Pine Crossbills 9781472597182, 9781408137406, 9781408137390

Table of contents :
Cover
Contents
Preface
1 Crossbills
2 The Scottish Pine Crossbill
3 The Crossbill Hunters
4 Haunts and Bird Neighbours
5 Flocks and Groups
6 Territory
7 Courtship, Display and Behaviour
8 Nest
9 Laying Season, Clutch and Egg
10 Brooding
11 Young Crossbills
12 Voice
13 Nest Diaries
14 Food
15 Competitors and Predators
16 Distribution in Scotland
17 Numbers and Movements
18 Speculations
APPENDICES
1 Crossbill Taxonomy
2 Nest Diary
3 List of Nests
4 Behaviour at the Nest
5 Parasites
Selected Bibliography
Acknowledgments
Tables
Index
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
R
S
T
U
V
W
Y
Z

Citation preview

PINE CROSSBILLS A Scottish contribution

By the same author: THE GREENSHANK (Collins 1951) THE SNOW BUNTING (Oliver & Boyd 1966) HIGHLAND BIRDS (Highlands and Islands Development Board 1971

2nd edition 1974 THE DOTTEREL (Collins 1973) THE CAIRNGORMS (withAdam Watson--Collins 1974)

In preparation: GREENSHANKS (Poyser)

PINE CROSSBILLS A Scottish contribution DESMOND NETHERSOLE-THOMPSON

Drawings by DONALD WATSON

T & A D POYSER Berkhamsted

First published 1975 by T & AD Poyser Ltd Print-on-demand and digital editions published 2010 by T & AD Poyser, an imprint of A&C Black Publishers Ltd, 36 Soho Square, London W1D 3QY www.acblack.com Copyright © 1975 by Desmond Nethersole-Thompson The right of Desmond Nethersole-Thompson to be identified as the author of this work has been asserted by him in accordance with the Copyright, Designs and Patents Act 1988. ISBN (print) 978-1-4081-3740-6 ISBN (epub) 978-1-4081-3741-3 ISBN (e-pdf) 978-1-4081-3739-0 A CIP catalogue record for this book is available from the British Library All rights reserved. No part of this publication may be reproduced or used in any form or by any means – photographic, electronic or mechanical, including photocopying, recording, taping or information storage or retrieval systems – without permission of the publishers.

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For Bruin, Patrick, Richard, Eamonn Maimie and Katharine

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CONTENTS

Preface by Dr Ian NBfJJton

1 Crossbills 2 3 4 5 6 7 8

9 10 11 12 13 14 15 16 17 18

11

The Crossbill Hunters

13 20 30

Haunts and Bird Neighbours

40

The Scottish Pine Crossbill

Flocks and Groups Territory Courtship, Display and Behaviour Nest Laying Season, Clutch and Egg Brooding Young Crossbills Voice Nest Diaries Food Competitors and Predators Distribution in Scotland Numbers and Movements Speculations

51 57 65 74 85 92 102 116 134 142 156 163 175 187

APPENDICES

1 Crossbill Taxonomy by Alan G. 2

Nest Diary

3 List of Nests

191 202 216

4-

Behaviour at the Nest

5 Parasites

218 219

Tables (see list, below)

221 227 230

Index

249

Selected Bibliography Acknowledgments

LIST OF TABLES (pages 230 to 248) 1 Nest-site selection and nest-building

2 Nest-sites 3

Monthly clutch-size/laying season

4 Clutch size/number of clutches, Scottish pine crossbill 5 Clutch size/number of clutches

6 First and replacement clutches of same 18 females 7 Egg measurements

8 Incubation patterns of British finches 9 Quantity of spruce seeds eaten by crossbills in one day during winter/spring at Kandalashka

10 Numbers of Scottish pine crossbills in relation to Scots pine cone crop 1933-1942, Upper Strathspey 11 Numbers in relation to Scots pine crop 12 Numbers and laying season, Fairburn, Easter Ross (1898-1907) 13 Breeding numbers in relation to Scots pine cone crop, Easter Ross (1952-1974) 14 Scottish pine crossbill populations 15

Scottish pine crossbill and siskin

16 Measurements in millimetres and weight in grammes of adult crossbills 17 Moulting

PLATES COLOUR (between pages 24 and 25) Scottish pine crossbills sketched by George Lodge while staying at Fairburn, in Easter Ross, 20th February 1907

MONOCHROME (between pages 96 and 97) 1 Cock Scottish pine crossbill 2 Haunts of Scottish pine crossbills--Glenmore, Inverness-shire; and Ostergotland, Sweden 3 Cock common crossbill 4 Hen common crossbill with building material 5 The pylon hide at a Scottish pine crossbill's nest 6 Scottish pine crossbill about to brood eggs Hen showing neck-raised fear posture 7 Pair of Scottish pine crossbills at the nest 8 Hen Scottish pine crossbill brooding 9 Pine crossbills--a study of beaks 10 Female pine crossbill feeding youngster 11 Cock about to feed young while hen begs Cock feeding her 12 Cock Scottish pine crossbill feeding fledgling 13 Nearly fledged young Young Scottish pine crossbills in nest 14

Fledged young common crossbill, begging Juvenile common crossbill feeding young of second brood

10 Plates 15 Fledged young common crossbill waits for food while hen broods young Juvenile common crossbill waits for food while he feeds newly hatched chicks Cock common crossbill feeding fledgling 16 Young male pine crossbill drinking Male common crossbill drinking

PREFACE

This book describes in detail the life-history and behaviour of the largebilled crossbills which live in the native pinewoods of northern Scotland. These are rare birds, sporadic in occurrence, which most British birdwatchers have never even seen. However, with their striking appearance, singular behaviour and irregular migrations, crossbill, of one sort or another have excited men for centuries: at least since 1251 when Matthew Paris documented for the first time an invasion of these strange birds into southern England. Crossbills are finches which are specialised to feed from the cones of conifer trees. And to the fruiting of such trees their whole lives are geared. Those birds which most of us know from their curoiroltra periodic invasions into Britain are Common Crossbills from northern Europe, which breed mainly in areas of spruce. Two other crossbill species are found in the boreal forests of Eurasia, the slender-billed Two-barred Crossbill L. leucoptera, which lives mainly in Siberia in areas of larch, and the heavy-billed Parrot CrossbillL. pytyop,ittaCUI, which lives mainly in northwest Europe, in areas of pine. South of the boreal forest, in mountain areas where pines predominate, other large-billed crossbills occur, not only in Scotland, but also in the Balearics, North Africa, Corsica, Cyprus, the southwest Crimea and on several Asiatic ranges. AD these forms, isolated in pine areas, have developed large bills for dealing with hard cones. They have presented difficult problems for taxonomists and, as this book reveals, opinions still differ on whether to regard the ScottishCrossbill as a distinct species, a subspecies of L. curoirostra or a subspecies of L. pytyoplittacul. In my experience, crossbills are the most elusive and exasperatinl of the European finches to study. They are often present in an area for only a few months at a time, followed by years of absence; they nest in a difficult environment, often in winter when the ground is snow-eovered and temperatures are below freezing; and they may travel long distances from the nest in searchoffood. Theirnests, moreover, amid thick tree-top foliage, are hard to find and hard to reach. Only by long hours of patientobservation over many years could anyone hope to accumulate much understanding of their life-history and behaviour. In this book., Desmond NethersoleThompson has summarised more than 40 years of careful observation and recording, first on the Common Crossbills in the Breckland of East Anglia,

11

12 Preface and then on the Scottish Crossbills of Speyside, Sutherland and Ross. Practically every page bears witness to first-hand experience of the events described, and his own observations are supplemented throughout from correspondence and from examination of the literature, largely unavailable to the average British reader. Anyone who has had the pleasure of meeting Desmond NethersoleThompson cannot fail to be impressed by his achievements in the field, and by his immense knowledge and experience of matters ornithological. Remember, too, that he did much ofhis work free-lance, in relative isolation, and in the nineteen-thirties and 'forties, before there were textbooks on population and behaviour to point the way. He devoted himself particularly to four of the most characteristic birds of the Scottish Highlands, and has already produced monographs on the Greenshank, Snow Bunting and Dotterel. He has also written a quite different, and delightful book, Highland Birds, published in 1971by the Highlands and Islands Development Board. Whatever the subject, his writings are generally fresh and evocative, and full of enthusiasm and atmosphere. This book is no exception.

Edinburgh, 1975

I.NEWTON

12

CHAPTER 1

CROSSBILLS Birds well known in legend and history, crossbills have always fascinated me. In Central Europe, in contrast to the waxwing, described as the Pest Vogel, herald of the Apocalytptic horseman, the crossbill was venerated. Seeing crossbills, the children of Central Europe were told how the oddly shaped mandibles had become distorted by the attempts to wrench the nails from the hands of Christ as He was stretched on the Cross, and that the male Christ Bird's plumage still bore the stains of His blood. Crossbills were also said to arouse the children sleeping in the moonlight, to warn the householder against fire, and to watch over the woman of the house in childbirth. Thuringian peasants always liked to keep a crossbill about the house in the belief that the bird would draw to itself any sickness falling on the family, and that colds and rheumatism would pass from man to bird if its upper mandible bent to the right, while one with the mandible to the left rendered the same service to a woman. Tradition also recommended the water from which a crossbill had drunk as a specific against epilepsy. Most curious of all the superstitions was perhaps the belief that the body of a dead crossbill never decayed. History was mote precise but equally intriguing. In his Monastery at St Albans in 1251 Matthew Paris gave us the first description of crossbills in England. 'About the fruit season there appeared, in the orchards chiefly, some remarkable birds which had never been seen in England, somewhat larger than larks, which ate the kernel of the fruit and nothing else, whereby the trees were fruitless to the loss of many. The beaks of these birds were crossed, so that by this means they opened the fruit as if with pincers or a knife.' 13

14 Pine Crosshills In 1593, in the reign of Elizabeth, there was another account of these orchard raiders. 'There were greate plenty of strang birds, that shewed themselves at the time the apples were full rype, who fedde upon the kemells onely of those apples, and haveinge a bill with one beake wrythinge over the other; they were of the bignesse of a Bullfinch, the henne right like the henne of the Bullfinch in coulour; the cock a very glorious bird, in a manner al redde or yellowe on the brest, backe and head. It seemed they came out of some country not inhabited, for that they would at first abide shooting at them, either with pellet, bowe or other engine, and not remove till they were stricken downe. They were very good meate.' I had read that these strange mysterious birds occasionally arrived unexpectedly in huge invasions, known as irruptions. They came from dark and distant fir forests in Scandinavia, but here in Britain they then only seemed to breed in East Anglia and in a few remote forests in the Highlands of Scotland. In Field Studies of Some Rarer British Birds, John Walpole-Bond's stirring account of his hunts for crossbills' nests in Sussex gloriously vindicated the old Elizabethan Chroniclers' description. 'I stroked the sitting hen and stranger still she actually perched on my fingers as I examined her treasures.' On Saturday, when I was about 14 or 15 years old, I went to a cinema in King Street, Hammersmith, where I found, by accident, that the second feature was Edgar Chance's fascinating film The Cuckoo's Secret. It was like entering a new world. I later borrowed his book from the local public library, and was amazed by the thoroughness of his observations. To me, Chance was then a shadowy figure. I did not even know that he was an egg collector. Then, in 1926, I read in the newspapers that he had been fined heavily at a Court of Norfolk Justices for 'aiding and abetting' a farm bailiff to take crossbills' eggs for him. The Ornithological Establishment, and its more respectable toadies, certainly put Chance on the stocks. While I was staying with friends in Norfolk I heard about his annual forays in a fast car and that he always departed with boxes crammed with clutches of crossbills', thickknees', and woodlarks' eggs. As a young collector myself, these horrific and partly apocryphal tales only filled me with joy I I immediately identified with Chance, who soon almost gained the aura of an Olympic athlete or a test-match batsman. To the simple schoolboy, they were stoning a prophet. I too would go to Norfolk. and hunt for crossbills' nests. I made more friends, read many books and went to Museums. One vivid memory was of a visit to a quite unusual Museum in Dyke Road, Brighton, where Edward Booth's great collection of stuffed birds was housed. In the Bird Room of the British Museum I later discovered the huge volumes of his Rough Notes, from which I learnt that crossbills also nested in forests in the Scottish Highlands. 'It has invariably been in

Crossbills 15 March when I have met with the nests of this species; the young, I remarked, were generally hatched towards the end of the month or early in April. On March 25, 1898, there was a heavy fall of snow over the north of Scotland; and while passing through a fir wood near Inverness I noticed that the snow appeared to be piled to the height of at least four or five inches on the top of some nests I had seen a few days previously. I did not make a close examination, merely turning the glasses to the nests, which were at about a height of twenty-five to thirty feet from the ground. It is a curious fact that in every instance the birds must have been sitting at the time, as a few days later I watched them feeding their newly hatched young at each nest.' What amazingly hardy little birds they must be, I thought, rearing their chicks in the snows and blizzards of remote northern forests. Soon afterwards I read a most exciting paper on crossbills in Norfolk and Suffolk by Norman Gilroy, a nest-hunter of no ordinary skill and ability, who used to walk briskly along the roads around Thetford and Brandon, periodically pausing to point up to crossbills' nests at the ends of projecting branches, and excitedly instructing his more agile companions to examine them. In 1923 Gilroy and Chance had great success with the crossbills in Breckland, when they found nearly 20 nests. In the late 1920s and early 1930s, I sometimes watched crossbills flying over the Surrey heaths and commons where I was watching hobbies or searching for nests of Dartford warblers and woodlarks; but I found no nests and really learnt little about them there. At this time I met Edgar Chance, and spent one or two days with him hunting for crossbills in Surrey. Chance, I remember, thought little of Surrey as a crossbill haunt, and spoke rather wistfully of early mornings in the Breck country, where several cock crossbills often simultaneously sang and challenged one another near their nests on roadside pine tops. By 1932 I had gone to Norfolk and Suffolk and was already finding crossbills' nests there. I used to stay with an old nester near Wisbech in Cambridgeshire, which is some miles from the crossbill country. An elderly man, with a florid complexion, my friend was a man of substance and repute, a pillar of the local establishment, a Justice of the Peace, and Chairman of the Highways Committee of the local Council. Even better, he had a most glamorous daughter, whose great delight was to make her father's guests comfortable. I need hardly say that I always enjoyed staying at this large and cosy house, and setting out for the crossbill country in a stately Humber limousine, well provided with hampers of provisions, and thermos flasks of mushroom soup, which the charming daughter had lovingly prepared. This delightful friend had a secure place in the hierarchy of the egging fraternity-the crossbillers' link manl He was kindly disposed to pick up any nests with incomplete clutches which the hunters had located on their weekend raids. The crossbill was his favourite bird, but he was

16 Pine Crossbills also a wizard at finding the nests of other Breckland birds. His method of finding stone curlews' and stonechats' nests was unadventurous but often successful. He used to drive his car slowly onto the breck, where the stone curlews were nesting. He then slowly stepped out and banged the door to flush the birds from their nests. Then, after a short and leisurely walk, his stocky and tweedy figure retired to the car. The unfortunate stone curlews then slowly ran back to their eggs. The old Justice wore peculiar spectaclebinoculars, which often fell off his nose just when he was about to mark down the returning birds. This always caused an outburst of frustration and fury, but he eventually emerged with a large collecting box. Wearing these spectacle-binoculars he also used to gaze hopefully into the pines, carefully scanning them for the little dark lumps at the end of the branches. At this time I was a master at a Prep School and had only limited leisure; but I made the most of any free time that I had. From February onwards, at 4 o'clock on Sunday mornings, friends arrived at the school, honked loudly under my window, and then took me to Breckland to look for crossbills. We always devoted the first two weekends in March to ravens in Wales and Cornwall, departing in rather ancient cars well weighed down with climbing ropes, eros-bars and steel helmets. Afterwards we resumed our 'studies of the crossbill' until the second weekend in April. We timed our journeys to arrive at dawn beside a row of pines close to the Newmarket Race Course. We seldom had much success there, but I do remember a cock crossbill singing vigorously in the pink. flush of an early February morning. Sometimes Cecil Stoney, the famous Irish nesthunting Squire and ornithologist, came with us. A glutton for eggs and punishment he made certain that every possible crossbill's nest was found and examined 1 I doubt whether we learnt much of real value on these weekend forays, but we occasionally watched interesting incidents of behaviour. We saw a cock crossbill in green feather flying behind a hen which was building her nest in a windbreak of pines close to a farm near Hockwold. The cock's plumage and situation of the nest were both unusual. Almost all the other nests that we found were in pines beside roads. I also learnt that hen crossbills did not always start sitting on the first egg laid; sharp February or early March frosts sometimes split or cracked the one or two unbrooded eggs. We also quickly discovered that, apart from the periodic invasions or irruptions from northern Europe, the size of the Breckland populations of crossbills greatly fluctuated from year to year. But what fun bird watching was in these days, with everything seemingly so delightfully simple and uncomplicatedl I had an exciting climb to a nest far out on a branch on a tree beside the Roman Catholic Church at Brandon. I can still see my Wisbech friend's crimson face, and the familiar binocular-spectacles, anxiously looking up at me as I inched myself along the creaking branchl

