970, 982) and these seasonal migrations optimize foraging conditions post-calving (Klein 983, Russell et al. 993). Kuropat and Bryant (980) hypothesized that the buds of the sedge Eriophorum angustifolium are especially nutritious and are the attractive feature of calving grounds. Consistent with this hypothesis it has been suggested that caribou generally migrate in groups to provide an opportunity for the young animals to learn the migration routes (Espmark 970) and stimulate migration (Duquette and Klein 987). Also, a general view is that the rate of travel varies between late and early

Spacing Theory of Calving and Migration | 435

phenology years so that animals will reach their calving grounds on schedule (Skoog 968; Kelsall 968). Furthermore, if the animals arrive prior to calving, the migration ceased: This suggests a goal has been reached (Kelsall 968). It is accepted that calving grounds commonly remain in the same general area for years and even decades (Skoog 968; Gunn and Miller 986) and that females usually show philopatry between migrations. The above observations thus generally support the hypothesis that migration is destination-oriented. We tested the “destination-oriented” nutritional hypothesis by measuring the fecal nitrogen (FN) of the spring diet of cows of the George River herd and other migratory herds in North America that had migrated to calving grounds and comparing it concurrently with that of bulls not on the calving grounds. If females migrated to calving grounds to secure a high-quality diet, the FN in their feces should exceed that of males who lagged behind at lower elevations or latitudes. This analysis indicated that females on calving grounds in five migratory herds had a less nutritious diet than males in late May and June (fig. 5.2). Heard et al. (996) reached a similar conclusion for the Bathurst herd in the Northwest Territories, as did Russell et al. (993) relative to the Porcupine herd in the Yukon. In our analysis the diet quality did not differ between males and females when sharing the same range on the Slate Islands in Lake Superior (fig. 5.2). Another control was that five males on the calving ground of the George River with the females (6–23 June 988) had a mean FN of .58% ± 0.06%, identical to that of females. The nitrogen in plant species eaten by males in Alaska and the George River herd at the time of fecal collections equalled 3.84% ± 0.38% (N = 0) and for females was a third less, 2.42% ± 0.% (n = 9) (P = 0.00). The highest N value among the plants used by females of the Western Arctic herd in Alaska was for the flowering heads of Eriophorum on 7 June (N = 2.86%). Males in this herd as well as in the 40-Mile and Delta herds in Alaska shifted north later than the females (Bergerud 996), feeding on earlier phenology forage of birch and willow buds and leaves that had nitrogen values that ranged from 4.29–6.24%. When we collected the feces of the males of the George River herd on 3–4 June 988, they were 30 km further south and west of the calving females below the tree line and were selecting the new green sprouts of bog bean (Menyanthes trifoliata), N = 3.98% ± 0.35%. Females on the tundra calving ground at that time were selecting the newly emerged stems and flowers of the sedge Scirpus cespitosus, N = 2.54% ± 0.26%, and early greening leaves of Arctostaphylos alpina, N = 2.80%. The fecal nitrogen of the females in the George in mid-June is less than that for males: .58% ± 0.032% for females vs .97% ± 0.042% for males (fig. 5.2). In July females may still have a nutrition shortfall compared with males: FN 2.37% ± 0.095% for females vs 2.83% ± 0.% for males. These results suggest that if parturient females’ primary concern is to maximize the quality of their diet at calving, they should not migrate to calving grounds but remain with the bulls (Russell et al. 993). The females pay an addi-

PERCENT FECAL NITROGEN

3.5 MALES BELOW TREE LINE FEMALES ABOVE TREE LINE BOTH SEXES ABOVE TREE LINE

3.0

2.5

2.0

NET LOSS NOT MADE UP AFTER CALVING

1.5

1.0 15

20 25 JUNE

30

5

10

15 20 JULY

25

30

5 10 15 AUGUST

3.5

NON-MIGRATORY HERD

MIGRATORY HERDS 2.5

0

GEORGE RIVER

DELTA

40-MILE

WESTERN ARCTIC

PENN ISLAND

3.30 (45) 3 year average

1.71 0.034 (29)

2.35 0.030 (34)

1.98 0.037 (29)

2.18 0.027 (25)

1.99 0.036 (10)

2.18 0.079 (22)

1.78 0.056 (18)

0.5

2.32 0.109 (20)

1.0

1.58 0.032 (11)

1.5

3.46 (39) 3 year average

2.0

1.97 0.042 (17)

PERCENTAGE OF FECAL NITROGEN

3.0

SLATE ISLAND

Fig. 15.2 Spring segregation of males and females. In the spring migration males lag behind migrating females in May and June, remaining at lower elevations or latitudes than females, seeking the early green forage rich in nitrogen, whereas females migrate to tundra calving grounds where the phenology is delayed and forage less nutritious than where the males feed. The fecal nitrogen comparisons of males and females in the various herds (bottom) were secured within as short a time frame as possible at calving. For the George River the collections were conservative relative to the hypothesis, males were sampled 13–14 June in the taiga near Lac Champdore and females on the tundra at Indian House Lake after 14 June to 16–19 June 1988. The Delta, 40-Mile, and Western Arctic herds are in Alaska and the Penn Island and Slate Islands are in Ontario.

Spacing Theory of Calving and Migration | 437

tional cost by depleting their fat reserves during the long migration before the advent of new growth (fig. 9.5; Whitten and Cameron 980). The growing season commences about 2–3 weeks earlier at the latitude where the bulls are in Alaska, NWT, and Ungava than at the calving grounds. The bulls move north at a more leisurely pace, following the advance of the growing season (Whitten and Cameron 980; Heard et al. 996), and they reach female locations by the beginning of July where both sexes reduce mosquito harassment by massing on the windswept tundra. Bulls can generally maintain or increase body weights and fat reserves from April–July (Dauphiné 976; Whitten and Cameron 980). The bulls, not the cows, move in the spring in order to maximize diet quality. The hypothesis that cows migrate in spring in order to reach a forage destination at calving is not supported. These spring migrations, which take them back to winter conditions, result in a negative energy balance and weight loss for migratory cows compared to that of cows who might choose to remain with the bulls farther south and thus follow the green phenology north (Russell et al. 993). The diet quality of cows at parturition is less than the bulls remaining further south or at lower elevations. The weight of calves at birth reflects the conditions and weights of their dams. Whitten et al. (992) reported that in the Porcupine herd 59–74% of the calves that died in three springs within a month of birth did so within 48 hours of birth, and that these calves weighed less than calves that survived the critical period. Thus it is disadvantageous for cows to return to calving grounds prior to green-up on the basis of the intrinsic viability of their calves at birth. Predation Displacement Hypothesis A displacement hypothesis could apply if caribou migrate (especially preparturient females) to avoid predators that are more common in the taiga. Female caribou inhabiting mountains and also female mountain sheep (Ovis canadensis) and elk (Cervus canadensis) make altitudinal movements prior to calving that reduce predation risk (Bergerud et al. 984; Festa-Bianchet 988; Bergerud and Elliott 998). In Asia females of the Tibetan antelope (Pantholops hodgsoni) and the Asian saiga (Saiga tatarica) (Bannikov et al. 967) make long spring migrations to inhospitable regions with fewer predators for parturition, leaving the males behind in more optimal foraging habitats. Fryxell et al. (988) proposed that the wildebeest (Connochaetes taurinus) in Africa migrates in the wet season to ranges with fewer predators and they note that the three species of ungulates that migrate in savannah ecosystems outnumber the three sedentary species by –6 times, and they attributed this to lower mortality rates because of displacement from predators. Similarly, North American woodland caribou make much shorter migrations than the migratory barren-ground herds and their densities are only one-tenth that of the migratory herds (Bergerud 980, 988b); the pre-

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settlement numbers of these woodland animals was possibly only one-tenth that of the migratory herds (Bergerud 2000). The displacement hypothesis that migration reduces predation risk was partially tested by Heard et al. (996), who quantified the abundance of wolves in June on the calving grounds of the four major migratory herds in the NWT as well as on the winter range of these herds in March/April. Wolves were 5 times more abundant on the winter ranges south of tree line than on the calving grounds based on aerial observations: Winter Ranges – 79 ± .2 wolves/00 flying hours (n = 2, 234 hours) Calving Grounds – 5 ± 0. wolves/00 flying hours (n = ,545 hours). Hayes and Russell (2000) quantified the seasonal aspects of wolf predation by following radio-collared wolf packs preying on the Porcupine herd in the Yukon and Alaska. The seasonal percentages of the total kill of caribou were estimated at: approximately 38% in late winter; approximately 22% in spring ; % (probably spring migration); % calving; 3% post-calving; % in early summer; % in mid-summer; 9% in late summer and fall migration; and 22% in rut and late fall. They confirmed that their model supported Bergerud and Page’s idea (987) that spacing away was also an effective antipredator strategy of adult caribou (also Kelsall 968; Bergerud 974b). The migration of the cows to calving grounds on the tundra has effectively displaced them from high numbers of their chief predator. Biologists in the NWT have expended considerable effort in locating wolf dens to test the displacement hypothesis. They located 209 dens, the majority in the vicinity of the tree line (Heard and Williams 992). In earlier years both Kuyt (972) and Jacobson (979) had shown that wolves in their study areas in the NWT denned generally near tree line where they had more access to alternative prey when the caribou herds were farther north of the tree line. That finding was also reported in Alaska (Garner and Reynolds 986) and in the USSR (Bibikov et al. 983). However, could the den locations be a biased sample resulting from biologists making a greater search effort south of trees? Heard and Fleck tested this objectively (unpublished) by placing radio transmitters on 35 wolves that were hunting the Bathurst herd in late winter. The biologists had no prior knowledge where the wolves would den. Twenty-two of the wolves followed the herd northeast as it crossed the tree line heading for the calving ground (fig. 5.3), but only two males continued to the calving grounds; the females denned in the vicinity of the tree line, with 0 dens located 364 km ± 9.6 km from the southern edge of the calving ground. Wolves at these dens had a hunting radius from the dens of 9.8 km ± .6 km; hence the caribou calved far beyond their reach. Barren-ground caribou generally remain above tree line during the summer months (fig. 4.2) during the

Spacing Theory of Calving and Migration | 439 115

o

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Fig. 15.3 Migration of wolves. Wolves that depend on caribou in the Arctic commonly vacate their denning territories in the fall and winter and follow the caribou into the taiga; in the spring they reverse their migration (Kelsall 1968, Ballard et al. 1997). The wolves in this fig. were radio tagged in the NW T in the winter in an area where they were associated with a large concentration of cows and calves of the Bathurst herd. The wolves moved north with this herd in spring migration but the breeding wolf pairs dropped out to den near tree line while the female caribou continued to migrate to their calving ground with most of the wolves left behind. Work was done in 1979 and 1980 under the supervision of D.C. Heard and Susan Fleck (unpublished).

interval when denning wolves farther south have limited mobility due to rearing pups. If wolves followed the caribou to the calving grounds to den, they could face starvation when the herds vacated the calving grounds in the post-calving movements. Both Kuyt (972) and Williams (990) observed that pups commonly died when prey was scarce in the vicinity of den sites. We flew extensively in 982 and 983 in Labrador searching for wolves and their den sites. Unfortunately, at that time wolves had declined from rabies.

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Fig. 15.4 The sex and age of George River caribou killed by wolves during spring migration 1982. Of the 39 kills found, only 4 (10%) were above the tree line on the Labrador tundra (all females). The males that lagged behind were killed below tree line (n = 13), many after the females had migrated further east which increased the conspicuousness of the males to wolves. Unfortunately 1982 followed a rabies outbreak and the wolves were at their lowest numbers during the study (fig. 1.11). We observed only scattered individuals with three or fewer animals per pack.

Nonetheless we observed 46 wolves, of which 40 were at or below the tree line and only 6 (3%) were on the tundra. Furthermore, we located 47 caribou killed by wolves; 40 of these were also in the taiga; 7 were on the tundra. These surveys also showed that male caribou were more likely to be killed than females. Males and females were equally represented in the kill (table .6), but the ratio of males to females in the living population was about :2 (table 0.4). The mean distance from tree line that males were killed was 206 km ± 25.3 km (n = 7) whereas 4 females killed in the taiga were an average of 35 km ± 26.9 km from the tree line – they were migrating towards it (fig. 5.4). The greater vulnerability of males to predation did not depend on fat reserves; the femoral fat of males killed was 8.6% ± .7% (n = 9); that of females killed was 82.8% ± 2.53% (n = ). However,

Spacing Theory of Calving and Migration | 44

the wolves were killing a higher percentage of older animals (table .6) that were probably not in prime condition. As the females migrated to habitats with fewer wolves, the lagging males became more vulnerable, consistent with the displacement theory for the spring migration of females. There are a few examples in the literature where the displacement distance from the arctic or alpine tree line has been quantified and we have survival data (Bergerud and Page 987; Bergerud and Ballard 988). The Nelchina herd in Alaska generally calved on the same high plateau 950–72 (Skoog 968; Pitcher 983) where recruitment was commonly greater than stabilizing R s of 25 calves per 00 females. However, in three springs (964, 965 and 966) snow cover was so extensive that many cows did not reach the calving ground. Instead they calved at lower elevations below tree line and nearer to denning wolves (see Ballard et al. 987). These three cohorts suffered mortality more than 2.5 times that of the previous three cohorts, 96–63 (Bergerud and Ballard 988). The most comprehensive documentation of the displacement of calving caribou from their predators in the literature was documented in the 980s with a massive study that located the denning sites of wolves and brown bears and the nest sites of golden eagles (Aquila chrysaetos) relative to the calving grounds of the Porcupine herd (Garner and Reynolds 986). The females of this herd consistently calf on the coastal plain north of the Brooks Range, Alaska (fig. 5.5) where the phenology is delayed and snow common at calving (Griffith et al. 2002, fig. 3.8). Their predators have been left behind in the mountains of the Brooks Range. The actual dens or areas of concentrated summer activity of wolves were all more than 25 km from the southern edge of the concentrated calving. Only 9 of 54 old and current den sites of brown bears were on the calving grounds, and only  out of 6 golden eagle nests (fig. 5.5). Eagles caused the greatest calf loss of calves both less than 48 hours old and up to 3 weeks of age (Whitten et al. 992), and it was the immature eagles that were not anchored to nest sites that were most responsible (David Mossop, biologist, personal communication). This mammoth documentation of the proximity of a complete suite of predators to calving caribou is unlikely to be equaled. In addition, the location of the calving ground on the coastal plain varied between years 972–86 dependent upon snow cover (Eastland 99). In 0 years when calf percentages were measured in the summer and/or fall, R was positively correlated with the distance the cows had successfully displaced north of the tree line and north of wolf denning sites, r = 0.602, P < 0.0 (Bergerud 987). More recently, snow cover was so heavy in June 2000 and June 200 that many females calved south of the coastal plain (2000) and also south of the tree line (200). Much closer to wolf populations (Hays and Russell 2000) calf mortality in June was 37% ± 2.0 compared to 23% ± 0.49 in the previous 4 years (estimated from Griffith et al. 2002, fig. 3.26).

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Fig. 15.5 The calving ground of the Porcupine caribou herd in Alaska/Yukon is on the coastal plain. The common predators of wolves, grizzly bears, and golden eagles are mostly located in the foothills of the Brooks Range rather than on the coastal plain used for calving. The locations of the calving grounds varied between years based on snow cover and not because of overgrazing, as was the case for the George River (fig. originally published Bergerud 1996).

Further evidence that the long migrations to calving grounds in the arctic reduce predation comes from comparing the survival of woodland caribou (that do not make long migrations and live south of tree line closer to predators than the migratory herds) to survival rates of those that migrate several hundred km and calve on common calving grounds (fig. 5.). The woodland caribou commonly lose 50% of their calves to predators, mostly in their first few weeks of life (Bergerud 980; Fuller and Keith 98; Page 985; Seip 992; Seip and Cichowski 996; Schaefer et al. 999; Hayes et al. 2003; McLoughlin et al. 2003; and Jenkins and Barten 2005). The early mortality of the calves of barren-ground migratory herds is generally 0% or less (Miller and Broughton 976; Bergerud 980). In this study the George River herd lost 6.6% (8 years of data) of their calves by two weeks of age. However, generally the migratory herds have better survival than sedentary herds that make short migrations and disperse at calving. The mean recruitment for 7 migratory herds in Canada averaged 22% ± .2% calves

Spacing Theory of Calving and Migration | 443

over a period of 2–8 years/herd; for 7 migratory herds in Alaska, the average was 23% ± .2% calves at 6–2 months of age. In contrast, 7 sedentary woodland herds averaged 3% ± 0.82% calves per year over a period of 2–8 years (Bergerud 988b). Long displacement movements to calving grounds in the arctic where there are fewer predators than there are in the taiga does pay off in reproductive fitness: The migratory herds commonly reach densities 5–0 times that of sedentary herds (Bergerud 980, 992). Tyler and Oritsland (989) asked the intriguing question: “Why don’t Svalbard reindeer migrate?” They went on to a discussion of the dispersion of resources. But the parsimonious explanation is that Svalbard caribou are the only caribou herd in the world that has evolved without effective predators; they had no evolutionary imperative to displace themselves in the spring to habitats of low predation risk. In one sense one could say that migratory females migrate to displaced destinations that have been arrived at through a process of natural selection. One can visualize this sequence: Females colonized the landscapes vacated by the Laurentide Ice sheet. Those who calved the farthest south would encounter more predators than animals farther north of tree line, although the latter foraged on a reduced phytomass. In other words, calving females could compensate for the lack of low-risk habitat by moving farther north, away from the more diversified southern fauna of alternative prey and predators, but not without a nutritional trade-off (fig. 4.). Ultimately these females congregated on habitats with the fewest predators and some snow-free areas where their calves could take advantage of their cryptic colouring: These habitats became the calving grounds. Such aggregated females would have the added survival advantages of increased vigilance and of sharing their neonate vulnerability with their neighbours. The Location and Shifting of Calving Grounds Contrary to the calving ground locations at long distances from the tree line for herds in NWT and Alaska (fig. 5.), many animals of the George River and the Leaf River herds in the 970s calved near or at the tree line. In those years portions of the George River herd calved south of tree line near Lac Champdore/Vannes Lake (55°50' N, 66°20' W), as well as on the height of land north of tree line (fig. 5.6). The southern ground was called the Lac Champdore calving ground; the northern one at the height of land was called “Caribou House” (in reference to the Naskapi Caribou God). Quebec biologist Le Henaff located a calving ground farther west along the Leaf River in 974. This herd was named the Leaf River herd, and similar to animals at Lac Champdore, females in this herd calved at or below tree line (fig. 5.7). This calving ground was 400 km south of where western animals had been reported calving in the 800s (see Spiess 979). However, both calving grounds shifted beyond the tree line in the 980s (figs. 5.6, 5.7). By

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Fig. 15.6 The annual calving distributions (overlapped) for the Lac Champdore, Caribou House, and Harp Lake calving grounds, 1973 to 1985. The years studied varied between areas as follows (years searched/years calving present): Caribou House 12/12; Lac Champdore 9/7, Harp Lake 4/3. In 1979 5,186 caribou were censused at the Lac Champdore calving ground; the area was not searched in 1980 but in 1981 it had been deserted. Caribou were calving at Harp Lake in 1975 (731 counted) but none were present when next checked in 1979. The original figure was prepared by Dalton and Luttich (1986).

99 the Leaf River animals were calving 300 km further north, and by 2000 they were an additional 00 km further north – approaching the reported calving ground location of a century earlier. The shifts of the Lac Champdore and Leaf River calving grounds to the north were not a result of overgrazing. We conducted range studies at both Lac Champdore and the Leaf River in 988 and there were little signs of overgrazing. At Lac Champdore, males were present in June 988 and fed on early bog bean; they had more nitrogen in their feces than did females calving east of the George River (fig. 5.2).

Spacing Theory of Calving and Migration | 445

HUDSON 1991

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Fig. 15.7 As it increased in numbers, in 1975 to 2000, the Leaf River herd shifted further north for parturition to an area where it was reported to have calved during the last high population in the 1870s. When it was low in numbers it calved adjacent to the tree line as did a portion of the George River herd (fig. 15.6) (also Bergerud 1958). Large arrows are fall movement routes. The annual distributions were mapped by biologists of the Quebec Wildlife Service (Ministère du Loisir, de la Chasse et de la Pêche).

Nor does the distribution of calving caribou fit the hypothesis that expectant females position themselves to avail themselves of new growth as the snow pack recedes (Eastland 99). We did not observe early greens being uncovered as snow receded, even with the later calving dates in the 980s. Snow cover was generally less at Caribou House than it was to the east or north (fig. 5.8). Nor did the cows migrate farther from the tree line in years with less snow in order to stay abreast of the receding snow line. Cows did calve on uplands with up to

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Fig. 15.8 The composite Caribou House calving ground 1973 to 1995 (broken) based on ascertaining the annual centres of the distributions. Also shown is the total number of bears seen on the aerial June searches made by Luttich over the years and his estimates in 13 years of the mean percentage of snow still on the ground at calving. The general routes used by satellite females returning are shown as well as the only two wolf dens we located. Note that the calving ground in well centred in the available tundra on the Labrador Peninsula.

75% snow cover, but they were also present where snow cover was absent. The mean snow cover in the areas used most consistently at calving averaged 34% in 3 years (fig. 5.8). In the 980s the cows did not follow a snow line to the northeast once mobility had increased after calving; rather, they moved north to the vicinity of the Ungava Bay coast (fig. 3.8), where the vegetation was extremely denuded (fig. 7.). Neither calving nor post-calving distributions were consistent with the hypothesis that they are driven by the search for early greens emerging from beneath receding snow cover (Eastland 99).

Spacing Theory of Calving and Migration | 447

The northern shifts of the George River and the Leaf River herds would have reduced the physical condition of the pre-parturient females at a time when one would expect them to select areas of maximum nutritional availability. The growing season at the Lac Champdore calving ground commences about 5 June (fig. .5) and the mean peak calving date when we first started our study was 4.3 June 975–78 (table 9.3). The growing season at Caribou House commences about 20 June (fig. .5) and the later (mean peak) calving dates in the 980s (commonly 2–3 June 984–89, table 9.3) would mean less nutritious forage for the females in the last week prior to parturition, a critical week in determining the birth size of neonates (fig. 8.2). The Leaf River also moved to calving locations farther north, from an area where the growing season arrived about 5 June to one where it arrived about 30 June. If the calving there also peaked in the first week of June, as it had for the George prior to the 980s, their newborn calves could have been smaller than the George calves (fig. 8.4). Females Shifted to Reduce Predation Risk The northward movement of the females on the two calving grounds located in 973/975 (Leaf and Lac Champdore) occurred 976–79 when wolves were increasing (fig. .) and calf recruitment for the George River herd was decreasing (Bergerud 996). On most calving grounds in North America males are rare. However, there was a significant number of males at the Leaf River ground at tree line in 974 ( male/9 females) and at Lac Champdore in 979 ( male/4.5 females). In later years when these calving grounds had moved farther north to the tundra, some males were still present (Crête et al. 99; fig. 5.7). The females, not the males, shifted to more open and later-phenology habitats. Additionally, the density of females on these grounds before they shifted north was low: 0.6/km² at Leaf River in 975; 2.8 females/km² at Lac Champdore in 974; 0.9/km² in 979. These are low densities for migratory herds at calving (Fleck and Gunn 982; Whitten et al. 992; Fancy et al. 994) but they are consistent with what is expected of dispersed ungulates in forested habitats (Geist and Walthers 974). By 982 – the year just prior to the one when the animals moved from the taiga to the tundra for parturition – the density of the animals on the Leaf River calving ground had increased (fig. 5.7) and probably exceeded 5/km². The change in density is consistent with the generally-accepted hypothesis that aggregation reduces predation risk for open-dwelling ungulates. By 982 the herd had increased and become more conspicuous to wolves, but there may still have been reluctance to leave and move further north. Wolves are more common along tree line, and some females still calved in forested cover that lacked open vistas for detecting approaching predators. The evidence shows that two primary calving grounds in Ungava were deserted when wolf numbers were increasing. The females – not the bulls – then sacrificed the earlier phenology and more

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nutritious forage of the taiga for habitats of greater visibility that reduced predation risk. The Caribou House calving ground was centred on the height of land (Quebec/Labrador border) in the 970s (figs. 5.8, 5.9). This is a high, inhospitable area with a late growing season. But the grounds were equidistant from the George River – where wolves travelled – and the coast – where bears were common (fig. 5.8). Furthermore, bears may have increased during this study (a correlation/regression analysis of bears seen on-year, 975–89 broken, was significant, r = 0.579, n = 3, Y = -34.977 + 0.482X). The Caribou House calving ground, in the very centre of the Labrador tundra, was an area of reduced predation risk. In later years (with the possible exception of 993) the centre of annual calving distributions shifted, but nevertheless remained above tree line (fig. 5.8). The calving ground of the Bathurst herd in the Northwest Territories in the 950s – during a period of wolf removals (Kelsall 968) – was immediately adjacent to the southern end of Bathurst Inlet (Kelsall 968) in an area which, like that of the Leaf and George, had an early spring phenology. After the end of the NWT wolf-removal program in 96, the wolves would have repopulated to the Inlet where there was a variety of prey species, and by 966 the calving ground had shifted to the Kent Peninsula (Fleck and Gunn 982). In later years (990s) the herd again shifted its calving location to areas west and south of Bathurst Inlet. These latter areas had the fewest denning wolves north of the tree line in the herd’s range (Heard and Williams 992), but they also had a later phenology than did Bathurst Inlet. Similarly, the Beverly herd in the NWT in the late 950s calved in the area of the earliest phenology in its summer range, immediately north and south of the Thelon River (Kelsall 968). Following the removal program, this area was repopulated with the highest density of denning wolves in the NWT (Kuyt 972; Fleck and Gunn 982; Heard and Williams 992). Here, also, the calving ground of the herd pulled away from the vicinity of wolf concentration. In the years that the wolves declined (from control) 957–6 (Bergerud 996), the mean distance of the centre of the calving ground from Beverly Lake was 68 km ± 3 km, but with the end of control, and for the period 965–80 (6 years shown, Fleck and Gunn 982), the distance to the centre of the calving concentration from Beverly Lake and the Thelon River was 28 km ± 2 km (n = 6). Migratory caribou can shift their calving-ground locations. Valkenburg and Davis (986) were the first to challenge an earlier premise that calving females invariably showed fidelity to their calving grounds. They documented several major shifts of the 40-Mile herd calving ground over an interval of 85 years, in a herd that has been plagued with heavy wolf and bear predation (Valkenburg et al. 994; Boertje et al. 996). We believe that some of these shifts of the large migratory herds in North America are proximate behavioural responses to reduce contact with wolf populations.

0

5

0

10 KILOMETRES 5

10 MILES

+ CALVES

FO

RD

H

NON-PAROUS

ORD N FI RO B E

PRIMOGENITOR WILDLIFE STATION

R I VER

GE

LARGER AGGREGATIONS + CALVES

IVE E R OR G

YEARLINGS

YEARLINGS

R

NON-PAROUS

MALES & YEARLINGS

FALCOZ HEIGHT OF LAND INDIAN HOUSE LAKE

Fig. 15.9 The Caribou House herd calving ground in 1977 on the height of land, prior to the expansions of the calving ground in latter years. Note that some yearling males are located with the males along the George River where birch supplies were still plentiful in 1977. Also shown is the location of the wildlife station at Hebron Fiord build by Stuart Luttich in order to be near the calving ground. Caribou returned to this calving area in most years.

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Snow Cover on Calving Grounds Caribou commonly calve adjacent to snow cover contours of < 75% cover (Fleck and Gunn 982, Eastland 99), yet young calves are not cryptic when on snow. Young caribou calves, in contrast to their lighter-coloured dams, are born a chocolate or reddish brown and are exceedingly cryptic only when reclining on brown substrates (see photographs of cryptic calves, Bergerud and Elliott 986). Caribou biologists only attempt calf/cow classifications when the calves are more visible, when groups are travelling. Jenkins and Barten (2005) quantified snow/ bare ground percentages and the predation of calves. The best crypsis occurred where the ratio of melted snow and bare ground was 62%:48%. An interesting analogy in convergent evolution is the dark colour of the newborn of Tibetan antelope, the chiru, in contrast to the lighter colour of its dam. In colour, a newborn chiru is a dead ringer for a neonate caribou calf (see photograph in National Geographic: April 2003, 20). Both species migrate to bleak calving grounds in the vicinity of snow cover to reduce predation risk. The lighter-coloured dams are conspicuous, an aid in aggregating and socialization, while their progeny are inconspicuous, blending in with their background. Another possible advantage of calving in patchy snow cover is that wolves may avoid them. Kelsall (968) was of the opinion that wolves would go miles out of the way to avoid wet/snowy areas. Young caribou calves are basically followers (Lent 964); but in the first two days of life they are hiders, resting on brown substrates (Skogland 989a). We have seen young calves that have been chased and lost contact with their dams adopt the prone-head, low posture when they fell on a brown surface. Bergerud observed a chase in which a bear, still in pursuit of the adult female, ran right past the fallen calf. In the NWT Miller et al. (985) showed that wolves were responsible for 65% of the mortality of calves in their first week of life; calves under 2 days old were killed less often than calves 2 to 7 days old (table 5.2). Adams in Alaska found that wolves killed calves at rates of approximately 2% to 4% per day age 3 to 3, but he reported none killed by wolves at  to 2 days old, although grizzly bears were more successful killing 2-day-old calves (Mech et al. 998). However, the bears’ technique is different: They search for noisy, conspicuous cow herds, then charge the herd, securing calves that are left behind or fail to keep up in the stampede. The excessive weakness of -day-old calves is likely compensated by the dispersion of cows at parturition when the cows feed on brown substrates and their nearby neonates can remain relatively inconspicuous. Cows in labour commonly get left behind when the group they were travelling with moves on. They remain apart while the calf gains strength and the two-way bond with its mother is strengthened as well.