Crossbills 17 In 1932 and 1933 I made what were almost Grand Tours of the but it was not until the spring of 1935, when I was already Iiving m Spey Valley, that I started to study crossbills in Scotland. These Speyside crossbills puzzled me. While passing through Rothiemurchus Forest in 1933, I heard a deep and angry cry high up in the pines, a call that I had never heard before. To my surprise, I found that this came from a group of crossbills. In all these years in Breckland I had certainly never heard anything remotely resembling it. In Strathspey, crossbill country was also quite different from any of myoid hunting grounds in Norfolk and Suffolk. Here there were great expanses of old pines, hundreds of acres of almost unbroken forest, with a few wet bogs where the pines grew small and stunted. I soon found that the crossbills' nests were not restricted to the edges of wood or forest or beside paths and tracks; in open forest they nested in almost any part of it. From mid-January to mid-April I was off on my dilapidated bicycle, but how different Speyside was from Breckland. In late February many crossbills were still in flocks; I had to walk and cycle many miles before finding my first nest in the last week of March, when I located a small breeding group in a plantation of old pines close to a keeper's cottage. Thenceforward, until 1942, I followed the crossbills and slowly began to understand a little about them. At first everything was gloriously new. I watched my crossbills mating and discovered how subtly a winter flock changed to a mating party and from a mating party to mated groups. I studied patterns of territory and dispersion and watched how hens built their nests. I· sat under trees and I climbed to nests. I watched hens brooding and saw cocks feeding them. One hen pitched on my fingers and allowed me to catch her. I still vividly recall the sharp resiny scent of her body. I saw pairs rear their young and followed them and their broods through the forest. Soon my notebooks were full, but this was only a beginning. By the end of April greenshanks had courted and started to lay and eagles and crested tits were brooding. In May the crossbills competed for my favour with greenshanks and golden plover and from early June with dotterel and snow bunting. Although spring and summer were marvellously stimulating and exciting, how different it was in late autumn and winter. Then the red grouse were almost the only active birds on the moors around the cottage in Abernethy, where we were often snowbound and cut off for several weeks. The walls of the rough stone and lime cottage, with the big stone slates, were stout enough, but the wind blew through the rooms and rain seeped through almost invisible cracks in the wall. Worse, in a big snowstorm, snow piled up under the slates and froze on the roof. Then, in the thaw, it melted and poured through the roof, soaking everything, even the table on which I was writing. Of course, there was never enough money-food and fuel were always scarce. But

18 Pine Crossbills these physical hardships were mild compared to the intellectual isolation. I had few books, there was no library, I could not afford a newspaper and until 1936 I had no radio. A subscription to an Ornithological Journal was out of my reach. Each Christmas, however, an old student friend at L.S.E. made me a gift of a dozen Penguins. What joy I had from these sixpenny paperbacks. They were a mixed bunch, but included Julian Huxley's Essays of a Biologist, Evelyn Waugh's Decline and Fall and Liddell Hart's Foch, Man ofOrleans. It was in two volumes of Penguin that I also now first read Cherry-Garrard's Worst Journey in the World, which I still believe is one of the greatest books ever written. In bad moments it made one ashamed of momentary weakness. For intellectual stimulation I depended on the letters of my few faithful friends in the south. Jourdain was wonderful. Almost every week he wrote me a long letter and always enclosed reprints of his own scientific papers and those of others. I still remember my excitement when he lent me a copy of Niko Tinbergen's pioneer paper on the behaviour of red-necked phalaropes in East Greenland, and learnt how much there was in common between these lovely birds and the dotterels which I was studying intensively. I later read Tinbergen's paper on the snow bunting and discovered great differences in the territorial patterns of the Greenland and Caimgonn birds. Stoney and Witherby were others who helped to keep me in touch. In this way I never lost contact with the outside world of ornithology. After the war I was back in Speyside, where I continued to watch crossbills and my other special birds. In 1947 and 1952friends built pylon hides at two of the crossbills' nests that I had found. I shall never forget sitting in one of these shaky hides, the canvas beating, and the boards groaning in the wind. How exciting to sit beside the hen, watch the scarlet cock arrive to feed her, and record every moment and action. By 1962 I was studying crossbills in quite different kinds of country in Easter Ross and Sutherland. Here there were fewer tracts of old forest. The few crossbills were nesting in old and open plantations and in small self-sown pinewoods, as well as in relicts of Caledonian Forest. On a rather 'snell' late April afternoon in 1970I found my first crossbill's nest in Sutherland. The cock was a little beauty, almost crimson of breast and rump, but with darker almost black primaries; the hen was green and more dumpy. Both flicked their wings and tails in excitement and used these loud deep calls which I now know so well. As I sat watching them, a merlin flew low over the wood and the crossbills gave different cries. When the sun shone after flurries of sleet and snow, siskins sang and made wavering bat-like display-flights. A few days before I had watched the crossbills deftly levering out pine seeds from the cones they firmly held in their feet and, as always, I had marvelled at these unusual little finches and their extraordinary crossed beaks.

Crossbills 19

Pine Crossbills is my fourth monograph. While I was studying the bird

in the field, cross-indexing my field notes, and corresponding with specialists and enthusiasts here and overseas, I knew that I always had one almost imponderable problem to overcome. What was the origin of the crossbills in our Highland forests? I knew that they differed from those which I had watched in the Breckland and I believed that they might be of the same ancestral stock as the pine or parrot crossbills of the pine forests of Northern Europe. There have always been pieces missing from the jigsaw, but I have tried to discover some of them and put them into place.

CHAPTER 2

THE SCOTTISH PINE CROSSBILL Crossbills are a most puzzling group. I knew that Scottish crossbills had already perplexed distinguished taxonomists all over the world. They are still in debate. In 1937L. Griscom, in his Monographic Study oftheRed Crossbill, held that the parrot crossbill of northern Europe was merely an isolated but well-developed race of curoirostra, breeding in a different ecological niche in the same range without interbreeding and hybridisation. In 1953 Meinertzhagen and Williamson also regarded curoirostra and pytyopsittacus as conspecific, suggesting that the isolation and different ecological niches of the two races had prevented dilution. In 1956, however, the Taxonomic Committee of the B.O.U. not only treated these two crossbills as separate species, but placed the Scottish crossbill as a relict form of the pine cone feedingpytyopsiitacus. Later, in 1953,Peter Davis adopted a still more original line, maintaining that all crossbills are emergent interspecies. The Doctors have certainly disagreed] However, Alan Knox, who is making a detailed study of the taxonomy of Loxia, has written a summary of his work, which appears in Appendix 1. His interpretation of the facts about the Scottish bird differs slightly from mine. What are the facts? All crossbills have clearly stemmed from a recent common ancestor and have evolved special beaks to deal with their most favoured conifers. The pine-feeding pytyopsittacus of northern Europe has thus developed a larger and more powerful beak than curoirostra which predominantly feeds on spruce. However, curoirostra in tum has a deeper and stronger beak than the larch-feeding two-barred crossbill Leucoptera of northern Asia. The beaks of our Scottish pine crossbills, as I 20

The Scottish Crossoiti 21

shall call them, are usually intermediate in size between those of the pine and common crossbills, The origin of the Scottish pine crossbill and its place in this complexjigsaw is more difficult to determine, because several other large-beaked races, usually attributed to curoirostra, are largely restricted to habitats in various kinds of pine, for example, the largebeaked races in Corsica, Balearics, North Africa, Cyprus, and possibly in south-west Crimea. All these races could have stemmed from curoirostra invasions and then become isolated in the pines. Likewise, the dwarf small-beaked Lie. himalayensis has probably become adapted to the predominantly soft larch cones in the Himalayan region (Newton, pers.

comm.).

Except in Scotland, however, the pine crossbill pytyopsittacus breeds entirely within the range of curoirostra, yet still maintains a separate identity apparently without interbreeding or hybridising. In the breeding habitats and ranges of the Scottish pine crossbill, moreover, large invasions of continental curoirostra frequently pass through and winter on the fringes of-pine forests in northern Scotland, without permanently establishing their own stable breeding groups or diluting the native stock. Common crossbills do periodically nest in or around the habitats of Scottish pine crossbill relicts, particularly in good years for pine cones. In 1936, for example, I located two pairs breeding in mixed conifers near Dulnain Bridge. These had the 'narrow bills and lacked the diagnostic calls of our native birds. It had also long been suspected that common crossbills breed periodically in lower Deeside, but no breeding birds had been shot to prove the point. In 1974, however, Alan Knox studied crossbills in middle, lower and upper Deeside, 'All the birds seen from Glen Tanar inland are Scottish, there is no doubt of that from the size and shape of the bills. There may be some continental birds among them, but I had a good look and could not find any. However, on 20 April, I found the Glen Dye birds (about 12-15 in a loose flock) feeding on Scots pine, and these all had very narrow bills. Then, on the 22nd, I found a young bird withthem; and there were probably more. Two males shot on 27th confirmed my belief and these were positive curoirostra. This means confirmed breeding this year and almost certain breeding in 1973. On 10 November 1972 Nick Picozzi handled and measured a continental crossbill near Blackball and a family party was subsequently seen there in the following spring.' In 1974 I also met with two groups of common crossbills in Sutherland. On Apri120 one consisted of five birds, three cocks and two hens. However these were not then breeding, although one. cock fed and then copulated with a hen. This was in a mixed conifer wood in which Scottish pine crossbills sometimes breed. I later met with a small party of common crossbills containing juveniles in another mixed conifer wood. How and why have the different species of crossbill evolved? Their common ancestor was presumably a small cone-seed eating finch with a

22 Pine Crossbills straight beak. Selection later perpetuated a new stock bred from a few individuals whose beaks had a tendency to cross. With its crossed mandibles the emergent crossbill was then able to extract seeds from unopened cones and thus eventually to breed earlier than the parent stock which could only exploit opening or discharging cones. Did crossbills originate in larch forests in Asia and later colonise spruce and pine in Europe and have new species evolved over long periods or comparatively lately? The two-barred crossbill of the Asian larch forests was possibly the parent species of palearctic crossbills, the common or spruce crossbill curoirostra developing from it while colonising spruce forests. Common crossbills--probably throw-backs to the original parent species--with white wing-bars have been recorded. The origin of the pine crossbill with its entire breeding range contained within that of curvirostra is intriguing. The nearctic region holds no comparable largebeaked race or species. Where then did great tracts of pine woods exist in boreal Europe except in association with spruce? In Scotland our native crossbills have slightly smaller beaks and wings than pytyopsittacus; although at least from the last glaciation until the late 19th century they have probably bred almost exclusively in pine habitats. Surely, then, we might have expected them to possess even larger beaks than curoirostra. Newton writes, 'These various difficulties cease to exist, however, if it is assumed that the pine crossbill of Europe evolved from the Scottish crossbill, rather than vice-versa. The isolated pine forests of Scotland provided the environment necessary for a large-billed form to evolve. If the Scottish form secondarily colonised Europe, it might then have developed an even larger bill through competition with the medium-billed curoirostra already there. This would lead to greater ecological segregation between the two forms enabling them to co-exist permanently. This process, called 'character displacement', has taken place in the evolution of other species pairs, which differ more in structure and ecology where they overlap than where they live separately. For example, the two nuthatches (Sitta tephronota and S. neumaye,) differ more in body and bill size in Persia, where both occur, than to the east or west where only one or other is found.' This ingenious hypothesis offers a possible solution to our problem but, in my judgment, Scotland was not necessarily the exclusive ancestral home of the pine crossbill. Mter the last glaciation there was no spruce in the British Isles and little or none in many parts of Fenno-Scandia. Even now, for example, spruce is not a native species west of Voss in south-west Norway. How might these forest patterns have affected the evolution of crossbills? In the inter-glacials, or after the last Ice Age, large-beaked pine crossbills probably thrived in the extensive pine forests of north-west and central Europe. But, as the pines retreated northwards, these large-beaked groups are likely to have become isolated in the pines of northern Scotland

The Scottish Crossbill 23 and in parts of north-west Europe, where they had already developed beaks to be or,to compete successfully with penodic Invasions of common crossbills, which probably originated from spruce in eastern U.S.S.R. or northern Asia. In these phases, pine was dominant and spruce only likely to advance in milder periods of In one of the crested tit, an exceptionally sedentary bird With no breeding groups in any other part of Britain, probably settled as a relict in the pines of northern Scotland where Strathspey is still its main redoubt. So far, however, my thoughts were purely speculative. I now asked Sir Harry Godwin whether it was possible to date the advance of spruce into western Norway and southern Sweden, and whether there were periods when parts of these areas were predominantly pinecovered but isolated on most sides by sea and in the north by ice, or only by an' extremely narrow strip of forest into Finland. Sir Harry told me that by a combination of pollen analysis and radio carbon data, his former student, Dr Philip Tallantire, had been able to trace 'The establishment (not necessarily migration) of spruce from eastern Finland westwards through the last 5000 years.... Whilst the north sea was still dry there may well mixed) growing then, but that when it was achave been pine forests tively submerging the spruce was no nearer than west European Russia. This date, about 5000 years ago, was more or less the time of maximum salinity of the Baltic, so that the isolation of south Sweden and Norway then, and for the next 2000 years or more, from spruce forests was complete.' This exciting research naturally led me to correspond with Dr Tallantire, who informed me that before 1000 BC spruce was certainly not a general component in Swedish and Norwegian forests, and that it was not general in Finland before. In all three countries, however, where microclimate was exceptionally favourable, there could have been small.isolated stands of spruce, although it was only invading the Baltic coastal lands after 4000 BC. There is still insufficient data to trace the progression of spruce in the Soviet Union, but there was probably little in the Russian forests before 4000 BC, except possibly in the north-east and in the region towards the Urals or Volga. The progression from birch to pine/birch took place in south Norway, south Denmark and south Finland at around 7000 BC, reaching northern regions about 6200 BC, with the pines arriving in some of the higher southern areas as late as 5000 BC. In the latter areas pine is now absent and is only marginal in the far north. The pines only arrived in the climatic optimum. The dead ice mass, covering most of Finland and the Bothnia Gulf and most of northern Sweden, was probably fairly extensive about 7500 BC, but 500 years later it was rapidly disappearing. However, there may have been a few local patches where vegetation colonised. But isostatic depressions and extensive melt-water in the Baltic then covered the

24 Pine Crossbills modem coastal plain. Pines thus possibly did not reach the birch forests north of Trondheim in quantity much before 7000 Be. The last glaciation was not a solid ice sheet which clamped down and then melted. For many hundreds, or even thousands, of years inter-stadia! conditions predominated. Birch, pine and spruce, for example, were found in deposits at Shaleford 60,800 years Be, although Britain was probably treeless about 20,000 years later. This fascinating research helps to explain how the pine crossbills of northern Europe evolved and possibly why our Scottish pine crossbills differ from curoirostra but have smaller beaks and wings than pytyopsittacus. Only when spruce became firmly established in a milder climate were groups of spruce or common crossbills from the east likely to have settled permanently within the breeding range of the pine crossbill. In northern Europe, as the spruce advanced through Finland into Scandinavia, competition between the larger-beaked residents and the invaders probably resulted in the pine crossbill developing a still larger beak, enabling it to dominate in the pines and leaving curoirostra to settle in the new spruce forests. In northern Scotland, however, Norway spruce has never been a native species since the last glaciation. Here it is only a recent exotic introduction like the sitka spruce. Our relict pine crossbills, therefore, have not faced such acute competition and have had no need to evolve such heavy beaks as their fellow survivors in boreal Europe, but curoirostra has so far failed to establish permanent colonies within its main breeding range in the old pines. What then are the characters and mechanisms which help to maintain reproductive isolation between pine and common crossbills on the continent and the Scottish pine and the invading curoirostra in the north of Scotland] The ecological niches of pine, common and two-barred crossbills are not so rigid and well-defined as earlier work seemed to suggest. Around Kandalashka, for example, where the large mixed pinespruce forests are probably exceptionally favourable to crossbills, pine crossbills sometimes breed almost as early as the common crossbills in years of bumper spruce crop. These mixed habitats also periodically enable all three species to breed in the same year and the pine and common crossbills to enjoy two consecutive breeding periods, March-April in spruce and in May-June in pines. In Sweden, Olsson also noticed that some pairs of pine crossbills fed almost entirely on spruce seeds during incubation, but abruptly changed to the pines when rearing their young. Around Helsinki, which probably provides only marginal habitats for the pine crossbills, Hilden found that the two species did not breed in the same

forests in the same year. There, common crossbills settled in peak years of spruce cone crop and pine crossbill in good years for pine cones, bumper or rich crops of the two trees seldom synchronising in the same area. In 1967, for example, pine crossbills bred in some numbers in the south-west

G eorge Lodge sat besid e th ese be autiful Scot tish pine crossbills and sketc hed them while stay ing at Fairburn in Easter Ross on 20 February 1907

The Scottish Crossbill

25

coastalregionof Finland,wherethere was an excellent pineconecrop,but

no curoirostra nests were then recorded. In 1968, on the contrary, when there was an extremely good spruce cone crop in this region, curoirostra nested abundantly, but there were no breeding pytyopsittacus. In these habitats, however, common crossbills nest more densely and in much greater numbers during their peak years than do pine crossbills which always appear to be relatively scarce in Finland. It is also of interest that in 1936 and 1974, two years when common crossbills bred in Scottish pine crossbill country, there was a good pine cone crop with the seeds presumably more than usually accessible to curoirostra. Apart from different food, there is another possible ecological distinction between the common and pine crossbills in Fenno-Scandia and Britain, with the large species usuallyhaving a shorter and rather later breeding season. In the Scottish Highlands, for instance, our resident pine crossbills usually nest later than the curoirostra groups in the planted pines of East Anglia and they lack the prolonged nesting season now familiar in the sitka spruce country in southern Scotland. In FennoScandia there is a similar pattern; almost half the clutches recorded in the sample were completed in April. In Finland, for example, all seven nests found by Hilden and his friends had clutches in April. This difference is probably partly due to the pine cones opening later than those of spruce. There are other more significant factors. In Scotland I have remarked upon the differences in some of the calls and in the use of song between our resident pine crossbills and those of the continental birds. Particular calls are, I believe, important signals in securing reproductive separation between the two forms. In Europe other observers have had the same experience. Kokhanov emphasises the lower, louder and harsher voice of pytyopsittacus which is particularly noticeable when both species are flying in mixed flocks. Scottish pine crossbills also appear to make less use of the circling song-flights which Newton has recorded in curoirostra, but we await a detailed study of the signals used by the two crossbills in their common habitats in boreal Europe. There are morphological differences. The size and shape of the Scottish pine crossbill's beak is usually intermediate between those of the European pine crossbill and the common crossbill, but there is some overlapping. While examining British Museum skins, I also noticed that the pine crossbill's head was larger and broader than that of curoirostra, and that the heads of Scottish pine crossbills, though smaller than those of pytyopsittacus, were nevertheless broader and generally less pointed than those of curoirostra. The size and shape of the head is thus possibly another diagnostic character. These differences are interesting, as Tordoff (1954), in his studies of captive crossbills, found that the head, face and tail were 'the parts of the birds possessing the highest valence in recognition of individual crossbills by one another.' The shape and size of head and beak