Spacing Theory of Calving and Migration | 45

Table 15.2 The mortality rates of young calves on the Beverly calving ground, 1981–84 (from Miller et al. 1985) Age of Calves

0–1 day 2–3 days 4–7 days Total

% Killed by Wolves

% Died Other Causes

15 (26) 57 (96) 27 (46) 65 (168)

56 (51) 33 (30) 10 (9) 35 (90)

Hunting wolves should focus on noisy nursery herds with active calves rather on dispersed cows that may or may not have a newborn calf nearby. Wolves that attack cow-calf groups can frequently kill several calves in the same encounter, even though the calves may be more than one day old. Surplus killing of calves by wolves is common on the calving grounds of migratory herds (Miller et al. 985). Cows migrating to calving grounds frequently halt their movement before reaching the calving ground when they encounter continuous snow cover. We do not believe they halt because of the hindrance of snow cover or the necessity of digging feeding craters, a winter-long activity. In 968 Bergerud observed calving caribou in the Kaminuriak herd continuing to migrate in mid-June when the lakes were covered with slush and early calves were mired down and being attacked by Jaegers (Stercorarius spp.). Cows probably halt when they encounter continuous snow on spring migration because it is likely that the calving ground at higher latitude also has continuous snow cover where their brown calves would not be cryptic. Caribou in the mountains commonly cross continuous snow belts in mountain passes when moving to the alpine in the Krumholz belt where they reach brown substrates. The only caribou that we know that calve consistently on 00% snow cover are some mountain caribou at the southern edge of the North American range. These animals calve widely-scattered and under forest canopies (Simpson and Woods 987), where they can use the forest cover to reduce the risk of discovery from golden eagles and mammalian predators. Calving Grounds at Maximum Distances from Tree Line The spring migration routes of cows to the calving grounds in the NWT are mostly perpendicular to the tree line (Banfield 954; Kelsall 968; Fleck and Gunn 982), and the calving grounds are generally as far from the tree line as the cows can get while still having some bare ground for calving (fig. 5.). Caribou in the NWT halted at 70–90% snow contours (Fleck and Gunn 982); the Porcupine herd migrated up to the 75% contour (Eastland 99). If one moves perpendicular to tree line, the caribou intersect snow contours at right angles, leaving the tree

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line behind with the fewest kilometres of travel distance. Spring migration routes plot as arrows pointing at the calving ground (see Fleck and Gunn 982; Kelsall 968). Other calving grounds are as far as females can travel before reaching the Arctic Ocean (Bluenose, and formerly the Bathurst herd) or 75% snow (Beverly and Kaminuriak herds). By calving at the maximum distance from tree line that physical barriers permit, caribou enhance survival of their progeny. We located only two wolf dens on the Labrador tundra (fig. 5.8), both removed from the calving grounds. In Alaska the Porcupine calving ground is displaced from the major distribution of bears, wolves, and eagles. The southern boundary for calving is basically fixed at the interface of the foothills and the coastal plain (fig. 5.5). Again, the Bathurst herd in the NWT has consistently calved to the east and west of Bathurst Inlet: Plant phytomass, phenology, and weather are more favourable in the Inlet (but see Heard et al. 996), but there are more wolves denning there as well. The adjacent Beverly herd has also shown fidelity to limited calving areas – one south of the Thelon River and one north. Along the river, phenology is advanced and there is an outlier of trees, but the eskers along the river are home to a cluster of wolf dens (Kuyt 972; Heard and Williams 992). These herds have shown strong fidelity to those calving ranges some distance away from wolves (Heard et al. 996), and these calving grounds did not increase in size as herd numbers expanded in the 980s (Fleck and Gunn 982). The critical evidence in deciding if predation risk explains the spring migration of females of caribou and other polygynous species is to document that the females have selected areas with fewer predators regardless of forage supplies, whereas the males who are not burdened with the care of vulnerable neonates have opted for habitats with superior forage, even if this entails predation risk. This is exactly what happens in these migratory herds of caribou. Density Dependence of Calving Ground Location In 973 and 977 the centre of Caribou House was at the height of land 80 km north and east of the tree line at the southern end of Indian House Lake (figs. 5.8, 5.9), a maximum displacement from predators. As the herd increased in size after 974, the calving grounds also grew in area and the annual distribution of centres shifted to the southwest (figs. 5.8). By 992 the centre of the calving ground was only 50 km northeast of Indian House Lake and in 993 and 995 the caribou were calving equal distances both to the east and west of the George River. We attribute these changes in the annual distributions to overgrazing, not to social interactions per se. The increase in the size of the calving ground (fig. 5.0) was correlated with the percentage of antlerless females in the herd (fig. 9.3), which relates to nutritional problems and the increasing size of the herd (fig.

Spacing Theory of Calving and Migration | 453

DISTANCE FROM THE CENTRE OF THE CALVING GROUND TO THE GEORGE RIVER (km)

150

Y = 426.714  4.420X r = 0.849 n = 21

100

50

0 73

75

77

79

81

83

85

87

89

91

93

83

85

87

89

91

93

SIZE OF THE CALVING GROUND (1,000 km²)

40

30

Y=

20 ±

80 1 + 173461.5e 0.124X r2 = 0.842 n = 20

NOT ALL BOUNDARIES DEFINED

10

0 73

75

77

79

81

CALVING SEASONS Fig. 15.10 As the calving ground increased in size, it shifted nearer to the tree line and the George River.

0.4), and was also correlated with the decline in the annual growth increments of birch – the most important forage species (fig. 9.3). The shift of the grounds to the southwest and a north-south elongation which brought the grounds closer and parallel to the George River (fig. 5.8) resulted because animals had moved from the mostly heavily overgrazed habitats along the height of land, where trampling had greatly denuded the vegetation, to lower elevations that had not been as heavily trampled previously (fig. 5.). Each year the expansion of the calving ground incorporated habitats not previously used for calving (table 5.3). An average of 32% ± 6.0% of the calving grounds 974–90 included new habitats, a total of 56,000 km², or greater than the entire tundra area. By the 990s nearly

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PERCENTAGE OF GROUND IN RANGE STATION IN GRID THAT WAS TURF IN 1988

40

GRIDS CARIBOU SHIFTED AWAY FROM GRIDS ADJACENT TO GEORGE RIVER

H SOUT TING SHIF ND WEST A

30

20

Y=

10

150 1 + 84.150X 0.778 r = 0.627 n = 19

0 0

10

20

30

40

MEAN PERCENTAGE OF THE LAT./LONG. GRID OCCUPIED AT CALVING IN 20 YEARS

Fig. 15.11 A component of the shifting of the calving ground nearer to the George River was that animals vacated the most overgrazed habitats along the height of land and moved downslope.

all the tundra on the Labrador Peninsula south of the Torngat Mountains had been utilized one or more years for calving (fig. 5.8). Cows were prepared to calve in habitats with reduced visibility and shorter lead times for escape in order to avoid their trampled summer range (the forage/prediction trade-off, fig. 4.). The only other caribou herd similar in size to the George River herd in the 980s was the Taimyr herd in Russia (Bergerud 988b) and it also shifted closer to tree line as it increased. From 966–72, that herd averaged 32,000 animals and calved in two areas of about 50,000 km² located 350 km ± 50 km north of the tree line. From 980–93 the herd averaged 562,000 ± 4,000 animals (0 censuses), and there were four calving grounds totalling 62,000 km² with a reduced distance from tree line of only 75 km ± 32 km (data from Pavlov et al. 996). Both the Taimyr (2.6 wolves/,000 km²) and the George River have had low numbers of wolves on their tundra landscapes in recent decades (Klein and Kuzyakin

Spacing Theory of Calving and Migration | 455

Table 15.3 1973–90 Spring Year

The range expansion of the Caribou House calving ground from

Size of Ground (km²)

1

4,300 7,000 5,800 3,800 5,900 4,600 5,900 7,800 9,300 9,600 9,000 14,600 15,700 20,200 23,900 18,500 27,300

100¹ 47² 51 12 25 10 48 8 67 25 26 28 25 15 27 1 35

– 53 10 39 20 22 38 13 8 44 22 24 16 13 18 22 9

– – 3 14 25 19 8 35 7 8 34 13 11 14 14 16 8

– – – 35 13 18 4 14 9 8 7 21 12 15 11 17 4

– – – – 17 11 2 11 4 8 5 5 18 11 10 11 6

– – – – – 21³ – 11 3 4 3 3 5 15 6 12 6

– – – – – – – 7 2 2 2 2 6 5 9 5 8

– – – – – – – – 1 1 1 3 4 5 2 11 6

– – – – – – – – – tr tr 1 3 3 2 3 9

– – – – – – – – – – – 1 3 3 2 1+ 4+

Total Km² (1,000)

56

38

28

21

16

12

9

6

5

2

Mean %⁴

32

23

18

13

9

8

5

4

4

2

1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1984 1985 1986 1987 1988 1989 1990

% of Ground Repeatly Occupied in Subsequent Years 2 3 4 5 6 7 8 9

10

¹ Assume 00% grazed for first time 973; ² 47% (3,330 km²) grazed only 974 (year 2) 53% grazed in both 974 and 973; ³ 2% (966 km²) grazed all 6 years; ⁴ The regression of km² percent grazed on years ( to 0) (Y = -88.748X⁰.¹²⁹ + 20), r² = 0.989. (no data 983)

982). Probably wolf abundance on the calving grounds of these herds was similar to that recorded for the Bluenose herd in NWT,  wolf/00 flying hours (from Heard et al. 996). If wolf numbers had been higher, such as the 8–45 wolves seen per 00 flying hours recorded for the calving grounds of the Bathurst and Beverly herds in NWT (Heard et al. 996), possibly the females in the Taimyr and George would not have increased their predation risk by shifting closer to tree line for parturition. Cows in the Bathurst and Beverly herds consistently calved in the same locations in the 970s, even though densities in some years exceeded 5 animals/km² (Fleck and Gunn 982). The Beverly herd continued to calve north of the Thelon River in the 980s, when Thomas and Kiliaan (998) found it in good condition in the winter. However, the Bathurst herd shifted its calving ground west from the Kent Peninsula in the late 980s or early 990s to Bathurst Inlet (Heard personal communication; Heard et al. 996; Gunn et al. 2005), where the phytomass was greater and the phenology earlier, and where wolves were also more common

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than on the Kent Peninsula. Later the herd shifted a second time west of Bathurst Inlet. Thus there is ample evidence that migratory caribou shift their calving grounds between years (also Valkenburg and Davis 986) both farther from tree line – Leaf and George River; and also closer to tree line at high numbers – Taimyr, George River, Bathurst (probably in response to a reduction in forage). These options still relate to staying on the tundra, away from the higher densities of wolves in the taiga and its reduced visibility. As the George shifted closer to tree line in the 980–990s, calf recruitment declined as the summer mortality-rate index increased. The mortality-rate index took into account changes in pregnancy rates, which were the major component in the size of the fall calf percentages. The mortality index [(parous cows/00 cows) – (fall calves/00 females)] divided by (parous cows/00 cows) was only weakly correlated with the distance of the calving ground from tree line (r = -0.44, n = 2) and more strongly correlated with the size of the calving ground (r = 0.728, n = 20, 983 excluded). The mortality index increased as the birth weights of calves declined 978–92 in  seasons (r = -0.794). Furthermore, the size of the calving ground appeared to reflect the condition of females, since it increased as the percentages of bald females in the autumn increased and growth of birch declined. From this we conclude that the extension of the calving ground towards the taiga did not result in expanded predation, and the greater calf mortality that accompanied this expansion is better explained by a decline in the condition of the cows and calves as a result of overgrazing. Timing of Births Reproductive fitness theory predicts that caribou calves should be born when conditions are most favourable for survival. For ungulates in the northern hemisphere, the season of birth is the spring, and there is some evidence that differences in timing of births among discrete populations have a genetic component (see Skogland 989b). The calving chronology for different herds in North America spans a period, based on peak calving dates, from the second and third weeks in May until the second and third weeks in June (fig. 5.2). Skogland (989b, 50) said, “It therefore appears that the time and timing of births in Rangifer is best explained as an adaptation to the onset of the plant growth season.” The timing of parturition for herds in North America was highly correlated with the start and length of the growing season (fig. 5.2). The peak calving dates for the George River in the 970s were the first week of June, consistent with the growing season hypothesis. However, the later calving in the years after 984 – a mean of 3 June – was the most deviant calving date in North America based on the regression of birth dates on the length of the growing season (fig. 5.2). Still, within herds there is

MAY 3 = PEAK CALVING 3rd WEEK MAY 1J

UN

3M

E

3J

AY

UN E

2–

3J

1 JUNE

2J

UN

E

UN E

1 JUNE

175

25

3M

AY

4 MAY

160

Y=

129.680X X  12.547 r2 = 0.991 n = 23

15

GEORGE RIVER 1980s Y = 172.456  0.210X r2 = 0.717

10

n = 23 155

5

GEORGE RIVER 1970s

150

30

145

25

140

20

MIGRATORY SEDENTARY

MAY

PEAK CALVING DATES (JULIAN)

165

20

JUNE

170

50

60

70

80

90

100 110 120 130 140 150 160

LENGTH OF GROWING SEASON Fig. 15.12 The dates of peak calving for caribou populations in North America are correlated with the length of the growing season as well as the start of plant growth. Note that the later calving of the George River herd with high populations in the 1980s resulted in it having the most deviant calving period of the populations tabulated. The calving dates are based on a wide search of the caribou literature but also Bergerud has conducted calving studies in all the regions except the Arctic Islands.

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generally a variation in dates between years of 6 to 0 days (Lent 964; Bergerud 975; Skogland 989b; Adams and Dale 998b). Hence the shift in peak dates from 4 June to 3 June at Caribou House in the 980s is within observed departures elsewhere. The seasonal-nutritional hypothesis predicts that calving should occur in a sequence in which peak lactation demands coincide with the spring flush in the quality/quantity of green phytomass. Our best data for testing this synchronization was gathered in 989. Even with late calving in 989 (a mean date of 3 June), the birth sequence coincided with the green phenology. In 989 the peak in the nutritional quality of birch/willow occurred about 24 June (fig. 7.4), and the highest fecal nitrogen readings for females date from a few days later. Birch leaves reached full development in 989 about 8 June, and birch exceeded > 20% of the diet by 9 June (table 7.). Good foraging conditions continued until about 8 July, when mosquitoes became bothersome. In general the growth of tundra vegetation peaks about 40–50 days after the start of green-up (Wielgolaski and Karenlampi 975; Bliss 977; Tiezen 978). The maximum quality/quantity of forage for the George should then have occurred in the first and second weeks of July in 989. If calves make their maximum demands in lactation by the age of 2 to 3 weeks (Luick 977), then the maximum nursing demands of calves born on 3 June coincided with the abundance of green phytomass, although they were slightly later than peak quality. For calves born a week earlier in the 970s, maximum lactation demands would have coincided with the availability of the highest plant quality, but would possibly have been a little too soon for their dams to benefit from the greatest variety of new phytomass. Both the early and late calving dates that we observed over a 20-year interval fit the growing season hypothesis. However, the agreement of calving dates with nutritional flush does not guarantee the nutritional well-being of the lactating females if the dry matter intake is inadequate – as it was in 988 and 989 (fig. 7.7; Camps and Linders 989). The calving dates for three herds in Alaska that gave birth at dates similar to the George River in the 970s (the Western Arctic, Central Arctic, and Porcupine herds) are consistent with the nutritional hypothesis: Peaks in nutritive value of forage and phytomass in greens occur in the last week of June and first week of July when the calves are 2–3 weeks of age (Lent 966; Tiezen 978; Kuropat and Bryant 980; Cameron et al. 993; Russell et al. 993). The George River herd and these three Alaskan herds each have their peaks within a few days of the start of the growing season. But the herds that inhabit the Alaskan Range in central Alaska (the Mulchatna, Denali, Delta, Nelchina, and 40-Mile herds), as well as the montane herds in northern British Columbia and the Yukon and the sedentary herds in the boreal forest, all have their peak calving dates nearly 2 weeks after the start of the growing season (fig. 5.2). Some of the migratory herds in Alaska and the Northwest Territories even complete calving before the growing season commences (fig. 5.2; Fleck and Gunn

Spacing Theory of Calving and Migration | 459

982; Gunn 989; Heard 989). The Western Arctic herd in northwestern Alaska starts calving about 28 May but the growing season doesn’t start until approximately 5 June (Skogland 989), whereas the Svalbard caribou start calving at the beginning of June and new plant growth appears about 8 days later. And on the Arctic Islands, the short growing season means that Peary caribou must start calving by mid-June; they must wait until the beginning of July for new plant growth (Skogland 989b). The herds in North America that calve after the start of the growing season (a mean delay of 3 ± .6 days (n = 3) could calve at least 30 days earlier without experiencing perinatal mortality if the females were in normal condition. These are the herds that give birth to calves > 7 kg, while those herds that calve prior to the start of plant growth have progeny that have birth weights of < 6 kg (see table 8.3). The level of predation differs vastly between the herds that calve before the season starts and those that wait for the new growth. The neonates of the Alaska Range herds, as well as the montane populations, face extreme predation by both bears and wolves. For these herds mortality rates of calves by 30 days of age generally exceed 60% (Bergerud and Page 987; Seip 992; Adams et al. 995a, b; Bergerud and Elliott 998), of which two thirds is caused by predators. These herds wait to calve until brown substrates are available at higher elevations for their calves to blend with the background so they can disperse away from the lowland travel routes of predators (Bergerud and Page 987). By calving late, these females – prior to dispersing – can remain in lowland habitats foraging for as long as 2 weeks on high-quality emerging greens. Then, shortly prior to parturition, they shift to more inhospitable habitats for birth. The females of several of these populations are at lower elevations in May than in any other season of the year. This nutritional boost should result in larger calves that are less vulnerable to predators. Those herds that calve after the growing season commences – the sedentary herds – reside where the growing season is ≥ 0 days. Such a long season, even if not fully utilized for post-birth growth, is long enough to provide calves with sufficient size to cope with winter severity; it is also long enough that cows can usually regain condition for fall estrus. The Arctic herds that generally lose < 5% of their young in the first 30 days of life can afford to produce smaller calves by pushing calving forward in June prior to green-up. Given the shorter season, this maximizes the period of growth for their progeny and thus lessens the possibility that calves will have insufficient stature to cope with the harsh Arctic winters, especially on the Arctic Islands (Thomas 982) and in Svalbard (Tyler 987). The George River herd had few predators on the summer range during this study and plentiful forage in the winter, conditions in which we would expect calving dates to be most in tune with the growing season, which in turn should result in maximizing condition in the fall for breeding. The synchronization of

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calving with the appearance of greens does carry a risk, however: If the spring season is greatly delayed (as it was in 992), calves of undernourished cows may experience high perinatal mortality rates (as we recorded that spring). We have postulated in chapter 6 that the trigger for the major decline of the George River herd about 880 was caused by a series of extremely cold springs, colder than any in the 20th century (fig. 6.). Synchrony of Births The majority of caribou calves in North America are born within a period of 2 weeks (Lent 964; Bergerud 975). The George River cows in the 970s calved between 30 May and 2 June in about 3 days, and in the 980s over an interval of 3 weeks from 4 June to 25 June (figs. 9.4, 9.5; table 9.3). Caribou calve over a shorter interval than other ungulates in North America with the exception of antelope (Antilocapra americana), and over a shorter interval than tropical ungulates as well (review Rutberg 984, 987). Two hypotheses are commonly invoked to explain birth synchrony in ungulates. The first is seasonality: Births are timed to minimize environmental problems or energy expenditure for dams and offspring (Leuthold 977; Bunnell 982; Sadlier 987). The second hypothesis is predation: Births are synchronized to reduce predation on vulnerable newborns. In this case there has been normalizing selection against late- and early-born progeny (Estes 966, 976; Kruuk 972; Bergerud 974b). Bergerud argued that early- and late-born calves delivered on open tundra landscapes could be conspicuous to predators and that by calving in synchrony, caribou can form large nursery herds that increase vigilance and result in saturation and confusion on the part of predators. The concept of the “selfish herd” (Hamilton 97) would apply. In reference to the latter hypothesis, Wilson (975, 42) remarked that “the idea that synchronized births in these [caribou] and other mammals represents an adaptation specifically evolved to thwart predation is an attractive hypothesis, but it has not yet been subjected to adequate testing.” Skogland (989) rejected the hypothesis because the caribou in Svalbard that have evolved without predators showed extreme synchrony in births. All the calf births occur within 0 days, a period confirmed by Tyler (987). Skogland (989b, 56) concluded that “the most proximate factor in timing as well as synchrony of births of wild reindeer appears to be plant phenology.” The shorter the growing season the greater the synchrony. Post et al. (2003) found a close correlation in Alaska where predators were present, but also in Greenland, where – similar to Svalbard – wolves had been absent for 4,000 years according to Meldgaard (986). It’s the old chicken and egg story. Which came first? As yet, no one has documented breeding synchrony for a tropical ungulate living within the following conditions: the pres-

Spacing Theory of Calving and Migration | 46

ence of predators in an open landscape; and a climate that is more uniform and without phenology pulses. However, in North America there was no correlation between the length of the calving interval and the length of the growing season for 4 populations where calving dates have been documented (r = 0.023). The mean length of calving for these 4 herds was 7. ± .8 days. Caribou in Newfoundland at 50° N calve in approximately 7+ days in a region with a 60-day growing season, as do caribou in the Beverly herd, NWT, at 65° N with a 70-day season, and animals on Victoria Island, at 70° N with only 50 days of plant growth (Kelsall 957; Bergerud 975; Gunn 989). Also, 3 of the 6 herds in Norway discussed by Skogland (989) had calving intervals restricted to approximately 7 days. All of the North American herds coexisting with predators, as well as the 3 herds in Norway that nearly lack predators, had the common benefit of adequate winter pastures. The three herds in Norway/Svalbard with more restricted calving intervals (< 9 days) had inadequate winter forage. Furthermore, these three herds (Snøhetta, Hardangervidda, and Reindalen) all had major die-offs of calves in the winter; the Snøhetta and Hardangervidda also experienced major perinatal mortality (Skogland 985; Tyler 987). Such differential mortality of malnourished neonates – the loss of small-bodied, late-born young – could result in differential selection for a narrower window of birth dates, consistent with the seasonality/growth hypothesis. The hypothesis that synchrony is predator-related rests on the idea that earlyand late-born calves are conspicuous and that calves born in large herds in the peak interval would benefit from the effects of saturation and confusion on the part of predators (Bergerud 974b). The mean age of death for wolf predation in the Denali herd, Alaska, was .7 ± 0.25 days (n = 4); the peak age at death was 7.2 ± 0.25 days (n = 35) from the start of calving and 8. ± 0.85 days (n = 35) from the peak calving date (Adams et al. 995a, b). Adams et al. (995b) further showed that calves born during the peak calving interval (5–8 days from the start of calving) had superior survival to calves born early (< 5 days from commencement) and late (> 8 days after commencement). The survival of peak calves was 80% ± 0.075% until 5 days of age; for early calves it was 49% ± 0.25%Sx; and for late born, 60% ± 0.075%Sx. They felt that early calves may have had insufficient numbers to swamp predators and were the first to aggregate in nursery herds, attracting wolves. The higher predation mortality of early- and late-born calves has also been documented for the Porcupine herd, and the Mentasta Alaskan herds (Baten et al. 200; Griffith et al. 2002). Early-born calves are the first to aggregate in nursery herds where the majority of wolf kills occur. Wolf predation of young calves often results in surplus killing, with several calves killed in the same encounter (table .7; Miller et al. 985; Mech et al. 998). For this to have happened, calves must have been in nursery groups. According to Adams et al. (995a, 59), “late calves experienced poor survival because predators were

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attracted to areas where caribou were calving, and vulnerable newborn calves were rapidly detected and killed.” Therefore peak-born calves accrued the most benefit from synchronous calving. In his extensive review of birth synchrony in ruminants, Rutberg (987) felt that predation was an important factor in the brief calving season of ruminants that calved in landscapes lacking cover and produced precocial young that showed the “following response.” He concluded that synchrony probably did not evolve from predation. Instead, Rutberg believed that “predation on newborns would tighten birth synchrony in populations already displaying seasonal birth peaks, presumably in response to seasonal changes in food availability” (ibid. 705). This explanation would then explain synchrony in caribou calving in a very seasonal environment, in the absence of predators (Norway, Greenland, and Svalbard). It would also explain synchrony for those herds where there is documentation that wolves and bears have been more successful capturing early- and late-born calves. Thus synchronized calving probably evolved because of the North’s short growing season (Rutberg 987; Post et al. 2003). However, when coupled with the open tundra environment, synchronous calving encourages gregarious behaviour (Bergerud 974b) that is generally an effective strategy in reducing predation losses – even though such aggregating at times results in surplus killing. Homing and Navigation The female caribou in the George River herd returned home to the Labrador tundra each spring to calve east of the George River where predation risk was reduced (fig. 5.8). The satellite monitoring documented that the return trip of some females exceeded ,00 km. This may be the longest migration recorded for an ungulate in North America. In some years (988, 990) females returned from local winter areas on routes through habitats they had not frequented previously. The return trip in 993 was from an area where they had not wintered since 974. The next year some females returned from north of Lake Melville from a region where there had been no migratory caribou in recent times (fig. 2.2). There is an extensive empirical as well as experimental literature on the means used across the animal phyla (bees, ants, fish, amphibians, reptiles, and birds) to navigate and return to home ranges. Less appears known about the navigational skills of mammals, especially those not amenable to laboratory experiments (reviews Waterman 989; Bovet 992; Papi 992; Dingle 996). We tested the hypothesis that caribou practice true navigation based on the homing behaviour of 8 VHF -collared females 986–92. “True navigation occurs when an animal has to rely on local cues to calculate the goal direction, which is selected by means of a compass, no matter whether it is over a familiar area or not” (Papi 992, 3). Animals that practice true navigation completing long and complex migrations

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returning to specific areas require a biological clock, a sense of distance (a map), and a compass (reviews Waterman 989; Papi 992; Bovet 992; Dingle 996). Bovet provided a map (992, 326) showing the “true migration” of a radiocollared female caribou of the Western Arctic herd leaving her winter range 5 May and travelling on a relatively straight azimuth north to her calving area approximately 375 km to calve on 5 June (original radio tracking from Craighead and Craighead 987). Bovet generalized (ibid., 349) that “mammals can use the sun as a compass … , that they can use a world-wide compass, independent of local cues, and that their capability to determine use and keep real azimuths is more than a mystical possibility.” To investigate the navigational skills of caribou we quantified the approximate date that satellite-monitored females left their local winter ranges and commenced long directional movements towards the Labrador tundra and Caribou House. We tabulated the days of travel enroute going east until they reached the George River, and we measured both the straight line distance (shortest) between the local winter range and the River, as well as the length of the route followed, ignoring minor deflections. Also tabulated was the time and route length until 3 May, approximately 2 days prior to peak calving. Commonly cows were captured and recaptured for collaring in June, complicating continuous tracking until parturition. We also quantified the distance and date of the last major change in direction enroute to the “goals” of the River and the locations reached by 3 May. Cows homing to the Labrador tundra approached the calving ground from the south, southwest, west, and northwest in various years (fig. 5.8). Several females travelled towards the tundra without major changes in directions for over 200 km, especially those whose return route was southeast passing by Kuujjuaq and Ungava Bay (see 986–87; 990–9; and 99–92; figs. 2.5, 2.6). Clearly animals were homing to the tundra east of the George River. The mean date the females started their return trip was 8 April (Julian date 98 ± 5.7) n = 8 female. There was a 69-day spread in the initiation dates from the local ranges from 8 February to 6 May. Most of the 8 females started migrating at a time when snow cover was still deep, prior to sun crusts or bare ground resultant from snow melt. The date of the mean maximum snow depth in the 6 years of radio tracking of returning females occurred 29 March (Julian 88 ± 0.82, n = 6) (see fig. 3.3) and averaged 03 cm ± 0.69 cm at Schefferville. Hence returning movements commenced coincident with maximum snow cover. Animals were not released by a change in snow gradients (Pruitt 959) or by the appearance of brown substrates or vegetation. The females that were farthest from the calving ground generally began their homeward trek before females that had wintered nearer to the calving ground. The correlation between the date of commencement and the straight-line dis-

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Fig. 15.13 The 18 satellite females we monitored from 1987 to 1992 that homed to the Labrador tundra generally started their return journey earlier if they were a long distance from Labrador. These females also varied their rate of speed in response to their distance from the Labrador tundra, indicating that they had a map and a clock.

tance to the George River was r = -0.742 P < 0.0, n = 8 (fig. 5.3). For those females that skirted the snowy central taiga entirely by following the tree line past Kuujjuaq, the correlation between the date of migration and the length of these longer routes was also highly correlated, r = -0.72, n = 8. The daily rates of travel were also correlated with the distances the animals had to travel to reach the Labrador tundra (fig. 5.3).

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Fig. 15.14 A number of the returning satellite females to the Labrador tundra corrected their azimuths to Caribou House as they neared or entered the centre of habitation, suggesting they were using landmarks in the area familiar to them.

These data support the hypothesis that caribou are “true navigators” and have a sense of time (biological clock) and an understanding of distance (a map). The fact that the animals sometimes reached the calving grounds, without backtracking, from areas not previously visited and from a circle radius of 80° (fig. 5.8) suggests the use of a compass. Several animals returning from the southeast, west, and northwest made rather abrupt azimuth changes as they approached the Labrador tundra (fig. 5.4). These corrections all occurred as they entered or moved through the range that was occupied continuously since we commenced monitoring, the area they had travelled previously (fig. 2.). In those years that the females wintered in the east, their focus narrowed as they approached Indian House Lake (fig. 5.5), which suggests landmark navigation. We equate the centre of habitation with the home range of the herd, an area with landmark familiarity. Possibly these

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Fig. 15.15 Orientation of females to the calving grounds. In latter years when the animals remained further east in the winter their spring movements in mid-May appeared oriented to the headwaters of the George River and Indian House Lake, which is in the centre of the centre of habitation (fig. 12.1). Data provided by Renewable Resources under contract with the Department of National Defense.

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course changes resulted from pilotage. Pilotage occurs when animals are familiar with an array of landmarks and can reach a known site (area) without the use of a compass (Papi 992). Students of navigation theory agree that animals commonly use a variety of methods in reaching homing sites. We consider the calving ground the hub of the annual movement cycle, the focus of their “Loop of Life.” Experimental Evidence of True Navigation The movement of caribou transplanted from Newfoundland to Maine in 963 was an experiment relative to navigation and the results were consistent with the hypothesis that caribou have a geographical grid and means to set courses. On 24 November 963, 24 adults (7 males and 7 females) were released (most by helicopter) on the alpine on the top of Mt. Katahdin, Maine, where native animals had last been seen in 908 and 94 (Cringan 956). These animals had been captured swimming Lake Victoria in Newfoundland during fall migration and were transported in closed semi-trailer trucks to the base of the mountain. Mt. Katahdin is the highest peak in Maine (,606 m) and is located in the centre of a wilderness state park from which caribou were free to egress in all directions. The animals remained on or near the peak throughout the winter. The herd was segregated by altitude from white-tailed deer (Odocoileus virginianus) infected with Pneumostrongylus tenuis as well as from the intermediate gastropod hosts of the disease. This disease is fatal to caribou (Anderson, R.C. 972; Lankester and Fong 989; Bergerud and Mercer 989). In the spring the animals left the mountain and commenced to disperse. They could have calved on Mt. Katahdin, an alpine habitat similar to their calving ground in Newfoundland, where there was reduced predation risk from lynx and black bears, both natural predators in Newfoundland. Instead they left the mountain, possibly migrating, and contacted P.tenuis by ingesting the gastropod carriers of the disease in the lowlands adjacent to the mountain. The animals seen in the lowlands 964–66 moved most frequently to the northeast, several on azimuths that would have taken them back to the Newfoundland calving ground 960 km distant (fig. 5.6). Fourteen sightings were within 45° of the 57° N Newfoundland homing azimuth. Four sightings were in the direction that they would have taken in their spring migration if they had commenced migrating from their normal winter range in Newfoundland (Bergerud 97b, fig. 3). These movements from the Mountain (23 sightings) were a significant departure from a random scatter dispersal (chi-sq. P < 0.0). If the animals had only a compass and wished to home, they should have gone NNW. To follow the correct azimuth towards Newfoundland they needed both a map and a compass. The female farthest from the release site in 964 had travelled 00 km from Katahdin on the true homing azimuth 57° toward the Newfoundland calving

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Fig. 15.16 Experimental evidence of homing. Caribou from Newfoundland were released on the top of Mt. Katahdin in Maine in November, 1963. The animals remained on the top of the mountain on the tundra throughout the winter. In the spring they left the mountain and appeared to be embarked on spring migration, presumably to reach their calving ground. The spring/summer azimuths that many of animals followed were oriented in the direction that would lead them to their Newfoundland calving grounds, 960 km distant on Buchan’s Plateau (see Bergerud 1971b, fig. 3). The animal locations in Maine were provided by Francis Dunn.

site. The animals all died before any made the New Brunswick border, ending the experiment. In the past 20 years several hundred caribou in seven arctic migratory herds ranging between 0° W and 50° W have been equipped with satellite radios by the game biologists in Alaska and the Northwest Territories and tracked in spring migration from their winter ranges to their calving grounds (a compact disc of the UHF locations in Alaska and NWT provided by Douglas Heard). Nine distinct winter ranges were involved. From these detailed radio locations one can estimate the approximate dates that many of the animals in the samples

Spacing Theory of Calving and Migration | 469

commenced moving in a consistent direction north or on the azimuth towards their calving grounds and compare this with the distances they had to navigate to reach their respective calving grounds. The animals that had the greatest distance to navigate generally started their journey before those populations that had wintered closer to their calving locations. Travel rates varied from 5 to 5 km per day. Our analysis of this data, although subject to considerable interpretation, indicated a significant correlation between the days of travel and the distance they had to go (r = 0.698, n = 9). The regression of days on route and distance was Y = 22.493 + 0.089X. Nor did all the herds head directly towards their calving ground. That fact has been long recognized for the Porcupine herd, but another example was the Bathurst herd, which in some years migrated first mostly west, crossing the north end of Great Slave Lake, then turning directly northeast towards their calving ground near Bathurst Inlet. The evidence is at hand: Caribou have a map, a clock, and a compass to navigate the arctic prairies. They know where they are and where they need to go to reduce predation risk for their neonates. With the concept of a compass, map, and clock, we can explore an earlier question, which is, “What are the environmental clues that trigger fall movements south and spring movement north?” (Bergerud 974b). Dugmore (93) told us that the Newfoundland caribou started south after the first heavy snow on the tundra. The theory held, and when the first snows came to the Buchans Plateau, Nfld., we expected the animals to cross the Lake Victoria road going south and they did (Bergerud 974b, fig. 8). On the other hand, the environmental clues that were supposed to trigger spring migration did not do so: Neither the appearance of brown spring substrate (new forage access), hard-packed spring snow, nor snow fences (Pruitt 959) started the Newfoundland caribou north (Bergerud 974b, table 3). Even stranger, herds left a common winter range at different times if the distance to return to their calving areas varied (Bergerud 974b). Recently the Buchans Plateau herd in Newfoundland has overgrazed its summer tundra range and Mahoney and Schaefer (2002) report that animals start south sooner than previously and delay their spring return. These earlier fall departures are consistent with the view that the basic ingredient triggering southern movements is the availability of forage as affected by snow cover; however, to delay in the spring while still located in the south would suggest a complex understanding of the distribution of food resources up ahead as well as a sense of time. Birth Site Fidelity After 980 all the females in the George calved on the Labrador tundra. However the centres of the annual locations of the calving grounds were constantly shifting (fig. 5.8). Additionally, the perimeters of the distributions were altered

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annually; a mean of 32% of the annual distributions (974–90, table 5.3) represented new habitats each season where the mass calving had not occurred since our monitoring had begun. The females were not showing persistent philopatry to previous calving sites as has been documented for some females in sedentary boreal and montane herds in North America (Hatler 986; Brown et al. 986). Females did not home to the precise locations used in previous years, but they still might have shown a geographical preference in June that was more than random. To test for coarse-grained, geographical orienting, we compared the distance between consecutive calving sites of individual radio-collared females (the homing distance) with the distances of these same females from other females on the calving ground on the same date (random measurement). More precisely, the homing distance for FemaleA was the distance from her location at the peak of calving in Year¹ to that in Year²; the random distance was her location at peak calving in Year² to that of FemaleB, FemaleC, FemaleD, etc., in Year². The precise locations of all these radio-collared females on the calving grounds had large errors, the exact date of calving was not known, radio locations without visual truthing can be inaccurate, and the animals move extensively in a matter of hours. All these biases should be equally represented in our comparisons of homing and random indices. The mean distances between locations of calving females between consecutive years commonly varied from 60–50 km and grew larger as the calving area expanded (table 5.4), but the distances between the geographical centres between years did not increase correspondingly (fig. 5.7). The random distances were generally greater than the consecutive inter-year sightings of the same female but were not statistically different within years, nor were slope coefficients of homing and random distances (fig. 5.7) statistically different within years. These slope coefficients were similar to the slope increase in the size of the total calving ground expansions (fig. 5.7). The random index that included many more females (table 5.4) was probably biased higher by a few females each year that were clearly outliers. In 99 we had our first evidence of a female moving her calving location to the Leaf River herd (fig. 5.8) and this became a stampede. By July 200, 22 of 29 animals tagged on the Labrador summer range had emigrated to the Leaf River summer range (Couturier et al. 2004). In an attempt to obtain a better understanding of the association of calving fidelity with cow-calf bonding, Goudreault and Luttich (985) radio-collared 40 male and female yearlings and 0 of their dams 7–9 September 983 as they were swimming the Koksoak River moving west. Luttich located these radiocollared animals over the next 4 years to understand geographical affinities and the orientation of young females relative to their mothers’ locations on the calving ground (fig. 5.9).

Spacing Theory of Calving and Migration | 47

Table 15.4 A comparison of the distances between calving locations¹ of radiocollared females in Year 1 vs Year 2 and the random distance from these same females to other radio-collared caribou females in Year 2 Type of Radio Collars and Years Compared

VHF Radio Female

1984 to 1985² 1985 to 1986 1986 to 1987 UHF Radio Females 1986 to 1987 1987 to 1988 1988 to 1989 1989 to 1990 1990 to 1991 1991 to 1992 1992 to 1993 Means

Kilometres between Locations, between Consecutive Sightings, to Other Calving Females Year 1 vs 2 (Homing Index) Year 2 to 2 (Random)

62.0 ± 18.3 (11) 71.0 ± 11.9 (9) 60.0 ± 8.7 (21)

64.0 ± 3.5 (109) 73.0 ± 5.3 (90) 99.0 ± 7.9 (21)

68.0 ± 14.2 (4) 98.0 ± 34.6 (4) 111.0 ± 36.3 (3) 110.0 ± 2 7.3 (3) none 135.0 ± 27.7 (5) 129.0 ± 31.0 (8)

78.0 ± 9.4 (12) 115.0 ± 14.5 (20) 121.0 ± 12.1 (15) 134.0 ± 12.5 (18) 113.0 ± 15.0 (15) 160.0 ± 16.0 (24) 188.0 ± 19.3 (80)

93.8 ± 10.4 (9)

114.7 ± 12.4 (10)

¹ Primarily mid-June locations and may not be actual calving locations ² For the homing index: the distance between the location of radio Female (A) at calving in midJune 984 and her calving location in mid-June 985. For the random index: the mean distance in 985 of Female A to other radio Females, B, C, D, etc, in June 985. Is she closer in 985 to her last year’s site (984) than to the locations of other radio females that returned in 985?

There was some suggestion of geographical affinities within the annual calving distributions of the animals tagged in September 983. The returning tagged females, as well as their progeny, used only the southern half of the calving ground in 984 (fig. 5.9). Again, in 985 and 986 they were back in the same general area northeast of Indian House Lake (fig. 5.9). Four of the original dams tagged September 983 were near each other in June 987, whereas their female progeny – now 4 years old – were more scattered (fig. 5.9). Another cohort of females tagged in June 986 generally maintained their southern, central, or northern locations in June 987 (fig. 5.20). The northern animals were still north in 988, possibly now considered Torngat animals. On the other hand, some of the other females of the 986 group had made major shifts north and south by 988 (fig. 5.20). There may be a geographical homing bias, but it is clearly not invariable. Another possibility is that the females are not orienting in a coarse-grained sense to calving localities but to familiar animals or to subgroups within the herd as Parker (972b) and Miller (974) suggested for the Kaminuriak and Beverly herds in the NWT. However, in Alaska, Valkenburg et al. (983) tagged animals together and later found them apart, as did Fong et al. (99) in Newfoundland.

±

SIZE OF THE CALVING GROUND (×1,000 km²)

30

±

25 20 15

±

SIZE OF THE CALVING GROUND 1979–93

10

Y = 128.188 + 1.70X r = 0.918

5

n = 14

0 DISTANCE BETWEEN JUNE LOCATIONS HOMING RANDOM

Y = 948.572 + 11.866X r = 0.881 n = 19

150 DISTANCE BETWEEN CALVING CENTRES 100

VHF

50

SHIFT NORTH

UHF

SHIFT SOUTH

KILOMETRES BETWEEN

200

0 78–79

80–81

82–83

84–85

86–87

88–89

90–91

92–93

YEARS Fig. 15.17 Philopatry of George River females to Caribou House. The homing (calving) locations of satellite females in Year¹ vs Year² with a random index. The random index measured the distance between her calving location in Year² compared to other radiocollared females in Year². Was a female closer to her last year’s location the next year or was she not nearer based on her location to other radio-collared females? There was no evidence that females homed to last year’s location at calving but they still may have selected locations from prior knowledge on the basis of a shift of the entire calving ground. The distances between return locations increased as the area of calving increased in response to habitat degradation. Also shown are the distances between annual consecutive calving centres shown in fig. 15.8, which showed no overall increase as the herd increased since new calving areas were incorporated into the overall calving region at a 33% rate. However note the great distance that the calving ground moved between 1992 and 1993. In the latter year there was little snow cover at calving and mosquitoes appeared early.

Spacing Theory of Calving and Migration | 473

1989–90

1990–91

SEPTEMBER

28/5/91

27/6/89

HAD CALVED

19/4

15/8

25/7 18/11

29/5/90

15/9 26/2

23/9

NEW AREA FOR HERD

15/12

14/8

2/8

21/11

NOVEMBER

1991–92

3/7/91

NEW COLLAR HAD CALVED

1/8

DECEMBER 8/10

6/6/90

9/8

WITH CALF

SEPTEMBER

1992–93

REVERSED DIRECTION LOCALIZED

23/7

8/8

17/7

TREE LINE 29/7 30/8

29/9 15/10

SEPTEMBER

30/5/92

21/7

DEAD

END OF MARCH 1993

SEPTEMBER

3/6/92

27/9

29/10

11/20 26/12

4/12

Fig. 15.18 One example of a female changing calving locations. In the first two years she calved at Caribou House, then moved to the Leaf River calving ground and calved there, then remained below tree line in the fourth spring (and may not have had a calf), and then in her fifth spring season returned to the George River tundra where she would likely have calved if she had not died. Also note the sharp turning angles she made in the months of September and December when many George River females change directions. We believe these course alterations result from the changing quality of forage as the growing season ends and the availability of ice and more snow cover in December changes forage/ predation-risk location options.

A further test was made when Vandal et al. (989) tagged 50 females, again swimming the Koksoak River, in the fall of 984 (26 September to 3 October). The location of these females 6–7 June 985 did not show that females tagged on the same day the previous autumn had remained in contact when calving. Seventeen females tagged 7 September had split with five on the north half of the calving ground (north of 57°30' N) and 0 in the southern half and two west of the calving distribution. Ten females released on 29 September 984 were distributed in June 985: three on the north half of the calving ground and seven on

1360

IN TORNGATS

6 98

1

1360

0120

1750

84

19

85 19

YEARLING NOS. REACHING CALVING GROUND BEFORE MOTHER

4 ORIGINAL 1983 MATERNAL FEMALES ALIVE IN 1987

1987 1350

1360 1350

1640

1380

1350 0120

1380

1350 1380

1380 1370

1984

CALF DIED 1650 1550 1330

1750

1985 6–11 JUNE MOTHERS 2 YEAR

1750 1570 1650

0120

1986 11 JUNE MOTHERS 3 YEAR

1570

AR L

IN G

1370

1987 11 JUNE MOTHERS 4 YEAR

HE

R

YE

1984

1730

0120 HER YEARLING

1985

1987

1350

CALF DIED

INDIAN HOUSE LAKE 1986

2–3 JUNE MOTHERS YEARLING YEARLING

MATERNAL HER

YEARLING

1690 MOTHER DIED YEARLINGS ON SOUTHERN PORTION 1984 0 0

0120

25

50 KILOMETRES 25

50 MILES

Fig. 15.19 Comparison of maternal calving locations with those of their female progeny. The distribution in June (1984 to 1987) of 10 adult females and their calves plus 30 other short yearlings all collared with 50 VHF radios in September 1983 and followed to Caribou House from 1984 to 1987. Note that the male and female yearlings in 1984 are on the southern edge of the calving ground and not segregated as they may have been in earlier years with different forage/risk options. The female yearlings show no clear orientation to their dam’s location either in 1984 or in any of the three subsequent years. Only the original 10 yearlings tagged with their mothers are shown with the radio numbers but the other yearlings originally tagged and returning as adults are shown to better understand how they distributed themselves in later years, especially relative to calving grounds extensions. Note that the four remaining adult females tagged together in September 1983 are in close proximity in 1987.

JUNE LOCATIONS 1986 1987 1988

CALVING GROUND BOUNDARIES 1986 1987 1988

1988

HE

B

IORD NF O R

1987

88 GEORGE

RI

VE R IND

87

HOUSE IAN LAKE

86

1986 0 0

25

50 KILOMETRES 25

50 MILES

Fig. 15.20 Fidelity of females to their prior calving location. The consecutive locations of 26 females radio-collared in June 1986 on the calving grounds and relocated in June 1987 and 1988. This data could suggest that females are familiar or desire to return to general areas within the calving distribution (especially 1986 vs 1987) but major shifts of the calving ground between years seem also involved in their locations. There is still many things to learn about these ships of the arctic prairies.

476 | TH E R E T U R N O F C A R I BO U TO U N G AVA

the south. The total return of 48 females that crossed the Koksoak within 8 days of each other was 3 south of 57°30' N, 24 to the north and  to the west of the ground. We have been unable to formulate a hypothesis to reconcile these apparent inconsistencies in philopatry. The analysis is consistent with the view that the animals have intimate knowledge of their habitat and their locations while still maintaining an open, gregarious society (Lent 964; Bergerud 974b). Homing of Yearlings A common belief is that yearling females learn the return routes to the calving ground by travelling with their dams on the fall and spring migrations. Handreared caribou calves captured in Newfoundland on their first day of life never developed migratory or homing behaviour when later released unaccompanied by adults (Bergerud 974b). An alternative hypothesis to the “learned-route” hypothesis is that the young calves – both females and males – first formulate their map in the first 2 months of life when travelling with their dams on the calving ground and surrounding tundra. Our radio tracking of calves collared in September 983, April 986, and September 987 (Vandal et al. 989) suggested that both male and female yearlings frequently returned to their home range on the Labrador tundra not in the company of their dams (see Skoog 968; Gates et al. 983). In some years they also returned unaccompanied by their dams on routes not followed the previous fall, when they left the tundra with their dams. Our best data on this point was secured on the basis of the 20 male and 20 female yearlings radio-collared in September 983 along with 0 of their dams on the Koksoak River (Vandal et al. 989). On 4 April 984, 6 of the 0 calves that had radio-collared dams were still with their dams returning east near the area where they had been captured going west the previous fall (3 calves and one mother had died). Presumably the pair bonds were still intact. By  May three weeks later and six weeks prior to calving, 8 of the 20 male yearlings tagged the previous fall, and 7 of the 20 female yearlings, had returned to the calving ground as had 3 of the tagged dams (fig. 5.9). These three dams were not with their calves. Three of the remaining 7 calves whose dams had been collared were still alive and present; one dam had died, another was not located, and the third was 30 km from its yearling. By 2–3 June, two more of the originally tagged dams had returned, as well as 3 more yearlings of the tagged mothers. The three yearlings whose dams were present on the calving ground were 9, 26, and 46 km from their mothers. Another tagged yearling was still with its dam near Kuujjuaq (200+ km west), and the remaining yearling was still migrating, but west of the George River and 25 km ahead of its mother on the route (fig. 5.9). These data suggest that the pair bond had rapidly weakened for many of the winter cow/calf pairs during the rapid spring movement that commenced near Kuujjuaq 220 km

Spacing Theory of Calving and Migration | 477

west of the George River. These returning yearlings may have simply returned by following the lead of other adults, but 0 of the yearling were at the front of the movement  May. Not only the female yearlings but also the males had homed. Again, in the 985 cohort, 7 females and 6 males tagged at Lac Nepihjee 8–23 April 986 west of Kuujjuaq had all homed to the calving ground by  June 987. In the literature male yearlings are thought to lag behind in migration and drop out in habitats south of the calving ground (Kelsall 968). In 5 years the sex ratio of yearlings at Caribou House was 40:60 (39.8% ± .39%) whereas in March–April when the yearlings were still with their dams west of tundra, the ratio was 46:54 (45.6% ± 2.2%, n = 0 years). Male short yearlings have a higher winter mortality rate than females (chapter ). Of the 20 male and 20 female yearlings tagged September 983, 5 males and only  female died prior to April. Unbalanced sex ratios favouring females on the George River herd’s calving ground do not necessarily mean that many males have not homed and are with the adult males. We argue that males can home as well as females, consistent with the view that the maps of home are formulated the first 2 months of life and have survival and fitness consequences for both sexes. Note that adult males in all the migratory herds in Canada join the females and yearlings in July on the tundra near the calving ground. These males return to the tundra to seek relief from mosquitoes on the windswept tundra and in the large post-calving aggregations that reduce harassment; also food quality peaks on the tundra in July. Both sexes need maps of their summer home range north of trees. We need to question many of the ideas in the caribou literature that assume fixed adaptive schedules and rigorous adherence to behaviour dictated by the environment. As an example, most caribou biologists believe that male yearlings drop out of spring migration before females, a sequence Bergerud observed for the Bathurst herd in 982 and Luttich observed for the George River herd in 977 (fig. 5.9). These yearlings in 977 did the expected, feeding with the males in the lush birch vegetation that was still present along the George River, removed from the females to the east at Caribou House. But by 984, the male and female yearlings were together with the females on the calving ground west of the George River (fig. 5.9). Fitness options change in response to changing forage, predation risk, and animal condition. In 977 the yearlings were large; forage was still plentiful; and the wolves had recently declined from a rabies outbreak. By 984 the calves were smaller; birch growth was declining (fig. 7.3); and some yearlings were still nursing their dams in June, unheard of before. If we have learned one thing, it is how adaptable this species is. The crazed running from warble flies is not the mad behaviour that earlier workers believed. Caribou are the true denizens of the tree line and do not wander the vast landscapes in rigid behaviour patterns. The two major themes of this chapter have been: the ability of caribou to retain a memory of their space and to navigate within it; and their need to reduce pre-

478 | TH E R E T U R N O F C A R I BO U TO U N G AVA

dation risk by migrating to a calving area on the tundra away from wolves denning near tree line. Such calving grounds are generally in remote, inhospitable areas with reduced flora and delayed phenology. Another theme is flexibility. A recent paper (Otto et al. 2006) documented that the George River females in recent years now move to their tundra calving ground 36 days later than they did 20 years ago, whereas the average date of departure post-calving from the tundra has remained the same, despite an overgrazed range. In contrast, with low foraging pressure in the 970s, the George animals remained near the calving ground on the tundra even into the fall for breeding (fig. 2.2). This recent pre-calving pause before arriving at the overgrazed range suggests a memory of the reduced forage ahead: The animals delay before tree line – to build their condition prior to parturition – but are not prepared to leave early after calving until the mosquito season is past. The first priority of the spring migration of pre-parturient females in North America is to reach the relative safety of the tundra for parturition and, secondarily, to maximize their condition – when possible – in the later stages of gestation and thereby enhance neonate birth weights and viability. Calving grounds are not selected for their forage characteristics. They are selected for their value as low-risk areas, and animals can be expected to delay their arrival until parturition is imminent if the forage on the low-risk calving grounds has been degraded previously.

CHAPTER SIXTEEN

Population Regulation

The interaction between natural mortality and population density constitutes the central element of any population model of ungulates (Caughley 977). A limiting factor may operate independently of density, but the impact of a regulating factor varies with density. The idea that population growth would be limited is credited to Malthus (803); that this can operate through factors that vary with density we credit to Howard and Fiske (9), and these density-dependent factors can influence either reproductive rates or mortality (Lack 954). In our analysis of demography as it relates to densities, we have divided the growth of the herd into three phases: increase (973–June 984); high numbers (June 984–June 988); and decrease (June 989–June 993). The total numbers that we use to calculate densities track the annual mean of the Cagean and census estimates 973–84 (fig. 0.4) and the numbers generated from R/M schedules 984–93 (starting with the census estimate in 984 (table 0.5). Summer densities are these population estimates divided by the 47,000 km² of tundra habitat used June–August on the Labrador Peninsula (fig. 2.7). Caribou were generally present throughout this area each summer, with some animals visiting the coast. Much of the Torngat Mountains was excluded since the UHF and VHF radio-tracked animals seldom used these high mountains except in 993 (Couturier et al. 996). The potential winter range was the lichen woodlands below tree line on the Labrador and Upper Ungava Peninsulas, and in some years it included tundra areas that the caribou visited north of the Leaf River on the Ungava Peninsula (fig. 2.7). We estimated winter densities annually for each winter (982–93) based on the locations of UHF /VHF radios (see Vandal et al. 989). The winter distributions 973–75 were based on winter radio monitoring conducted by Drolet and Dauphiné (976). For the period 975–82 (prior to radio

480 | TH E R E T U R N O F C A R I BO U TO U N G AVA

tracking), winter distributions were determined from aerial surveys. If we knew the distribution of animals in mid-winter, we felt we had sufficient knowledge to estimate an annual range by joining such mid-winter distributions with the area above tree line on the Labrador Peninsula (fig. 2.7). To recap, for summer densities the population estimates were divided by a common divisor (47,000 km²) while for winter densities population estimates were divided by different divisors based on variable winter distributions. Clearly all the estimated densites resulting from those areas where animals were known to be present were minimum estimates. Additionally, the caribou at any one moment are aggregated in much smaller areas so that instantaneous densities would be much greater than these annual/seasonal estimates. Parturition Rates Pregnancy/parous percentages for adult caribou in North America show little variation over a wide range of densities (Bergerud 97b; Davis and Valkenburg 99). The densities in the summer are the most important since it is the nutrition in the growing season that results in body growth and condition and determines if a female ovulates in the autumn (Cameron et al. 993; Cameron 994; Cameron and Ver Hoef 994; Chan-McLeod et al. 994). The relevant densities should be those that relate to the growing season. As Thomas and Barry (990b, 257) stated, “fecundity is a measure of the energy reserves and nutrition of caribou at the time of breeding in late October.” Caribou are not like white-tailed deer, where litter size and the age of puberty are sensitive to nutritional regimes. Caribou, with their litter size of one, don’t have this plasticity; and they generally do not reach puberity until their 3rd year (Bergerud 980). For the George River herd, we could not detect any change in pregnancy/ parous percentages over a range of summer densities increasing from 4 to 8–9 animals/km² 976–82 (fig. 6.). Pregnancy percentages in the literature are consistent with our finding of little variation over a wide range of densities < 9/km². The parous percentage for the Avalon herd in Newfoundland averaged 72.5% ± .67% for an interval of 0 years when summer densities increased from 0.2 to 2 animals/km² (Bergerud et al. 983). Again, for the Porcupine herd percentages showed no trend over  years (80.9% ± 0.5%) when the herd increased from 35,000 animals in 983 to 60,000 by 992 (summer densities above the arctic tree line would have ranged from 2.8 to 4.0/km² [Fancy et al. 994]). The Delta herd in Alaska averaged 83.3% ± 2.50% parturition rate 98–89 with densities ranging from 0.48/km² (979) to 0.93/km² (989) based on the total annual range (Davis et al. 986; Davis and Valkenburg 99; Valkenburg et al. 996a). The Central Arctic herd had parous percentages 978–87 of 79.4% ± 3.73% (excluding 2year-old females) during a period when densities above tree line increased from 0.2/km² in 977 to 0.4/km² by 988 (Cameron et al. 993; Cameron and Ver Hoef 994). Together with the George River herd, these herds provide parturition rates

70

CALF WINTER MORTALITY

60

WINTER

40 NO CLASSIFICATION

30

R

20

R

R

R = RABIES

10 0 70 SUMMER

CALF MORTALITY RATES

50

R

74

76

78

80

82

84

86

88

90

50

% PREGNANT/PAROUS OR % FEMALE SURVIVAL

40

SURVIVAL

100

Y = 221.845  1.522X r = 0.874

90

70

PREGNANCY

Y = 125.904 0.408X r = 0.122

60 14 12

TOO MANY

10

CARIBOU/km²

94

CALF SUMMER MORTALITY

60

80

92

Y = 84.702 – 0.172X r = 0.067

SUMMER

8 6

WINTER

4 2 0

74

76

78

80

82

84

86

88

90

92

94

COHORTS OR YEARS Fig. 16.1 Comparison of calf and adult female mortality rates and pregnancy rates with summer and winter densities. The cross-hatched area indicates the summer densities that were too high and resulted in reduced natality, the major factor in the decline of the herd.