26 Pine Crossbills and the diagnostic calls, therefore, all probably help to inhibit interbreeding and dilution in the wild. INTERBREEDING AND HYBRIDISATION

In the wild I have read no account of interbreeding and subsequent hybridisation of pine and common crossbills in Europe or in Scotland. In aviaries, however, the story appears to be different. A. P. Gray (1958) reported the successful crossing of pine and common crossbills with the production of apparently fertile hybrids. In the United States, Tordoff also crossed a common crossbill with a two-barred crossbill in a cage, producing a fertile hybrid from it. The hybrid is now stuffed in the Ann Arbor Museum in Michigan. This shows how closely related our most strikingly differentiated crossbills are and that they are probably still emerging. In Scotland, one of Ian Newton's correspondents watched a cock common crossbill flying with a hen two-barred crossbill which apparently had young on the wing. It is possible, however, that this particular two-barred bird was one of those rare throw backs to which I have referred. David Tuckwell of Forres also crossed a hen Scottish pine crossbill, which had a damaged wing, with a cock crossbill 'said to have been imported from Austria'. These birds mated successfully, the hen building nests and laying eggs for seven years, in the first six of which two broods were reared annually. The young cocks of this mating weremuch redder in colour than their father. THE CYPR US CROSSB ILL(Loxia c. guillemardi)

Much research into the history and origins of large-beaked races of curoirostra will be needed before we can assess their evolution. In Cyprus the male of L. c. guillemardi, a large-beaked race, which is apparently mainly restricted to Pinus nigra woods near Troodos, differs from curoirostra of northern Europe by its markedly olive-yellow breast and belly. Griscom suggested that guillemardi possibly arrived in Cyprus from the west or north-west and that it and the other Mediterranean races are relicts which had originally settled during the Pleistocene glaciation when various land bridges existed. However, Dr G. M. Serafim, Director of Forests in Cyprus, tells me that Cyprus was an island during the glaciation period, which seemingly did not affect it very much. Pinus brutia, the main pine species there, grows from around sea level to about 4500 feet on the southern slopes and roughly to 3000feet in northern Troodos. Pinus nigra and Juniperus foetidissima, to a much less extent, thrive up to about 6400 feet. Cedar was probably more widespread in the distant past and has been recently introduced to the habitats of Pinus nigra, but the recently introduced spruce and silver fir, have probably never been native species in Cyprus. I have tried to discover something about the voice, behaviour, and

The Scottish Crossbill 27 breeding habitats of guillemardi, but no one appears to have studied.it in depth. There are apparently a few recent records of continental invasions and irruptions, but this well-definedrace has clearly avoided dilution. Was the ancestral stock originally a pine or a spruce feeder? If the original colonisation was by spruce-feeding curoirostra, guillemardi possibly developed its distinctive beaks and colouring in the last few thousand years. THE SCOTTISH PINE CROSSBILL

How should we place the large-beaked relict crossbiUs resident in the north of Scotland? Both the European and Scottish pine crossbills presumably originated from cumrostra stock from spruce forests in Eurasia and later became isolated in pine forests remote from spruce. I have now suggested how, when, and where, this may have happened. Both these pine crossbills have long histories of settlement in pines and are noticeably less eruptive than is curoirostra. In Scotland, indeed, our resident stock seems to make comparatively short movements between the various Caledonian pine relicts and their outliers. Here they have successfully maintained their separate identity and have avoided dilution and hybridisation despite frequent invasions of curoirostra from the continent. Widespread interbreeding and hybridisation would have clearly long ago destroyed the characters of these relicts, but this has not happened. Are the Scottish birds, therefore, (1) a well-defined race of curoirostra (2) a smaller form of the European pytyoplittacus (3) a distinct monotypic species. Newton (pers. eomm.) argues for sub-specific status 'As I see it, the only good grounds for calling the Scottish bird a pytyopsittaCfl,s is that it is apparently reproductively isolated from L.c. curoirostra. The same is almost certainly true for all the southern races of crossbills, both large and smallbilled forms. The European pytyop,ittaCfl,$ is the only one which lives in permanent contact with L,c, curoirostra, without regular interbreeding, whereas with the various other races, contact with L.c. curoirostra is irregular and restricted to invasion years. Yet the fact that all these southern races have evolved, and retained their distinctness, despite wave after wave of immigration from the north, implies to me that there is little or no interbreeding and hence effective reproductive isolation between L.c. curoirostra and all its various races. It seems to be reasonable, then, (1) to give the European pytyoplittaCfl,s full specific status, as it lives in permanent contact with Lie, curoirostra; (2) to class all the others, including the Scottish, which have sporadic contact, as emergent interspecies, and representing a step between subspecies and full species; (3) to give all the latter races Latin names which imply derivation from L.c.

28 Pine Crossbills curoirostra; i. e. to class them all as subspecies of this latter form. Presumably the present large number of L:c. curoirostra in Britain, and

their permanent existence here, is a recent artefact, resulting from the planting of spruce and other soft cone conifers by man, often in areas where the natural tree cover would be deciduous.' How then should we place our relict Scottish pine crossbill, which Ian Newton regards as a well-defined race of curoirostra and Alan Knox (Appendix 1) as a monotypic species, closely related to curoirostra, but reproductively isolated? These Scottish pine crossbills require special treatment, as they are probably relicts of the original stock of pine-feeding crossbills which settled in Scotland when the pines had retreated from England and central Europe. Their habitats in the old pine forests of northern Scotland are possibly unique in north-west Europe. These native pinewoods contained no spruce until the 17th and no larch until the 18th century AD. Our crossbills have thus probably bred in almost exclusively pine habitats for nearly 7000 years. Here they have maintained a separate identity and have avoided dilution and emigration despite innumerable invasions of common crossbills from northern Europe. This separation has been achieved, moreover, by subtle morphological, vocal, behavioural and ecological differences, which are evidently clearer to the invaders than to human assessors. Although curoirostra groups are likely to have bred periodically in good seed years, the resident pine crossbills evidently dominated and survived better when cones were scarce. To compete effectively and to maintain a pennanent presence, curoirostra possibly requires considerable tracts of spruce which was lacking in the Highland pinewoods. The Scottish pine crossbill has thus had no need to evolve a still larger beak. If, however, large plantations of Norway and sitka spruce and other exotic conifers become permanent features in and around the old Caledonian pine relicts, the Scottish pine crossbill may ultimately evolve a larger beak and other tools of effective competition and distinctness. But that would be in the remotest future. We do not know if European pine crossbills occasionally invade or breed in Scottish pinewoods. Like our relict, this is a less eruptive bird and less volatile than the spruce-feeding curoirostra. Would the two pine crossbills interbreed and leave fertile offspring or would they maintain separate identities as do our relicts and invading curoirostra ? As the Scottish and European pine crossbills both appear to belong to a recent common stock, I would redesignate the Scottish crossbill Loxia pinicola pinicola and tentatively place the European pine crossbill, which has evolved a stage further, as Loxia pinicola pytyopsittacus. However, every distinctive relict population of pine crossbill should now be reassessed in the field as well as in the museum. For some of these populations, which are still apparently emerging quite rapidly, may also be

The Scottish Crossbill 29 separable from curoirostra. Since writing this chapter, my friend Bill Bourne has kindly sent me Finn Salomonsen's comments on the distribution and origin of the pine crossbill. Here they are: 'Breeding range Scandinavia and northern Russia, and also Estonia and sporadically along the Baltic coast south to Poland and Eastern Germany. This distribution, which does not agree with any of the usual faunal types, is very peculiar and is not shared by any other bird species. The Parrot Crossbill must be regarded as a derivative of the Scotch Crossbill (Loxia scotica Hartert), which is completely intermediate between the ordinary Crossbill (curvirostra) and the Parrot Crossbill, and like the latter, feeds on pine seeds. The Scotch Crossbill is usually regarded as a subspecies of the ordinary Crossbill (curoirostra), but is better treated as a full species. When this species immigrated to the Scandinavian-North Russian breeding area of curoirostra the morphological differences between the two species increased, which is a well known biological phenomenon (character displacement).' (Salomonsen 1963).

Breeding range of (above) two-barred crossbill Loxia leucoptera and (below) European and Scottish pine crossbi11s Loxiapi"icola IPP.

CHAPTER 3

THE CROSSBILL HUNTERS Hunting for the nests of pine crossbills in big forests is almost as exacting a sport as that entailed in the tracking down of siskins and greenshanks. At its best, the keenest nest hunter finds all the thrills that he or she may desire. Many now frown at the sport of nest hunting which they connect with egg collecting, but how wrong they are. This sport has everything. You have to hunt, detect, understand, and interpret; and sometimes, when rock, tree, marsh and loch are involved, the bright eyes of danger are always shining. Then everything is still more urgent, exciting and demanding. Tracking down difficult nests is almost like a passionate experience in which the bird and you are lovers. There is the chase, a slow beginning, mounting tension, the climax, and then that wonderful feeling of fulfilment and content. Take a crisp and sunny day in March and walk in a Highland forest where crossbills are around. On dark February mornings you have watched the cocks scuffling, singing and mating. Now you hope to find a nest. You walk slowly, sometimes stumbling in the long' heather or slithering on hidden black ice. Often pausing to listen, you pass through the almost silent and lifeless wood. A pied woodpecker fJueks loudly and crested and coal tits forage in the pines. At first you hear no crossbills, but 30

The Crossbill Hun'ers 31 this windless day is an ally. Suddenly, far above the trees, a small dark bird bounds overhead, calling sharply. Once it pauses, flutters and sings and, on a tree below, another cock crossbill sings in challenge. But the small speck flies on until you lose it against a distant bottle-green background. You impatiently drop your glasses and your heart seems to miss a beat before you faintly hear deep calls in the distance. You run forward, but your thumping heart soon drowns the cries. Still, you now know direction and flight line. Eyes fixed ahead, you walk briskly forward, but long before you reach your mark the crossbill has flown back. You reach the wood where the crossbill had called, peer up into the canopy until your neck is stiff and your eyes are watering, but you can see no nest. So, sit down and wait. Alternately beating your hands and stamping around to bring back life to deadened feet, the next hour and a half passes slowly. Tormented by doubt, you start peering and craning again. Has that crossbill really a nest for you to find? Suddenly, in the distance, you hear the sharp call and then the deeper tooping which the cock often uses near the nest. But you have not been as clever as you had hoped. The calls are still far away and the ground is rough and difficult. You try to run, but trip over a root, and down you go full length. Up you get, but this time you will see no small and excited scarlet bird on a pine. There he is flying fast and already far away. You are getting warmer, and the time now passes less slowly. Soon disappointment is in the past. On top of that old pine the cock crossbill chatters angrily and flirts wings and tail. Hands shaking you raise your glass and never allow him out of your sight. For the next 10 minutes the cock keeps calling before going silent. Then, with loudly rustling wings, he flies to another tree top and again starts those angry calls. With your neck stretched upwards you stumble after him. Suddenly, high up and still unseen, you hear the faint mouse-like squeaks of the brooding hen. You cannot yet see the nest, but up there, all aquiver, she is begging the cock to feed her. Watch him, for he will lead you to her and the nest. Now the cock is quiet and pecks nervously at spines before he flies heavily to an outftung branch. That little black lump is the nest, and the cock is standing on its rim. See how he jerks back his head and then bends forward to gulp up seeds for his sitting mate, whose up stretched head and neck and flickering wings you can now plainly see. A bare minute later the cock flutters to the top of the tree, peers round nervously, calls softly, and then bounds away. Climb the tree, edge yourself along the branch, and you almost touch the hen before she leaves the nest and flutters round you. In the rather shallow cup, built on a platform of small twigs, are four greenish-white eggs, spotted with orange-red. The hen scolds angrily and flies from twig to twig, sometimes on a tree a few yards away, but at others just beside you. Before you reach the trunk and start climbing down she creeps along the branch, steps into the nest, and then with little shufHes and shimmies starts brooding. This is the classic method of finding a pine

32 Pine Crossbills crossbill's nest in a large wood, but few hunts have such a perfect ending. On many days you will have nothing to show for your efforts except tingling finger tips and almost frozen feet. Some pine crossbills have unorthodox patterns, sometimes arriving suddenly and visiting the nest without giving a single call. In April 1968 and 1969 I was puzzled by two which behaved like this, but they were usually feeding and started their flights from pines within 200 to 300 yards of their nests. In April 1974 I spent three days trying to find a nest on a hillside in Easter Ross which was littered with old fallen trees, heavily overgrown by long heather. How difficult it was to follow the cock. He only occasionally tooped when about to visit the hen, which I eventually found sitting on four eggs in the crown of a tall pine, in a nest 60 feet above ground, and almost invisible. That cock never flicked wings or tail even when he was most excited. By concentrating at the wrong end of a nesting flight, you sometimes fall into the pit which greenshank hunters dread. The cock behaves almost exactly as if he was about to feed a brooding hen. You watch him fly into a distant clump where he toops excitedly, but long before you arrive he has gone. Confident that he will show you the nest on his next visit, you wait patiently for a couple of hours. Again he flies in, calls loudly, and then slips away through the canopy. Thoroughly puzzled, you look up into every tree, glassing crown and crotch and scanning the ends of lateral branches. But you find nothing. You grit your teeth and wait but, deep down, you guess what has happened. Now you must start all over again and retrace the cock's flight-line I In a large open pinewood several pairs sometimes have their nests spaced about 7S to 300 yards apart. But you first have to find them. You have watched the group disperse and perhaps seen a pair choose its nest site, or watched a hen building. Those angry scuffling cocks tend to confuse you, and in a big wood a hen is often quiet and difficult to follow while she is building. Soon, however, you recognise the rather stiff and furtive flight of a building hen. At other times two hens fighting, or the loud song of a guarding cock, helps you to find the nest. Cocks do not always feed their hens at the nest. The hen sometimes flies out to meet him. In March 1936I saw a cock arrive and start to call angrily before flying about 2S yards to the top of another tree. As he did so, a hen left a clump of pines and pitched on a dead branch about 10 feet above ground. Here she opened her beak and shivered her wings, and the cock immediately flew down and fed her. Then she fluttered from tree to tree and so up to the crown of a pine, where I couldjust see the nest, which was about 40 to 50 feet up. Pairs which are feeding broods at the nest usually have a peculiar flight, cock and hen then flying close together, one just behind the other, often below the level of the tree tops and seldom much above them. They rarely

The Crossbill Hunters 33 call and usually visit their young rather furtively. Afterwards they quietly disappear. How different from the rapid excited nestward flights of cocks, usually calling sharply, as they fly towards nests and brooding hens. None of the old naturalists gave a full description of how they found pine crossbills' nests in the Highlands. In 1848 Lewis Dunbar took the first recorded nest on Speyside, and in the 1850s the Ross-shire forester, Alexander Macdonald of Scotsburn, along with his brother, supplied clutches of pine crossbills and siskins to Harvie-Brown, Hancock, and other Sassenach collectors. In 1871, much later, Harvie-Brown told H. E. Dresser: 'In Inverness the crossbill breeds in the forest of Rothiemurchus and on the banks of the River Spey. It was here that Mr Hancock saw a nest at 80 great a height that it could not be procured.' It must indeed have been a difficult nest to have defeated the indomitable Dunbarl The predatory Edward Booth of Brighton was more interested in 'obtaining' skins than in eggs. In 1876, after a ferocious attack on the red kites of Abernethy Forest, he went after crossbi11s in Rothiemurchus. 'At last the bright red bird and a green one were seen near the top of a high tree close to Coylumbridge. The pair were knocked down by the two barrels but the green bird could not be found, having probably fallen into the river and been swept away. The other was recovered after a long search. In falling it had clung by one claw to a branch and was hanging head downwards.' He also shot a cock at Erchless Castle near Beauly. 'It proved to be of a kind of orange-red and quite different in colour to those lately killed.' Hunting for common crossbi11s' nests in the roadside pines of Breckland is a far less exacting sport. I occasionally found nests in farm windbreaks, but almost all were in single or double roadside pine rows near Mildenhall, Brandon, Thetford, Hockwold and Icklingham. We occasionally watched a hen building or a cock feeding his hen at the nest, but we usually found the nests by spotting them as we walked along the road. The Cuckoo's Secret made Edgar Chance a Superman to me, but I did .not meet him until 1931. Although now remembered mainly for his research on the cuckoo, Chance also intensively studied greenshank and dottere1 in Scotland, and hobby, woodlark and red-backed shrike in England. Many of his notes and data cards, along with his vast egg collection, now in the British Museum, have been of much value to the researcher. A director of Chance & Hunt, Ltd., Chemical Manufacturers, of Birmingham and London, he had a complex personality. Prickly, dogmatic, grasping, paranoically suspicious of rival collectors, stingy, but occasionally impusively generous, Chance was also stimulating, exuberant, enthusiastic, compelling and, if he 80 desired, one who could almost charm birds off a tree I Gifted with a keen critical mind, he was his own worst enemy, taking up and throwing away friendships almost like gloves. I vividly remember my first meeting with him in his London