482 | TH E R E T U R N O F C A R I BO U TO U N G AVA

that span a range of densities from 0.5/km² to 9/km² that did not contribute to population regulation. These data fit the natality model for Alaskan caribou (Davis and Valkenburg 99) where parturition rates remain constant over a wide range and then rapidly decline. The rapid decline for the George River herd occurred after 983 when densities rapidly increased beyond 9/km² (fig. 6.). The contribution of the George River herd to our understanding of Davis and Valkenburg’s model of threshold densities is the quantification of the threshold density at which point abrupt declines in fecundity occur. Since this happens only at extremely high densities, it has not been observed in other North American herds. This major decline for the George was extremely rapid, occurring in an interval of only 2–3 years. Parturition rates were still high in 982 (> 90%), but were reduced to < 70% by 984 (table 0.; fig. 6.; Couturier et al. 990; Crête and Huot 993). This rapid decline in pregnancy rates resulted from a synchronous and similarly rapid decline in several indices of physical condition (fig. 9.20). The key year was 983: Growth of birch declined by 9%; males with regal antlers were gone in one season (fig. 9.20). Unfortunately, 983 is the only year for which we have no gauge of pregnancy rates or parous percentages; however, there was a strong 983 cohort in October (table 0.). The females must still have been fecund in May/June 983. The story finishes in 984, when the peak of calving advanced 4 days from 8 June to 2 June (later breeding in October 983), and bald females increased by 57% (fig. 9.20). The correlation between parturition rates and antlerless females was r = -0.757, n = 0. The change in condition and the decline in pregnancy rates resulted primarily from the additions of the 982 and 983 cohorts to the populations (44 and 32 calves/00 females respectively, uncorrected) as yearlings. The census in 984 was 537,000 caribou based on extrapolations from Crête et al. (99), and yearlings of the 983 cohort alone represented 25% of the 293,000 animals on the calving ground (Crête et al. 99), or 73,000+ animals. The summer density went from 9/km² (983) to .4/km² by 984. Additionally, Crête et al. (99) estimated the herd in the fall of 984 (including calves) at 643,600 animals. Based on the age array of the animals that died at Limestone Falls in September 984 (fig. .8), the 982 cohort would have represented 3% of the herd (84,000); the 983 cohort 4% (90,000). A density threshold was exceeded with the addition of only 2 or 3 cohorts. There was a density-dependent component in fecundity, but it occurred only at extreme densities. This lack of density-dependent restraint is consistent with the view that caribou have not evolved intrinsic self-regulation because evolving adaptations to counter predation was a more pressing need (Bergerud 97b). At extremely low densities, Davis and Valkenburg’s natality model graphed a rapid increase in parturition rates. One view would be that this reflects the fact that yearlings may conceive at low densities. But it is not clear that low densities

Population Regulation | 483

per se are the determinants of increased summer growth sufficient for young animals to reach an estrus threshold. Summer densities were low for the Interior herd in Newfoundland in the 950s (Bergerud 97b), yet few 2-year-old females were parturient. The highest conception rate for yearlings in the literature is that of the Delta herd 978–79, when 67% of 2 females produced calves (Davis et al. 99). However, the overall density was approximately 0.4/km², which is relatively high – similar to densities in the Porcupine and Central Arctic herds where the converse held and few yearlings were parturient (Whitten et al. 992; Cameron et al. 993). Four factors that could affect summer growth of yearlings are () the density of animals competing for forage; (2) the length of the growing season; (3) the length of foraging time as affected by insect harassment; and (4) the opportunities for optimal foraging relative to predation risk. The high conception rates of yearlings introduced to predator-free maritime islands – such as Brunette Island, Newfoundland (Bergerud 97b), and Coats Island, NWT (Parker 975) – can be explained by a combination of all four factors. However, the pregnancy of young females in the Delta herd cannot, since both insects and predators were present and densities were much greater than were initial densities on the islands where populations had been introduced. Given a high-quality summer range, we hypothesize that the key for conception in young animals is an early and long growing season. Possibly there is also a forage factor that we are yet to discover, such as a cool, moist growing season, a characteristic of islands. However, the evidence at hand suggests that the interaction of low densities with forage alone is not sufficient explanation for the pregnancy rate of first-time breeders. The pregnancy of yearlings in the George River herd in 980 was 43% (n = 2) (Parker 98) and it had been the animals in the best physical condition that had conceived in October 979. The spring of 979 was extremely early; the ice left Knob Lake 4 June (8 days earlier than the 40-year mean) (fig. .4); and the mean May temperature was 4.4°C – the highest reading in 39 years (the 39-year mean 954–93 was 0.8°C). In the Delta herd in Alaska Davis et al. (99) could not show a weight difference at 7–2 months of age (spring ages) between the 978/979 cohorts – when many yearlings conceived – and other less fecund cohorts, but it is the fall weights that need to be measured (Dauphiné 976; Cameron et al. 993; Thomas and Kiliaan 998). The high yearling pregnancy rate in 980 for the George River herd may not have applied to other years before 984 if the growing seasons then were shorter. In the period 954–93 the start of the growing season in northern Ungava varied by 30 days; an addition of up to 30 days to the relatively short growing season would be a major bonus for weight gain. After the 982 cohort, the size of yearlings declined with high densities and reduced forage (fig. 8.5). In the face of less forage in those years, longer seasons would not have been sufficient to improve conception rates for yearlings.

484 | TH E R E T U R N O F C A R I BO U TO U N G AVA

Summer Calf Mortality The early summer loss of calves in the first two weeks of life was quite constant in this study except in 992 (table 0.) and was not correlated with total numbers (r = -0.27, n = 9); However, it was correlated with birth weights (r = -0.907, n = 6). A major component in perinatal viability is the calf’s weight at birth, and in  years these weights were correlated with May temperatures (fig. 8.4) and presumably with the growth of the fetus in the last trimester (Skogland 984b). We have shown that females make a significant movement in April/May that may provide them with early greens (fig. 2.3) and that the low birth weights of the 992 cohort appear to be related to retarded body growth due to the late phenology in May 992 (fig. 8.4). Calves in the next year, 993, weighed as much at birth as calves born 5 years earlier in 978. Birth weights and intrinsic viability may relate more to spring phenologies than to population size. The overall mortality rate of calves until the fall showed little variation in the years of increase 974–83 (45.6% ± 0.44%, C.V. 8.47%) (fig. 6.). Mortality also remained constant for years of high population 984–88 (47.6% ± .42%, C.V. 6.64%) despite the decline in pregnancy rates and its role in reducing recruitment (not to be confused with mortality) beginning in 984. On the other hand, in the decline phase 989–93, mortality did increase (56.5% ± 4.37%, C.V. 7.37%), despite relatively constant natality (fig. 6.). The high coefficient of variation resulted because of extreme mortality in 992 – 66.6%; and low mortality in 993 – 42.2% (fig. 6.).. Accidents – especially drowning – could have increased as numbers rose. However, the population size was decreasing after 988. In the 970s when the herd calved at Caribou House at the headwaters of the Ford and Falcoz Rivers, some animals moved east towards the Labrador Coast on routes that generally paralleled the drainage. But in the 980s the animals from the much larger calving grounds located farther to the west and south moved north towards Ungava Bay. This route was parallel to the George River, but at right angles to such major tributaries as the Ford and Falcoz Rivers. We found calves that had drowned and outfitters reported others. Furthermore, in the 980s calves were born about 0 days later than in the 970s when flooding may have been more frequent than it is in early June. This increased mortality would then have a density-dependent backdrop. Again, travelling further and moving faster might increase mortality as herd numbers expanded. A regression of summer mortality rates against the total, straight, linear distance travelled annually between calving grounds to rutting locations was significant; but it was also negative (r = -0.743, n = 8): Summer mortality decreased as the distance travelled increased 986–93. The correlation between km travelled/day in July and summer mortality 986–92 was also negative (r = -0.75, n = 7). One’s intuition suggests that accidental mortality would increase with mobility and distance travelled. However, increased mobility fur-

Population Regulation | 485

Table 16.1 The comparison of parameters affecting summer calf survival between years of low constant mortality 1973–85 and increasing mortality 1986–92 Environmental Parameter

Constant Mortality 1973–85

Increasing Mortality¹ 1986–92

Calf Mortality (%) Tree Line West (km) Tree Line South (km) Calving Ground Size (km²) Calf Birth Weight (kg) Wolf Havests Totals Early Calf Mortality Antlerless Females Density Summer/km²

44.5 ± 3.07 (13) 78.7 ± 24.50 (13) 155.4 ± 35.41 (13) 7,250 ± 3,100 (13) 7.0 ± 0.49 (4) 83.2 ± 35.57 (11) 9.3 ± 3.05 (3) 2.7 ± 0.97 (10) 7.2 ± 3.03 (13)

55.16 ± 8.77 (7) 32.9 ± 11.41 (7) 123.0 ± 45.76 (7) 22,600 ± 53,00 (7) 6.1 ± 0.81 (5) 171.0 ± 50.23 (3) 8.4 ± 7.02 (5) 7.9 ± 1.25 (6) 12.2 ± 1.49 (7)

t-test Probability

0.018 0.001 0.135 0.001 0.087 0.082 0.815 0.001 0.001

¹ Note, not the decline phase 989–93, n=5.

ther from tree line might have reduced contact with wolves, thereby varying losses inversely with density. In the context of calf development, the early socialization of dam and calf has been deemed important (Lent 964, 966). Bergerud has noted that newborn calves – with their cryptic reddish-brown colour – are less noticeable when isolated and lying down with their dams than they are when they are older and more active and vocal in nursery groups. The mortality rate of young calves described by Miller et al. (985) suggests that very young calves are less susceptible to predation than calves 2–4 days old. We do not know if wolves may prefer to tackle groups with multiple calves, but at any rate young calves still separate from nursery groups would not be subject to such multiple kills. The increased mobility of the cows after parturition in the 980s should have increased their conspicuousness and detection by wolves. But, again, the data does not support this theory since the increase in summer mortality in the late 980s (fig. 6.) resulted after the high numbers earlier in the decade that would have initiated that increased mobility (see Crête et al. 99). The increase in summer mortality rates after 986 (table 6.; figs. 6., 6.2) were correlated with wolf numbers (fig. 6.2) and calf birth mass 984–93 (fig. 6.3); additionally, mortality was correlated with the percentage of antlerless females – our best index of female condition (fig. 6.2). The index of baldness (polled) was in turn correlated with the annual growth of birch. The summer physical condition of calves should reflect the milk supply of females – our indices of female condition and energy budget calculations indicated that cows 988–92 did not meet milk targets, which in turn were functions of spring and July diets and insect harassment (see Camps and Linders 989 and Appendix on energy budget calculations).

65

65

r = 0.616 P = 0.003 n = 21

60 55

55

50

50

45

45

40

40

35

35 80

75

SUMMER CALF MORTALITY (%)

r = 0.748 P = 0.002 n = 14

60

85

90

100

50

COHORTS

200

150

WOLVES HARVESTED

65

65

r = 0.528 P = 0.014 n = 21

60 55

r = 0.613 P = 0.003 n = 21

50 45

45

40

40

35

35 80

100

120

140

160

180

200

220

0

65

10

5

20

15

25

30

SIZE OF CALVING GROUND (×1,000 km²)

km TO TREE LINE TO SOUTH 65

r = 0.368 P = 0.101 n = 21

60 55

r = 0.796 P = 0.001 n = 16

50

50

45

45

40

40

35

35 0

2

4

6

8

10

12

DENSITY ABOVE TREE LINE (km²)

Fig. 16.2 (above) parameters.

14

2

3

4

5

ANTLERLESS

6

7

(%)

8

9

The summer mortality rates of calves compared with relevant

Fig. 16.3 (facing page) The mortality of calves in the summer decreased when the calves were larger at birth in 8 years. The mortality index was the difference between the estimated calves per 100 females at parturition and the calves per 100 females in the autumn classification counts.

Population Regulation | 487

45

1992 (80)

SUMMER MORTALITY INDEX (PARTURITION TO FALL)

SAMPLE SIZE

40

20% NEWBORNS DIE

1991 (19)

1988 (18)

35

r = 0.934 n=8

1985 (102) 1984 (2)

30

1987 (17) 1986 (24)

1993 (10)

25

20 4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

MEAN BIRTH WEIGHT OF CALVES (kg)

Space as an index of predation risk also appeared to affect summer mortality. Our indices were () the distance (km) between the centres of the annual calving grounds as measured south to the tree line at approximately 56° N; (2) the distance from the centre of the calving ground west to the George River; and (3) the annual size of the calving grounds in km². The correlation coefficients of space with summer mortality rates were: with tree line south, r = -0.528, P = 0.04; with tree line west, r = -0.43, P = 0.06; and with the extent of the calving ground, r = 0.63, P = 0.003 (table 6.; fig. 6.2). Calving areas are selected to reduce predation risk (Bergerud 996). If the area is small and far from where wolves den, survival should be high. As the George grew larger and the calving ground became overgrazed, the females were prepared to sacrifice some security and extended their calving to the south and west, which provided some rotation of spring pastures. With the animals spaced over a much larger area, wolves should have made contact more frequently, potentially increasing calf losses. The abundance of wolves was correlated with summer mortality rates (fig. 6.2). The summer mortality rates were correlated with many factors: Multiple regression techniques did not improve our understanding of it. Calf survival was relatively constant 973–85 (table 6.), with a small coefficient of variation. After 986 survival decreased and became more variable (fig. 6.2). Survival in 992 was especially deviant. The constant rates prior to 986 imply that variations in wolf numbers and spacing strategies had minor impacts, but with a decline in

488 | TH E R E T U R N O F C A R I BO U TO U N G AVA

condition after 984, the impact of wolf numbers and the distribution of the cows and calves probably all contributed to the increased mortality. The key factor was condition/vulnerability, which increased regularly with density. A factor in the relatively constant survival 973–85 could have been the annual variations in the calving locations that delayed density-dependent overgrazing. The mean density of females and yearlings on the calving grounds based on total population estimates (no allowance for animals off calving grounds) was 3 ± 3./km² 974–90 (n = 7) and showed no increase in density when regressed on year (Y = ,784.97 - 0.885X, r = -0.348). By rotating pastures within the available low-risk habitat above tree line and thus partially maintaining space as numbers increased, the cows were able to compensate forage requirements to some extent as herd size increased. However, they reached a point when most of the habitat above tree line had been occupied one or more years (fig. 5.8) and impacts on physical condition were inevitable. The calving areas after 983 were not localized in the safest habitats along the height of land (Caribou House) but approached the tree line on the southern and western boundaries, especially in 990 and 99 (fig. 5.8). This meant that wolves had less distance to travel to find young animals. The calves were predisposed by their low birth weights to wolf predation, which indeed appears to have been the primary reason for increased mortality rates. This mortality sequence stressed density-dependence in the later years but annual variations from phenology created additional impacts. For example, 992, the year of highest summer mortality (an estimated loss of 67% of the calves), had the latest growing season in recent years: Calves were small, and based on the antlerless index (9.9% antlerless), females were in the poorest summer condition. According to our analysis, density had already fallen to < 0/km², yet the losses were the largest recorded (fig. 6.). The very next year, 993, was an early phenology year with large calves at birth. Summer mortality was similar to 974 when there were at least 200,000 fewer animals. Neither densities nor range conditions could have changed so rapidly – birch showed poor growth in both years – and yet losses in these two adjacent years represent the extremes since weather records have been gathered in 954. The distances that females travelled in spring migration of 993 were short, whereas in 992 they were extremely long. Perhaps an early phenology cannot improve upon an already good potential (the excellent condition of the females in April 993 following a short migration) to the same extent that a late phenology can subtract from an already poor potential (such as that which followed the long migration in 992). Winter Mortality of Calves There is now a general consensus among caribou biologists that the calves in large migratory herds in North America born on calving grounds in the alpine

Population Regulation | 489

or arctic tundra have higher mortality rates than adults in their first winter of life. This mortality commonly occurs after the herds migrate south of tree line and are subjected to increased predation from wolves. In this investigation, the mean calves/00 females in their first autumn was 44.0 ± 2. calves (n = 2 years). Five or six months later in early spring, the percentage had declined to 26.9 ± 3.0 calves/00 females (table 0.). If we correct this spring percentage by 24% (as discussed earlier) to 35 calves/00, there was still a substantially higher mortality of calves over winter. If the over-winter mortality of cows had averaged 0% per year over the course of these same years (974–93), the mean winter mortality rate of calves over the same time frame would be 28%. Another classification technique used to assess winter mortality compares the recruitment composition of the herd when the cohorts have reached the age of 5 months with that of 7 months. Differences should relate to winter mortality since there is no evidence that yearlings die at higher rates than adults in their second summer of life (Hearn et al. 990; Fancy et al. 994; and Crête et al. 996). For example, we examined the composition of the caribou that drowned at Limestone Falls in September 984. There were ,08 calves and 922 yearlings, a decline of 7%. In fact, this ratio should have been the reverse, since the 983 cohort (the yearlings) was much larger at 5 months of age (50. calves/00 females, n = 2,47), than the 984 calf cohort at the same age (38.8 calves/00 females, n = 2,839). From the same mass drownings at Limestone Falls, Messier et al. (988) estimated the mean mortality of adult females at %, a clear example of the better survival of adults. Calves have higher mortality than adults in winter because of predation; the differential vulnerability of young animals was most pronounced in the fall and early winter. We documented this by sampling repeatedly throughout the winter for the 98 cohort. By late winter the most susceptible calves would have died, and the mortality of the surviving calves was similar to that of adults. The higher mortality rate for calves just after they enter the taiga in the fall/early winter appears to apply as well to the migratory herds in Alaska (see Fancy et al. 994; Dale et al. 995). The winter mortality of calves showed wide extremes during this study, dropping radically after rabies outbreaks (fig. 6.). Winter mortality was not correlated with fat reserves (fig. .) or with winter densities (r = -0.342, n = 4). Mortality increased in the latter years of the study when summer densities were greater than 0/km² (fig. 6.). Winter mortality was also greater in the years that followed an increase in antlerless females in the autumn, although 992–93 represents an exception to this: 992 had the highest percentage of antlerless females (9.9%, n = 3,835) but low winter mortality (992–93), but this can be explained by the high mortality in the previous spring/summer, which left only the most fit for the winter. Additionally, there was a rabies outbreak at about this time (fig. .).

MANDIBLE LENGTH (mm)

270

Y = 239.377  1.227X  0.012X2 r = 0.691

260

250

n = 148 x = 11.4/yr. LARGE

240

75

SMALL

80

85

90

COHORTS (22 MONTHS OF AGE)

BETWEEN FALL & SPRING) (PERCENTAGE DECLINE OF CALVES/100

CALF MORTALITY INDEX

70

Y = 24.127 + 0.139X

60

(80)

(89)

r = 0.942 n=8

(90) 50

(87)

(91)

SMALLER SHORT YEARLINGS

(86)

LARGE SHORT YEARLINGS

40

COHORTS AFTER RABIES

(88) (75)

30

(92)

92 COHORT

(85)

(79)

20

(83) (84)

(78) (74)

(77) (81)

10

(92) 0

300

(82) 400

500

(76) 600

700

800

900

SNOW DEPTH INDEX

Fig. 16.4 The mortality of calves over the winter compared to winter snow depths and the mandible size of 22-month-old yearlings. The sample size of mandible length of calves was inadequate to evaluate if there was a trend in size, thus we used the mandible sample based on 22-month-old animals. The mortality index is based on the calves per 100 females in the fall vs the calves (short yearlings) per 100 females the next spring. The index does not include the correction for the estimated overwinter mortality of females as does fig. 11.5. (No mandibles for the 1988 cohort, considered small.)

Population Regulation | 49

Winter mortality was also correlated with the number of wolves harvested at Kuujjuaq (r = 0.677, n = 4 years). This was our most reliable index to the abundance of wolves since the caribou in many years wintered in the vicinity of Kuujjuaq and/or migrated by this settlement. Presumably the wolves were in attendance. An exception was the winter of 980–8, when mortality was extreme (> 60%) but the wolf harvest was low – only 87 animals. Unfortunately, the winter of 980–8 was one of the three winters in the study when we did not know the precise winter location of the herd, so we cannot attest to the validity of the wolf population for that year. The sequence of winter mortality with a density-dependent component is that in years when the females were in poor condition and calves had high death rates in the summer, these same cohorts continued to experience high mortality in their first winter (with the exception of the 992 cohort). The calves born after the summer range was degraded had low growth rates (Crête and Huot 994) and may have been more vulnerable to predation, especially in winters of deep snow (fig. 6.4). Because of a poor sample size, we have to judge the body size of calves in their first winter by using animals 2 months older (they do, however, follow the same curve). Thus figure 6.4 shows only the mandible sizes of 22-monthold animals. We could not document that the size of mandibles of 0-month-old animals declined in parallel with degradation of the range (table 3), but the 22month index is consistent with the possibility that wolf predation in the early winter was selective to the smaller calves. Additionally, the 0- to 2-month-old animals weighed more in three Aprils before high numbers (56 kg ± 5.2 kg, 33 calves) than in three years (983, 985, and 986) after summer densities exceeded 9/km² (4.7 kg ± .45 kg, 22 calves) (table 8.). Adult Mortality The adult mortality rate of 7 herds in North America increased as wolf numbers rose. The curvilinear regression of M on wolves/,000 km² was Y = 4.766 + 0.699X¹.²⁷⁵, r² = 73% (fig. 4.4 from Bergerud and Elliott 986). We have no reliable figures on wolf numbers in this study, but the mortality rate of females determined by radio telemetry was correlated with the harvest of wolves at Kuujjuaq in the 5 years that statistics were concurrent (r = 0.92). Mortality rates were further correlated with the condition index of antlerless females (fig. 6.5) and with summer densities (fig. 6.). Forage would not recover immediately as numbers declined: There would be lags in the recovery of birch if a major portion had been killed (fig. 7.6), and certainly there would also be lags in the recovery of sensitive tundra shrubs on denuded substrates (fig. 7.6). These are density-dependent effects that persist after numbers have declined. The annual mortality rates of cows increased in years when there was greater snow cover (fig. 6.6). Although the size of females may have decreased with the

492 | TH E R E T U R N O F C A R I BO U TO U N G AVA 20 91–92

FEMALE MORTALITY RATE

92–93 15

90–91

Y = 1.159 + 1.795X r = 0.940 n=8

88–89 89–90

10 86–87 85–86 5

84–85

0 1

2

3

4

5

6

7

8

9

10

11

12

PERCENTAGE OF ANTLERLESS ADULT FEMALES Fig. 16.5 The annual mortality rate of radio-tagged females increased when plotted against the percentage of females without visible antlers in the proceeding fall. This is consistent with a decline in the physical condition of females as the herd increased (see fig. 9.3, table 10.5).

overgrazed summer pastures (table 8.7), this is probably not simply a factor of vulnerability to wolf predation (as was the increased mortality rates of smaller calves 984–9). Mortality rates of females were also greater in severe winters for the Delta and 40-Mile herds in Alaska (fig. 6.6). For these herds as well as for the George River herd, winter food shortages were not a factor in the increase rates (Bergerud 2000). Until recently we had assumed that caribou have an advantage over wolves in deep snow. However, this intuition was in error: Wolves have an increasing advantage as snow loads build (Dale et al. 995; Mech et al. 998). An additional component of the increased mortality of females in the late 980s (fig. 6.6) was the higher losses in July (Hearn et al. 990), when they were in their poorest condition. The mortality of adult males was not measured directly; instead it was calculated using the constant sex ratios of recruits and adults. These calculations indicate that males commonly had much higher death rates than females, a disparity that is obvious from the age arrays from the Limestone Fall drownings, from other age arrays in the literature (see Miller 974 for a review), and from radio telemetry studies (Hearn et al. 990; Davis and Valkenburg 979). Fancy et al. (994) found no difference in the mortality rates for males and females for the

Population Regulation | 493 25

DELTA HERD, r = 0.634 (n = 17) GEORGE RIVER, r = 0.824 (n = 8)

ANNUAL FEMALE MORTALITY RATE (%)

40-MILE, r = 0.792 (n = 8)

20

15

10

5

0

DELTA 1

2

3

4

5

300

400

500

600 500

700

6

GEORGE RIVER 800

40-MILE 50

70

90

110

130

150

170

190

WINTER SEVERITY INDEXES Fig. 16.6 The mortality rates of females in three herds in North America increased in winters of deep snow, primarily because females are more vulnerable to wolf predation as snow cover increases (see Mech et al. 1998).

Porcupine herd 982–89. However some explanation is in order, since sex ratio in that herd is similar to other herds in North America: approximately  male/2 females (Surrendi and De Bock 976; Urquhart 983). Using the equation for calculating the mortality rate of males Mm = Mf (0.2627)R shows us that when the herd was increasing 974–84 with a low mortality of females and high recruitment (R), the difference in mortality rates between the sexes was greater than in later years when herd numbers were lower and recruitment was lower. We found only one male (age 7), on 30 August 988, that died from starvation (metatarsal fat 4%); but we found 4 females that starved in the

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summer. The greater difference between males and females in mortality in the early years is estimated at 3% (females 9%, males 22%). There was only a 4% difference 990–9 to 992–93 (table 0.5); this we attribute to the greater summer starvation of females, and perhaps to the increased vulnerability of smaller, malnourished females to predation. In general, males age faster than females and spend more time south of tree line where wolves are more abundant; thus they should always have higher mortality rates from predation than females. Mech et al. (998) recently reported that wolves killed 5 bulls and 43 cows in the Denali herd where the adult sex ratio favoured females. It does appear that females paid a higher price in mortality for the degraded summer range in Ungava than males; we could not document any change in the overall sex ratio of survivors, but we did note that males seemed to have better success at making their fall weights. The Foraging Carrying Capacity (K) The relative importance of winter forage, primarily lichens, vs the green foods of the growing season in the density-dependent population regulation of caribou has been contentious both in the Palearctic (Reimers 980, 983a, b; Skogland 983, 984a, 985) and in the Nearctic (Klein 970; Bergerud 974c; Miller 976a, b) and remains contentious to this day (Klein 99; Bergerud 992, 2000; Reimers 997). Two demographic effects are involved, winter starvation and calf recruitment (a product of fecundity and calf survival). Do winter lichen supplies per se determine winter starvation rates, or are both summer and winter resources involved in these mortality rates? Is fecundity primarily a factor of densitydependent interactions with winter forage (Skogland 983, 985), or is forage in the growing season more important, determining first condition, and then fecundity and neonatal viability (Reimers 983)? More importantly: What drives carrying capacity? What forage should we measure to determine the equilibrium between population and food supply? And at what point will the population crash? A reduced reproductive rate and lowered viability of calves could facilitate the attainment of equilibrium. We’ll show below that summer forage is crucial in determining reproductive success, and the latter alone, in the absence of starvation, can stabilize the population, albeit at a lower equilibrium. Thus this study supports Reimers’ view. Winter Starvation Skogland (980) combined the phytomass of lichens and vascular plants to predict the biomass of caribou stocking (kg body mass x animals/km²) for 6 Arctic herds. The regression of log₁₀ mean live Rangifer biomass (kg BW km²) (Y) on the log₁₀ of phytomass (gDM/m²) (X) for these herds plus the South Georgia population (Leader-William 988) was log Y = -.0 + .60 logX (Y=0.097x¹.⁶). An esti-

Population Regulation | 495

mate of the lichen phytomass for the George River herd in 988 is 22 g/m² (Crête et al. 990b) and our estimate of green vascular plants beyond tree line was 8 g/m² (table 7.6). The predicted animal biomass for the George River herd in about 988 from the Skogland/Leader-Williams equation is 477–48 kg/km². The biomass of individual George River animals in 976, before overgrazing, was about 97.5 kg, based on a ratio of 25% bulls, 50% cows, 0% yearlings, and 5% calves in March (weights from Drolet and Dauphiné 976). Hence the predicted annual stocking for Ungava is 4.9 animals/km² (> 2 million animals). The George River herd has never exceeded 2 animals/km², even when the Leaf River herd was relatively small. These calculations were based on forage measurements in 988 when forage, especially green food, had been greatly reduced, perhaps by 50% (Camps and Linders 989; Crête et al. 990a; Crête and Huot 993; Manseau et al. 996; this study). One cannot use the overall abundance of food (lichens and vascular) to predict total herd numbers. One of the herds in Skogland’s regression was the Central Arctic herd that in 975 had a stocking of 0.46/km², or 5,000 animals (White et al. 975); by 989 the herd had increased threefold to 6,000; by 200 it reached 27,000, with a decline in the stocking as the herd expanded its range (Davis and Valkenburg 99; Cameron et al. 2002). If winter lichens determine carrying capacity, it should be apparent for the two herds in North America with the highest densities: the George River herd (this study); and the Slate Islands herd in Ontario. The mean density for the latter herd was 7.2 ± 0.25 caribou per km² 974–200, n = 28 years (Bergerud 996, 200). Winter starvation was common on the Slate Islands but not for the George River (Bergerud 996, 200). In some years George River animals have been in poor physical condition in the autumn when they left the summer pastures (Couturier et al. 988, 990; Huot 989). Nonetheless, the large, remaining, winter supplies of lichens prevented mortality and winter weight loss was minimal (Couturier et al. 988; this study). Thus a shortage of summer foods – in conjunction with good supplies of winter foods – was not sufficient cause for winter starvation. On the Slate Islands the animals lost 5% of their fall weights in 5 winters, but starvation did not occur – regardless of the abundance of winter lichens – if the females entered the winter with weights > 90 kg. However, when fall weights were 80–85 kg, some animals died even when winter lichens supplies were above normal (Bergerud 996). Winter lichens did not determine carrying capacity and a shortage of winter lichens is not sufficient cause for mortality. If winter forage determines carrying capacity, their shortage should be sufficient to cause winter starvation and there would be examples in the literature where animals have entered the winter in good condition and yet died because of winter forage shortages caused by their own grazing or Kw < Ks. The animals on South Georgia had severely impacted their summer range during the interval that many animals were dying over winter (Leader-Williams 980, 988). LeaderWilliams indicated that his summer species selectivity index was 38 for the Royal

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Bay herd (a high degree of selectivity) but only 8.9 for the Barff herd. Summer shrub supplies declined for both herds and enclosures showed overgrazing impact for all the major forage species. Even on Svalbard, where animals have a longer growing season than Peary caribou, there were summer food problems. Demography followed a sequence of good and bad adjacent years (Tyler 987) with dieoffs in 978–79, 980–8, and 983–84. Birth rates were lower in springs following the die-offs, then increased with reduced densities in the next spring. Birth rates were only 9.8 ± 5.39 (n = 3) following die-offs but tripled in recovery years to 58.6 ± .20 (n = 3); winter mortality and natality were correlated r = 0.987 (n = 6). These winter deaths were mostly calves; thus the poor natality was due to low conceptions at high numbers – a summer food problem. Such a rapid turn-over and recovery can only be explained by the quick recovery of summer foods. The females on Svalbard had the longest feeding bouts in the literature, 63 minutes. We believe these two herds, South Georgia and Svalbard, at the two extremes of latitude for caribou, were regulated by summer food problems. It is an oversimplification to argue that winter forage sets the upper limit to populations (Scotter 964; Klein 968). North American caribou biologists have inherited the concept that winter forage determines carrying capacity from studies of domestic reindeer in Europe kept on restricted winter pastures. But it is normally the range above tree line that is utilized in June and July that remains constant in size, and when the same areas are repeatedly grazed, there can be major impacts from trampling. The size of winter ranges varies with population in free-ranging continental herds, and it is constantly expanding and contracting between winters. On these pastures the lichens are partially protected from trampling by snow cover. Unfortunately, several of the most thorough range studies in the literature are of arctic herds where there was no clear tree line demarcation between summer and winter pastures (Klein 968; White et al. 975; Tyler 987; Leader-Williams 980, 988), and this has confounded our understanding of the relative importance of summer vs winter pastures in demography. Range Fecundity and Calf Survival Skogland (983, 984b, 985, 986b, and 990) argued that annual changes in fecundity, calf survival, and body mass for wild reindeer in Norway are best explained as a density-dependent response to winter lichen supplies. Helle and Kojola (994) and Kojola et al. (995) have reached similar conclusions for semidomesticated reindeer in Finland, whereas Reimers, who has recently reviewed the two arguments (Reimers 997), has stressed the role of the summer diet in the demography of the Norwegian herds (– 980, 983). The consensus in North America is that the nutrition of the animals during the growing season has the major impact on fecundity (White et al. 975; Cameron et al. 992). In chap-

Population Regulation | 497

ter 7 we documented severely overgrazed June and July ranges for the George River herd, whereas lichens remained abundant on winter pastures, and after 983 fecundity declined for the females (Messier et al. 988; Couturier et al. 990; Crête et al. 996). Skogland’s conclusions were based on demonstrating a significant negative regression for 6 herds by () regressing fecundity on total herd density (Skogland 985, fig. 3); (2) regressing calf recruitment (calves/00 females) on total reindeer densities (2 herds, 37 data points, ibid., fig. 4); and (3) regressing calf recruitment on winter densities for three herds (ibid., fig. 5). In these analyses, Skogland used a fixed total range for each herd (ibid., table ) as well as a fixed proportion of the total area as the winter habitat. This meant that as a herd increased or decreased in numbers – such as Knutshø-Snøhetta and Hardangervidda – both winter and summer densities increased. The correlation between winter and summer densities for the eight herds discussed was r = 0.924. If parameters such as fecundity are correlated with winter herd densities as Skogland argues, they were also correlated with summer numbers. For example, the correlation between fecundity and winter densities for the six herds listed in Skogland (985) was r = -0.637; for fecundity and summer densities r = -0.85. In North America when the large migratory herds increased in numbers they expanded their range (fig. I .; Kelsall 968; Skoog 968), but the major expansion was on winter pastures (see also Simmons et al. 979). This expansion buffers densities and grazing impact more on winter ranges than on summer pastures. Such a range expansion occurred for the George River herd and overall densities never exceeded 2/km², but summer densities went well beyond 0/km² (fig. 6.). It is hard to accept that densities < 2/km² for winter pastures would seriously affect fecundity or calf survival. In Norway Skogland (985) showed a fecundity of 67 calves/00 females for the Knutshø herd with a winter density of .4/km²; but for the Hardangervidda herd the fecundity was 73.6% ± 0.59% (n = 7) 974–84 when winter densities were 3 times greater than at Knutshø (8 animals/km²). Skogland (990) showed a rate of increase for the Hardangervidda herd of .07 954–65 until the herd reached 32,000 animals and seriously reduced lichen supplies. The herd declined to 8,000 by 972. The herd again increased 972–84 at a finite rate of increase of .09. We do not see how lichen resources could recover sufficiently to allow another population increase in a period of 5–7 years. A more likely sequence was that green forage showed a more rapid response following the decline from 32,000 to 8,000 and provided the nutrition for relatively high fecundity. We do not dispute that the high winter numbers reduced lichen supplies, but Skogland provided no data on density impacts on spring and summer pastures. The nutrition of cows in the last few weeks before parturition is a major factor in the birth weight of calves (Skogland 984b). For the George River herd birth mass was correlated with May temperatures, which suggests a component of

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phenology and early greens in the pre-parturient diet. Several continental herds in North America are able to find green foods in May, 2–4 weeks prior to parturition (Bergerud and Nolan 970; Bergerud 972; Boertje 98; Davis et al. 982; Russell et al. 993). However, we know less about the diet of caribou in May than for any other season (see Klein 990). If we amend Skogland’s definition of winter diet to October to March–April and exclude May, and if we also define the growing season as May to September (Reimers 997), then the body mass and demographic parameters Skogland related to winter diet can be better explained by density-dependent interaction with nutritious food in the growing season (May plus summer). Again, if Skogland’s winter density figures are valid (Skogland 983, table ), and herds in Norway do not increase their winter ranges as numbers grow, there would be severe competition in May for the early greens that impact calf birth mass and survival. Furthermore, the ability of yearlings to meet threshold weights for reaching puberty (Reimers 983a; White 983) should also be a factor of early nutrients as delineated by the length of the growing season. With this scenario the impacted spring and summer range of the George River should have major demographic consequences on fecundity and survival. We have provided above an explanation for the literature’s various interpretations of the relative importance of winter vs growing season pastures. Population Model Here in this pristine wilderness where Charles Elton first documented the pulsing cycles of mammals, we had the opportunity to delve deeper into the relative contributions of the first, second, and third trophic interactions. As Bergerud stated 40 years ago, “The expanding central and northern Ungava population [caribou] presents a unique opportunity to explore natural population controls” (Bergerud 967, 64). At the time, the caribou had excellent survival in the presence of low numbers of predators. The wolves were left undisturbed, as we recommended, and the wolf population recovered from near extinction. By 976–80 there were 200,000 caribou and perhaps 2,000–3,000 wolves, or approximately one wolf per 67–00 caribou – a predator-prey ratio that is within the range in which predation can halt an increase in caribou numbers (Bergerud 983). In fact the wolves did halt the increase. Each year 976–80 as wolf numbers increased the winter survival of calves decreased. By 980 the spring recruitment represented an addition of only –2% to the population (table 0.); this equalled the mortality rate of adult females and population growth ceased. Then the wolf population declined 60–80% from rabies (fig. .): The herd was released from predation and quickly expanded to 500,000+ (fall calves excluded) by 984 (fig. .) (338,000 females estimated in herd [Crête et al. 99]).

Population Regulation | 499

Messier et al. (988) postulated that the wolves were not the regulator in the George River herd because its large expansion would make it inaccessible to denning wolves. However, the herd did remain accessible to wolves well into the fall, crossing the tree line in August and September. The fecundity of the wolves was high, as was pup survival (Parker and Luttich 986). As the herd expanded its range west in the winter, the pups would have been sufficiently large to move with their prey. Recent studies in Alaska and the NWT demonstrate that wolf packs can completely change their territories after caribou vacate their areas if other ungulate species are not available (Ballard et al. 997). Biologists have known since Kelsall (968) that wolves in the NWT aggregate in the winter near the large female/calf aggregations, irrespective of their normal territorial behaviour (Miller 975; Parker 973; Fleck and Gunn 982). In March 982 Bergerud witnessed a daily stream of wolf packs that passed by his campsite in the NWT as they kept abreast of the Bathurst herd in its shift to the north. The Ungava caribou population was not part of a simple predator-prey system as presented in the models of Gause and Huffaker. Predator-prey interaction was not self-contained: Wolves were not limited by their prey or by the space involved or by disparate fauna; they were limited by disease. Thus the Ungava caribou were not regulated by wolf predation. In the absence of sufficient wolf predation the caribou overgrazed their summer range (chapter 7). This led to negative summer energy budgets (Appendix), which in turn led to reduced body sizes and physical conditions (chapter 0) insufficient for maintaining high fecundity and survival rates (chapter ). We argue that this same sequence (fig. 6.7) applies to the great decline in the 870–880s, 00 years earlier (fig. 6.). The most fundamental impact of an inadequate summer diet was the decline in pregnancy rates from over 90% to a low of 60–65% 986–93. This is the lowest rate documented for a major North American herd: 30% of the potential for herd growth was gone. Calves were smaller at birth and died at higher rates in the summer than previously; they were also especially susceptible in the winter to wolf predation as modulated by snow depths (fig. 6.4). Adult females in poor condition also died at higher rates, increasing from a possible low of only 5% per year to 9% (table 0.5; fig. 6.5). Some females were so anaemic that they succumbed in the summer to starvation under the multiple burdens of an inadequate June/July diet; the requirements of lactation; and harassment by mosquitoes. Hunting mortality remained unchanged 982–92 at 25,000+ animals per year (fig. .2), but with natural and hunting mortality both additive and greatly in excess of recruitment, the herd declined from possibly 700,000 in 988 – the largest herd in the world – to 400,000 in 993 (still 400,000 in 200). Predation by wolves did not regulate the George River herd. Messier et al. (988) provided an alternate explanation for the cycles in migratory caribou in

500 | TH E R E T U R N O F C A R I BO U TO U N G AVA TOTAL ADULTS + YEARLINGS 1 JUNE YEAR 1

MAY / JUNE TEMPERATURE

SUMMER DENSITY (ABOVE TREE LINE)

PRIOR DENSITIES

SUMMER FORAGE AVAILABLE

GROWING SEASON LENGTH

SUMMER WEATHER INSECT HARASSMENT

ADULT PHYSICAL CONDITION

BIRTH RATE (YEAR 2)

CALF BIRTH WEIGHT

PREDATION & ACCIDENTS

SUMMER CALF SURVIVAL AND SIZE

SUMMER ADULT SURVIVAL HUNTING WINTER ADULT SURVIVAL

WOLVES × SNOW DEPTH

WINTER CALF SURVIVAL

ADULT ALIVE SPRING

TOTAL ADULTS + YEARLINGS 1 JUNE YEAR 2

YEARLING ALIVE SPRING

IMPACT VARIABLES MOST

FLOW

MODERATE LEAST

Fig. 16.7

The density-dependent population model for the George River herd.

North America which is based on Caughley and Lawton’s (976) paradigm. This stressed that a rapidly increasing ungulate population would severely overshoot the carrying capacity of its winter range, given the slow growth of winter lichens. The maximum winter densities of the 7 largest migratory herds were only 2.2 ± 0.30 per km². The mean maximum summer densities of these same 7 herds in recent times was .6 ± 0.40 animals per km² (extremes 0.7–4.3/km²) (Bergerud 996), nowhere near approaching the 0/km² of the George River herd. Research on these 7 herds has failed to show major changes in fecundity or starvation in accordance with such an hypothesis (Bergerud 2000). The herd with the smallest summer range above tree line (the Blue Nose herd, 90,000 km²) reached only 20,000 animals (.3/km²) – far below summer carrying capacity. The herd with

Population Regulation | 50

the largest potential range above tree line (the Beverly, 363,000 km²) had a recent high population of 335,000 animals (review Bergerud 996). The size of these herds has not oscillated in accordance with Caughley’s (977) model. To the contrary, there is evidence that for several of the large migratory herds predation has played a role in reducing calf percentages sufficient (0% or less) to halt increases and possibly enough to cause a decline. Several examples include the Bathurst/Beverly herds (Kelsall 968); the Kaminuriak (Parker 972a); the Nelchina herd (Bergerud and Ballard 988); and the 40-Mile herd (Boertje et al. 996). Recently the Porcupine herd has also declined concurrent with increased predation (Hayes and Russell 2000; Griffith et al. 2002). There is some evidence that the large herds can make major distribution shifts if wolves become too abundant. This may have happened in the case of the Kaminuriak in the 960s, resulting in heavier predation (Parker 972a; Bergerud 996). But clearly wolf predation cannot limit numbers if there are insufficient wolves in the system. Wolf densities must be in excess of 6 wolves/,000 km² (fig. 4.4) to cause negative demography. When wolf numbers are insufficient to limit the growth of caribou – either because of an insufficient prey base or because of recurring disease – summer forage then can become limiting. This is what occurred for the George River herd, and it fits with Caughley’s (977) carrying capacity model: The herd declined and has reached a lower, more substantive equilibrium with its summer food resources. That equilibrium – based on the rapid changes in condition about 982/83 – appears to be in the range of 250,000 animals (5–6/km²). However, this is a quantitative K in numbers: It will not produce animals of superior physical quality as in the increase phase. We may not see again the larger body and antler sizes of the 970s for this reason: When the eruption started in the 950s, the George River herd’s food resource was unique – an untouched phytomass that had been accumulating for decades. A Shortage of Summer Foods In the preface we asked if the George River herd could be used as a model to explain the fluctuations of other large herds in North America and their corresponding changes in distribution. We also asked if there were elements in the regulation of the George River herd’s population that are relevant to the other large migratory herds of North America. First we documented that in the 950s, when numbers were low, the herd was able to escape extinction and make a comeback, reaching a population ceiling similar to that of the 880s (fig. 6.) This probably would not have occurred if the fauna in Ungava had been more diverse and if there had been moose there to maintain wolf presence. The study showed that wolves cannot exist without ungulate prey (recall that the large buffalo wolves disappeared when the buffalo were gone). In the interior of Alaska there are several herds (e.g., Denali, Delta, 40-Mile) that in the past have remained low in

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numbers for long periods – the so-called predator pit (Walters et al. 98). These herds coexist with other ungulates (moose and mountain sheep) that maintain high wolf populations when the caribou numbers are low; wolves then switch to caribou when they again become prevalent, and thereby prevent major population increases. We learned in the 970s that wolf numbers have the potential to increase and thus halt an increase in caribou numbers, but we also learned that rabies outbreaks were a natural check to such a scenario. There are many herds in North America that coexist with wolf populations where rabies are endemic (the Arctic slope herds in Alaska and those in southwestern Alaska). Wolves in these areas never reach > 7 wolves/,000 km², the required density for halting the growth of the caribou herds (Bergerud and Elliott 998). Caribou biologists have argued for decades that the regulating factor for caribou was the abundance of winter lichens (review Bergerud 974a). We learned that at high caribou numbers (≥ 0/km²) the George River herd was regulated by a shortage of summer food rather than by winter lichens as postulated by Messier et al. (988). This density-dependent regulation of the George River herd resulted primarily from a reduction in fecundity that manifested itself in a matter of only two years when densities exceeded 0/km² of summer range (table 0.). Pregnancy rates of North American herds are rather constant over a wide range of summer densities (Bergerud 978) and so they do not contribute much to density-dependent regulation. Adams and Dale (998a) recently reviewed the pregnancy rates for North American herds. The mean pregnancy rate for females ≥ 3 years of age was 85% ± 2.3% (n = 4), CV only 0%. The mean for the George River herd after 984 was the lowest rate in North America; it was clearly a density-dependent response to the overgrazing that delayed puberty in 2- and 3year-old females and resulted in skipped pregnancies among the older females. The best example in the literature of a similar regulation caused by reduced summer forage is the decline of the Nelchina herd in Alaska. The herd reached 7,000 in 962 with summer densities ± 0/km² in the Talkeetna Mountains (see Skoog 968, 37, Range Units 5, 2) then declined rapidly 962–73, reaching a low of fewer than 0,000 animals (Bos 975). Pegau (972) reported in the 960s that the forage in these mountains had been overgrazed. Physical condition would have declined: Valkenburg et al. (99) noted a reduction in mandible size. Additionally, a series of deep snows occurred in the winters of 964, 965, and 966 (review Bergerud and Ballard 988), and many females did not manage to reach the traditional calving ground in the spring (Skoog 968, 439). These females calved at lower elevations where they were unable to space away from wolves and the three cohorts failed (Bergerud and Ballard 988). The calves in these three cohorts likely had low birth weights because the prolonged delay of the growing seasons in May affected fetal growth, a finding we documented for the 992 cohort (fig. 8.2). Their reduced size would have increased their vulnerability to

Population Regulation | 503

wolf predation (see Adams et al. 995b). The decline was thus a complex interaction of high numbers impacting summer forage (as in this study) and weather (late springs), both of which contributed to reduced birth size and increased vulnerability to wolf predation. The latter was accelerated because snow cover inhibited the females from spacing away to the safer, traditional calving ground. After its decline, the Nelchina herd was able to escape from the predator pit – a domain of stability at lower population levels – because of reduced wolf numbers, and by the mid-990s it reached 50,000, with evidence of reduced body size among the calves and reduced natality (Tobey and Scotton 200). This second phase of overgrazing occurred at a lower density than in the 960s, but possibly the standing phytomass had been reduced by repeated overuse: Even in the 980s, range surveys emphasized winter lichens rather than summer herbaceous growth (Lieb et al. 984). The 40-Mile herd may also have been regulated in the 920s by high numbers overgrazing summer forage. Olaus Murie counted a portion of the herd migrating in 920 (Murie 935) and extrapolating from this count he estimated a total herd size of 668,000. That seems reasonable: The total range of this large herd was approximately 350,000 km² (estimated from the distribution map of Valkenburg and Davis 986), or a density of .6/km². Bergerud (980) regressed range size on population size for 4 large migratory herds, and the regression was significant (Bergerud 980, fig. 9). From this regression the estimated size of the range for 668,000 animals was 440,000 km². The George River herd in this study occupied 350,000 km² at numbers of 550,000 (fig. 2.4). The core summer range of the 40Mile herd in the 920s appears to have been 30,000 to 35,000 km² (Skoog 956; Valkenburg and Davis 986) which translates to summer densities above 0/km², the level which leads to density-dependent regulation, as in the case of the George River herd. In recent time the herd declined from 50,000 in 963 to a low of 5,300 by 973 during a period of unfavourable winter weather, short growing seasons, and high wolf numbers (Valkenburg et al. 994; Boertje and Gardner 998). Another example is the Western Arctic herd in Alaska. It increased from 89,000 in 977 to 459,000 in 995 (λ = .0) and then declined to 44,000 by 998 – a loss of 8,000 animals with λ = 0.99 (Dau 2003). The Alaska Fish and Game monitored this herd’s growth with 4 censuses in 22 years, a remarkable accomplishment. Adult female mortality showed little change from 984–85 to 200–02 at 4.9% ± 0.86%. However, recruitment to 0– months of age dropped below 25/00 cows after 990 (data from Dau 2003), and was very low for the 200, 2002, and 2003 cohorts: 9, 5, and 9 calves per 00 females respectively, which will take the herd further down. The estimated percentage of maternal cows on the calving ground 987–93 was 74% ± 4.82% (n = 6) and then declined 996–2003 to 64% ± 2.8% (n = 8), although note that we excluded 994 and 995 at peak population. The herd reached a density on the summer range (90,000 km²) of 5./km², whereas the density in the non-growing season was .8/km² (260,000 km²). The

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decline of the herd thus reflects reduced natality with high summer densities, similar to the George River. This herd had a previous high in about 964 which Skoog (968) suggested was as much 300,000 animals. However, mandible lengths during the later phase of increase (976–88) were greater than in 959–67 (Valkenburg et al. 996b) when the population was declining from the high in 964. This suggests that Skoog’s (968) estimate in 964 was low. The dynamics of this herd have resulted in an overgrazed summer range twice in the past 50 years coincident with low wolf population and rabies outbreaks (James 983; Ballard et al. 997; Ballard and Krausman 997). Valkenburg et al. (996b, ), in noting that the population had “fluctuated considerably in size,” concluded that “the herd remained at low levels from the 880s to the 930s probably because of overexploitation.” It all seems familiar: Two herds (the George River and the Western Arctic) at different ends of the continent both following the same trajectories in the past 00 years. The Mulchatna herd in southwestern Alaska is another candidate for overgrazing its summer range. The herd increased from 8,599 in 98 to 92,88 by 996 λ = .7 (Valkenburg et al. 2003a). Calves per 00 females averaged 45.7 ± 4.64 (n = 6) at 5 months of age during this increase. In 999 when the herd was counted again, it numbered 75,000 (λ = 0.97) and recruitment was down to 28.2 ± 3.08 calves per 00 females in the fall. Valkenburg (et al.) commented that wolf predation was not serious for this herd and that they had noted smallerantlered trophy males by 995. The herd shifted to a new calving ground farther west 993–99 and greatly expanded its winter range (Hinkes et al. 2005). The core summer range had been 3,93 km² and the summer density had reached 6.5/km² at peak numbers in 996. Like the George River herd, this herd likely overgrazed its summer core, which resulted in reduced natality of 2- and 3-year-old females and led to the decline. Other cases of density-dependent reduction in summer forage will emerge now that we realize it is not winter lichens that set the carrying capacity. The Southern Alaska Peninsula herd is located south of the Mulchatna on the tip of the Alaskan Peninsula where maritime influences are strong and icing has occurred in the past (Skoog 968). The herd reached 0,200 animals in 983, declined to ,500 by 995 and then started its recovery in 997. The spring/summer range was estimated at ,548 to 2,700 km²; hence the peak densities were 3.5–6.5/km² (Post and Klein 999). The herd overgrazed its summer range, which resulted in reduced natality and increased mortality (Post and Klein 999; Valkenburg et al. 2003a; Sellers et al. 2003) – just like the sequence that led to the decline of the George River herd. However, in this case the overgrazing occurred despite predation from wolves and bears. But the major contribution of these data concerns the herd’s quick recovery: After only two years 995 and 996 at densities of 0.5 to .0 animals/km², the improvement in physical condition was sufficient to initiate an increase. By 999 the pregnancy rate had reached 93%

Population Regulation | 505

(Sellers et al. 2003). In other words, summer foods can come back quickly, which – now that we know lichen abundance does not determine numbers – also frees us from the mistaken idea that phytomass recovery takes decades. The Porcupine herd in Alaska is another herd that has declined 989–200, from 78,000 to 23,000 λ = 0.97 (Griffith et al. 2002). This herd is the most intensively researched population in North America and the most controversial because of fears that the calving ground on the coastal plain will be compromised if the petroleum reserves there are developed. The overall summer density of the animals in about 989 was approximately 2.6 caribou/km² (78,000 animals/69,000 km² summer range, estimated from maps in Russell et al. 992); the area in the non-snow season was estimated at 59,400 km² by Hayes and Russell (2000), which translates to 3 caribou/km² (78,000/59,400 km² ). These densities did not impact summer nutrition sufficient to reduce parturition rates (see Griffith et al. 2002). Demographic data for the Porcupine herd showed little variability between the key years of increase 983–89 and decrease 989–92 (Walsh et al. 995). Calf mortality during June for the increase phase averaged 29% (6 years) and during the decrease phase 23% (n = 2); natality averaged 80% in the increase phase (n = 7) and 8% in the decrease phase (n = 4); and adult female mortality averaged 6% for the increase and 7% for the decrease (data adapted from Walsh 995). Another scenario is that the combination of late springs and deep winter snows resulted in heavy mortality of small calves in the winter from wolf predation. The wolf population on the winter range was estimated at 6/,000 km² (Hayes and Russell 2000) and was probably higher than that preying on the Western Arctic and Mulchatna animals since those wolves have more contact with rabid foxes. Heavy snow cover lasting into May was the rule in the years 988–89 to 992–93 (Adams et al. 995a, b; Boertje et al. 996; Valkenburg et al. 996a). Note that small neonates were the norm in the years that the George River overgrazed its growing season range because of reduced fetal growth in the last 30 days of gestation in May (fig. 8.2). These smaller calves in Ungava were more vulnerable to predation in deep snows than were cohorts born before the range was denuded (fig. 6.4). The newborns calves in Ungava were especially undersized in the extremely late season of 992 and early mortality in June was 20%. The highest mortality of calves in the Porcupine during the month of June in 7 years of records was 43% in 992 (data calculated from Griffith et al. 200). This sequence we believe was a factor in the decline of the Porcupine herd. Fancy et al. (994) also speculated that over-winter mortality of calves could be a factor in the decline of the Porcupine, especially following the extreme cold in 992. Additionally, calves born in the cohorts of 2000 and 200 would have been undersized. Springs in both years were extremely late and the whole herd calved south of the coastal plain in the Yukon, where predators would have been more common (Hayes and Russell 2000)

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Griffith et al. (2002) made the interesting point that the growth of the Porcupine herd, from the time counting commenced in the 970s, has lagged behind the other herds on the Arctic slope in its rate of increase: Porcupine λ = .05 (979-89) vs Teshepuk λ = .6 (979–93); Central Arctic λ = .9 (978–92); and Western Arctic λ = .0 (979–93). The Porcupine must contend with an abundant predator fauna. The herd may continue down and reach such a low level that it enters a lower stability domain maintained by predation, as had the 40-Mile Alaskan herd in recent decades (Valkenburg et al. 994); however, the 40-Mile has recently increased gradually from 0,000 animals in 98 to 43,000 by 2003 as a result of predator management of wolves and bears and hunting restrictions (Gronquist et al. 2005). A worst-case, stochastic scenario for declines in general might comprise a sequence of density-dependent effects enmeshed with density-independent effects. For example: The George River females returned in April 992 from a long migration (a density-dependent space response – DD) with reduced fat reserves (fig. 9.5). The start of the 992 growing season was the latest on record (density independent – Di), the calves born were underweight, some didn’t make critical birth weights, and the summer range previously had been overgrazed (DD). Additionally, temperatures remained cold throughout the summer (Di) which reduced body growth rates. Snow came early, reducing the fall feeding pause (Di) (fig. 3.2). The cumulatively unfavorable scenario continued in Alaska but not Ungava: The following winter 992–93 was severe and the underweight calves’ (DD + Di) vulnerability to wolf predation because of their size was compounded by deep snow (Mech et al. 998). These are stochastic events but they could come in runs. The extremely cold spring of 992, followed by the deep snows in 992–93, will stand for many years as a reminder of how stochastic events can complicate our understanding of density dependence in population regulation. Who would have thought that a volcano in the Philippines would cool summer temperature to such an extent that it affected fecundity and calf survival across the entire Arctic of North America, thousands of miles away? The four most studied herds in the Northwest Territories – the Blue Nose, Bathurst, Beverly, and Kaminuriak – also appear to have declined from high populations in the 980s. For example, the number of breeding females in the Bathurst herd, estimated at 203,800 in 986, was only 80,756 in 2003, a decline of 60% (Gunn et al. 2005). The herd had previously been as high as 460,000 animals (Heard 989). The summer range appears to be approximately 00,000 km², with densities approaching 5/km² – the point where natality could be affected. The apparent decline of individual herds in the NWT may also reflect shifts in range between the major herds that go undetected because the four herds are seldom censused concurrently. Shifts between herds have been documented in Ungava (Couturier et al. 2004), with more animals leaving the overgrazed George River summer range to go north to the Leaf River tundra than vice versa.