34 Pine Crossbills office.Wearing a well-padded jacket and fox-eoloured plusfours, he spoke at high speed and bounced about his desk like a rubber ball. Before we left for lunch he had peremptorily rung for his secretary and had .dictated an angry letter to an egg-collecting acquaintance who had apparendy made disparaging remarks about his data I In his later years Chance became still more difficult and cranky and turned to religion. No one then knew, however, that he was contracting Parkinson's Disease, the effects of which often appear to show long before the disease is diagnosed. He died in 1955, almost unacknowledged, and without a worthy obituary in a standard ornithological journal. He thus joined Frank Kirkman, Edmund Selous and J. P. Burkitt, all men of genius, whom the complacent mandarins of contemporary ornithological high society ignored in their lifetimes. It is an open secret that Chance and I bitterly quarrelled and had no direct contact after about 1937. But this has never affected my judgment of his work as an ornithologist. He was one of the giants. I am glad that I knew him. Before his conviction in 1926, Edgar Chance spent many early springs around Brandon and Thetford. His observations there often differ from mine on the pine crossbills of the Highlands. In Breckland he often found that the cock crossbills gave away the nest by singing vigorously close to brooding hens, whereas in the Highlands they are seldom so accommodating. Breeding in rows of pines, rather than in large woods, possibly encouraged the denser Breckland population into situations of challenge and conflict. The facts are not in dispute. What marvellous and exciting hunts he hadl On 27 March 1925 he wrote: 'Heard cock-bird singing lustily and quickly found the nest close by, as is so usual. The hen bird was not on the eggs.' An hour previously EPC had taken two clutches, of four eggs each, on the Thetford-B arnham road. 'Best day's sport with crossbills I ever enjoyed. Grand National Day.' His notes are always fresh and vivid. Those for Sunday, 4 February 1923 read 'Thetford, Suffolk. On lateral bough of a small Scotch fir about 10 feet from trunk and 20 feet from ground, in one of a row of Scotch firs alongside drive to Nunnery Farm, on road to Euston. Female crossbill only Bushed from nest by violently shaking tree; she then remained among the twigs of the branch, only to return to her eggs whilst the observers stood by watching her, and the cock chip chipping in alarm. Typical behaviour of this species. The earliest taken eggs in the whole of EPC's collection.' This greatly interests me as a cock pine crossbill would have used the deep angry diagnostic toop. But what a ruthless and single-minded egger he was. Here he is on 21 February 1925. 'Motoring from Bracknell that morning, EPC picked up the Lees, Senior and Junior, from Huntingdon at Newmarket Station. The nest was quickly found. The bough on which the nest rested actually hung right over the drive and was just reached by using a 42 rung ladder from

The CrossbillHunters 35 which Eddie Lees managed to scramble along the bough to within reach of the nest. The hen bird sat close throughout the proceedings which, in all, lasted over an hour. And on one occasion the cock bird came and fed her on the nest, which was about 35 feet from the ground near the extremity of a long horizontal bough in one of a single row of Scotch fir trees, running along the side of a private road about 50 yards from the keeper's lodge.' Norman Gilroy, my greenshank hero, was the outstanding crossbill hunter in the 1920s. A stockily-built man, with bright blue eyes and a rather squeaky voice, Gilroy usually wore a Norfolk jacket, a loose overcoat, and a cap with a button. Speaking in quick staccato sentences he always bubbled with enthusiasm. This remarkable 'hunter' excelled wherever he went. In 1928 he was let loose in the forest marshes of the Pasvik in Finnmark, where he achieved one of the greatest feats of nest hunting. Among his finds were three nests of bar-tailed godwit, three of dusky redshank, two of wood sandpiper, a broad-billed sandpiper, six greenshanks and a pine grosbeak. He also found and took two clutches of waxwings' eggs, thus joining the small select group of Britishers who followed the great John Wolley. To Gilroy, the Breckland crossbills were sweet but easy meat. 'The cock gives away the secret, either by feeding his sitting hen, by singing constantly in its immediate neighbourhood, or by becoming quite unnecessarily alarmed and chipping without reason.' Since the war, the harrying of the Breckland crossbills has continued, but there have been a few genuine crossbill lovers and students. The late Alex Robertson took fine photographs and learnt much about breeding behaviour in the face of almost intolerable frustration. From 1935 onwards Jack Robson, a Suffolk. banker, studied breeding behaviour and has seen over 100 nests. Two Brecklanders, L. R. Flack and Jonah Rolph ofLakenheath, have also used their skillas nest huntersto learn much about the local crossbills and their breeding biology. Before the war, H. T. Gosnell hunted for crossbills' nests in more difficult country on the heaths of Surrey, Hampshire and Sussex. In his book The ScienceofBirdnesting he wrote, 'Ears should be kept open for the cock's song uttered from the tip of a pine, as he often sings near the nest or even on the same tree.' Gosnell found nests by watching the hen building, sometimes raiding chicken runs for feathers, 'the pair with loud chip-chips flying in a bee-line right out of sight.' He also occasionally watched the cock feeding the sitting hen. 'This is done in a flash and may be easily missed, especially as some nests are placed high up and are invisible from the ground.' Myoid friend Jock Walpole-Bond, a field ornithologist and nest hunter of outstanding ability, tracked down many nests in Sussex, where the crossbills are often a difficult quarry. He regularly found them nesting in large pinewoods near Midhurst where he found eight nests after the

36 Pine Crossbills 1935-36 irruption. 'The male often contributes to your success by perching conspicuously on even the tree containing the nest and then on the approach of fancied danger perhaps settling up cries in defiance and fear.' Unlike many of his egg-eollecting contemporaries Jock contributed much to ornithology. His 3-Volume History of Sussex Birds is a classic. This redoubtable hunter had an exceptionally good ear for bird calls, a wonderful eye, and great courage and skill as a tree climber and cragsman. In the New Forest small groups of common crossbills sometimes nest in enormous Douglas firs. Don Humphrey, an experienced and skilful nest hunter, tells me that some nests are up to SO to 100 feet above ground and often 'obscured from above by over-hanging prongs and are 7 to 15 feet out on limbs.' This is a more formidable challenge than crossbill hunting in Norfolk and Suffolk. In other parts of England and Ireland the eggers were busy. An Irish Squire, a deputy-lieutenant for the County of Donegal, Cecil Stoney's fidelity to the Crown of England was unacceptable after the Treaty of 1921. A former headmaster of a Prep School near Dublin, Stoney now established himself as a coach and crammer at Ascot. With almost telescopic eyesight and good hearing, allied to an extraordinary sense of timing, he was possibly the finest all-round nest finder of his generation. One of the hardiest of all the hunters, he habitually rose at dawn and sometimes stayed out all night wrapped up in his old overcoat. In the mid-1930s he was most successful in Breckland and also found four nests in Ireland, including one in a spruce and another in a larch, in Co. Wicklow. Clement Carroll, a Tipperary Squire, and Leslie Montgomery, a Dublin business executive, were other outstanding Irish crossbill hunters. A good field ornithologist, Carroll climbed to over 300 peregrines' eyries in Ireland, and took 25 clutches of crossbills' eggs in larch, spruce and pinewoods, mostly in the Galtee Mountains in Co. Tipperary. In the Anglo-Irish War, in the 1920s, he hunted the woods of Tipperary and the cliffsof Waterford, with a safe conduct from the British Security Forces in one pocket, and one from the IRA in another. Yet he lived to the ripe old age of SQ-odd years I A remarkable tree climber, Montgomery also reached nine crossbills' nests in Co. Wicklow, but never more than two in.any one year. Horace William Wheelwright-son of a Northamptonshire Parson-had great success in finding the nests of pine crossbills in Northem Europe. Wheelwright, who worked in Wermland, Sweden in the 1850s and 1860s was the first British ornithologist to discover that green sandpipers laid their eggs in the old nests of hooded crows, fieldfares, and other forest birds. He collected a series of pine and common crossbi11s' eggs and skins which are still in John Hancock's Museum in Newcastle-on-Tyne. This fine observer noticed that the pine and common crossbills never seemed to breed together in the same forest in the same year and that the pine crossbills nested on stony rises where the pines were well apart, and

The Crossbill Hunters 37 never in deep forest. Modem Scandinavian ornithologists have been even less specific about their methods of nest finding. In 1944 Peter Valeur, who found seven pine crossbills' nests in southern Norway, listened for the cocks' songs or watched hens building just after sunrise in thin forests. around large swamps. Between 1962-64 Ivar 0ye found eight nests in Nordmore, where he tells us that, 'to find a nest look for a spot where there are many cones on the ground. Then listen for the well known calls.' In 1968 and 1971 O. Spjetvill also discovered three nests by hearing the cocks sing and then spotting the hens building. These three Norwegian observers, and Viking Olsson in Sweden, all noticed that pine crossbills avoided dense woods, nesting in well spaced pines in open or thin forests, close to forest bogs, or on outside trees close to clearings, paths or forest rides. The Russian ornithologists, V. D. Kokhanov and U. G. Gaev, who wrote the detailed account of crossbills in the Murmansk Region, do not tell us how they found 24 nests of pine crossbills, 13 of common crossbills, and four of two-barred crossbills, Their team included foresters and young naturalists from the town schools, and they evidently watched building hens, and cocks feeding hens at the nest, as they give most careful descriptions of this behaviour. Another Russian ornithologist, D. N. Ternovskij, found common crossbills' nests in the big forests of the Soviet Union by (1) searching likely woods, (2) watching cocks fighting, (3) noting the alarm calls of cocks and pairs, (4) watching the crossbills mobbing predators and dogs and (5) following up courting pairs. In the saga of the pine crossbills, no one has ever equalled the achievements of the Highland Laird, William Stirling of Fairburn in Easter Ross. As a young man, while staying with Jock Walpole-Bond, I first heard about this remarkable man who had crossbills and siskins nesting in enormous pines and larches almost beside his door. Stirling's great drive and enthusiasm made him the greatest of all the early pine crossbill hunters. He even chose his keepers for their ability to scale tall trees and to find difficult nests. Between 1900-07 they climbed to at least 91 nests, with 16 in 1904, 19 in 1907, and a wonderful 'bag' of 23 in 1903, the largest annual 'bag' ever recorded north of the Great Glen. Every year Stirling invited famous nest hunters and egg collectors to stay with him. The 'home team' found the nests, to which the guests climbed and took the eggs. In 1901 Frederick Courteney Selous, naturalist, hunter and explorer, stayed with Stirling. For such a wonderful sportsman and field naturalist, Selous's nest hunting methods were extremely unadventurous. Apparently in great haste to complete his egg collection, he travelled from country house to country house to pick up clutches of rare birds' eggs which his friends had marked down for him. In March 1901 he climbed to five pine crossbills' nests in the policies of Fair-

38 Pine Crossbills burn. These eggs are now in the British Museum Collection, but the accompanying notes tell us absolutely nothing except date and location. In April 1905-a late spring--Gilroy was on the ground. Here he had his first experience of crossbills, which he accepted as being of the same species as those he was later to hunt in Breckland. Bums, the keeper, had marked down five nests, but when Gilroy climbed up to them he found that two were full of snow and the eggs split by frost. However, Bums gave him two more clutches which he had taken in the previous week. At Fairburn, 1907 was a year of surprise and excitement. George Lodge, Bird Artist and Naturalist, was one of the guests. 'February 20, 1907 With Stirling to make studies of crossbills and nests for a couple of pictures he wants me to paint for him. His keepers knew of S nests, so we spent the aftemoon among the birds. One of these nests was practically inaccessible, right at the top of a Scots fir, on an outlying branch, so we left it alone. Another was found only today and had two eggs. This was in a small Scots fir about 2S feet up and built against the main stem, which appears to be an unusual position. Another was at the top of a high fir, and contained one egg a few days before. Now there were only broken egg shells, so I kept this nest. 'I went up to the other two nests which were both high in fairly tall Scots firs. The first was deserted and had only 2 eggs. I sat in the tree and made a sketch of the nest and its surroundings. It was snowing fast all the time. I took the eggs and then one of the men came up with a saw and cut off the branch with the nest for me to take away.... 'The next nest I visited contained 3 eggs much incubated. A lot of snow now and curling on the pond. 'February 23 Went to the crossbill's nest in which we left 2 eggs on 20th. The nest was deserted, full of snow, and the eggs cracked with the frost. 'February 24 We noticed a pair of crossbills fly past once or twice, and back again in the same direction. So we lay in wait along their line of flight and soon marked them down to their nest which the hen was building at the end of a horizontal branch of a Scots pine about 30 feet from the ground. The cock bird took no part in the building preparations, but sat still at the top of the tree. He accompanied the hen each time she went off for more building material, which journeys seemed always to be in the same direction. 'February 25 The hen crossbill still busy with her building.' At the end of March, Edgar Chance joined the house party. On the 29th and 30th the keepers showed him nine nests, one with five eggs. One nest was on a long outspread branch about SO feet up a Scots pine and to obtain this 'the bough was tied to a higher bough and then sawn off. When drawn close to the trunk the bird left the nest.' Another nest was placed against the trunk of a larch and about 30 feet above ground. Chance enthused, 'cock bright red, hen dull green, saw pair of birds to perfection.'

The Crossbill Hunters 39 Major Stirling had a white steam car. This year it was working overtime. On 6 April he and his son, John, drove to Muir of Ord Station to collect Raymond Tomkinson of Kidderminster, Before lunch Tomkinson climbed to two nests, fairly high up pine trees. A third nest, near the house, was still empty; a week later, while removing the four eggs, the keeper broke one. But the best was still to come. 'Mter lunch Tomkinson climbed a high pine tree and right at the top found a nest with six eggs in. Naturally Major Stirling had them for his own collection, and gives a clutch of five, which is unusual, in exchange.' This was the first set of six eggs ever recorded in Scotland, and only one other is known. The wonderful story of the Fairburn pine crossbills has a sad ending. William Stirling died in 1914 at the early age of 55, and most of these marvellous woods were cut down in the First World War, thus ending the only detailed and continuous record of pine crossbill groups in the northern Highlands.

CHAPTER 4

HAUNTS AND BIRD NEIGHBOURS Scottish pine crossbills are the first birds to become alive in almost silent woods and forest. In early February, after many days of hard frost, you walk into the forest in bright sunshine. On the dark green foliage frozen snow sparkles brilliantly. By noon, as the sun strengthens, big lumps of melted snow fall almost silently from the branches, often covering you with soft clammy wetness. Outside the woods red deer feed on the few bare patches of peat bog from which sun and wind have shifted some of the deeper snow. In this white glare your eyes water and you stumble and drop through the brittle upper crust of deep drifts. In the shadow of the trees it is cold out of the sun and how silent the woods are I Few birds are about, but small parties of coal tits and some crested tits flit from tree to tree and sometimes drop onto the tips of rank heather projecting through the snow. Higher up the hill a great spotted woodpecker lJueks sharply, but you seldom see these shy birds. As you flounder through the trees huge cock capercaillies, which have been

feeding silently on buds and shoots, go crashing through the branches;

almost always, they see you before you see them. A few blackcocks or greyhens rise from the edges or clearings and far out on the piebald moor an early golden plover creaks plaintively in a peat hag. Earlier in the morning red grouse cocks becked, but they are now quiet and difficult to pick 40

Haunts and Bird Neighbours 41 out on the black patches, although a cock's red comb occasionally shows up. A few weeks later hen sparrowhawks soar high over the trees, squealing as they chase and chivvy the cocks. Now paired and busy, crested tits purr softly in the branches and upper foliage and singing their 'hurdy gurdy' songs, cock siskins fly like large butterflies in loops and circles around the pine tops. The moor is now also alive. Snipe drum over the mosses, oystercatchers hold their strange piping parties on bald moorland, and a few cock lapwings alternately tumble and corkscrew through the air or try to entice hens to their arenas in open places. Soon the greenshank.s will return to the forest bogs and wooded edges and ring ouzels will pipe in the rocky gorges. This is the pine crossbill country in the old forests of Strathspey. It is here that you must seek them. What strangely discriminating birds these crossbills are. Even in their favourite woods they prefer open sunny parts to stands with closer canopies. In these well-spaced woods, the pine crossbills may nest anywhere, even far inside the forest, not merely on the edges or in the openings and clearings; but they do like plenty of water. Peat runnels and water holes often allow them to bathe and drink. Other pairs nest in clearings where woodmen have spared a few clumps of pines. Scattered pines on flats close to Loch Morlich were favourite haunts, but this attractive ground has now been ploughed up for planting. There other pairs nested on stunted pines in forest bogs or on those growing on small islands and hillocks of drift which had escaped the many forest fires. Although our crossbills choose so many different kinds of woods their haunts are usually subtly distinct. Almost always you spot the likely places where you later find the birds. In the primeval relicts they nest on flats, steep or gentle slopes, on scattered trees on sunny hilltops, and often in clumps undergrown with tall rank.heather. The size and height of the trees seem to matter little, but they prefer the old pines, even those that are dwarf or stunted. Some nest in lines and clumps around large lochs, but the woods beside Loch an Eilein seldom attracted many nesting pairs. An erratic hen occasionally chooses an isolated pine in a clearing, but few sought the closer more densely canopied Caledonian woods. In 1960, however, one nest was fully 100 yards inside a rather thicker wood deep in Rothiemurchus Forest. About a mile away a second pair was nesting in an outside tree in a more widely spread stand. In the 1930s and 1940s plantations of mature pines attracted more pairs than the old Caledonian forest. These groups favoured large, moderatelysized, or even small, but always well-tbimled woods, with trees of about 80 to 100 years old. In molt year., in one bil wood near Loch Garten, five to seven pairs nested. In. year. of poor or only modest pine seed, groves of larches helped to feedthe crollbills and assisted the hensto breed. The pines were of native Abernethy stock, then about 80 to 90 years old, and were

42 Pine Crossbills

planted on fertile glacial drift. Sadly, these fine woods were felled in 1945. Some smaller woods were apparently marginal and less attractive. A more thickly planted wood beside Revack Moor held breeding groups in 1935 and 1936, but thereafter I found no more nests before the pines were felled in 1944. Yet, from 1935 to 1945, a smaller and more open clump little larger than a farm windbreak, always held at least one breeding pair. In 1936 four pairs nested. A few pine crossbills also regularly built their nests in open stands near Avengormack between Nethybridge and Grantownon-Spey. On the edges of Abernethy and Rothiemurchus Forests, crossbills often select mature pine plantations containing a few larches. Two small woods near Nethybridge, much favoured by crossbills, were within t mile of clumps of old spruce above the river. I sometimes watched cocks and hens attacking these big spruce cones. Other pairs settled in sunny glades close to roadside cottages and a few in the policies of mansion houses. Groups breeding near Dulnain Bridge often exploited old larches, although they usually nested in pines. Curr Wood, where the crossbills often nested, was grown from Abernethy Forest seed, planted about 1880. In bumper years some pine crossbills also bred in the tall pines around Castle Grant. These trees were about 250 years old when the great gale of January 1952 uprooted them. Most crossbills, however, seemed to prefer trees of smaller stature. In Deeside I have only located Scottish pine crossbills in Glen Tanar and Ballochbuie Forests; but in the 1940s and 1950s many nested in Mar Forest. On lower Deeside there were large groups of common crossbills in 1971-74, but only a few seemed to nest. The most natural forest in Deeside, Glen Tanar, is not unlike the old Speyside woods, but most of its pines are about 150 to 200 years old. Enclosed by high fences and largely cleared of red deer, the Glen Tanar pines regenerate naturally, particularly close to streams and in open parts and clearings. A few pine crossbills possibly nest annually in these fine pinewoods, which sometimes carry many in bumper seed years. However, between 1967-73 I have never met with really high populations. Two nests, which Alan Knox found in 1974, were both in old pines and about 70 feet above ground. One was inside the forest, the other in a well-thinned but old plantation outside it. Ballochbuie contains magnificent relict pines, mostly about 15O-200years old. Large groups and herds of red deer have prevented the trees fr-om regenerating although some are now enclosed. I have watched crossbills feeding in younger pines close to the Dee, but I saw no nests between 1967-74. In June 1971, however, I watched pine crossbills moving through the older woods higher up the hill. The pines of Mar Forest are old, straight and tall, but many are dying. There are so many red deer that the ground below the trees often stinks of their dung and urine. In years of good cone crop these great woods have

Haunts and Bird Neighbours

43

held many breeding pine crossbills. There were good numbers in 1974-75. Few siskins nest far inside the old Deeside forests, but there are often large groups on the sunny fringes and in mixed conifers outside the relict pines. In these ancient forests chaffinches are dominant and willow warblers almost equally plentiful on scrubby edges and among young trees. Glen Tanar looks ideal for crested tits, but I have never heard their trill and purr there. However, in the winter of 1973-74, crested tits were heard in several of the old pinewoods of Dee. Coal tits and goldcrests are in the pines and great and blue tits in scattered birches and in clumps of broad-leaved trees close to cottages and houses. Mistle and song thrushes and blackbirds sing on the outskirts, but do so less often in the depths than in some of the old Speyside woods. Redstarts are in the more open woods and around clearings, creepers and spotted flycatchers nest, and grey wagtails and dippers are on the burns. Glen Tanar and Ballochbuie are famous capercaillie haunts and blackcocks have their leks close to the birches. These woods have more golden eagles' eyries than those of Spey. Sparrowhawks, kestrels and buzzards nest in the pines and a few merlins on open heathery braes. But I do miss the forest bogs and squashy places. Except on a few high forest meadows there are no greenshanks, and golden plovers nest well up the hill. Marginally less attractive for birds than those of Strathspey, these fine old forests still have great charm and fascination. Woods in which pine crossbills breed in Easter Ross greatly differ from those of Spey and Dee. Between 1952-74 I have regularly found up to three pairs of crossbills nesting in a straggling wind-sown pinewood growing on the slopes of a small rounded hill about two miles from the Kyle of Sutherland. Many trees are twisted, stunted and have bushy tops and most are about 30 to 50 feet high and roughly 80 to 100 years old. The crossbills prefer openings and clearings where the pines have escaped axe and fire. In some years, as in 1974, these trees, with their tops open to the sun, have produced grand loads of golden cones. Under their favourite trees the cones which the crossbills have partly emptied lie thick on the ground. Here I have spent many happy days watching pine crossbills and sometimes groups of non-breeding common crossbills as well. In this little wood crested tits nested annually between 1952-69 and in 1974 they are back again. I always enjoy watching and listening to these explosive little tits and occasionally finding a nest in a rotten pine stump or a brood of young with their excited and noisy parents. In these years buzzards have usually nested and sometimes a pair of sparrowhawks. In 1973 and 1974 kestrels had nests. Hen haniers and short-eared owls sometimes haunt the newly-planted hillside outside the high fence and tawny owls and hooded crows breed regularly. Great spotted woodpeckers drum and bore in the whitened skeletons of fire-blasted trees. In years of heavy larch or pine yield, groups of siskins nest in the openings and on the edges. Black grouse and woodcock are also here. Coal tits, wrens, robins, goldcrests,

44 Pine Crossbills willow warblers and chaffinches are the dominant small birds and tree pipits, redstarts, yellowhammers, whinchats, and now stonechats, sing from trees, stumps, and brashings on the fringes. Spotted flycatchers, great and blue tits, are in the birches, and redpolls sing and loop over the younger pines on lower slopes. In 1974 some goldfinches and many greenfinches competed with the crossbills for the pine seed exploding from the cones in the warm April sunshine. In wet dips and hollows are groups of nesting redshanks and curlews court and chase on outlying moorland edges. I have even watched a cock curlew's fascinating wing flapping parade and his mating with a hen among the scattered hillside pines. Red grouse and golden plovers are on the heather and greenshanks nest higher up the valley. Sometimes a cock greenshank sky dances over a burnt patch of my wood, but I have never found a nest or brood. A grand little wood, it is always full of unexpected thrills and surprises. A few miles further west is a relict of 'grytt fiz woods' in which the pines in the more open stands are from 150 to over 200 years old. In these last ten years pine crossbills have usually haunted and sometimes nested in these fine trees growing on siliceous granulites on glacial drift. Buzzards and sparrowhawks nest in tall pines growing on steep heathery braes and hillocks. There are often many siskins in the pines and redpolls in the birches. Redwings have nested, dippers, grey and pied wagtails are on the burns, and great spotted woodpeckers, redstarts, bullfinches in the woods, where chaffinches and willow warblers are dominant. The most regular pine crossbill haunt in Easter Ross is a complex of mixed conifer woods about 20 miles further south. Here a few old pines, tall, straight and about 150 to 200 years old, have been spared as seed trees. In one fine clump rising above a rounded hillock, I have often watched the crossbills feeding. Here they also often attack the cones of mature but younger planted pines and birches, but less frequently feed on cones of spruce and the exotic conifers which are also growing in these woods. These crossbills favour old pines in well-spread plantations and clumps of smaller and more stunted trees growing higher up in wet peaty hollows. In these woods crested tits occasionally nest, and many siskins are in the larches and some redpolls in the birches. In early spring I have listened to sparrowhawks in their high pursuits and magpies chattering in spruce thickets on the outskirts. Pied woodpeckers drum on pine and beech, dippers and grey wagtails haunt streams, and long-tailed tits the scrubby edges. I have often heard the raven croak as he flies high above the trees towards his nest in a distant crag.

The Forestry Commission has planted what was left of some other old pinewoods in north-east Ross. All that now remains of the old woods are some scattered and well-dispersed clumps growing on different parts of the hillside and beside or close to a loch. All around them are plantations of

Haunts and Bird Neighbours 45 younger pines and of spruce, larch and Douglas fir. In 1974 I noticed that the pine crossbills almost invariably fed on the old pine tops, ignoring what appeared to be quite rich crops on the younger conifers. At this stage, therefore, their true habitat is much smaller and more restricted than superficially appears, being almost entirely confined to the scattered groups of old pines. This shows how selective Scottish pine crossbills usually are. Apart from the crossbills, these are exciting woods with plenty of siskins and other small forest birds. Sparrowhawks, buzzards and kestrels and a solitary pair of herons nest in the depths. Hen harriers and sometimes short-eared owls display over the outer plantations, and there are greenshanks and black-throated divers on the moors and flows above. Sutherland no longer has relicts of the old Caledonian Forest; but there are still a few good pinewoods in the south-east of the county. Sadly, the wood where I found my first Sutherland pine crossbill's nest in 1970 had been felled when I returned in the following March. Another crossbill pinewood in Sutherland has some larches growing through it and along the edges. Some of the pines have already been felled, but the well-spaced trees in the clearings still attract a few nesting pine crossbills as well as wandering curoirostra. While waiting for the crossbills you often watch a hen sparrowhawk joining her mate in courtship flights and chases. Pied woodpeckers sometimes feed high up in the larches, mistle thrushes sing in the openings, and wood pigeons display in the depths of the wood. In the early morning and evening cock woodcocks squeak and croak and take part in noisy excited chases. A pair of buzzards have their eyries, and ravens sometimes bark and tumble high above the wood. In the scrub, wrens tack noisily and tree pipits sing from scattered pines along the edges. Here, in 1974, I heard a crested tit and saw a pair of willow tits courting. Roe deer go bounding gracefully through the trees. This is a wood of real character. From .1971 onwards, pine crossbills have nested in another wood which is close to colonies of common terns breeding on a stony spit. Ringed plovers and oystercatchers have nests along the shore. In winter and early spring there are many ducks on loch and mud flats. I like best to watch the shelducks courting; the cock bobbing and the pair flying in great loops and circles. Here, not far from this crossbill wood, white-billed divers, rednecked grebe, surf scoter and king eider were reported in winter. In some years many cock siskins sing around pine, spruce and larch. What evocative sounds you hear as you hunt for crossbills in a wood where dull moments are few 1Crossbills have also nested in the best woods for capercaillie in Sutherland, where the crossbills seem to favour scattered pines in clearings and in swampy places. Buzzard, sparrowhawk and long-eared owl sometimes nest there and herons in a young pine plantation nearby. In Moray pine crossbills breed in older stands of pines in Monaughty and Culbin Forests. These Culbin plantations carry more capercaillie than

46 Pine Crossbills any woods in which I have worked and crested tits nest ill: good numbers in old stumps which the foresters have spared. Coal tits are.plentiful but siskins scarce. There is a small heronry and buzzards nest m the older forest. On the sea shore, outside the woods, common and sandwich terns have colonies and many com buntings used to nest on nearby farmlands. In other parts of Moray the crossbills sometimes favour old pine plantations and large windbreaks. They have also nested in old but stunted Scots pines near Lochindorb and other places. In' autumn and winter our bird's choice of habitat is wider and more arbitrary. In northern Scotland native crossbills now often settle in groves of larches and in woods of mixed conifers as well as in pines. In the 1949s' Richard Perry sometimes watched a flock of up to 40 pine crossbills wintering in a larch grove near Drumguish, where they fed on pine buds and larch cones. They may also feed on younger pines than in their main breeding season, but some wander widely in the old forest, though seldom in high numbers. Mixed conifer woods are always a good bet in winter when you are looking for them. PINE CROSSBILL IN NORTHERN EUROPE

In the 1860s Wheelwright noticed that pine and common crossbills did not breed in the same year in the forests of Wermland, Sweden. In autumns when the spruce had a rich crop of cones, flocks of common crossbills usually arrived and started to breed later in the winter. Pine crossbills, on the other hand, only nested there when the pines were heavy with cones. In Wermland, however, pine and spruce both apparently had rich crops every third or fourth year, but their coning seldom synchronised. Pine crossbills almost invariably chose small pines, 'never in deep forests, but always on a stony rise, where the pines are small and wide apart.' How like some Scottish Highland haunts I In 1958 and 1963, in Ostergotland, Olsson also noticed that his pine crossbills avoided dense woods and selected trees in the open parts of the forest or those growing close to rides or clearings. Nevertheless, his fine photographs of nesting habitat suggest that these Swedish pine crossbills nested in a newer and less widely-spaced kind of pinewood than those usually chosen in northern Scotland. Olsson's pine crossbills fed on spruce seeds until the young had hatched, thenceforward exploiting the opening pine cones. Pine crossbills have many different neighbours and haunts in Norway. In 1944 Valeur, who found scattered colonies east of Kristiansand South remarked that all his birds nested in thin pine forests close to large bogs, and Spjstvill also reported that the nests in Trondelag were built on the fringe of thick forest (chiefly pine), but close to more open terrain which was mainly boggy. Hugh Blair describes a wonderful June morning on the Pasvik. 'As the first mists rolled over, a pair of black-throated divers, coming from the

Haunts and Bird Neighbour, 47 river, circled once or twice overhead and descended headlong into one of two nearby forest lakes, a pair of bean-geese flapping noisily across the other at almost the same moment. A dusky redshank was the next bird to break the silence and then the ringing calls of a considerable party of parrot crossbills suddenly arose from the pines below. Although the birds were invisible amongst the sombre greenery, their movements could be traced by their almost incessant clamour until they had passed beyond hearing. Barely had the descent of the fell been completed when a second large band drew near. The whole company pitched into the pines overhead, calling excitedly as they swarmed amongst the branches, where many at once fell upon the cones with which the trees were burdened...• As the uproar of their concerted voices died away, yet a third flock-fully as large as either of the others--came within hearing. But this turned aside to mob a fledgling Lapp owl which some of its outliers had come upon in the thinner forest on the fringes of a swamp.' Blair tells me that the Norwegian pine forests rarely, if ever, lack at least a sprinkling of deciduous trees, chiefly birch. Pine crossbills thus have a surprising variety of other bird neighbours before they wander away with their broods. A list compiled south of the Arctic Circle includes the following: goshawk, sparrowhawk, merlin, hazel grouse (restricted to the eastern valleys), capercaillie, blackgrouse, great black woodpecker (scarce), pied woodpecker, cuckoo, hooded crow, willow warbler, goldcrest, pied flycatcher, spotted flycatcher, tree pipit, robin (scarce), fieldfare, redwing, song thrust, northern willow tit, crested tit (to lat. 65°), chaffinch, brambling, siskin, common crossbill and northern bullfinch. In some of the higher-lying forests there are also three-toed woodpeckers, Siberian jays and Lapp tits. Within recent years-e-no doubt as a result of the cooler climate--a few waxwings and pine grosbeaks have also bred in the sub-arctic forests. At intervals a pair of Tengmalm's owls or, more rarely, hawk owls, will take over a hollow tree in a pine crossbill haunt, and such convenient nesting sites regularly attract goosanders and, in some districts, goldeneyes, should there be a lake or river nearby. At higher levels, where the pines encircle peat mosses, some greenshanks become forest birds, the hens laying amongst the trees, well away from the nearest clearing. Of late, ospreys have returned in increasing numbers to old longdeserted haunts, further to swell the numbers of the pine crossbills' likely neighbours. Of these species, the goldcrest, crested tit and siskin do not cross the arctic circle, while the willow tit, chaffinch and bullfinch are much scarcer beyond that latitude. On the other hand, the Siberianjay and Lapp tit both became more numerous and more generally distributed; while Tengmalm's owl and hawk owl occur more frequently; and the hazel grouse reappears in the Pasvik Valley. The list reaches an even greater tally in East Finnmark, with the addition of the smew, rough-legged buzzard,

48 Pine Crossbills dusky redshank and wood sandpiper-both of which like the greenshank will nest amongst tall pines--Lapp owl (at long intervals), waxwing and pine grosbeak. Bluethroat and grey wagtail have also claims as they sometimes nest in little pockets of marsh on a pine-elad ridge in the Pasvik valley, and a few golden eagles still cling to these forests. Exceptional neighbours of the pine crossbills were a pair of arctic terns with a nest on a small forest pool and a pair of swifts found in an old woodpecker's hole. In Finland most pine crossbills choose pines growing on rocky but flat ground, with an undergrowth of lichens, and Myrtillus. They prefer very light open woods, usually nesting near openings, on the edges of or beside rides, or occasionally in solitary pines (Hilden and Stjernberg, per«. comm.). Dementiev and Gladkov give a similar general description of the habitat of pine crossbills in USSR, where they usually breed in tall pine forests. In the Lapland Reserve they also nest in watershed pinewoods and in spruce-pine forests, as well as on bogs with scattered pines. In Murman Region, Kokhanov tells me that their breeding habitats are rather different. Here they nest in all kinds of conifer woods with special preference for mixed pine-spruce forest, where they favour open woods with well dispersed trees. In denser forests they usually build their nests near meadows, bogs, forest paths and clearings. Most nests, however, were found on spruce trees. Common and two-barred crossbills also share these habitats. In northern Europe pine crossbills are not confined to pinewoods in winter but feed on spruce, larch and sometimes on rowan berries. In November 1929, however, Finn Salomonsen noticed that the groups of parrot crossbills in Zealand forests in Denmark fed mainly on pine cones, even in mixed conifer woods where there were many spruce and some birch and alder. COMMON CROSSBILLS

In England and Scotland common crossbills have now established breeding groups in several different kinds of habitat. In southern Scotland, where many groups had already settled before the large 1966-67 invasion, most of the pairs are nesting and feeding in sitka spruce plantations. Here there are the usual small forest birds, but in many woods sparrowhawks are breeding at exceptionally high density. In these woods the crossbills sometimes nest continuously from October to June, but they seldom breed in high numbers in any particular wood in consecutive years. Some of these mobile groups appear to have a rough three-year circuit (I. Newton, pers. comm.). In Argyll and probably in parts of Perth, and other districts in northern Scotland, curoirostra also seems to be settling in the maturing conifer plantations, but little is known about them. Habitats in