Population Regulation | 507

However, to date, satellite-collared animals have not made major lateral shifts in the NWT. If all four major herds reached maximum numbers at the same time, the total could be more than a million animals, but the summer ranges could accommodate such numbers if there are shifts between ranges. The wolves in the Northwest Territory are migratory and follow the herds south of tree line. Predation as a cause of population fluctuations should not be ruled out. There have been few reports of rabid wolves in the Northwest Territories, which seems strange since the arctic fox rabies vector is present (MacInnes 987). The only estimate – or guess – we’ve seen published for this wolf population is 8,000 animals 38 years ago (Kelsall 968). These wolves could thus reach densities greater than 8/000 km² (or alternatively one wolf per 00 caribou), sufficient to initiate a decline (fig. 4.4; Bergerud 983), especially if there were to be a run of winters with deep snow and late springs. A wolf removal program was conducted in the NWT from 95–52 to 96–62. Prior to the program, winter calf recruitment for the years of 947, 948, and 949 averaged 8.5%. Then, in 950 it declined to 7.6% (Kelsall 968, table 8). As the wolves declined, recruitment of calves increased from 6.9% in 955 to 20% in 958, 25% in 959 and 2.5% for the 960 cohort (Kelsall 968, table 4). The correlation between calf recruitment and wolves harvested in 0 years of wolf management is significant, r = -633 (Bergerud 996). This is experimental evidence that wolf predation can impact caribou recruitment. We should consider that the unexplained fluctuations in the herds in the NWT in recent decades have elements of predator and prey interactions in the sensu of Huffaker. He demonstrated in classical predator-prey cycle experiments, using a phytophagous mite species and predator mite species, that predator/prey fluctuations were reduced by increasing the complexity of the habitats which included oranges for the phytophagous mite and oranges plus rubber balls for the predator to search. The increased complexity and extent of the searching-and-hiding habitat was the key to increasing the persistence of both mite species (Huffaker 958). When migratory caribou herd decline, their range retracts to their centre of habitation, generally located on summer ranges above the tree line (Skoog 968). In the case of the George River, the wolves disappeared after the herd had retracted its range in the 940–950s. In the absence of natural predation, the herd started back. In the NWT, wolf dens are primarily located along tree line, presumably because in these locations prey is more predictable and favourable for pup survival. In the case of the George River herd in this study, the most frequently occupied habitat blocks were adjacent to the tree line. However, we know, that in some years, wolf pups have starved even at tree line in the NWT (Kuyt 972; Heard and Williams 992). But pup survival should improve when the herds are large and caribou pass close to den sites at tree line as they move between the taiga and the tundra. When the herds are low in numbers their con-

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tracted range should result in increased pup mortality. The vast areas of tundra/ taiga provide the complexity (the space) needed for persistence, but within this arena, predator/prey cycles still play a part. And of course the system will be perturbed by hunting/trapping impacts; there may also be disease problems. Then there are the confounding influence of density-independent effects, temperatures, snowfall, spring phenology, and so on. It is probably going to require increased monitoring of the numbers of caribou and wolf populations and their movements as well as experimental evidence to sort all this out. It does, however, seem that John Kelsall and Ronald Skoog laid the framework for solving this paradigm 40 years ago. Final Comments The natural experiment argued for in 967 – not to tamper with the growth of the George River herd and, more particularly, not to reduce wolf numbers – was allowed to reach its conclusion. From it we learned: that wolves with endemic rabies could not regulate the herd; that summer food problems resulting from a small summer range resulted in extreme densities in excess of 0 animals/km² that in turn resulted in negative demography, operating primarily on natality; and finally, that the classic view – winter lichen abundance can limit the growth of the migratory herds – is invalid if the animals can continue to extend their space across the winter landscapes. With global warming already a concern in Alaska, there are serious predation problems on the horizon that trivialize forage concerns (chapter 4). If major arctic herds are to persist with these major changes in faunal diversity and floral biotypes, it is important that biologists and environmentalists abandon the protectionist attitude toward wolf management that has already resulted in the extinction of so many woodland caribou populations (Bergerud 2000). This protection is old news: The battle to honour and save the wolf has been fought and won. But we know from the history of the George River herd that if we want to have wolves in these simple arctic systems, it is necessary to have ungulates in the second trophic level. If we manage predator and prey as a system, there is a future for both. Several herds in Alaska increased 980–89 and then declined 989–93, when several deep-snow winters and, more importantly, reduced growing seasons, followed in sequence (Valkenburg et al. 996a). This is not population regulation, as densities were not involved. However, such declines can take a population to a lower level, where density-dependent predation can lead further to a lower persistent population (Walters et al. 98). Such synchrony can lead to cycles in phase which may encourage the idea that caribou fluctuations are climate-related (Gunn 2003). But density-dependent cycles can also occur, as in this study, when numbers expand on a limited summer range and exceed the carrying capacity. In this case, reduced natality and increased mortality result in a decline – not

Population Regulation | 509

extinction – that becomes protracted by predation by wolf and man alike. If later the system is perturbed and the population escapes from a mode of lower stability, it may grow in the same limited space to a similar carrying capacity as previously, and the cycle can achieve a similar amplitude. That is the story of the George River herd, now and in the past, as it has been directed by the master of the caribou from his mythic mountain domain beyond the horizon. We wish the deer well and hope this study will help them on their “endless march” across the barrens down through time.

So my string was strung. Always for me now would be the gray barrens, stretching far and on, always the lakes and lodge-smokes on their shores. Always would the people watch the deer, always stand silent at the shore, as friends would wave as they go; the land be ever theirs. The light of the days that have been never quite fails the wilderness traveller; his feet may remain afar, but his mind returns. Where the caribou are standing On the gilded hills of morning, Where the white moss meets the footsteps And the way is long before. William Brooks Cabot, 1912 (Labrador, 1920, 265–6)

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A PPE N D I X

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Summer Energy Budgets for Lactating Females

This appendix evaluates the energy status of George River female caribou based on a daily balance of energy intake and expenditure. Only since the 980s have computer modeling and simulation integrated caribou activity and forage abundance to the level of energetic expenditure and energy intake (Fancy 986; Kremsater et al. 989; Hovey et al. 989). These models are designed to evaluate growth or decline of female body weight along with the effects of weight fluctuations on fetus growth, lactation, and calf survival population dynamics. The George River scenario shows a decline in forage availability and quality on, predominantly, the calving and summer ranges (Bergerud 988a, 996; Crête et al. 990a; Crête and Huot 993, chapter 7). Such a situation may lead to an increase in foraging-related activities and/or a reduction in the daily dry matter intake. Either way, the energy balance will be negatively affected and caribou will have to rely upon body reserves to compensate for the deficit; first body fat will be catabolized but in cases of a severely negative balance, body protein will be used also. Our model predicts daily weight fluctuations, providing an insight into the physical condition of female caribou. We gathered data during the summer months of 988, 989, 990, and 99 on days when observations could be made. Generally, we moved along with the George River herd from the calving grounds (tundra) to slightly milder coastal regions along Ungava Bay, the summering area (upland tundra), and the northern fringes of the boreal forest. Model Description Energy budgets simply determine a surplus or deficit in energy at the end of the day by subtracting expenditures from intake. This model (fig. A) has used the

54 | A PPEN D I X FORAGE INTAKE

MAINTENANCE

GROSS ENERGY INTAKE GEI

HEAT INCREMENT

DIGESTIBILITY FACTOR Qd ACTIVITY COSTS DIGESTIBLE ENERGY INTAKE DEI HAIR GROWTH

METABOLIZABILITY FACTOR Qm METABOLIZABLE ENERGY INTAKE MEI

EXPENDITURE I

BALANCE if – and protein loss > 500 Target Lactation * 0

if – and protein loss > 250 but < 500 Target Lactation * 0.25

if + but < costs for Target Lactation Target Lactation * 0.75

if – and protein loss > 0 but < 250 Target Lactation * 0.5

LACTATION

if + and > Target Lact. Target Lactation * 1.00 MEI

TOTAL ENERGY EXPENDITURE

ENERGY BALANCE + = WEIGHT GAIN

0 = NO WEIGHT CHANGE

– = WEIGHT LOSS

– = negative BALANCE 1 or ENERGY BALANCE + = positive BALANCE 1 or ENERGY BALANCE

Fig. 1A

The flow of the energy expenditure and intake model.

studies of Fancy (986) and those of the Porcupine herd (Kremsater et al. 989) as its framework. Wherever applicable, calculations have been adjusted to conform to the data available for the George River herd. What makes this model (even) more complicated than the ones mentioned above is that: () we incorporated self-generated intake rates that were adjusted to the biomass at each location; (2) we used activity extrapolations based on satellite telemetry; and (3) we adjusted

Summer Energy Budgets for Lactating Females | 55

milk production by means of the daily energy balance. The model uses forage intake and energy expenditures to calculate a preliminary energy balance which was then used to determine the level of milk production. Lactation costs are then added to the daily energy expenditures and the sum was subtracted from the total energy intake to provide a daily energy balance and predict weight fluctuation of female caribou. Energy Intake. Establishing energy-intake values required the determination of forage ingestation, daily dry matter intake (DMI), and the digestibility (Qd) and metabolizability (Qm) of the forage, resulting in respectively the digestible energy intake (DEI) and the metabolizable energy intake (MEI). The determination of DEI and MEI has been worked out by other ungulate physiologists (Robbins et al. 975; Boertje R. 98, 985; White et al. 98; Fancy 986) Some of their equations are presented here but many steps are too detailed to be discussed here; L. Camps has prepared an appendix (APPEND.) of more detailed calculations involving 40 additional equations that can be secured upon request. Much more complex and controversial is the determination of forage ingestion and DMI . Forage Ingestation Determination of forage ingestion has required an experimental approach: caribou can be fistulated and led across the tundra to graze (Trudell and White 98) or can be fed a balanced diet (Bergerud 977; Luick 977). However, fistulated and diet-fed caribou will not provide a forage intake comparable to a nonexperimental situation because of differences in energy expenditure between penned and free roaming caribou (equals variation in intake needs) and the experimental nature of intake determination. We estimated forage intake by combining the observed number of bites per minute with the bite size for a specific forage category. When caribou were observed feeding in areas with a high homogeneity of one of the following forage categories: Betula glandulosa, Salix spp., grasses, lichens and the combined category of grass/herbs, we recorded the number of distinct jaw movements and the grazed distance per minute. These observations were done from distances not exceeding 30 metres. After having established the mean bite rate per forage class, we proceeded to hand-strip forage by using the same grazed distance in the same feeding location employed by the caribou under observation. Intake (bite size) of grasses, lichens, and grass/herbs was determined by hand-grazing these selected sites for  minute. We went along the measured distance with one person setting the pace by calling “bite” at regular interval (60 seconds/bite rate) and the other proceeding along the line while opening

56 | A PPEN D I X

and closing one hand parallel to, but ± 3 cm above, ground level. When closed to a fist, vegetation was torn off or dislodged by moving the hand up and forward. We preferred this method over clipping the vegetation because it incorporated various levels of effectiveness related to condition and phenology of the vegetation and prevailing weather conditions. When caribou were feeding on Betula and Salix the number branch-stripping or bites per minute were recorded. After the observation, the stripped length was measured. Once a mean strip count/ minute was obtained, the actual bite size (leaf intake) was determined by stripping unbrowsed branches from the same feeding plots. We noticed that the flexible terminal tips of the twigs were removed, probably ingested along with the leaves, and therefore calculated a correction based on the difference between lengths before and after stripping. We assumed the intake for Vaccinium, Arctostaphylos, and Loislaria to be 25% of the intake of Betula glandulosa. The bite size for bryophytes could not be determined because only twice were caribou observed feeding on mosses alone. Vegetation was collected, air dried, and later oven dried (5 hours at 70°C before establishing forage intake. After most observations the plot was inventoried for plant cover and biomass. The results of these experimental forage-intake trials were used as baseline intake values. Data were collected in the 988 season and applied throughout consecutive years, adjusted per research location relative to the biomass of forage categories in random feeding plots. We are aware of the potential biases for our intake estimates. We may have inaccurately determined the bite rate, especially when caribou are grazing on lichens when they nibble more than performing distinct jaw movements (Trudell and White 98). Simulating forage intake by grazing with a hand is a creative solution for a difficult problem, the outcome depending on consistency, forage condition, phenology, and the determined bite rate. Nevertheless we feel our methodological approach to determine leaf intake from deciduous shrubs of birch and willow is accurate and results of grass and lichens intake compare favourably with studies that employed more sophisticated techniques (Trudell and White 98). Calculation of DMI The most straightforward approach is to multiply the forage intake per minute by the time a caribou spent feeding. Unfortunately this does not apply because of differences in range quality throughout the study area and among years. Therefore the obtained intake for each forage category (xD) had to be corrected () per research location by comparing differences in biomass between the sites where a caribou was observed feeding (BIOFEED) and simulation (BIOSIM) plots: ()

CORDMI ax % = BIOFEED x/BIOSIM x

Summer Energy Budgets for Lactating Females | 57

where biomass is expressed as the mean gram dry weight/m², CORDMI a is adjusted for each research location and forage loss throughout the span of the study. When the distances between the observer and a feeding caribou was such that the particular forage category could not be determined accurately, the foraging time was allotted to the unknown forage category. To assign forage categories to these observations we used rumen contents analyses of female George River caribou by Gauthier and Shooner (988) and Crête et al. (990). Obviously, the forage availability in the unknown category varied among research locations as well. Correction factor (2) compares the biomass of forage categories (x) in a random survey of caribou feeding sites (BIORANDOM) to the biomass of the simulation sites (BIOSIM) (2) CORDMI bx % = BIORANDOM x/BIOSIM x since the average biomass in caribou feeding sites was usually lower than in the more homogenous simulation site, a decrease in bite size resulted. In cases when feeding site biomass was higher a higher bite size was obtained (APPEN .). By multiplying the now correct DMI per minute with the minutes caribou fed on each forage group the total DMI per observation period can be calculated by summation. To extrapolate this to a 24-hour DMI we used the extrapolation index (EXPOLDMI) (APPEN .) based on satellite telemetry activity codes and daily prevailing insect-harassment levels while assuming that diet composition is similar throughout 24 hours. Daily DMI can now be calculated by: (3) DMI (kg) = (DMI known) + DMI unknown) × EXPOLDMI where DMI known sums forage intake during observations when forage categories x could be determined (MINFEED known, in minutes): (4) DMI known (kg) = (bite size forage groupx × CORDMI a x × MINFEED knownx) and DMI unknown (kg) sums the intake of forage during observations when forage categories x could not be determined (MINFEED unknown, in minutes): (5) DMI unknown (kg) = (bite size forage groupx × CORDMI bx × MINFEED unknownx) CORDMI bx (%) = BIORANDOM x/BIOSIM x Since the average biomass in caribou feeding sites was usually lower than in the more homogenous simulation site, a decrease in bite size resulted. In cases when feeding site biomass was higher a higher bite size was obtained (APPEN .).

58 | A PPEN D I X

Energy Expenditure The energy model uses as its input the daily metabolizable energy intake (MEI) and the total daily energy expenditure. Both parameters eventually will determine whether a female caribou maintains body weight (expenditure equals intake), gains weight (energy surplus), or loses weight (energy deficit). Unfortunately this simplicity is deceptive as the model proves to be an intricate web of energetic relationships mostly based upon studies by Hudson and White (985), Fancy (986), and Hovey et al. (989). Using Hovey et al. (989) energy expenditure calculations can be grouped into 3 categories: () Maintenance costs (2) Activity costs (3) Production costs We combined the equations of Blaxter (962), Moen (973), Robbins (973), and ARC (965, 980) with Fancy (986): (6) Daily Expenditure (kj) = MC + DAC + PC where MC is the maintenance costs, DAC the daily activity costs, and PC the production costs. All units are kj/day. Maintenance Costs ( MC )

MC consists of metabolic maintenance (MAINT), thermoregulation (CT), and heat increment of feeding (HI). Blix (986) reports that reindeer are able to main-

tain a thermo gradient between the body core and environment of up to 00°C. Therefore caribou rarely experience temperatures below their lower critical value (White and Yousef 978; Nilssen et al. 984) and CT is assumed to be negligible. An extensive literature relates to the determination of metabolic rates in ruminants: cattle (Blaxter 962); sheep (Osuji 974); reindeer (Segal 962; McEwan 970; White and Yousef 978; Nilssen et al. 984); and caribou (Makarova and Segal 958; McEwan 970; Young and McEwan 975; White 980; and Fancy 986). To calculate metabolic maintenance costs we used an equation from Hudson and Christopherson (985): (7) MAINT (KJ /DAY) = HP /EFFMAINT where HP is the daily heat production (appendix and equation 9) and EFFMAINT is the efficiency at which metabolizable energy can be used for energy

Summer Energy Budgets for Lactating Females | 59

maintenance (Hudson and White 985) (APPEN .). DHeat increment of feeding HI is calculated after Fancy (986): (8) HI (kj/day) = (.0 - EFFMAINT) × MEI where MEI is the metabolizable energy intake (APPEN .). Daily Activity Costs ( DAC ) As input for the model we used observations of individual lactating female caribou observed during daylight hours through a spotting scope. Caribou were chosen randomly and followed no longer than twenty minutes. Mathematical models of daily energy expenditure are based on the assumption that the cost of each activity over and above maintenance costs can be summed arithmetically (Hudson and White 985; Fancy 986; Hovey et al. 989). The daily activity costs (DAC ) are therefore calculated as the sum of each activity: (9) DAC (kj/day) = CFORAGE + CSTAND + CLOC + CLY where CFORAGE is the cost of feeding, ruminating, and searching, CSTAND the cost for standing, and CLOC the cost for locomotion. The cost of lying (CLY) is set to zero because it is incorporated in metabolic costs. All activity expenditure calculation following Fancy (986). For the estimation of energy requirements we used data published by Blaxter (962), Osuji (974), White and Yousef (978), Boertje (985), and Fancy (986). The basic equation for each activity (ACTCOST) is: (0) ACTCOST (kj/day) = COST × TOTACT × WT where COST (kj) is the energetic cost of each activity, TOTACT (ratio) is the proportion of the day a caribou was engaged in that activity, and WT is the weight of the caribou in kilograms. The equations to calculation foraging, standing, and locomotion are in appen . TOTACT is the result of adjusting the data gathered during observation period to 24 hours (APPEN .). Production Costs (PC ) Cost of Lactation

Our annual research period started after peak calving so that gestation costs did not have to be taken into account. The cost of lactation in our model is based upon Hovey et al. (989) who calculated daily target output rates for milk production

520 | A PPEN D I X

and adjusted those by the female’s energy status. When the female experiences energy surplus, milk production is at target level. When not enough energy is ingested to meet target demands, the output of milk is reduced in direct proportion by what she needs for maximum production and what she has available. The first step is to calculate the target milk production (TARMP, White and Allaye-Chan in Hovey et al. 989, APPEN .) and the total amount of energy this represents (CLACT, APPEN .). The second step is to determine whether enough energy has been ingested to balance requirements for maintenance, activities, and hair production (ENBALANCE ) (APPEN). In doing so the model predicts whether body solids will have to be metabolized to produce milk in which case target lactation cannot be met (METFAT 68, ENBALANCE [APPEN .]). Finally the model calculates the amount of body protein loss (PLOSS [APPEN .]) if target lactation was to be met that day and then proceeds to adjust the milk production within reasonable limits: when ENBALANCE results in PLOSS ≥ 500: CLACT × 0 when ENBALANCE results in PLOSS > 250 < 500: CLACT × 0.25 when ENBALANCE results in PLOSS > 0 < 250: CLACT × 0.50 when ENBALANCE is positive but < CLACT × 0.75 when ENBALANCE is positive and ≥ CLACT × .0 With the addition of the previous corrections, the assumed total lactation costs (TOTLACT) can be calculated as: () TOTLACT (kj/day) = CLACT × ratio, where ratios vary from 0 to .0 Body Growth and Fattening The model ultimately determines the amount of weight loss or weight gain per day which will be used to determine the starting weight for the next day that observations are made. The first step is to calculate the total daily energy budget: (2) ENBUDGET (kj/day) = MAINT + HI + DAC + TOTLACT Where MEI is the metabolizable energy intake (APPEN .). To determine daily weight fluctuations, the energy surplus or deficit will have to be converted to body mass. Based on caribou experiencing gross under nutrition Hoey et al. (989) restricted the maximum amount of fat loss to 68 g/day (METFAT 68) (APPEN .). The energy deficit will therefore first be compensated by a maximum fat loss of 68 g after which only protein will be metabolized. Since the metabolization of body solids follows a 0.73:0.27 fat to protein ratio (Torbitt et al. 985; Fancy 986)

Summer Energy Budgets for Lactating Females | 52

a 68-gram fat loss will result in a 25.5-gram protein loss or the equivalent of 2,774.37 kj (APPEN .). If more than 68 g of fat are metabolized the fat: protein ratio will be 0.. The total daily fluctuations in protein (PROTLOSS /PROTGAIN), fat (FATLOSS /FATGAIN), and body weight (WTLOSS /WTGAIN) are described by three scenarios: (4) when TOTENBALANCE is ≤ 2,774.37 kj; PROTLOSS (g/day) = 25.5 + (ENBUDGET - MEI 2,774.37/23.85/0.84) FATLOSS (g/day) = 68 WTLOSS (g/day) = PROTLOSS + FATLOSS (5) when TOTENBALANCE < 0 > -2,774.37 kj PROTLOSS (g/day) = (0.27 × ENBALANCE )/23.85/0.84 FATLOSS (g/day) = (0.73 × ENBALANCE )/39.75/0.84 WTLOSS (g/day) = PROTLOSS + FATLOSS (6) when TOTENBALANCE is positive PROTGAIN (g/day) = 0.27 × ([ENBALANCE /23.85] × EFFPROD) FATGAIN (g/day) = 0.73 × ([ENBALANCE /39.75] × EFFPROD) WTGAIN (g/day) = PROTGAIN + FATGAIN

EFFPROD is the efficiency of using metabolizable energy from body growth (APPEN .). The efficiency with which body solids are metabolized is set to 84% (ARC 980). The energy content of  gram of fat is 39.75 kj and for  gram of protein 23.85 kj (Van Es 977). For the production of hair (HAIRCOST) we used the estimate of Boertje (985) of 620 kj/day. Satellite Telemetry Data provided through satellite telemetry programs established by the Newfoundland and Labrador Wildlife division were used to complement the energy budget model. In most cases satellite collars (Telonics, Maryland, USA) provided data on a four-day cycle. We used satellite telemetry data from George River adult female caribou only. Satellite data provided information of activity and travel characteristics and are used to determine extrapolation factors to extend forage intake and activity to 24-hour input values for the model (APPEN .). Satellite telemetry data provided 2 sets of captivity parameters; short-term (STA) and long-term activity (LTA). Mercury switches in the collar can flick a maximum of 60 times per minute if (the neck of) the caribou moves continuously. Short-term activity codes therefore represent the number of seconds per minute a caribou was active during satellite overpass and are stored in counts

522 | A PPEN D I X

varying from 0 to 60. Regelin and Whitten (986) and Fancy et al. (989) noted correlations of short-term activity counts with caribou behaviour and divided the counts into 5 behaviour classes: lying = mean count of /minute foraging = mean count of 4.5/minute standing = mean count of 0/minute walking = mean count of 27/minute running = mean count of 55/minute The long-term activity index is based on the constant accumulation of shortterm activity count and indicates activity during 24 hours prior to satellite overpass. We compared the satellite generated long-term activity with our own observed activity budgets (APPEN .) and found that both indices are acceptably similar during the pre-insect season. However in the only year with distinct periods of insect activity (988) discrepancies between both parameters during days of insect harassment indicated that caribou were less active outside observation hours. Based on this discrepancy and a 24-hour observation on 6–7 July in 990, caribou then seem to engage in more feeding and less locomotion during cooler and darker periods of the day. We assumed that during periods of insect activity, caribou adopted pre-insect activity budgets from 00:00–07:00 hours during periods when mosquitoes are active and from 20:00–08:00 hours during periods when warble flies and/or tabanids are active. Based on daily insect monitoring data, periods of insect activity each study year were: 988 Mosquitoes 2–3 July, Warble flies –3 August 989 Tabanids –4 July 990 Mosquitoes 2–5 July 99 No insect activity Coordinates provided through satellite telemetry were processed by ARGOS data utility software to obtain daily travel distances up to December 990. In 99 and 992 location data were processed through DBASE III + programming and selected location data were plotted on maps (:500,000) to determine travel distance and speed. In June 988 satellite-collared caribou from the Red Wine caribou herd transmitted on a daily basis. When the straight-line distances from day  to day 4 were compared with the sum of individual distances, 4-day intervals underestimate the actual travelled distances by 30% (n=4). For the purpose of calculating energy requirements we multiplied the satellite-generated travel distance by .3 (APPEN .). Travel routes were also copied onto :250,000 scale maps and by counting contours daily differences in altitude were determined (APPEN .).

Summer Energy Budgets for Lactating Females | 523

Table 1A Bite rate, bite size, and forage intake as determined by observation (this study) and jaw-movement recordings for bite rate compared with Central Arctic herd¹ Forage Category

George River Herd (1988) Bite Rate Bite Size Biomass (Bites/Min.) (mg Drywt) g/m²

Grasses² Grasses/Herbs Lichens Betula³ Salix⁴

98.0 185.0 192.0 32.2 30.5

12.0 25.4 44.0 10.7 24.0

26.0 21.2 443.0 30.1 76.4

Central Arctic Herd Bite Rate Bite Size Biomass (Bites/Min.) (mg Drywt) g/m²

173 – 205 186 177

20 – 32 58.8 52.9

25.9 – 263.1 – –

Forage Intake per Minute (Gram Dry Weight)

Betula Salix Grasses Grasses/Herbs Lichens Tundra Shrubs⁵ Bryophytes ¹ ² ³ ⁴ ⁵ ⁶ ⁷

3.44 7.32 2.38 4.69 8.45 0.86⁶ 0.50⁷

40.92 40.71 4.46 – 6.56 – –

Central Arctic herd from Trudell and White 98 For George River mainly misc spp. and Scirpus, for Central Arctic Carex aquatilis For George River Betula glandulose and for Central Arctic Betula nana For George River Salix planifolia, for Central Arctic Salix pulchra Vaccinium spp. and Arctostaphylos spp. Assumed to be 25% Betula intake Assumed based on moss cover and moss biomass during simulations

Energy Intake Bite rates are strongly correlated with the coverage of the target species (Trudell and White 98) so that a scarce distribution of palatable plant proportions in a feeding site will negatively affect the number of bites per minute. Bite rate for the 5 forage groups (table A) were generally within the forage found by Trudell and White (98) except for both Betula and Salix. Our lower bite rates can likely be attributed to decreased biomass of the recently overgrazed summer range which resulted in less leaves and more denuded leaders. Under these circumstances caribou may resort to stripping more than biting, also lowering the bite rate per minute. While bite rates of graminoids and shrubs are more easily determined because of distinct head/jaw movements, lichen ingestion was difficult to monitor because of the frequent lip movements rather than distinctive bites and the lichens on the summer ranges were extremely fragmented. Although the mean

524 | A PPEN D I X

biomass in our lichen simulation sites was 89 g/m² higher, bite rates are similar in both studies (table A), supporting the finding of White and Trudell (98) that physical proportions of lichens are important. Bite size is related to phytomass of palatable plant proportions in a feeding plot (Trudell and White 98), but may differ between feeding sites because of factors such as soil fertility, exposure, and accessibility. Comparing bite sizes for 4 forage classes with the results of the Central Arctic herd showed that for graminoids bite sizes were low, although bite rate and biomass were equal. Bite sizes for Betula glandulosa and Betula nana were correlated to phytomass which strengthens the assumption that our much less precise technique appears comparable to experiments with fistulated caribou. Since our intake estimates were within reasonable range of data reported by Trudell and White (98) we feel confident in using them for determination of daily dry matter intake. Diet Composition Graminoids increasingly dominated the June diet of George River females from 58% in 988 to 80% in 99 (table 2A). Since very little herbs remained on the summer range, graminoids were the dominant forage emerging after snowmelt. As shown by Bliss (962), West and Meng (966), Pegau (968), Miller (976a), Holleman et al. (980), White (980), and Boertje (98) the calorific contents of forage varies little, approximately 20 kj per gram dry weight. The digestibility (APPEN .) however greatly influences the availability of forage calories for metabolism. Although caribou feed selectively in order to avoid high crude fiber levels (White et al. 98), up to 60% of ingested graminoids may be dead at the start of the George River growing season and thus highly indigestible and inadequate to balance energy requirements. Depending on phenology, buds and/or leaves from highly-digestible shrubs (Betula, Vaccinium, and Salix) made up to 8% of ingested forage (table 2A) and although palatability, nutrient, and calorific values change (Hankioja 978), deciduous shrubs provided the bulk of energy for female caribou in July when up to 48% of the rumen contents was comprised of woody leaves and stems and 98% of the observed ingestation was birch and willow. We argue with Crête et al. (990a) that leaf rarity in July may have been a significant factor in regulating energy intake. Boertje (984) and Chapin (980) attributed a temporary intensive use of tundra shrubs Vaccinium and Arctostaphylos prior to bud break in birch to the combined effect of high nutrient content and low content of plant defense structures. Lichens were not abundant on the George River calving range, and although highly digestible, were available in diminishing quantities from 988 onward with ingestion decreasing to 2% in 990 (table 2A). Although Svalbard reindeer (Tyler 987) and Peary caribou take in moderate amounts of bryophytes throughout the

Summer Energy Budgets for Lactating Females | 525

Table 2A Late spring and summer diets (%of total diet) for George River females based on observations (1988–91) and rumen analysis by Crête et al. 1990a George River Observations Plant Categories

Jn

Graminoids 55 Grass/Herbs – Lichen 19 15 Betula Salix – 2 Shrubs² Bryophytes 6 Others – Woody Leaves – Woody Stems –

1988 Jy

Au

Jn

1989 Jy

Au

1990 Jn Jy

1991 Jn Jy

15 2 1 59 23 – – – – –

– – – 13 85 – – 2 – –

59 – – 32 – 8 – – – –

17 – 7 72 – 33 – – – –

– – 13 86 – – – – – –

77 – – 10 – 12 – – – –

80 – – 13 – 7 – – – –

14 – 2 80 – 3 – – – –

64 – – 34 1 2 – – – –

George R. (Rumens) 1988¹ Jn Jy

61 – 11 – – – – 3 7 3

34 – 8 (48) – (48) – 5 40 8

George River Observations (This study, 988, 989, 990, 99) George R. (Crête et al. 990a) ¹ Rumens in 988 n=7 in June and n= in July ² Tundra shrubs are mostly Vaccinium spp. and Arctostaphylos spp. (48) in rumen samples from all identified shrub fragments in rumens

year, they are not preferred as forage species because of their poor digestibility and are usually ingested along with other vegetation. Daily Dry Matter Intake There does not seem to be a consistent chronological trend in DMI among study years (table 3A ; fig. 7.2). The lowest seasonal DMI (.9 kg) was in 988, when and our sampling methods were being perfected, whereas the highest intake (4.2 kg) was in 99. DMI during periods of insect activity was directly dependent upon levels of insect harassment: when mosquitoes were active in July intakes were particularly low (2. kg in 988 and .8 kg in 990) due to a drastic decline in foraging time. During periods with warble fly or tabanid activity 988 and 990 DMI showed drastic fluctuations .8 kg to 4.5 kg (table 3A) but average intakes were higher than during mosquito harassment: 2.5 kg (988) and 2.6 kg (990). The diurnal activity of warble flies and tabanids probably requires foraging at night (Downes et al. 986) and on days that insects are not bothersome. The average DMI during periods of mosquito activity was consistently lower because mosquitoes were present in greater numbers inland and were also active during most dark hours, providing almost constant harassment. Chan-McLeod et al.