Haunts and Bird Neighbours 49 Northumberland are also in planted conifers and forests. From 1910 onwards common crossbills have bred continuously, but in widely varying numbers, in the East Anglian Breckland. The late A. W. P. Robertson considered that these groups were never fullyestablished until the post-war pine forests had matured, but this wonderful country has always supported nesting crossbills for over 60 years. Here few to many pairs have nested annually in single or double rows of pines, sometimes in windbreaks or in pine clumps beside dwelling houses around Newmarket, Lakenheath, Brandon, Icklingham, Weeting, Hockwold, Bamham and Thetford. Particularly in winter, these crossbills do feed in the new forests and plantations, but only seldom breed in them. Periodically these indigenous groups are reinforced by large nomadic flocks of invaders from northern Europe or the Soviet Union and then the crossbills breed in great numbers in the familiar haunts and in others more unexpected and less favoured in most years. Breckland, however, never lacks its crossbills which appear to change their nesting haunts from year to year. Around Lakenheath, for example, particular rows of pines are sometimes used only once in about three years, but no one has yet studied relationships between invadersand home birds. When I knew this Breckland in the early 1930s this was one of the most stirring and exciting bird grounds in all Britain. In February and early March the crossbills attracted us to the pine rows. Chaffinches were then their almost only neighbours, but around farms, cottages and houses there were always house sparrows, and mistle and song thrushes soon started singing in the pines. Later, when the crossbills were feeding their broods or the hens sitting on late nests, the great flinty Brecks became alive. While you watched crossbills in the pines you often heard the musical and nostalgic wailing of stone curlews and the almost unrivalled rich songs of woodlarks high up in the air. Still later, in thickets and spinneys, blackcaps, garden warblers and nightingales sang almost continuously. Further out on the flats of the open Breck, cock ringed plovers scurried after the hens, often slowing down their wing beats as they crossed and recrossed in invisible tracks in the air. On the rough edges and among the seedlings were red-backed shrikes, stonechats, whinchats, and wheatears nested on the flinty spaces in a few of the almost innumerable rabbit holes. In the marvellous country that I used to know, you also sometimes heard the whistling of gadwall close to the Little Ouse or perhaps, on days to be remembered, you might see a pair of Montagu's harriers soaring, floating and toying over a future nest haunt. Now much has changed. Most of the Breckland, where I hunted stone curlews or sought woodlarks, are thickly planted with commercial stands of pine. The stone curlews have gone or are concentrated in the few remaining open Brecks or in the fire-breaks between the woods. Some now also nest on the farmlands which man has clawed back from the Breck. Ringed plover, stonechat and

50 Pine Crossbills wheatear have also almost disappeared from my beloved haunts. Yet, thankfully, the crossbills still remain in many of the old and familiar pine rows. In southern England the crossbill groups are fewer, more scattered and far less stable. In Surrey the odd pair periodically nests in scattered belts, clumps, rows of small pines on the fringes of heaths or occasionally in stunted pines growing in peat bogs. This was, and still remains, most attractive bird country. In March and April I used to hunt down woodlarks' nests and in May and June watch the magnificent sky-plays of hobbies. Then, in the 1930s, after many mild winters, Dartford warblers were almost the commonest heathland birds, certainly breeding in greater numbers than stonechats and whinchats. There were also grasshopper warblers in a few wet and overgrown places, and at dawn or dusk so many cock nightjars often challenged one another that their churring sounded almost like the rattle of machine guns. Sparrowhawks, kestrels and carrion crows nested in large and smaller heathland woods and clumps and curlews bubbled over the boggy edges where the crossbill never quite belonged. In the New Forest, where a few crossbills regularly nested in pines in the 1930s, small groups now breed in tall Douglas firs, although some still choose pines and occasionally larches. In these wonderful woods the crossbills live with hobby, buzzard, and occasionally Montagu's harriers as neighbours. Woodlarks are still on the heaths and Dartford warblers in the gorse outside the pinewoods. In Dorset the few pairs favour the same kind of heathland, with isolated clumps and lines of pine, and they also have woodlark, Dartford warbler and hobby for company. In Ireland, where crossbills are now scarcer, there are small groups and isolated pairs in plantations of pine or in pines mixed with larch and spruce. The future will determine whether they will settle permanently in the new and now maturing conifer forests of the Republic.

CHAPTER 5

FLOCKS AND GROUPS Pine crossbills are social animals whose survival partly depends on the coherence of the flock. In any month you are likely to meet with groups of varying size which are associated for different purposes. Flocks of pine crossbills are always exciting. Sometimes the stout, crimson or red-brick parrot-like cocks are tense and passionate, their songs and chatter often rising to a harsh crescendo, at others they are quiet and inactive with passion and tension briefly dormant. Mixed flocks are also difficult to watch, the crossbills moving like mice through branch and foliage, contacting one another by soft almost inaudible calls. All you now hear are cones tumbling from branch to branch, seed cases spiralling in the sun, and an intermittent loud leathery rustle of strong wings. The scarlet, orange, or brick-red cocks harmonise with cone, trunk and branch, and the green hens with the spines, their different coloured liveries both providing excellent camouflage. All crossbills have a strong social drive which conflicts with a need for isolation, spacing, individual distance and territory. Yet, even in the breeding season, this dynamic sociality often leads to unexpected associations. In October and November pine crossbills often fight and bicker in their flocksjust as they do in mating assemblies before pairing; but I have never found nests between October and December, as regularly happens in the common crossbill groups in the mixed conifer forests of the Soviet Union and lately in the sitka spruce plantations of the south of Scotland. In November 1939, however, small mixed groups of pine crossbills in Strathspey behaved almost precisely like those in later pre-nesting assemblies. In these packs the cocks alternately fought with fierceness and 51

52 Pine Crossbills then fed on the pine cones. Time after time the crimson cock birds dropped their cones to jostle and bump one another off the tops or branches of the pines. This shows how erratic flocking behaviour is among these unusual birds, but all this did not lead to particularly early nesting. In the Murman Region a few pine crossbills pair up in October, but there, as in northern Scotland, they usually become alive from mid to late January when the cocks start singing vigorously, larger flocks fragment,"and pairs start to hive off. Although consistently shorter than that of curoirostra, the long and irregular breeding season makes subtle differences in the flocks difficult to compare, but sexual behaviour in late winter assemblies seldom leads to exceptionally early breeding. Cocks predominate in these winter groups which are often large in good seed years. At times, some of the cocks sing in harmony interrupted by bursts of stridency. At others, calling sharply, the flock flies from wood to wood, usually alighting near the tops of the trees. Afterwards the members quietly disperse although most usually feed high up, when they are often so quiet and unobtrusive that you must be close to hear their subdued contact calls and the discarded cones. In winter, Scottish pine crossbills are sometimes restless, warning companions by tooping loudly and calling insistently to induce the group to By away. These flocks often favour larches, whose upturned cones still retain seeds. The flock has helped crossbills to survive. Not only do the collective eyes of the group and their sharp-eyed sentries assist the members to avoid predators, but they also help to discover sources of food. Svardson (1957) suggests that when cone crops have failed over large regions and large flocks are on the move, crossbills may possibly find new and more abundant crops from a long distance away, by detecting subtle differences in the colour of the canopy. Groups of pioneers thus probably lead others to fresh feeding grounds and so enable them to survive in years of famine. In late December, January and early February, as numbers and the cone crops are more influential than the calendar, the pine crossbills form pairs in the flocks. In these excitable packs, cocks frequently sing from the tops or from exposed sprays high up in the trees, from which the more aggressive continuously supplant the less dominant. Some cocks now feed or go through the motions of feeding hens, sometimes scissor beaks and sway rhythmically with them, or perch on sprays just above them. You may also see a cock briefly mount or drop down onto the back of a hen, but these early couplings or courtship feedings are generally incomplete or symbolic. However, the loud songs of the more dominant cocks indicate mounting passion and increasing tension. Near Dulnain Bridge, Winifred Ross also saw cocks and hens bumping rivals ofIbranches. 'A bird sitting at the end of a branch is a temptation to every other member of the flock; males knock off males only, and females

Flocks and Groups 53 shove off females. Both either fly up or sidle along the branches to the other bird, and rather roughly bump the one at the end into the air, but they do not follow up with further aggression. There seems to be as much fighting between adult females as between males. My observations tend to show that the cocks fight most fiercely from September to December, and the females in January and February. The milder forms of combat consist of pecks, and bill snapping, with some feathers raised on the crown. Birds often face each other motionless for nearly a minute, bill open, and then crack their bills together several times without attempting to touch their opponent. The sound can be heard 20 to 30 yards away. At other times the bill-snapping may end in one bird making a plunge at the other, which may fly off to another tree and be followed up; or it may face up, and a real fight, breast to breast, ensues, claws and beak used; up in the air, down to the branches, even to the ground, and out into the open, with a few feathers flying.' Unfortunately, however, Miss Ross does not give precise dates and years which would enable us to assess the size of the flocks, the nature of the fighting, and whether pine or spruce crossbills, or both, were involved. In the chapter on sexual behaviour and display, I shall describe mating parties and assemblies. But there are at least two different kinds of mating groups. In years of high numbers, a rough peck order or hierarchy helps an orderly formation of pairs. This mechanism is more easily observed in an aviary than in the field, but some cocks in groups that I have most closely watched were clearly of high status. They continuously bumped and jostled rivals from the highest and most prominent parts of trees. In his studies of the social organisation of captive crossbills in aviaries, Tordoff (1954) discovered that his crossbills settled rank in the peck order by active fighting and by threat displays. Their flocks contained three distinct hierarchies: (1) a peck order of males; (2) a peck order offernales; (3) dominance of males over females. This efficient social organisation assisted the flocks to operate as a unit and thus had important survival value. In the wild, where space is unlimited and there is less need for individuals to browbeat one another, these hierarchies are less easy to distinguish, but they do exist, with particular cocks often dispossessing others from more favoured perches. Later you watch mating groups, consisting of some firmly established pairs accompanied by several unmated cocks in scarlet, orange, intermediate, and green plumage, together with one or more unmated hens, in a loose association. Soon the mated pairs hive off, although a few may still stay together, flying from wood to wood before finally settling their individual territories. Meanwhile, particularly in years of large populations, a surplus rump of mateless cocks, alone or in company of one or two unmated and unreceptive hens, often alight on trees in nesting territories from which the tenants usually eject them. The sex-beat of the members of these non-breeding groups varies greatly, some--possibly low status

54 Pine Crossbills birds--being quite passive, whereas other small 'cock packs' often consisting of vigorous angry red birds, sing loudly and jostle for position between meals. Several of these brilliant red birds almost simultaneously burst into song and then fly out in display-flight, slowly and deliberately beating their wings. Singing harshly, they now violently attack one another, grappling beak to beak and claw to claw in vicious fluttering battles which are occasionally continued on the ground under the trees. In these hierarchical groups dominant cocks usually feed or sing high up in the trees from the tops of which they rudely jostle less aggressive contenders. Sometimes, however, several cocks suddenly fly onto different tree tops, where they toop loudly or sing full greenfinch-songs. A few minutes later they start to chip sharply before re-assembling and flying away. Here flocking and isolation impulses are clearly at odds. However, a particular cock occasionally shows his independence by continuing to sing loudly after his companions have gone, but he seldom maintains this for long. Soon he shows signs of inner conflict, flicking his wings, making upward and downward head movements, or pecking fitfully at spines. A need for companionship or society is possibly becoming urgent. Chipping loudly, he soon follows his flock mates which are now calling in other parts of the wood. In years of moderate cone crop you may see other variations in the behaviour of smaller non-breeding rump parties. On 12 April 1941, while I was watching a group of excited unmated cocks, two plunged in spirals through the branches, five others sang greenfinch-songs in harmony, and others pursued the only hen in the pack. Finally the group broke up, some flying away, the others singing and display-flighting between the tops of larches and driving off rivals from particular trees. After a few minutes, however, they gave up and followed their associates. Surplus groups, containing more cocks than hens, often in a ratio of four to six cocks to one hen, periodically attach themselves to cocks whose hens are brooding eggs or young, or to pairs which have broods in their nests. The mated cock or pair then appears to lead the group from feeding ground to nest and then back again. Even if the breeding birds feed on a different tree or trees their noisy satellites follow them backwards and forwards, waiting until cock or pairs have fed hen or brood and then bounding after them. On approaching the nesting tree, the group usually pitch on nearby tree tops after the tenant or tenants have perched. Before going to the nest, the territory holder often flies over and roughly tips one or two from their stances. But the excited satellites usually continue to wait. In invasion years non-breeding groups of continental common crossbills also sometimes join up with a breeding cock pine crossbill. On 30 April 1967 I watched a party of six common crossbills fly in with Green Shoulders, the cock pine crossbill whose movements and behaviour we

Flocks and Groups 55 were recording at the nest. As usual, Green Shoulders alighted on the top of a tall pine about 50 yards from his nest and there started his loud tooping, Meanwhile, the common crossbills landed on two nearby trees, from which Green Shoulders immediately bumped off one of them and then flew across to the nest. The pack now followed, several actually landing on the nesting tree. After our bird had fed his hen all seven flew off together. The decisive flight and movements of the breeding cock was evidently inducing lower status birds to follow him. On the other hand, pairs of crossbills returning to feed their broods usually fly more hesitantly, seldom calling loudly, unless something disturbs them near the nest. The attachment of groups to pairs with young is thus less easy to explain. There are less orthodox associations. Two unmated cocks sometimes become companions, feeding and flying about together. Synchronising their movements from wood to wood or from clump to clump, some of these homosexual couples behave almost in the same way as heterosexual pairs. But I have never watched a cock copulate with another, although one often leads or dominates the other. I have also watched this unusual behaviour in a few other birds. Two cock greenshanks, for example, are occasionally partners in exciting and dramatic nuptial flights in which the more dominant of the two cocks takes the male rOle in the sky dance, the two cocks then turning and swerving in perfect harmony in the set pattern of this marvellous display when both sometimes look like midges against the grey background of the Highland sky. In early springs I have also seen a couple of cock golden plovers associating on a territory, one leading and possibly dominating the other. This unusual pattern may help sex rhythms to strengthen, but pairs of cock pine crossbills apparently use their associations as an asexual substitute for the real thing. An unmated cock uses its song as a social signal, another bachelor sometimes responding to it. The stranger's arrival usually upsets the singing bird which flicks wings and tail in the inward clash between his anger and fear drives. The next minute or two are decisive. The cock which had been singing may then attack his would-be companion or he may leave and flyaway with him. Mateless cocks also sometimes sing from tree tops to regain contact with lost comrades. Some cocks behave still more strangely. On 18 March 1938 a cock sang loudly from a tall pine about 100 yards from a larch where another cock was also singing. Mter a couple of minutes, the cock on the pine suddenly flew out on a 'butterfly' song flight, which ended by his perching 15-20 feet below the larch bird. At first the two cocks were passive, but both stopped singing. For six minutes the bird which had made the 'butterfly' flight fed nervously and then he suddenly flew up and jostled the other from the tree top where he cleaned his beak on an old point. But he was very tense. Without warning, other than tightening and sleeking his feathers, the top cock abruptly dropped down and chased the other in one of the most rapid spectacular

56 Pine Crossbills flights that I have ever seen crossbills make. Looking like flashes of crimson fire, the two cocks turned and twisted over at least one-quarter of mile of open country before they flashed over a glade. Neither returned. This was clearly a battle of dominance between two unmated but potentially breeding birds. Large post-breeding flocks are likely to contain several different elements, including rump parties predominantly of cocks, with a few nonbreeding or failed hens or pairs, later re-inforced by family groups consisting of cocks or hens, or both, along with their flying broods. After the young are on the wing, however, family parties often divide and disperse, each parent then leading, guarding and feeding one or two fledglings. The two parents and their young are thus likely to become members of different groups which have members of different families in them. As these flocks later wander to well separated post-breeding and winter feeding grounds, young from the same nest are sometimes reared in quite different environments. The youngsters in these flocks continuously use their insistent begging cries and behaviour, to which their parents and sometimes other members of the flock respond by feeding them, although it is difficult to assess how much food they receive from their elders, other than from their own parents. However, I have seen two different cocks feed the same youngster. These assistant or foster parents, presumably birds in breeding condition or those which have lost their own broods, thus respond to the young of other parents much in the same way that several fostering species may feed the same young cuckoo. As young crossbills take longer to attain independence and to acquire the ability to maintain themselves than do the young of any other finches, they clearly benefit from the presence and leadership of more experienced birds.