526 | A PPEN D I X

Table 3A Average dry matter intake ( DMI , kg) of lactating George River caribou compared to the Denali¹ and Central Arctic² herds in Alaska George River Herd

Summer June July August Pre-insect Mosquitoes Oestrids Tabanids

Denali

1988 (n)

1989 (n)

1990 (n)

1991 (n)

Mean

1978–79

Central Arctic 1972?

1.937 (41) 0.586 (11) 2.347 (18) 2.561 (12) 1.551 (21) 2.078 (9) 2.561 (12) –

3.066 (32) 3.097 (14) 2.989 (16) 3.469 (2) 2.649 (36) – – 2.675 (4)

2.910 (33) 3.823 (18) 1.735 (14) – – 1.843 (4) – –

4.223 (25) 4.548 (5) 4.132 (20) – – – – –

2.895 2.945 2.897 2.648 2.244 2.006 2.561 2.561

3.21 2.72 3.42 3.54 – – – –

– 2.90 3.22 3.22 – – – –

¹ Denali from Boertje (985) simulation value for August and latter half of July ² Central Arctic herd from White et al. 975 August taken from latter half of July

(995) argued that Rangifer fed ad libitum experience a depressed appetite drive and feed intake in July due to hot weather. DMI is dependent upon phenology; if sufficient standing biomass is unavailable, caribou will continue to forage but ingest relatively little. The prime example is the post-calving period in June 988 when 64% of the day spent feeding accounted for a DMI of only 0.586 kg/day. Our calculated sMI values are within range of DMI for Rangifer but sometimes differ significantly from other studies (table 3A). After 988 DMI of George River females is comparable with DMI estimates for other herds and in August exceed average quality. The George River summer range is overgrazed and quantities of highly metabolizable forage do not become available until deciduous shrubs start budding. As mentioned June diets are dominated by the intake of up to 80% grass in 99 of which up to 80% may consist of dead material (table 2A). Metabolizable Energy Intake ( MEI ) When forage is ingested its calorific content is not wholly available for metabolic processes. Part of the energy is locked into indigestible compounds and therefore lost (factor Qd) and only a portion of the digestible forage (factor Qm) can be used for metabolization (table 4A). Since MeI is largely dependent upon forage intake (DMI) similar fluctuations occur between both parameters. During the summers of 988 and 989, MeI increased from June to August. The June 988 MeI (4,47 kj) is extremely low because of low forage intake (0.586 kg). In midand late summer of both years MeI was largely determined by the ingestion of highly-digestible forage of birch and willow. During the summers of 990 and

Summer Energy Budgets for Lactating Females | 527

Table 4A Daily metabolizable energy intake ( MEI , kj/day) and the average metabolizability coefficient (QM ) for George River females and three Alaskan herds 1988 MEI /QM

Summer June July August Pre-insect Mosquitoes Oestrids Tabanids

19,599/ 0.44 4,417/ 0.38 22,148/ 0.42 29,693/ 0.53 13,271/ 0.39 21,071/ 0.46 29,693/ 0.53 –/–

George River Herd 1989 1990 1991 MEI /QM MEI /QM MEI /QM

24,340/ 0.37 20,357/ 0.33 26,302/ 0.39 36,533/ 0.48 24,417/ 0.35 –/–

Denali Mean

Porcupine Central Herd Arctic

MEI

MEI

MEI

MEI

21,185

34,980

–

–

19,410

29,282

28,168

28,343

22,862

37,405

59,901

34,479

33,113

38,150

–

28,343

19,616/ 0.34 23,192/ 0.32 15,017/ 0.38 –/–

28,372/ 0.33 29,674/ 0.32 27,981/ 0.33 –/– –/–

19,184

–

–

–

–/–

18,474

–

–

–

–/–

19,865/ 0.34 15,876/ 0.39 –/–

–/–

–

–

–

–

22,872/–

–/–

–/–

–

–

–

–

Denali herd weight for June female 00 kg and July/August 05 kg (Boertje 985). Porcupine female weight June 90 kg, Central Arctic lactating caribou 90 kg (White et al. 975). The low reading for the George River herd in June 988 may be in part explained because we were just developing the methods and also readings were done on the northern edge of the calving ground.

99, observations did not extend into August when foraging on birch and willow seems to enhance the diet, so that the average daily MeI in 990 is lower than in the preceding two years. MeI in July 990 was the lowest estimate for all years, and although birch accounted for 80% of the diet, the lack of sufficient quantities (.735 kg of forage daily) lowered MeI . MeI for the 99 period showed that quantity is not necessarily the answer to physiological well-being: a 38% increase in dmI compared to 989 did elevate MeI only 6.5%. Nevertheless, the highest MeI estimates were recorded in 99. Sprouting of deciduous shrubs was substantially delayed in the 99 season and female caribou were confined to poorly-digestible graminoids (80% in June and 64% in July). In comparison with other herds (table 4A) MeI for the George River females was consistently lower. By changing caribou behaviour, insect activity has profound effects on forage ingestion and MeI (table 4A). The advancing phenology and plant palatability make it difficult to compare MeI in periods of insect activity with the pre-insect season from an energy-intake point of view; 988 MeI was lowest before insect activity occurred although feeding activities were the highest, which has every-

528 | A PPEN D I X

ENERGY (× 1,000 kJ)

40

TOTAL EXPENDITURE LACTATION MAINTENANCE ACTIVITIES HEAT INCREMENT

35 30 25 20 15 10 5 0

Fig. 2A

1988

1989

YEAR

1990

1991

Daily energy expenditure segregated into the major losses.

thing to do with forage availability. The only study year that had distinct periods of insect harassment was 988. Daily MeI was higher during the periods when oestrids were active (August) than when mosquitoes were active (end of July) although diet and forage metabolizability were more or less the same (tables A and 4A). MeI fluctuated strongly during the periods of mosquito activity and was consistently lowered and more stable because mosquitoes are present in greater numbers, are active during dark hours, and trigger herd aggregation, all requiring forage intake and affecting MeI . When comparing MeI with the initial calorific contents of forage, the metabolizability factor Qm is obtained (table 4A). Qm changes with forage quality; the more digestible the forage, the higher its metabolizable value. Metabolizability rises when the summer progresses because the proportion of ingested highlydigestible live plant material increased. When during the summer birch and willow (live portions 00%) are ingested, Qm can be 0.57 whereas for a June diet based predominantly on graminoids, the average Qm will range from 0.24 to 0.38. Energy Expenditure Results Over the research period energetic requirements for body maintenance and homeothermy are by far the largest: between 35–45% of the total energy budget, followed by heat increment of feeding and lactation (table 5A ; fig. 2A). Daily activity costs weigh relatively light, although locomotion can represent up to 0% (988). Heat increment costs varied between 23 and 32% which conforms

Summer Energy Budgets for Lactating Females | 529

Table 5A Mean daily expenditures (kj) and their proportion of the total daily energy budget for George River caribou for the summers 1988 to 1991 Total Expenditure

Maintenance kj %

Heat kj %

Standing kj %

Locomotion Foraging kj % kj %

Lactation kj %

1988

Summer June July August Pre-insect Mosquito Oestrids

26,625 18,358 28,804 30,935 23,922 27,073 30,935

11,389 1,248 11,397 10,369 1,213 10,976 10,369

42.7 68.0 39.6 33.5 50.6 40.5 34.5

6,388 1,605 7,526 9,067 4,757 6,653 9,067

23.9 8.7 26.1 29.3 19.8 24.6 29.3

133 55 120 225 44 230 224

0.4 0.3 0.4 0.7 0.2 0.8 0.7

2,711 1,643 2,665 3,760 1,716 3,752 3,760

10.2 8.9 9.2 12.2 7.2 13.8 12.1

1,287 1,754 1,317 813 1,751 779 813

4.8 9.5 4.6 2.6 7.3 2.9 2.6

4,153 249 5,216 6,139 3,032 4,120 6,139

15.6 1.4 18.1 19.8 12.6 15.2 19.8

31,848 29,218 33,575 36,441 31,994 30,823

12,816 1,348 1,239 11,467 12,876 12,397

40.2 8,812 27.7 111 46.1 7,758 26.5 13 36.9 9,408 28.0 193 31.5 11,418 31.3 150 40.2 8,907 27.8 107 40.2 8,147 26.4 140

0.3 0.0 0.5 0.4 0.3 0.4

3,023 2,041 3,636 4,986 2,945 3,464

9.0 6.7 10.8 13.7 9.2 11.2

1,144 1,228 1,095 957 1,147 1,124

3.5 4.2 3.3 2.6 3.6 3.6

5,379 4,130 6,282 6,900 5,449 4,889

16.8 14.1 18.7 18.9 17.0 15.9

28,048 29,943 25,611 28,102 27,225

12,625 1,314 11,959 12,692 11,626

45.0 43.9 46.7 45.2 42.7

0.1 0.1 0.2 0.2 0.1

1,633 1,166 2,229 1,563 2,654

5.8 3.9 8.7 5.6 9.7

1,374 1,623 1,955 1,393 1,091

4.8 5.4 4.1 4.9 4.0

4,386 4,435 4,322 5,548 4,308

15.6 14.8 16.9 19.7 15.8

1989

Summer June July August Pre-insect Tabanid 1990

Summer June July Pre-insect Mosquito

7,424 8,969 5,438 7,539 5,711

26.4 29.9 21.2 26.8 21.0

44 44 44 45 33

1991

Summer June July

35,354 11,868 34.5 10,855 31.6 34,919 12,192 34.9 11,385 32.6 34,185 11,771 34.4 10,696 31.1

25 0.0 38 0.0 21 0.0

2,423 7.0 1,487 4.3 7,133 20.7 1,769 5.1 1,540 4.4 7,432 21.3 2,620 7.7 1,471 4.3 7,044 20.6

with Fancy (986) who reported 3% in March, 29% in April, and 22% in June for standard diets. The high increment cost for 99 is directly related to the poorly digestible diet of graminoids in June (80%) and July (64%). We agree with Fancy (986) on the importance of calculating heat increment costs separately since they may change considerably with fluctuation in the diet. Energy requirements for daily activities added up to 5% of the energy budget (table 5A). Of these requirements locomotion is the most demanding: up to 65% of activity expenditures. During periods of insect activity increase in energy requirements occurred: during mosquito harassment expenditures can be fairly constant (fig. 4.6, 988 Julian days 94–23) whereas they can fluctuate dramatically during warble fly and tabanid periods (fig. 4.6, 988 Julian dates 24–232 and 989 Julian dates 92–95). Although caribou require more energy for loco-

530 | A PPEN D I X 2,500

MILK PRODUCTION (ml)

TARGET LACTATION ACTUAL LACTATION

2,000

1,500

1,000

500

0

J

J

1988

A

J

J

A

1989

J

J

1990

J

J

1991

YEARS Fig. 3A Target lactation and actual milk production of George River lactating females during the study years of 1988 to 1991.

motion (walking and running) during insect harassment, those activities will only slightly elevate the total daily budget. It is not so much on the expenditure side that insects have a pronounced impact but more on preventing sufficient intake of forage. Lactation represented a fairly large proportion of the total energy requirements, 5–20% (table 5A ; fig. 2A). Lactation is dependent upon metabolizable energy that is available above normal daily energy requirements. Ideally, lactation is therefore largely determined by a surplus in the energy balance. However, cows will lactate even when their energy balance is negative (Hovey et al. 989), but will then metabolize body solids. In such a scenario target lactation will never be reached but will vary depending on the age of the calf and severity of the energy deficit (table 8.). Based on the differences between target lactation and real milk output during the study there seems to be a continuous shortage of milk for George River calves: target lactation was never reached in these years of high numbers (fig. 3A). Particularly during the first weeks of age calves experienced a shortage of milk when production was between 2 and 75% of target output (fig. 3A). During July and August (except 990) target lactation levels were met somewhat better (up to 85%) but the chronic shortage of milk production will hold serious implications for calf survival (White 983; Skogland 984b). When target lactation can be maintained throughout calf weaning the

Summer Energy Budgets for Lactating Females | 53

Table 6A

Daily summer scenarios for George River caribou, 1988–91 Average Age of Calf (days)

Target Lactation (ml)

13 30 55

1,648 1,969 1,781 1,154

8 28 58

1,659 1,530 1,841 1,118

7 24

13 29

Actual daily Target vs Production Actual (ml) Lactation (%)

Target Lactation Costs (kj)

Actual Lactation Costs (kj)

1988

Summer June July August

602 48 (?) 853 734

36.5 2.4 47.8 63.6

10,529 11,120 10,799 9,584

4,153 249 (?) 5,216 6,139

876 630 1,100 809

52.8 41.2 59.8 72.4

10,458 10,185 10,830 9,390

5,379 4,130 6,282 6,900

1,615 1,348 1,957

733 707 766

45.3 52.4 39.1

9,697 8,679 11,006

4,386 4,435 4,322

1,822 2,011 1,766

1,193 1,336 1,150

65.5 66.4 65.1

10,913 11,141 10,845

7,133 7,432 7,044

1989

Summer June July August 1990

Summer June July 1991

Summer June July

energetic requirements will become less with a progressing calf age because milk production decreases after the calf is older than 2 days and although there is a gradual increase in energy content of every ml of milk produced after the first three weeks of lactation, overall costs decline (table 6A). In the first two years, expenditures increased throughout the summer, whereas in 990 and 99 July requirements were smaller than in June (fig. 4.6). There is also a remarkable similarity in these fluctuations; when intake increases, expenditures will do likewise. There are several reasons for this. Firstly, lactation costs are determined on the basis of an energy deficit or surplus and are adjusted accordingly. When a lactating female loses 500 g of body solids per day, target lactation cannot be reached so lactation costs are lowered. When the energy deficit becomes less or when a surplus can be attained, more milk can be produced, increasing the energetic requirements. Secondly, an increase in forage intake requires more energy for digestive processes and there will also be an increase in the heat increment of feeding. Obviously, those costs will not increase on a : basis because ingestion of more forage would then be quite ineffective from an energetic point of view. The net result is that an increase in energy intake corresponds with an increase in energy expenditure. Only when intake is higher than

532 | A PPEN D I X

Table 7A Daily energy requirements (kj/kg 0.75) for George River lactating caribou and other studies George River (This Study)

Denali (Boertje 1985)

Central Arctic (White et al. 1975)

Western Arctic (Hollmann et al. 1980)

Porcupine Cen. Arctic Fancy (1986)

1,014 1,165 1,121

1,022 1,163 1,086

1,142 1,058 1,058

1,200–1,300 1,200–1,300 1,200–1,300

1,200–1,400¹ 2,004–2,170² –

Period

Post-calving Insect Season Summer

¹ Calving and post-calving for Porcupine females ² Insect season for Central Arctic females

total energy requirements (including lactation) will such a trend cease to exist; that did not happen very often for George River females. An exception to this is the maintenance costs which are ruled by body weight and the metabolizability of the forage (equation 7). Since metabolizability increases when more palatable vegetation becomes available, maintenance costs decreases slightly throughout the summer. Only after  August (> Julian date 22) did we observe a possible balanced budget (fig. 4.6). Unfortunately, 988 was the only year with sufficient data to show this. When comparing years to 3 July (< Julian date 22) then with the exception of 988, the discrepancy between intake and expenditure only widens. During periods of insect harassment it is the reduced forage intake that negatively influences the energy balance: forage intake regressions also showed slightly steeper slopes. Since George River caribou aggregated on an already overgrazed summer range they moved more often to locate suitable foraging sites and because of group size, foraging was frequently interrupted. This created a highly unfavorable situation for balancing energy requirements. It is our impression though that weight gain did occur after mosquitoes harassment was largely over and caribou travelled away from the overgrazed June/July range in smaller groups. Our model’s estimates of metabolizable energy requirements are in close range with those for other herds (table 7A). With the exception of the Western Arctic herd, requirements also increased during periods of insect activity. Fancy (986) reports higher requirements for Porcupine lactating caribou which is due to the substantial effect of lactation he calculated and the higher predicted daily travel rate of 30–70 km/day versus –5 km/day for George River females (mean June, July, and August 988 to 99). The somewhat higher overall requirements for other caribou herds are probably due to the incorporation of expenditures for growth and fattening, two categories that are not included in the George River energy model.

Summer Energy Budgets for Lactating Females | 533

Weight Implications The model provided sufficient data to quantify weight fluctuations in the months of June and July, a period when the weight cycle is expected to be low (Dauphiné 976) but should be in the early stages of recovering. A positive balance creates body growth whereas a negative balance metabolizes body solids, implicating weight loss. George River females, however, did not experience this turn around. The females kept losing weight, experiencing total weight losses of 5, , 2.5, and 6.7 kg respectively in 988, 989, 990, and 992 (table 8A). Because of the varying number of days of observation, daily weight losses were 0.359, 0.346, 0.328, and 0.250 kg for each of the four study years. There was a gradual decline in the amount of weight loss over the years and although weight was still lost during the summer of 99 the trend suggested a slight improvement. Caribou on a starvation diet metabolize a maximum of 68 g of fat per day (Hovey et al. 989). Since body solids are metabolized in a 0.73:0.27 fat to protein ratio, the metabolization of 68 g of fat involves 25 g of protein. The remainder of the energy deficit will be matched by burning body protein only, increasing weight loss sharply since protein (muscle) does not contain as much energy as fat. For June 988 and July 990 fat loss was maximum and associated with average protein loss of 582 and 45 g (table 8A). The June 988 value may be biased high since we were refining our observation techniques and observing at the extreme northern edge of the herd. On a daily basis however maximum fat loss resulted on a fair number of days in the four years (table 8A). The predicted weight loss by Fancy (986) for a 90 kg female during the first 9 days of calving is .8 kg of fat. This would result in a daily total weight loss of 0.274 kg which is 38 g less than the overall June average loss for the George females, excluding June in the calculations. But our observations were after calving (most calving occurs in June). During the various periods of insect activity George River caribou may have fared slightly better than in the June months. During mosquito harassment daily weight loss was still high (0.354 and 0.52 kg/day in 988 and 990). The diurnal activity of warble flies made it easier for caribou to compensate for lost foraging time at night or when weather conditions did not favour insects. In 988 this resulted in some days with a slight weight gain. Fancy (986) in modeling energy requirements for lactating Porcupine females (90 kg) calculated negative energy balance on days when mild or severe insect harassment occurred for more than 2 hours. For George River females negative energy balances occurred on days with mild/severe mosquito and warble/tabanid harassment (chapter 4, fig. 4.8) and Kelsall (975) also relates the frequency and intensity of insect harassment to the decreased possibility of acquiring fat deposition during the summer. However in August after mosquitoes abated, energy budgets were generally positive except on mild, calm days when warble flies and/or tabanids took up the chase.

534 | A PPEN D I X

Table 8A Average daily fluctuations for George River lactating female caribou during the 1988–91 seasons Season

Energy Balance (kj)

Total Weight Fluctuations (kg)

Body Fat Fluctuations (grams)

Body Protein Fluctuations (grams)

Body Weight (kg)

-7,026 -13,941(?) -6,656 -1,242 -10,720 -6,002 -1,242

-0.359 -0.650 -0.332 -0.133 -0.491 -0.354 -0.133

-37.5 -68.0 -42.9 -2.0 -67.5 -12.8 -2.0

-321.4 -582.5 -288.6 -131.4 -422.5 -341.2 -131.4

74.02 81.41 74.34 70.55 78.78 72.40 70.55

-7,507 -8,861 -7,272 +93 -8,291 -7,951

-0.346 -0.399 -0.321 -0.165 -0.344 -0.356

-57.3 -64.4 -62.6 +35.1 -56.6 -61.7

-288.4 -334.9 -258.7 -200.2 -287.6 -293.9

83.44 86.74 81.55 78.09 77.83 81.05

-8,432 -6,751 -10,593 -8,238 -11,352

-0.388 -0.315 -0.583 -0.397 -0.521

-60.1 -53.9 -68.0 -59.6 -68.0

-328.4 -260.7 -415.4 -321.1 -435.2

80.04 82.97 76.53 80.39 74.70

-5,982 -5,245 -6,204

-0.258 -0.222 -0.268

-62.8 -58.9 -63.9

-195.1 -163.6 -204.5

73.03 75.72 72.26

1988

Summer June July August Pre-insect Mosquito Oestrids 1989

Summer June July August Pre-insect Tabanids 1990

Summer June July Pre-insect Mosquito 1991

Summer June July

Starting weight 988 84.75 kg; final weight 69.7 Starting weight 989 89.2 kg; final weight 77.83 Starting weight 990 85.44 kg; final weight 72.90 Starting weight 99 76.25 kg; final weight 69.54

Surprisingly, George River females appear to be in reasonable physical shape during late winter (chapter 0). Summer weight loss can (partly) be compensated for by rapid fat disposition in late summer and early fall thorough increased intake of non-structural carbohydrates (Skoog 968; Boertje 985). The wintering ranges that the George River herd has occupied in the last decade support a significantly higher biomass and, through lower maintenance costs due to a decrease in metabolic rate, fattening could also take place during the winter.

Summer Energy Budgets for Lactating Females | 535

Table 9A Average daily summer weight fluctuations (kg) for lactating and barren George River females 1988 Lactating Barren

Weight Weight Change

75.02 -0.36

76.82 -0.25

1989 Lactating Barren

81.41 -0.34

86.34 -0.16

1990 Lactating Barren

74.34 -026

82.85 -0.21

1991 Lactating Barren

70.55 -0.26

76.39 -0.01

Weights mostly from captures made by S. Luttich in June (chapters 8 and 9)

The energy balance for non-lactating George River females can be obtained when lactation costs are subtracted from total energy requirements. Overall, non-lactating females spent 6.3% less energy that lactating females. The trend in weight fluctuations is similar to that of lactating females but only 80 g weight loss experienced during the summer (table 9A). Chan-McLeod et al. (995) found that daily energy requirements for non-lactating caribou fed ad libitum in an experimental situation was half that of lactating individuals. Barren females may therefore fare better than their pregnant and lactating peers. Females suffering from a prolonged energy deficit will likely delay the estrus cycle with one interval and may not conceive in their second year (Leader-Williams 980, White et al. 98). Dauphiné (976) found that it may be up to 3.5 years before peak conception and annual breeding is attained. It can be argued that lactating females surviving the summer may not be able to recuperate sufficiently before the rut and thus may not conceive in the same year as they produced a calf. Conclusions We conclude that the major ingredients for the almost continuous weight loss scenario of George River females is the lack of sufficient and highly-digestible forage and the impact of insect harassment. Ultimately this seems to regulate the George River herd through a combination of poorer cow and calf survival as well as decreased fecundity (chapter 3). Chan-McLeod et al. 994 showed that for penned Rangifer under controlled situations on an ad libitum feeding regime, energy intake is the only variable significantly affecting body mass. For George females the most distressing months are June because of the poor forage situation (highly indigestible, low biomass) and July because of mosquito harassment. The effect insects have on the energy budget is profound and not so much because they affect active expenditures (only about 0% of the energetic requirements go to activity), but because of reduced forage intake (fig. 4.8) and a decline in time spent feeding.. During mosquito activity a maximum daily weight loss of 0.7 kg is predicted since the harassment persists during most of the day. During periods

536 | A PPEN D I X

with tabanid and/or warble fly activity females may balance energetic requirements because a diurnal harassment pattern makes it possible of forage extensively at night. During early summer George River animals showed a disproportionate affection for the intake of graminoids up to 80%. Intake in this period is mostly based on the availability of graminoids over herbs (intake of herbs was practically nil) and deciduous shrubs. At the end of the summer caribou were sustained mostly by birch and willow and favoured graminoids (i.e. Poa spp) because these can maintain a high level of primary production associated with a reduction in nonstructural carbohydrates (Chapin 980). We noted that between 35–80% of individual Betula branches were dead due to the continuous removal of leaves and apical meristem: a 988 survey of an extensive field of birch after a herd of 8,000 caribou had fed there for 2 days showed an 80% reduction to green biomass. Lichens were rare on the summer range and in their diet because stands had been disturbed for foraging caribou and lichens above tree line were mostly dead and shattered (chapter 7). Intensified grazing has a profound effect upon individual plant species since each plant differs in its response to grazing and the animals are selective in their choices. It is therefore not surprising that overgrazing has substantially affected the plant community structure and ecosystem functions in the lowland tundra summer range. The trends for dry matter intake, metabolizable intake, and weight fluctuations show great similarity because they are all dependent upon forage intake. Since activities, once translated in energetic, are relatively constant for all caribou, weight trends follow those in forage intake. Energy Expenditure Activity requirements of George River females comprised about 0% of the energy budget. The bulk of the balance was determined by lactation, heat increment, and metabolic maintenance. We have shown that those expenditures require the largest energetic investments and therefore may more rapidly deplete body reserves. Non-lactating females are able to maintain higher body weights and spent on average 6% less energy. For George females, the combined effect of insufficient forage intake with relatively high energetic requirements through lactation, maintenance, and increasing locomotion resulted in an average weight loss of 0.342 kg/day, the majority of which was protein loss. On some days weight was gained, usually in late August, and possibly once having survived the summer, undernourished females may gain weight in late summer–early fall (ChanMcLeod 99; Renecker and Samuel 99 for mule deer). Fancy (986) models this impact in a hypothetical “worst-case-scenario” of low phytomass and insect harassment for lactating females; this scenario resulted in .8 kg weight loss. Our model’s weight loss ranged from 5.0 to 6.7 kg (much higher than other studies such as Boertje 985; Fancy 986; Chan-McLeod et al. 994) and some of our

Summer Energy Budgets for Lactating Females | 537

animals starved. Females found starved by L. Camps were 3 in 988, 2 in 987. On helicopter searches for radio-tagged animals S. Luttich located 9 starved females 982 to 987. In June 992 a lactating cow L. Camps was watching died abruptly after crossing a .5-km lake. The autopsy revealed very little body reserves along with a remarkably low subcutaneous temperature.

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Bibliography

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Gagnon, L., and Barrette, C. 986. Inventaire terrestre des caribous de la Rivière George sur l’aire de mise bas, June 986. Québec: Ministère du Loisir, de la Chasse et de la Pêche, Québec. Gagnon, L., and Barrette, C. 992. Antler casting and parturition in wild female caribou. J. Mammal. 3:440–42. Garner, G.W., and Reynolds, P.E., eds. 986. Final baseline study of the fish, wildlife and their habitats. Sec. 002C . Vol I , –392. Anchorage: US Dept. of the Interior, Fish and Wildlife Service Region 7. Gates, C.C., Heard, D.C., and Kearney, S. 983. Census of the Kaminuriak caribou population on its calving ground in 983. Unpubl. Rept. -29 Yellowknife: Northwest Territories Wildlife Service. Gates, D.M. 993. Climate Change and Its Biological Consequences. Sunderland: Sinauer Associates. Gauthier, L.R., and Shooner, G. 988. Analyse de laboratoire du contenu du rumen de 66 caribous récoltes au Nouveau-Québec. Rapport présenté au Ministère du Loisir, de la Chasse et de la Pêche: Gestion des Espèces et des Habitats. Loretteveille: Gilles Shooner and Assoc. Gauthier, L.R., Nault, R., and Créte, M. 989. Variations saisonnières du régime alimentaire des caribous du troupeau de la Rivière George, Québec Nordique. Naturaliste Canadien 6:0–2. Geist, V. 998. Deer of the World: Their Evolution, Behavior, and Ecology. Mechanisburg: Stackpole Press. Geist, V., and Walthers, F., eds. 974. The Behaviour of Ungulates and Its Relation to Management, Vol.I and Vol. II . Morges: IUCN . Gerhart, K.L., White, R.G., Cameron, R.D., and Russell, D.E. 996. Body composition and nutrient reserves of Arctic caribou. Can. J. Zool. 74:36–46. Goudreault, F., Le Hénaff, D., Crête, M., and Luttich, S. 985. Dénombrement des caribous sur l’aire de mise bas du troupeau de la Rivière George par photographies aériennes verticales en juin 984. Québec: Ministère du Loisir, de la Chasse et de la Pêche. Goudreault, F., and Luttich, S. 985. The impact of simultaneous handling of caribou cows (Rangifer tarandus caribou) and their calves on the post release mother-infant bond. Proc. 2nd North American Caribou Workshop, 3–38. Montreal: McGill Subarctic Research Station. Grady, F., and Garton, E.R. 982. Pleistocene fauna from New Trout Cave. Cap. Caves Bull. :62–69. Graham, R.W., et al. (20 authors) 996. Spatial response of mammals to late Quaternary environmental fluctuations. Science 272:,60–06. Graham, R.W., Holman, J.A., and Parmalee, P.W. 983. Taponomy and paleoecology of the Christensen Bog mastodon bed, Hancock County, Indiana. Ill Rept. Invest. No 38. State Museum. Griffith, B., et al. 998. Effects of recent climate warming on caribou habitat and calf survival: implications for management. Poster at 8th North American Caribou Workshop. Whitehorse: Yukon Game Branch. – et al. 2002. The Porcupine herd. Arctic Refuge coastal plain terrestrial wildlife research summaries, 8–37. Biological Science Rept. USGS /BRD /BSR 2002-000. Springfield: US Dept of Commerce. Grimes, J.R., Eldridge, W., Grimes, B., Vaccaro, V., Vaccaro, F., Vaccaro, J., Vaccaro, N., and Orsin, A. 984. Bull Brook II . Archaeol. Eastern North America 2:59–83.