CHAPTER 6

TERRITORY Territory in the Scottish pine crossbill is exceptionally complex. Irritable and aggressive birds, with strong social drives, their territorial patterns lie between those of the chaffinch, with its well defined comprehensive breeding and feeding territory, and the small and much more flexible and loosely defended nesting territory of the siskin and other cardueline finches. In many ways it is easier to compare territorialism in the Scottish pine crossbill with that of the hawfinch, which also forages largely outside its small defended nesting territory. However, there are important differences which I shall describe later. In groups of unmated cock pine crossbills, anger and gregariousness frequently clash. A desire for aloneness, rather than orthodox territorialism, motivates many fierce fights, but the division between these two impulses is narrow. I have sketched how the cocks fight, contend and display in the flocks and how they sometimes briefly sing and advertise themselves before regrouping. In mixed groups and assemblies, however, cocks often fight to possess or to defend hens rather than for vacant living-space. Proximity to the hen is now largely the trigger for many harsh songs and violent melees, but they seldom establish firm territories or win permanent display centres. The social drive is still dominant. Later, when large mating assemblies have split into smaller parties,

57

58 Pine Crossbills groups of pairs hive off, but continue to wander from wood to wood, though still associating with one another. Periodically the cock, and occasionally the hen, challenge and fight others, but this pugnacity is not yet restricted to anyone particular defended area. Increasing desire for isolation and a continuous defence of the hen, rather than of territory, inspires the fighting. However, in years when there are few pine crossbills, or when highly sexed or aggressive cocks have failed to mate in the flocks, they occasionally employ orthodox territorial patterns to attract hens. In 1935, 1937 and 1957, for example, solitary cocks sang their advertising songs in particular parts of woods or in stands of old pines, always within a radius of about 500 yards. All three attracted hens which later built nests in the woods where they had sung so lately. Other cocks, using the same means, have not always had the same success. This reminds me of the unmated cock snow buntings which sometimes patrol vast ridges of stony scree while searching for hens. However, the cock pine crossbill's loud 'greenfinch song' is not restricted to territory or territorial situations. Unmated cocks, which have temporarily left the flock, frequently sing vehemently. On 19 March 1938, for example, one sang so loudly that I could hear his songs when I was 400 to 500 yards away. Before they have chosen their territories, two or several mated pairs often consort, visiting many woods before finally separating and settling down. In the Murman Region the Soviet team had the same experience. There each pair of pine crossbills also wandered from place to place before settling down on a territory of about 200 metres in diameter, in which the cocks sang and chased away any other singing males. I have watched small groups of mated pairs starting to disperse, the cocks then singing loudly, making display flights and glides, and noisily challenging groups and companions. On 23 March 1936 two pairs, still without firm territories, were at odds. The cocks now 'rattled', threatened, attacked and chased one another, one rapidly dominating the other. His mate also attacked the other hen, but she did not go at the second cock.For a few minutes there was much angry tension and loud angry tacking. Within a week both pairs had territories and had started to build in this small wood. While pairs are choosing their territories, a cock sometimes jostles and ejects the hen of an intruding pair, as well as ousting her mate. On 26 March 1936 I also saw a hen drive off a neighbouring cock and the tenant of the other tetritory expelled a trespassing hen. Yet neither pair had started to build. These noisy tack tack demonstrations, which sometimes tend to inhibit active fighting, thus probably have survival value. The cocks now often rattle their beaks, crouch forward, and display the scarlet interiors of their mouths as they threaten one another. Although hens display in the same way, their posturing is less dramatic. Most of these

Territory 59 battles are double fights between the rival cocks and the rival hens, but a cock occasionally attacks or threatens a hen or vice versa. Later, when two pairs are settling down on adjacent territories, a cock may evict the neighbouring hen, as well as angrily 'swearing at' and jostling the other cock. I have also watched this behaviour in reverse, the hen chivvying an intruding male. Before the pair finally establishes territory, the cock frequently sings loudly from tree tops, often attacking unattached pairs or supplanting groups of celibates which have alighted on defended trees. After the pair has acquired the territory, the cock and hen usually spend a few days feeding quietly within or close to it, the cock now repeatedly feeding his mate. The small defended area also enables cock and hen to court and copulate without being disturbed and the cock to help the hen to build up the reserves needed to produce eggs. Scottish pine crossbills thus differ fundamentally from redpolls which choose their nest-sites in advance of their small flexible nesting territories (Newton 1972). Between spasms of nest building, pine crossbills often copulate close to their nests. The defence of a few trees nearby thus prevents rivals from approaching a sexually 'ripe' hen. On 13 March 1936,for example, I watched two pairs building nests in trees which were roughly 50 yards apart. One tenant cock became angry and excited when his neighbours pitched close to his nest. Almost immediately he attacked and drove them back to their own territory where they started to feed. On 14 March 1938, two pairs challenged one another on the borders of their territories, with the two cocks tooping and singing in challenge. By that time both hens had partlyconstructed nests. At this stage pine and common crossbills occasionally behave strangely. In 1903, Stirling recorded two nests with eggs in the same tree and in Hampshire, in 1936, Gosnell had another unexpected experience. At 1.45 p.m. on 26 March, he saw what looked like the two house sparrows sitting beside one another on a roadside telegraph wire. 'As I came nearer two cock crossbills in brilliant red plumage flew and settled one on either side of them. All four were crossbills, the inner two hens. Both cocks turned inwards and fed the hen next to him ... and both hens then dropped to the verge of the road below, and tearing off a beakful of grass, flew straight to half-eompleted nests in adjacent pines not 50 yards away.' When the hen has laid her first egg, but has not yet started to brood it, the two birds often feed well away from the nest and thus do not intercept trespassers. If, however, the hen is sitting on one or two eggs, the cock usually drives off any intruders when he arrives to feed her. On 8 March 1936 I saw a cock, chipping excitedly, fly in circles over the nesting tree in a forest bog and then fly down to chase an intruding cock from three trees, one after the other. Whenever the trespasser pitched on a tree, the tenant flew at him, and he then chivvied four unmated coeks from another tree.

Pine Crossbills Before each charge he flicked wings and tail and tooped loudly from the tops of different pines. Then, after clearing his boundaries, he flew down, fed his hen, fluttered to the top of the nesting tree, and sang for a couple of minutes before bounding away. The tenant and the mated trespassing cock had both sung immediately before the home cock had attacked. The hen was sitting on the first two of her three eggs. During steady incubation territorial patterns vary greatly. As the cock often feeds a long way from the nest, thus leaving the territory unguarded, wandering pairs, flocks and groups sometimes exploit cones in it, occasionally alighting almost beside the sitting hen. On 18 April 1940 I watched a cock, which was about to feed his sitting mate, eject another whose hen had a partly-built nest about 70 yards away. Throughout the battle the brooding hen chittered and shivered her wings. After the tenant cock had fed his hen and flown away, the trespassers again started on the cones in the unguarded nesting tree until the tenant came back and again saw them off. During the next three hours this see-saw continued, the home-cock becoming exceptionally excited whenever he found the intruders on the nest tree. As long as her own mate was there the sitting hen squeaked shrilly and flicked her wings, but never left her two eggs to give battle. Pine crossbills have unusual territorial and social patterns. When the hen is brooding the cock usually feeds alone, often flying backwards and forwards to special trees in distant woods or clumps. Sometimes, however, two cocks from adjacent territories become food companions, foraging together, and defending groups of pines anything from a quarter to one mile, or more, from their nests. So strong is their association that they forage almost as a pair and from time to time fly back together to visit their brooding hens. At 15.45 on 28 April 1940, two cocks, belonging to nests about 70 yards apart, arrived together and settled on a tree near one of the nests. Almost immediately the tenant jostled his companion from tree to tree, but allowed him to stay on one that was about 20 yards away. While he went to his nest his comrade waited. Thereafter, both cocks departed to the second nest where the second cock now behaved as the first had done. Then, with the two hens fed and satisfied, these amazing cocks flew off to their common feeding ground. On 1 April 1939 I watched different behaviour. Two brilliant scarlet cocks arrived and pitched on a pine close to the nest that I was watching. I knew the tenant cock by his peculiarly coloured shoulders and was surprised to see the other cock fly over to the soliciting hen as she brooded her nest. At once the tenant ejected him, and he flew over the trees and far away. Later, during my long watch, I saw this scarlet tenant hustle a building pair, a wandering pair, and two cocks which flew in with him and settled about 30 yards from the nest, but he had no close relationship with any of them. During incubation territorial defence lapses when the cock is away 60

Territory 61 feeding, a pattern akin to that of greenshank, wooc;llark, siskin and other cardueline finches which usually feed far from their nests, but drive off intruders on periodic visits to their mates and territories. At this stage the functions of the small nesting territory is imprecise, but it ensures a reserve of cones close to the nest on which the sitting hen periodically feeds, particularly if her mate is lax or slow in feeding her. A territory also sometimes contains a pool or water hole in which the hen may drink or bathe when she leaves her eggs. In Breckland, where water is scarce, Robson also found that pools were important. During a hard frost he watched two pairs fly up to half a mile to a pool inside a nesting pair's territory. There the pair met them but did not drive them away. Air space above a territory is seldom defended, but a tenant cock sometimes answers the challenge of another which is flying overhead. When the airborne cock has sung loudly and briefly slowed down and flapped his wings, the cock below sings in counter-challenge. A crossbill's strong social impulse sometimes overcomes the territorial drive. This frequently happens in the face of possible enemies and predators. From time to time two pairs have mobbed me while I was close to a nest from which the hen had been flushed. The hen's deep metallic calls had first attracted her mate which started to toOl and demonstrate nearby. This commotion then alerted the second pair and soon all four birds were scolding and demonstrating close together. At first I found that the two pairs did not threaten one another, but after I had climbed down the tree the tenant cock rushed at the other which soon departed from the territory with his mate. Within a few minutes all became quiet and peaceful again. Territorial defence also often breaks down when a red squirrel approaches a nest. Then, perhaps, two pairs may start noisy scolding, and chaffinches add their alarm cries to the chorus. When the hen is brooding small chicks, the territorial pattern sometimes changes, the cock abandoning his more distant foraging grounds for those nearer the nest. However, then and later, he continues to harass any trespassers he meets. A little later defence of the nesting territory becomes so lax that a second pair occasionally starts to build close to a nest containing young. In late February 1936Robson watched a hen common crossbill building in the next tree to one holding a nest full of well-grown young. There was apparently no friction, but the pair with young only visited their nest about once every hour, and thus seldom encountered the builders. On the other hand, single unmated cocks, or small mixed groups, sometimes associate with the foraging cock or pair, waiting on a nearby tree until the breeding pair has fed its brood. Then, calling in excitement, they follow the parents, particularly the cock, which periodically jostle them away before visiting the nest. If, however, the intruder or intruders pitch on the nest tree, or on one immediately beside it, the parents usually chatter angrily in concert.

62 Pine Crossbills Immediately after the clumsy fledglings have left the nest, to which they may return to roost at night, the parents continue to defend the trees around the nest on which they feed periodically. In this way the small defended area continues to provide a reserve of cones. Soon after this, when parents and young move away, the territory ceases to exist. These, therefore, are the functions of territory in the pine crossbill. 1. An unmated cock in breeding condition, which had previously failed to secure a mate in the flock, sometimes successfully attracts one by defending and singing vigorously in groups of trees (flexible territory). 2. A defended nesting territory helps to disperse the pairs and probably diminishes predation risks. 3. Possession of a territory assists cock and hen to court without disturbance and interference and probably enables the cock to perfect his skill in feeding his hen. It also provides an 'address' to which either bird can return when separated from the other. 4. During incubation the hen can exploit cones on trees near the nest, thus augmenting the food which her mate provides and reducing the time spent off her eggs. The small defended territory is therefore likely to be most significant in periods of greatest stress (in exceptionally severe weather or when the cock is an inadequate provider). 5. Some cocks establish rudimentary food territories during brooding, defending particular trees or groups of trees against all except special companions. This helps them to forage fast enough to feed themselves as well as supplying sitting hens. In general, hierarchies in the flock probably determine the composition and individuals of breeding populations, but territory helps to space out the pairs. However, in years of peak numbers in extremely marginal habitats such as some of the pre-war Norfolk pine rows, only the higher status and most competitive birds possibly succeed in holding nesting territories. COMPARISONS WITH SOME OTHER FINCHES

Courtship, pair formation, and territorial patterns of chaffinches and bramblings differ fundamentally from those of cardueline finches. Cock chaffinches and bramblings establish and defend comprehensive territories to which they attract hens, and which contains all that is needed for successful breeding. Most of the cardueline finches establish, and rather loosely defend, much smaller nesting territories after they first select their actual nest sites. Afterwards they usually forage in groups, seldom feeding in their nesting territories, but travelling far and wide to meet' their needs. Although crossbills are now regarded as cardueline finches, they have rather different territorial adaptations. Pine crossbills usually settle on nesting territories before they choose their nest-sites and while their hens are sitting the cocks frequently resort to particular parts

Territory 63 of wood and forest, where they select pines with rich and accessible cones. Moreover, cock pine crossbills usually forage alone or with special companions rather than in groups as with redpolls and greenfinches. A small food reserve near the nest also seems more important to the pine crossbills than to other cardueline finches which appear to have less specialised feeding grounds. Nor do pine crossbills always nest in small groups or clusters, even in years of high numbers and of bumper cone crops. In the Highlands, nesting clusters usually originate when a mobile group of mated pairs simultaneously hive off in the same wood. Other pairs of pine crossbills breed in isolation, nesting anything from t to 1t miles apart. This happens in years of both plenty and scarcity. These solitary pairs, however, seem to react more strongly to intruder crossbills than do members of nesting clusters, although these are more aggressive on their territories than are siskin, redpoll and greenfinch. Like goldfinches, pine crossbills are more prone to attack trespassers feeding near the tree tops than possibly lower status birds below them. After chasing away intruders, on the other hand, they seldom make formal display-flights, but they do sometimes sing loudly. Bullfinches space out their nests apparently without establishing or defending nesting territories. The sequence and territorial patterns of the hawfinch, however, makes interesting comparison with those of the Scottish pine crossbill. Hawfinches have two differing methods of dispersion, some pairs breeding in groups of up to half a dozen, exceptionally up to 50 pairs in the same large wood (A. Whitaker, pers comm.), others in near isolation. Unlike pine crossbills, however, groups ofhawfinches often have greater stability, the same individuals probably nesting in a particular wood year after year, and even showing traditional attachment to particular nest sites. Here, some weeks before leading their hens to the small nesting territories, the cocks stake their claims by sitting quietly and passively on the trees where there had been nests in previous years. Later they defend the nesting tree and a few others around it against rivals, but after the hen has laid her eggs these hawfinches no longer defend any living-space (Mountfort, 1956). Two pairs thus occasionally have their nests in adjacent trees and exceptionally there are two on the same tree. Solitary-nesting hawfinches, on the other hand, behave more like pine crossbills, driving away intruders from their nesting territories throughout the breeding period. However, the territorial arrangements of pine crossbill and hawfinch groups especially differ. The territory drive is much weaker in the hawfinch than in the pine crossbill. In larger woods the crossbills' nests are usually spaced about 75-150 (exceptionally 50-300) yards apart, whereas hawfinches sometimes breed at much closer quarters and at higher density. Cock hawfinches and pine crossbills feed brooding hens at the nest, but hawfinches often supply insects to their young about every eight minutes, as opposed to the t to It hourly meals

64 Pine Crossbills provided by pairs of pine crossbills. Differing feeding ecologies of the two birds, therefore, possibly help to determine their territorial adaptations, but those of both species are quite different from the orthodox comprehensive territories of the predominantly insect-eating bramblings and chaffinches.

CHAPTER 7

COURTSHIP, DISPLAY AND BEHAVIOUR In early spring and late winter nothing is more evocative than the displays and mating of pine crossbills. On these unforgettable days you soon hear the cocks singing in loud chorus high up the trees, and your hand soon shakes as you fill your notebook with facts and question marks. Day after day you follow the flocks, often overlooking subtle nuances of behaviour, although you notice that the cocks are singing more loudly and fighting more freely. But, at first, there are few signs of courtship. Then, perhaps, a cock busily 'crackling' a cone abruptly stops and sings sweetly before hopping along a branch to touch a hen's beak. Previously the hens had turned upon and rejected persistent suitors, now they scissor beaks and swing rhythmically with them. Or the cock feeds or tries to feed the hen which accepts what he gives without moving or flicking her wings, and afterwards he may flutter onto a spray just above her, where he sings a few bars and again attacks the cones. In this tantalising phase of behaviour, when there are no firm pairs, I have seen two or three cocks feed the same hen. The hens, however, are not always accommodating. One often bends forward to threaten the approaching cock which immediately fluffs up his feathers to indicate readiness to flee. The hen is still dominant, the cock has to overcome her aggressiveness before she will allow him to approach her. In this early courtship of pine crossbills there is always a barely sup65

66 Pine Crossbills pressed tension and an air of expectancy. Periodically one or more of the cocks sing and flutter slowly around the tree tops or, chipping excitedly, one bounds after a hen, the two birds flying out and around the trees before returning to the group. Sometimes a hen also incites pursuit by breaking off a small twig, the cock following her when she flies away with it. In late January or early February there are days when you may see almost every nuance of sexual behaviour, whereas earlier only a few birds were sexually awakened. In the larch and pine plantations around Dulnain Bridge, Ross (1948) also noticed that the community singing was most exciting: 'For one to It hours there may never be a moment without at least one cock being in the air with amazing varieties of evolution. The red coloured cocks give the best and longest show. On 1 February I saw a male leaving the tree, circling round, breaking suddenly and changing the tempo of the wing movements, then giving two to three peculiar twists from side to side and, before landing, hovering like a butterfly almost perpendicular with outstretched claws.' When a pair flew off together the communal display often broke up, the flock rising but soon settling in the same or an adjacent tree. These birds, however, appeared to pivot and sway, and to scissor bills much more freely than those that I have watched. Almost imperceptibly the more aroused or dominant birds begin to form mating parties in which all are bent on pairing. Those remaining as the rump of the originally larger flocks are probably lower in the hierarchy or are less sexually advanced. Hitherto, in the large assemblies, there were often long tranquil spells, periodically enriched by choral singing, but now there is a continuous chatter of angry calls and bursts of strident singing, with cocks often dropping cones to attack one another. In this exciting phase you may watch dramatic fights between two cocks which first sleek their wings and mantle feathers before flying at one another. Another cock suddenly sings harshly and sails out from the tree towards the rival. If the second cock accepts the challenge, the two gorgeous red birds meet in midair, fluttering, pecking and grappling claws in a spectacular aerial battle. In years of plenty this mixing of aggressive and courtship behaviour characterises many of these mating assemblies. On February 16, 1936, I watched four brick-red cocks singing from pine tops apparently guarding the four hens feeding immediately below them. If a rival pitched close to his hen the cock above sang furiously and attacked him. Ten days later pairs in a larger group were unstable. I watched one cock break off a twig and a hen follow him to a solitary tree. Another unceremoniously dropped down on a hen's back, instantly hopping off her almost like a copulating cock house sparrow. A third cock hopped up a branch towards a hen which bent forward to repulse him. Three other pairs sat side by side in the same tree. Time after time cocks sang and scuffled, but the whole group flew off together.