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Index

accidents: calves drowning, 296, 484; at Limestone Falls, 295–6, plates 22–3; locked antlers, 296, plate 28; parturition, 296, 427; thin-ice, plates 3–2 activity budgets: activities, 45–22; comparison between herds, 75; dry matter intake, 76; feeding bouts, 75; in insect season, 48; pre-insect (June), 74–5, 48; tables, 370, 45, 42 antlers: as condition index, 228–30; damage in fighting, 45; decline in size, 46, 48, 22–3, 24–5, 226–7; dominance casting hypothesis for females, 226–7; extended casting, 239–4; female mass, 208–; male mass, 2–2; morphology models for males, 42–7; morphology of sedentary vs migratory ecotypes, 42–3; noncast, chewed, 232–4; and nutrition, 25; nutrition/fetuses casting hypothesis, 229–3; polled/antlered (%), 227–8; time of casting for females, 225 Appalachian refuge in Pleistocene: caribou spacing from megafauna, 3; location, 70; mammalian species present, 62–3; time periods, 60–5 (see also periglacial refugium)

Arctic fox: abundance correlated with other canids, 307; cycles, 23; vector for rabies, 307–8 areas occupied (km²): above tree line, 322; annually, 322; for calving, 324, 455; rutting (98–9), 324; winter (982–83 to 99–92), 324 August dispersal: direction across tree line, 384, 393; food competition hypothesis, 399; food quality hypothesis, 399; maximum mobility, 350, 355–7, 368, 398; leaving overgrazed range, 63, 332; minimum densities, 427; minimum group size, 398; released from mosquitoes, 392, 394, 396, 42; oestrid hypothesis, 39; willow utilization, 55 azimuth routes: annual changes, 403; at end of growing season, 399–400; as lakes freeze, 400–; to low snow, 383, 400; variable fall/winter changes, 383 bears: black as replacements, 22; distribution of, 446; extinction of brown, 2; increase in numbers, 448; predation, 30 birch: annual growth, 77; browsing mortality of, 63; browsing-stimulated

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growth, 77; caribou condition correlated with growth of, 230; damage to correlated with other caribou impacts, 64; dates when 20%, of diet, 56; fecal nitrogen/plant nitrogen comparison, 60; importance as forage, 55–6; July diet (%), 56; phenology, 56; plant nitrogen daily, 60; retarded growth of, 77 birth mass: and dam’s mass, 90–2; female investment g/kcal, 9; and growing season, 94–5; and May temperatures, 94; survival weight, 96; and sex of calf, 87 birth synchrony: late/early selection, 46; normalizing selection, 460; predation risk hypothesis, 460; seasonal hypothesis, 460; selfish herd concept, 460; synchrony comparison, 970s vs 980s, 46 black flies: days active, 395; peak numbers, 366; phenology, 362, 366 Cabot, J., 07, 8 calving: chronology: annual, 225, 234–7; late calving dates, 23; prolonged gestation, 237; seasonal nutrition hypothesis, 237–9; transfer experiments, 237 – shifts: Bathurst/Beverly herds, 448; calving centres moved, 446; displaced from tree line, 446; moved from tree line in Ungava, 444–5; to reduce predation risk, 447–8; as response to overgrazing, 452–5; switching calving grounds, 470, 473 – locations, sedentary caribou: alpine sites, 37; characteristics, 434; lakes/ shore sites lines, 38–9; muskegs, 35–6; spaced-out, 34–5 Caniapiscau Herd: demography, 88–9; distribution, 39; population size, 88 Caniapiscau River, 6; reservoir impact, 89 Caribou House: calving tradition at, 324, 380, 444–6; height of land, 449; and Innu beliefs, 08–9; location of, 08 carrying capacity: classical theory, 42, 79–80; and growing season, defini-

tion, 495; and marrow fat, 292–5; other herds, 50–4; with restricted/unrestricted winter range, 496; and stocking rates, 495; and summer densities/ fecundity, 480–3; and winter starvation, 494–6, census 958: George River estimate, 3; hunting areas, 322, and see Naskapi hunters 958, plate 33; wolves, 24 centre of habitation: of caribou, 32; definition of, 32–2; of Naskapi, 322 Churchill Falls (formerly Hamilton Falls): date completed, 9; height of, 6; hydroelectric power, 7; Innu belief about, 7; Michikamau Lake, 7 Churchill River, 8 cold springs. See springs, cold condition indices: antlerless females, 227–8; antler size of males, 226–7; body mass, 263; condition matrix, 70; dates of calving, 234–9; fat reserves/migration distances, 249–52; liver weights, 24–2; synchrony of indices, 262–6 crypsis: hiders/followers, 450; predation rate, 450–; snow cover, 443 Davis Inlet, 6 demography of other herds: and predation possibilities, 505–7; and shortage of summer foods, 50–5 densities: of Alaskan herds, 327; and growing season, 427; as herd increased, 327; and leaving centre of habitation, 327; and reduced fecundity, 48; and “social stimulus,” 327; summer, 48; winter, 48 density-dependent regulation: density calculations, 479–80; impact variables, 70; parturition rates, 480–3; releasing density, 348; rotation of fall pastures, 325–6, 330; summer and winter, 48 diet, summer: birch phenology, 56; percent nitrogen, 57–9; species utilized, 56–60 directional movement: azimuths followed, 383; energy considerations, 38–3; environmental gradients, 38–3; esker influence, 346–7; topographical

INDEX |

funnelling, 38–3; wind direction and mosquitoes, 390– displacement distance: Bathurst Herd, 438–9; definition of, 437; Nelchina Herd, 44; Porcupine Herd, 44–2; between tree line and 75% snow, 433 distribution: annual, 324–5, 340; calving area, 326, 329, 342; density dependence, 330–, 327; monthly, 377–8; in rutting areas, 326, 330, 342; snow influence, 329–3; winter, 326, 329–3, 342 distributional patterns: areas by months (km²), 377–9; calving-contagious, 342; dispersion index, monthly (converging/ diverging philopatry), 377–8, 380; fallrepulsed, 342; fidelity index (distances between locations same date adjacent years), 380–; winter (Poisson rarerandom), 342 Dominion/St. Augustin Herds: extinction, 95; population estimate, 94 dry matter intake: summer 988–9, 76 early travellers. See Cabot, Flaherty, Hawkes, Hendry, Hind, Hubbard, Low, McLean, Payne, Strong, Turner, Wallace ecotypes: antler morphology, 4–3, 50; body size, 43, 50; sedentary/migratory, 34–5; spacing/calving, 34–8 Elton, Charles: on caribou/wolf decline, 894–923, 25; father of ecology, 23; on native starvation, 6 energetics, growing season: activity budgets, 74–6, 44–5; activity–24 hours, 47, 420–; animal densities, 427; competitive interference, 424–5; energy budget, 76, 46; group size, 44; insect harassment, 48–24; sexual segregation, 43 eskers: caribou movement, 347; location/ orientation, 8 extinct herds: Harp Lake, 40–; White Bear Herd, 39, 4 fat reserves: annual cycle, 249–5; birth weight of calves, 94–5; deposition strategies, 257–64; function, 257–6;

579

kidney fat/total body fat, 246; lactating/not lactating, 246; major decline in depositions, 247; migration, before and after, 244–5; migration distance and, 25–5; and migration/winter strategies, 256–7; and mobilization sequence, 226, 242–3; in pregnant/not pregnant females, 244; reserves of females, 243– 50; reserves of males, 250–; reserves with age, 253–4 fecal nitrogen (FN): August dispersal, 398, 42; birch compared, 60; daily values 989, 57; destination hypothesis, tested, 435–6; male/female values June, 57; values June to September, 59; secondary compounds, 57 feeding site selection, 72–3 fetal growth: growth curve, 88–9; and maternal nutrition, May, 93–5; winter severity and, 89 Flaherty, R.J., 2 fluctuation explanations: cold springs plus overgrazing, 46–8; forest fires, 37; increasing snow cover, 44–6; over-harvest, 38–4; predation, 42–4; Spanish influenza, 4 forest fire: annual, 8; burn cycle years, 9; burn rate, 8; forest rotation period, 09; and lichen regeneration, 7; maximum frequency of, 7; northern limit of, 5 Fort Chimo, 322 Fort McKenzie, 322 Fort Nascopie, 322 fossils: earliest, 54; by forest types, 56, 60; periglacial refugium list, 57–8; Sangamonian interglacial, 54–5; by time periods, 60; at Wisconsinan maximum, 56, 60 geographical locations. See maps, 6, 8, 39, 98, 322, and specific locations George River (settlement), 322 George River calving ground: age/sex segregation 977, 449; area, 324, 454; bears, 446; centre of tundra, 446; contagious distribution, 380; fecal nitrogen males/females, 436; green-up, 434;

580 | I N D E X

height of land, 444, 449; maximum distance tree line, 45–2; nitrogen of plants, 435; predation risk, 439, 442, 446; reduced predators, 434; return in 2006 to 979 area, 323, 454; return routes, 446; rotating range within tundra, 446, 455; shifting to reduce predation risk, 447–8; snow cover, 446, 450–; wolf dens, 446. See also Caribou House gestation: length, 238; prolonged, 50, 223 green forage shortage: Alaskan herds, 502–7; and cold springs (880s), 46, 72; critical summer densities, 500; effect of volcanoes on, 36; in 980s, 63–4 growing season: and body size, 5; and end of month snow depths, 3; and first frost dates, ; and lake ice and breakup, 0; length of, ; and maximum snow depths, 2–3; and snowfall, 0; and snowfall isopleths, 2; weather effects on, 298–300 growth: calf gains, 97, 204; retarded/ compensation, 97–203; yearling gains, 97, 204 Harp Lake Herd: area km² , 40; calving area, 444; extinction from hunting, 4; and isolated tundra, 39 harvest/hunting: George River (957–92), 297–8; historical harvest projections, 38–4; Hudson Bay post records, 2; hunting areas (958), 322; Indian House Lake crossing, 07; Innu hunters, 23–34; law of diminishing returns, 323; Moravian records of, 25; musket introduced, 39; Skidoo impact, 39, 4, 87, 92, 94–5, 0; Spanish influenza, 4; user groups, 297 Hawkes, E.W., 43 HBC /Moravian Posts: ammunition niggardly at, 4; dates established, 3; HBC journals 925–42, 2; skins traded at, 25, 43 Hebron, 322 Hendry, W., 6, 43

herd size (George River): age structure, 286; census (954–88), 3, 286; census (993), 288–9; M/R calculations, 289– 90; root scars, index, 286 Hind, H.Y., 37 historical caribou populations: cold springs plus overgrazing decline hypothesis, 46–8; decline after 820, 0–6; decline after 880, 8–20; domino theory of, 8; forest fires and decline, 37; hunting as cause of decline, 38–40, 43–4; icing hypothesis of decline, 42; length of hunting trips and, 4–5; low numbers (90–50s), 2; lowest population, 2; McLean’s observations of, 7; and predation, 42–4; retraction of range, 8; skins traded, 25; starvation and, 6; three herd belief, 0; wolf/ wolverine harvests and, 43; wolves/ wolverine index and, 25 homing to Labrador tundra: birth site fidelity, 469–74; date of initiation, 464; homing index, 47; landmark navigation, 465–6; return of yearlings, 476–7; speed of return, 464 Hopedale, 6, 322 Hubbard, M., 07 impact on flora: bare trails, 64; birch growth, 77–8; correlation matrix of impacts, 69–70; dead birch, 63–4, 69–70; forbs reduced, 72; impacts monthly, 73–4; phytomass removed, 64; recovery, 78–9; species abundance, 72; trampling/turf, 64, 66–70 Indian House Lake, 6; arrival of plants, 2; August dispersal, 380–7, 393; caribou migration routes/crossings, 07, 387, 393; centre of habitation, 322; collapse of Naskaupi Lake, 06; failure of the crossing, 09; native occupation, 06–7; scarcity (940s), 2; weather station, 45; wolf den, 446 individual distance: July massing, 385; mutual antler chewing, 234 Innu: centre of habitation, 322; dependent on caribou, 23–4; historical dates

INDEX |

reached Labrador, 23; historical life style, 23–4; Spanish influenza mortality, 4; starvation of, 6. See also Naskapi insects: abundance, 366, 389, 395; caribou and massing, 385–6; and caribou aggregation size, 363, 366–7, 398; diurnal/ nocturnal, 47, 420–; individual mobility, 363, 368, 370, 398; phenology, 362, 366; relief attempts from, 366, 369–70, 398; standing, 370; warble fly life cycle, 305, 366, 392; weather thresholds and, 389, 394–5; and wind direction, 390– June pause: birth/calf bonding, 359; mean date, 359 Lac Bienville Herd: demography, 88; distribution, 87; location, 39; population size, 87; pregnancy rate, 88; sex ratio, 88 Lac Joseph Herd: demography, 9, 93; distribution, 39, 90; over harvest, 9–2; recruitment, 9; Smallwood reservoir impact, 9–2 Lac Champdore, 387, 444 Lake Melville/Hamilton Inlet, 98, 00 Laurentide ice sheet: esker orientation, 8; forest advance, 69; Labrador coast location last ice, 70; Naskaupi Lake decant, 06; postglacial vegetation, 66–8; retreat of ice (0,000), 20–; southern edge (8,000–5,500), 60, 66, 68, 70 Leaf River, 6, 8, 322 Leaf River Herd: calving at tree line, 975, 445; calving ground location, 39; calving ground shifts, 445; calving shift (982), 447; census (200), 22, 80; growing season, 9; herd’s future, 80; historical distribution, 0–3; historical harvest, 2; range condition, 58, 60, 63–4; range survey, 53 Leopold, A.: wildlife management definition of, 04 lichens: abundance, 79, 266, 257; alpine lichens in the west, 5–6; bare trails, 62; biomass, 65–6; biomass removed,

58

64–5; caribou seek snow depth or, 334–5; common species, 52; correlation of impacts, 69–70; decline in species (975–93), 72; density-dependent use, 403; lichens shattered, 63; lichens vs shrubs, 58; mobility foraging lichens, 352; range expansion and, 322; recovery from fire, 8; regional impacts of, 64; rotate ranges for, 330, 342, 350; shattered, by month, 74; shattered, turf and twig correlated, 65; untouched mats, 4; utilization and abundance, 6–2; western tundra/eastern, 69; winter vs summer impacts, 65 lichen woodland: distribution, 5; growing season length, ; high lichen phytomass, 6; major plant species, 6; major winter range, 340 liver weights: comparison (992/993), 242; condition index, 24–2 Loop of Life: diagram, 402–3; environmental factors, 403 Low, A.P., 09, 0, , 37 Makkovik, 6 mandible growth: by age, 98–9, 202–3; by cohorts 989, 202; compensation, 20; environmental factors on, 200 mass: annual cycle females, 208–; captive females, 209; decline in size, 206; density effects, 209–0; and fecundity of yearlings, 29–2; lactating/pregnant, 209; nutrition effects, 209–; overwinter changes, 208; other herds, 204–5; rutting males, 2–4; sexual differences, 209–4; target weights for estrus, 29 May pause: early greens, 376; mean dates, 52, 359; near tree line, 375; optimal foraging vs risk, 375–6; preparturient cows, travel speed, 359 McLean, J., 07, 09, 0, 7 Mealy Mountains, 8 Mealy Mountain Herd: distribution, 39, 00; over-harvest, 0–3; population size, 96; recruitment, 96

582 | I N D E X

migration for calving: behaviour of other ungulates, 437–8; calving grounds description, 434; displacement/destination hypotheses, 432–7; displacement from predators, 438–43; ecotype mobility, 442; energy balance, 437; fecal nitrogen, males vs females, 435–6; habitat selected, 433–4; nitrogen in plants, 435; shift from tree line to tundra, 444– 5; wolf den locations, 438–9, 44–2; wolf numbers reduced, 438 milk supply: length of nursing bouts, 96; nursing frequency, 96; nutritional factors, see appendix monthly distributions (UHF females): area (km²), 379; locations, 375–8; tagged cohorts between years, 379 mortality: accidents, 295, 484; and birth weights, 276, 487; and cold temperatures (992), 298; critical birth weights, 9, 28; density dependent and George River, 48–9, 79, 266, 298; density dependent and sedentary herds, 84–6, 93, 00–2; and distance from tree line, 486; drowning, 295–6; in first summer, 276; hunting, 297–8; increasing phase (973–84), 282–3; in other migratory herds, 492; and predation, 305–0, 485; and rabies in wolves, 308–9; and shortage of summer food, 50–4; size of calves and, 490; snow depths and, 490; stable/declining phase, 284–5; starvation, 42, 294–5; and weather, 298–9; within 2 days, 270, 276 mosquitoes: and caribou activity budgets, 36, 365, 368–70, 45, 47, 49–2; and caribou aggregation size, 363, 366–7, 369, 387, 398; and caribou diurnal/nocturnal activity, 389–90, 47, 426; and caribou habitat selection, 38, 386, 397, 426; and caribou individual distance, 385–6; caribou released from, 396; and directions travelled by caribou, 386, 390–; emergence of delayed, 44; harassment by, 365, 368–70; mobility, 356–7, 359–6, 363–4, 370; peak abundance, 366–7, 395; phenology, 362, 366,

388, 394–5; and temperatures, 28, 362, 389, 397, 420; and wind direction, 390– movement routes: annual UHF routes (986–93), 344–46; August dispersal, 387, 393, 388; avoiding deep spring snow, 343; and azimuth changes in autumn, 399–40; the caribou highway, 343, 440; to Caribou House, 446, 465; favouring tree line, 440; fresh caribou trails (prior to ’82), 342–3; Indian House crossings, 07; individual UHF, 338–9, 345; Loop of Life, 403; low numbers moved east, 325, 330, 344; perpendicular to tree line, 34–2; and topographical funnelling, 347; tree line by Kuujjuaq, 346–7; and turf trails, 988, 343; using eskers, 347 movement stimuli: group size effect, 352, 363, 398; and use lichens/density dependent, 332, 349–5; Loop of Life summary, 403; social interactions, 35; “social stimulus concept,” 348–9 Nain, 6 Naskapi (see Innu): Caribou House belief, 08; centre of habitation, 322; interior living, 23–34; tent rings at Indian House Lake, 07 Native peoples: cultural history, 29; dates of arrival, 28, 23; historical distribution, 30; historical harvest, 2; hunting trips (700), 5, 39; Indian House crossing, 07, 23–34; present distribution/numbers, 6; Spanish influenza, 4; starvation, 8 navigation ability: dates start for Caribou House, 463–4; experimental evidence, 467–9; pilotage, 465–7; practice true navigation, 462–5; and speed on route, 464 Northwest River, 6 Nutak, 322 oestrids: abundance, 354, 366, 395; active days, 395; activity budget affected, 365, 369–70; annual emergence, 362; densi-

INDEX |

ties August dispersal, 392; densitydependent larval infections effect on fat reserves, 304; energy balance affected, 46, 49; evasive actions of caribou, 365–8, 398; and group size of caribou, 366–7, 398, 427; harassment during August, 368, 369–70, 392, 395–6, 48, 427; and increased movement of caribou, 363–4, 366–8, 398; larval loads, 302–3; life history stages, 362, 363, 392, 394; and physical status of caribou, 303–4; snow patch relief from, 396–7; wind/temperature tolerance, 395. See also warble flies Okak, 322 over-harvest, 87; Lac Joseph, 9–2; Mealy Mountain, 0–3; skidoo facilitated, 39; White Bear Herd, 39, 4 parasite occurrence: age susceptibility, 303; cestodes (tapeworms), 300–3; density dependent/independent, 302; effect on fat reserves, 304; nematodes (roundworms), 300; trematodes (flukes), 300– 4; virology/bacteriology, 300–. See also mosquitoes, oestrids Payne, F.F., 43 periglacial refugium: antler morphology, 64; in Appalachian Mountains, 59; caribou absent lowland tundra/taiga, 59–60; mammal species present, 62; recolonization north after megafauna extinct, 64–72; refuge from megafauna, 6–4 population dynamics of sedentary herds: density dependence, 84, 86; growth equation (λ), 8; male mortality equation, 82; mortality factors, 8; mortality rates, 88; population/recruitment summary, 86, 93; stabilizing density (DS), 84, 86; stabilizing recruitment (R S), 79, 83. See also individual herds population estimates: George River (GR ) (945–93), 286–7; GR (988–93), 287–9; GR (200), 80; Leaf River, 80, 445 population regulation model: adult mortality, 49–4; critical density, 482;

583

demography and densities, 48; fecundity of yearlings, 483; integration of factors, 500; major cause of decline, 482; parturition rates, 480–3; summer calf mortality, 484–8; winter calf mortality, 488–9 post-calving shift: azimuths to, 383; greens prior to insects, 36; group size, 36; high rivers and drownings, 382; low risk tundra, 382; mobility and plant cover, 36; river valleys and birch, 385 postglacial plant recolonization, 9–20 predation risk: calving grounds shifts, 443–7; climate warming, 430–; compact snow, 400–; crucial test for risk, 43; forage vs risk trade-off, 405; low snow and localization, 333–7, 374, 38, 40, 407; migration to low risk habitat, 36–9, , 433, 437–44, 448; northern limit of sedentary ecotype, 80–; pause/ hide strategy, 374, 40; sexual segregation in winter, 42; southern limit sedentary ecotype, 76–80; spacing of ecotypes at calving, 34–4; water as an equalizer, 74 pregnancy/parous rates: age of females, 275; annual, 270, 273–5; density dependent, 48–3; major decline, 270; natality and overgrazing, 274, 48; population growth phases, 275; reaching target estrus weights, 29 rabies: Arctic fox as vector, 307, 430; cyclic calf mortality, 308, 407, 48, 489–90; cyclic fox populations, 23; documented cases, 24–6; 982 outbreak, 306–9, 440, 498; synchronous canid abundance, 307 range contraction: crossing the tree line (August), 337; discrete rutting/winter concentrations, 332; lichen range rotation, 332–7; mobility declined, 336–7; return to centre of habitation, 332, 335 range expansion: calving, 326, 329, 334; calving to rutting areas, 329–30; densities at expansion, 327, 329; density at release, 348; density dependence, 325–6, 330–; discrete rut/winter distributions,

584 | I N D E X

325–6, 330; forage overgrazed, 329–30; rotation of pastures, 330, 332, snow depth factor, 326, 329–32, 332–4; taiga: tundra ratio, 328, 334; westward impetus, 329–30, 332 range predictability: UHF collared (986– 92), 337, 340; VHR collared (982–87), 337, 340 recolonization from periglacial refugium: forest biotypes occupied, 60, 68; after megafauna extinction, 65; routes followed, 66–8; sedentary/migratory ecotypes differentiate, 69–7; time to reach 56° N, 23 recruitment: Alaskan herds 0–2 months of age, 278; George River (fall), 5–6 months of age, 276–7; George River (spring) 0–2 months of age, 277–8 Red Wine Mountains, 8 Red Wine Herd: decline, 97–00; distribution, 39, 95, 98; population size, 96; recruitment, 96 reservoir impact: Caniapiscau, 89; Smallwood, 92 rutting pause: breeding dates, 238; high numbers central interior, 326; low numbers on tundra, 325; mean date, 359; range rotation, 330; speed, 238, 359 Schefferville, 6, 88 seasonal movements: August dispersal, 387–8, 39–8; azimuths followed, 383; mosquito season, 385–9; post-calving, 382–5; seeking lichens, 325, 332; snow cover, 44–5, 334, 406, 408–0; trail systems, 343 sedentary herds: extinct, 39, 4; moose moving north, 27, 77; nearly extinct, 96; over-harvest, 39, 4, 9–2, 95, 0–3; reservoir impacts, 89, 92–3; wolf management, 04. See also individual herds September pause: cessation of oestrids, 399; and compensatory foraging, 37–2; Loop of Life, 403; mean dates, 52, 359; optimal foraging vs risk, 37–2; travel speed, 359

sex ratios: age of dam, 33–4; aging in females:males, 280, 30–; all ages, 279, 282, 309, 32; antler morphology model, 44; between years, 32; at birth, 32–3; constant for adults, 82; fetal ratio, 32; Fisher principle at conception, 3; good/poor nutrition, 33–4; population growth phases, 279; predation impacts, 309, 35–7; sedentary herds, 88, 96–7, 00; as a species parameter, 267; and summer starvation, 284–5, 293; Trivers/ Willard hypothesis, 3; unbiased sample, 36 Smallwood Reservoir, 6 snow: antlered females (%), 228; beginning of month snow depths, 2–3; on the calving ground (%), 443, 446; mobility effect, 373–4; predation risk, 42–3; size of winter range, 33; snow isopleths, 2; snowfall, 0; temperature effects, 44–6; winter distributions relative to depths, 334; and wolf predation, 490, 493 social stimulus hypothesis: density interaction with green foods, 349; emigration to marginal habitats, 348; prevents overpopulation, 348; Skoog’s (968) hypothesis, 39, 348; winter lichens bias, 349 space, as density dependent (DD): between contrasting snow profiles, 350; correlation between fecal pellets and floral impacts, 69–70; and dominant activity, 35; between population size and travel rates, 349–50; with social facilitation parameters, 352 springs, cold: birch phenology, 56; birth weights, 88, 94; break-up dates, 0, 376; growing season length, ; perinatal mortality, 270; volcanic eruptions, 36 Strong, W.D., 07 summer forage: bare trails, 63–4; correlated impacts, 65, 69–70; dead birch, 63 7–2, 74; density-dependent summer impacts based on pellets/m² ,

INDEX |

69–70, 74; feeding sites vs random selection, 73; random phytomass summer, 73; reduced forbs, 70, 72; regional impacts, 67–8; trampling effects (twig and turf), 63–4; western vs eastern tundra, 67–8 survivorship curves: Limestone drownings, 36–7; Nain harvest of females, 277, 282–3 tabanids: August dispersal, 397; breed muskegs central Ungava, 39, 422; cause severe shaking, 27; phenology, 362, 367; species, 27–8; temperatures, 362 taxonomy: antler form Caboti vs caribou, 64; boundary between subspecies, 39–40; common gene pool, 3; location type specimen for Caboti, 48; mitochondrial DNA sequences, 3; northern and southern clades percentages, 32; transferrin marker, 32 timing of births: maximum nutritional hypothesis, 458; North American calving dates, 457; relative to growing season, 458–9 tooth wear: males, 3; older animals, 22; and overgrazed lichens, 66 Torngat Herd: antler morphology, 50; body size, 50; discrete status, 53; distribution, 46–7; fidelity, 49; mobility/ activity schedules, 49–52 Torngat Mountains, 8 travel speeds: acceleration/pauses (deceleration), 37–4; across Ungava (km/day), 354; between herds, 356–7; compared between years, 356–7; dates of pauses (slowest rates), 359; and environmental factors, 359; and growing season, 364; and insect harassment, 363–4, 368–70, 398; overgrazed/not overgrazed, 356–7; by months, 356–7; sequences, 372–5; as snow cover increases, 373 tree line: and growing season, ; habitat variables vegetation, snow, wind, juxtaposition, 5, 2, 39, 390–; key travel

585

route, 343, 378, 440; Labrador tundra extends north/south, 4, 39; Upper Ungava Peninsula tundra extends east/ west, 5, 39 tundra area (km²): Harp Lake, 39; Labrador Peninsula, 80; Upper Ungava Peninsula, 80 Turner, L.M., 07, 0, 39, 43 Ungava description: climate/weather, 9; forest fires, 7–9; growing season, 9, 5; lake ice, phenology, 0; minerals, 6–7; physical relief, 6–0; reservoirs, 6; road network, 6, 98; snowfall/depth, 0, 2–5, 3 Ungava fauna: Arctic fox cycles, 23; bears, 22; increasing moose, 27, 77–8; insects, 27–8; wolf harvest, 25–6, 43; wolf winter sightings, 26; wolverine, 22, 43 vegetation postglacial recolonization: emigration rates, 69; forest biotypes, 68; indicator plants, 66; organic sediments George River pollen diagrams, 20–; time birch reach 57°20' N, 20–; herbs/shrubs, 20–, 68 volcanoes and cold growing seasons: Krakatoa (883), 36; Pinatubo (99), 36, 48, 298, 506; Tambora (85), 36 Wallace, D., 43 warble flies: and caribou energy budgets, 49; caribou susceptibility to attack, 30–4; density independent, 302, 305; harassment on fattening, 304; phenology, 366. See also oestrids White Bear Herd, 39, 4, 95 wildlife cycles: first described, 25–6; fox cycles, back to 834, 23; hares and red foxes, 0 year cycle, 26; lemming and foxes, 3–4 year cycle, 26; rabies cycle, 430 (see also rabies) winter distribution strategy: optimal foraging vs risk, 404–5; sexual segregation, 42–3; snow cover vs lichens, 334,

586 | I N D E X

42–3; taiga vs tundra choices, 409–0; use of frozen lakes, 406, 40–; use of shallow snow, 334, 407–0. See also snow winter pastures: condition, 60–6; lichen abundance, 58, 6, 66; lichen utilization, 6; shrub cover vs lichens, 58 winter pause: advantage of compact snow, 40; annual days spent, 374; azimuths to and from, 383; dates paused, 359; mobility during, 359; most prolonged pause, 52; move to low snow profiles, 403; not density independent, 350 wolves: abundance, 22–6, 306; abundance correlated with other canids, 307; den at tree line, 34, 439, 44–2; finite

rate of increase, 306; harvest, 26, 306; hypotheses for low numbers, 305–6; numbers NWT winter ranges vs calving grounds, 438; periods when common then scarce, 22–4, 42–3; pup survival, 306; reproductive success, 306. See also rabies wolf predation: halted herd growth, 498; hypotheses for lack of predation regulation by wolves, 306–7; major cause of death, 293; predation of calves in winter, 308–0; prey selection, 309; ratio male:female killed taiga/tundra, 440–; surplus killing, 30; wolves displaced from calving ground, 43, 44–2; vulnerability in deep snow, 490–3