Courtship, Display and Behaviour 67 The next day a large group contained at least four mated pairs, two of which were feeding on the same pine, but on the next tree a cock ejected a rival. I also watched a cock feed a hen which briefly flicked her wings as he pushed seeds into her open beak. The same aftemoon four scarlet cocks and a hen shared a tree without fighting. This hen apparently did not stimulate the cocks or their sex beat was at a lower tempo. In another wood four pairs and an unmated scarlet cock were perched along a line of trees; the mated cocks, altemately singing loudly or softly, usually stood just above the hens which they were apparently guarding. In another group the mated cocks also sang softly and guarded their hens. Occasionally, however, the hens themselves sang from sprays above the cocks which were feeding immediately below them. In years of high numbers mating and pairing is a complex process. In that February I was thus able to watch several different kinds of mating parties. Hierarchical late winter and early spring assemblies are characterised by choral or community singing, early courtship feeding, beak scissoring, incomplete copulations, song-flights and sexual pursuits. Allthis probably helps to determine rank and status. These larger assemblies later disperse into smaller groups of more firmly attached pairs, often accompanied by a few unmated cocks and hens which are not apparently in full breeding condition. From mating parties small groups of pairs hive off before they have settled on territories. This results in solitary pairs moving until they settle on territories. Rump or surplus parties occur at most levels of population. These groups of greatly varying numbers largely consist of unmated cocks in every phase of plumage accompanied by a few non-breeding or possibly low-status hens. The predominance of cocks in this surplus is difficult to explain. In many ways cock crossbills face greater risks and pressures than hens. Courtship feeding probably assists the hen to produce her eggs in the harsh late winter and early spring weather. Some hens, particularly in poor seed years, possibly need the courtship feeding of two or more cocks before they can attain full breeding condition. Subsequently the cock provides the hen with almost all her food during incubation and for the first few days in the lives of the chicks. The cock thus has to work hard to feed both the hen and himself and he constantly exposes himself to predators on his movements to and from the nest. Selective pressures are thus likely to ensure the existence of a pool of surplus males as replacements, and possibly as foster parents for the flying young (p. 183). COURTSHIP FEEDING

After the cock has reached the hen and touched her beak, the two lovely crossbills may scissor beaks and sway rhythmically together. Approaching the hen, the cock sidles or hops along the branch and sometimes pivots from side to side. Then, just before reaching her, he sometimes rises

68 Pine Crossbills slightly above her. If the hen now crouches or stays put he may succeed in feeding her. However, some of his first attempts to feed the hen are unfinished or abortive. Still later, when the two birds have become truly mated, the hen crouches along branch or twig, shivering or flicking her wings like a young bird to incite her partner to feed her. The cock then erects himself or crouches just before placing his beak in hers. At other times, standing upright and facing one another near the top of a tree, the cock feeds the hen in a rather awkward posture which always reminds me of woodpeckers. Again, as he quietly feeds on a spray just above her head, a cock bends down and feeds the hen below him without her signalling with tremulously quivering wings. Mated cocks sometimes feed their hens two or three times within an hour. I once saw one feed his mate twice inside a minute. While she is soliciting, the hen may open her beak as well as shiver her wings, and the cock usually pushes his beak well inside hers, just as he does while feeding her on the nest. But the hen occasionally fails to stimulate the cock. On 8 March 1938, for example, a hen crouched with open beak and flicked her wings for several seconds after the cock had turned away from her. Three other cocks, however, themselves crouched and quivered their wing in front of their mates before they fed them. Courtship feeding occasionally leads to copulation. On 10April 1940, after he had fed his hen, the cock continued crouching and wing flicking and then abruptly fluttered onto her back. At the time, the hen had one egg in her nest. On 21 January 1934, Winifred Ross watched a cock singing and the hen sitting on the same branch. 'After about five minutes the hen stretched her neck and the cock opened his bill widely for a few seconds, then gripped her lower mandible, and for three minutes the two birds swayed backwards and forwards. The cock then fluttered heavily to an adjacent branch; the hen followed and he again caught her bill, swayed and fluttered off. The third time he caught her bill and they remained quite motionless for 2t minutes; they disengaged suddenly and the hen sprang into the branch above, the cock followed at once, mounted and mated, then both flew away together, calling.' On another day in late January she saw a cock fly down to a hen which opened her beak widely whereupon he pushed his own beak right down her throat; he did not appear to be feeding her, but held the position for half aminute, when both flew away to an adjacent branch and sat preening themselves. In early phases of courtship she also watched hens receiving food from different cocks. In late January three cocks were seen feeding the same hen 'regularly throughout the morning.' MATING

In courtship in the flock, cock and hen often seem to lack 'sympathy' or co-ordination, often failing to signal, or signalling incorrectly. Early acts of

Courtship, Display and Behaviour

69

mating are accordingly often incomplete or possibly symbolic. A cock pitches on the hen's back but she does not move her tail and the cloacas fail to meet. Yet, at this early stage, two or three different cocks sometimes mount the same hen on the same morning. The hen's acceptance of a male's intrusion into her living space indicates rising sex tempo, but little more. Mter the pair has formed, a hen sometimes initiates copulation before prospecting for a nest-site. On 17 March 1942 I saw a hen fly over a to a cock which was then singing quietly on a pine top about SO yards away. Pitching just below him, she now raised her tail and bent forward to excite him. The cock then gave a beautiful display flight, slowly beating his wings and flying rather erectly, his tail fanned out to show off his crimson rump-patch. Then, singing harshly, he returned, chased and successfully mated with the hen which rapidly inspected and tested crotches in several trees; but she did not built in any of them. Pine crossbills often copulate in lulls between building stints. The hen suddenly flies away from a partly built nest and signals to the cock by bending forward and raising her tail. The guarding cock then usually flies over and flutters onto her back without more ado. Sometimes, however, he approaches her in a kind of moth-flight, rapidly beating his wings through a small arc. These matings usually terminate the spell of nest-building, both birds flying away to feed. Just occasionally, however, the hen signals and is mated, but then briefly resumes building. On 8 March 1936, after breaking off and carrying several small twigs to the newly started nest platform, the hen flew out to the end of a twig where she leaned forward, solicited and accepted her mate, and then flew down to a small puddle in the peat. There she picked up a dab of wet black-looking moss and carried it straight back to the nest. Cock and hen then flew rather heavily to the top of a pine about 50 yards away where both started to feed. I have sometimes watched cocks chase and mount their hens which had been intermittently chittering on the nests which they were lining or shaping. A cock may also occasionally pursue his mate in a most spectacular and frenzied spiral flight through the branches and around the

70 Pine Crossbills trunk of a pine. Darting and twisting after the hen, his song rising to a harsh screech, he may now overtake and apparently successfully rape her. A hen continues to solicit and the cock to serve her when she has one or two eggs in her nest, but has not yet begun steady incubation. On 26 February 1942 I listened to the rapid chittering of a hen and then watched the cock twice fly onto her back within five minutes. The hen then returned to her nest where she bent down and apparently arranged her eggs. In late February, while watching a pair perched on the same tree, Winifred Ross noticed that the cock was singing loudly and calling for a mate, 'rising at times about a foot from the branch and turning his head from side to side.' The hen ignored this display but a second cock now pitched close to her and she immediately flew up, caught his bill, shook it and crouched down on a branch. The cock then flew on to her and mated. In late January she also watched a solitary hen continuously peering round, 'wings a quarter spread, flicking both wings and tail which was raised and expanded.' This she continued to do for five to six minutes but failed to call in a cock. Mating behaviour has many other subtle but always beautiful variations. One hen bent forward along a branch and the cock rapidly hopped towards her, then hovered just above her like some large exotic scarlet moth. Dropping lightly onto her back he stood for a moment beating his wings like a courting wader and after mating he stood up on her back and then dropped down onto the branch in front of her. During coupling the hen occasionally turns her head and the beaks of the two crossbills briefly meet in a kind of kiss. After mating, the hen often carries out emotion-releasing actions like shaking and fluffing her mantle feathers and preening or making the motions of preening. Both cock and hen also sometimes wipe their beaks on twigs or on weathered stumps. DISPLAY-FLIGHTS

Scottish pine crossbills have some beautiful forms of display-flight. Mated and unmated cocks sometimes launch themselves on butterflyflights with spread tails, slightly fluffed mantle feathers and slowly flapping wings. They now usually fly from one tree top to another, seldom flying in the continuous and erratic loops and circles of cock siskins, A cock may also glide with partly raised or set wings in a curve between tree top and tree top. More frequently, these dramatic flights occur in challenge and anger situations rather than those involving sex and mating. Common crossbills, however, will often make sustained circular flights over the trees, when they sing loudly and beat their wings (Newton 1972). Other cocks flutter up from the tops of trees, singing strongly and then fluttering down again. Cocks in groups containing no hens may also perform these butterfly flights. .

Courtship, Display and Behaviour 71 In the 'moth flight', usually when about to attack another cock, the cock rapidly beats his wings through a small arc. However, I have seen a cock hovering with tremulous wing beats, like a displaying redshank, just before he lands beside or on the back of a receptive hen. On 21 March 1938, before challenging the territory-holder, a cock fluttered from spray to spray violently quivering his wings. The tenant, however, soon ousted him from the tree top on which he had been perched. The home cock's wing beats were much deeper and slower. While flying over territories occupied by others, and occasionally before alighting in his own, a cock may sing strongly and slow his flight, flicking his wings or gliding briefly on set wings. You may also watch sexually roused cocks singing excitedly and flapping their wings almost like starlings. Unmated cocks also occasionally try to entice mated hens by singing and fluttering from spray to spray. POLYGAMY

The breeding patterns of crossbills discourage polygamy which would impose almost impossible strains on the cock as provider. In 1936, however, I watched a cock pine crossbill moving and associating with a couple of hens, both of which he was feeding, but I never discovered whether either or both ultimately built nests and produced eggs. The trio moved away from the wood where I had been watching them and I could never find them again. In later years I twice discovered cocks which had two hens with nests 200 to 300 yards apart, but in both triangles the two hens did not lay contemporaneously and the eggs did not hatch in either of the second hen's nests. The first nest in the 1952 trio held well grown chicks before the second hen laid her three eggs which proved to be infertile. Winifred Ross also .had some evidence of occasional polygamy. 'One cock I noted seldom stayed long on guard at the nest, and on following him up I discovered him feeding a second hen. On another occasion three birds--a cock and two hens--always came to the nest I was watching and when hen number one was on the nest he flew off with number two. The nest of number two was out of sight of number one's, about 300 yards away, but the cock bird's favourite singing perch was about midway between the two and in sight of both. It is possible there was a second cock not noted.' The fate of these nests was unfortunately unrecorded. However, for crossbills, polygamy is likely to be a rare and dangerous aberration. THREAT AND AGGRESSION

Two cocks sometimes crouch, facing one another with open beaks, to display the scarlet interiors of their mouths. Both mated cocks and members of flocks periodically threaten one another in this way. Two

72 Pine Crosshills pairs also often take part in the tack-tack displays in which the cocks rattle their beaks and call angrily, and the two hens also join in the loud chattering chorus. These displays sometimes lead to double fights, cock against cock and hen against hen, or the pairs may eventually separate and flyaway without actually fighting. At other times a cock may attack a hen or vice versa. In the flocks cocks often snap at one another, first opening their beaks and then bumping one another off the higher parts of the tree. Both cocks and hens flick wings and tails and call angrily in situations involving a clash between fear and aggression. A cock crossbill, which has seen a man close to its nesting tree, thus continues to demonstrate for several minutes, only ceasing through the need to feed the sitting hen. A hen disturbed from the nest behaves similarly, although her anger calls are separable from those of the cock. Ross noticed that young crossbills become aggressive at an early age, dabbing at one another in the nest and pushing each other off branches; 'this bumping off is also practised by adults. A bird sitting at the end of the branch is a temptation to every other member of the flock. Males knock off males only and females shove off females. Both either fly up or sidle along the branches to the other bird, but they do not follow up with further aggression. There seems to be as much fighting between adult females as between males.' Miss Ross also described crossbills pecking and bill snapping and raising their crown feathers. The birds faced one another for the best part of a minute, holding their beaks open and then clacking their mandibles together without attempting to attack an opponent. 'The sound could be heard 20 to 30 yards away. There were also occasionally real fights, one bird plunging at another or the two standing and facing up breast to breast and then the climax in the air, among the branches, and even on the ground, with a few feathers flying.' Hinde (1955) mentions menacing head-forward postures with the cock behaving aggressively towards the hen, particularly in the pre-nesting and nest-building phases, when he may supplant and then chase her. He also describes a cock common crossbill in an aviary sitting with wings drooped 'by rotation at the shoulder and, at higher intensities, extension of the wrists', to display the red rump feathers which he sometimes slightly raises. The cock also often calls, flicking wings and tail in time. Fluffing, which occasionally accompanies the head-forward threat, shows a thwarted tendency to flee. This is usually given by subordinate or dominated birds just before they fly or hop away. PIVOTING

A lateral movement of the body, sometimes accompanied by a disyllabic call', which was recorded by Hinde in his aviary. On the few occasions when I have seen a cock pivoting he was nervously approaching a hen.

Courtship, Display and Behaviour 73 DISTRACTION

·Two hens dropped from their nests almost to the ground and then rose in a steep arc. Time after time these hens behaved like this when disturbed from their nests. This most peculiar form of distraction flight possibly evolved from the need to deflect a predatory mammal like a red squirrel from the nest. SUNNING

In an aviary study of a flock of red crossbills, Tordoff(1954) discovered that they performed a highly ritualised form of sun bathing in the late morning of bright days. The sun-bather started by preening, scratching and then raising its feathers, usually with its back to the sun, then spread its primaries by extending the wrists. Its tail was also fanned to expose all feathers to the rays of the sun. Then the bird dropped its head to enable the rays to shine into one eye, 'the bird now appearing to be staring up and back over its shoulder. Finally the bill was opened until the tips were about opposite each other, thus exposing tongue and lining of the mouth and one side and base of the bill to the sun. In this extraordinary behaviour the crossbills sat passively for up to five minutes gazing straight into the sun. I have seen a cock pine crossbill doing this on the dead top of an old pine, but Tordoff's observations are more detailed.

CHAPTER 8

NEST To watch finches choosing their nest-sites is always a fascinating phase in which species and individuals vary greatly. Before they carve out territories, young cock chaffinches test crotches in many trees, but older more experienced males take no part in choosing a nest site. The paired hen selects it after rapidly inspecting places in different trees and then starts to build quite suddenly (P. Marler 1956). Giving a special call, the cock bullfinch leads the hen to possible nesting places in trees or shrubs in one of which he forms the platform of twigs on which his mate builds the rather loose nest (Newton 1972).The secretive cock hawfinch also chooses the nest crotch and then lays the foundation twigs (Wallin 1966). I have seen hen siskins and redpolls select nest sites, usually after brooding, testing, and going round and round the chosen fork for a few minutes, but I have also watched a hen siskin brood for nearly an hour at the end of the projecting pine branch where she eventually made her nest. Cock siskins and redpolls usually escort nest-building hens, often showing tension-releasing behaviour like false feeding and jerky movements of their beaks. In a Stalag in Bavaria, Peter Conder watched pairs of goldfinches visiting possible nesting places one after the other and flexing their legs and swivelling round; and all the time they gave thin tee-tee calls. It was not possible to determine which bird actually chose the site, but the hen usually built in the presence of a cock. Pairs of greenfinches start by picking up and dropping bits of nest material and then the pair jointly inspects possible nest sites. Newton found that the hen took the lead,

74

Nest 75 moving from side to side, crouching and moving round and round in each, while the male waited nearby, continuously singing and calling. The cock later occasionally takes a small part in building the nest (Table 1). Scottish pine crossbills have no firm patterns. Each pair has its own method of site selection which possibly depends on the particular sexual and building rhythms of the two birds. Some pairs examine possible nesting places before they have settled on territories and are still associating with other wandering pairs. On 31 March 1956 I watched two excited pairs which alternately flew together and then separated, while the hens prospected crotches in several different trees in a large wood. Nine days later one of these hens started a nest in one of the trees which she had then examined. This was an unusual pattern but in many phases of nest building pine crossbills often do behave unexpectedly. However, most pairs first settle on a territory before choosing the actual nest-site. I have seen Scottish pine crossbills use different methods of nest-site selection. Two hens began by brooding closely in forks of pines, looking almost as if they were sitting. A week later one had started to build in this crotch. I have also seen a cock sitting in a likely crotch at the end of a branch, but the hen did not build there. While sitting in these places the birds seemed both listless and broody. Normally, however, our pine crossbills look for nest sites together. On 15 April 1941, for example, a hen tested crotches in several different trees. Once she stood on a small twig, gazed intently under a large branch and several times she hung head downwards billing the ends of twigs without breaking them off. Finally, cock and hen gave up and started to feed. This was, however, only a short break. Soon the hen nervously rubbed her beak on a broken stump and later broke off twigs and started placing them at the end of a branch which she had previously examined. Time after time she arrived at and left the new nest by the same route, hopping up and down a thick lateral branch. Meanwhile, the cock sang softly from the top of the tree. When the hen had built the twig platform she sat on it, poking her head out to lift and arrange the twigs. Once, however, she paused, brooding it closely for three minutes. I have seen cocks attempt to start a nest by building rough platforms of twigs. On 6 March 1939, for example, the cock took two small twigs and a pine needle to a fork near the end of a long branch. While doing this he was quiet and remarkably furtive. Immediately afterwards he sang softly on a branch above and later gave a full loud song and copulated with the hen. But his initiative failed; the hen built the nest and laid her eggs in a tree about 20 yards away. On 16 April 1967 a grand crimson cock crossbill in Easter Ross suddenly began to carry twigs and pine needles to the crown of a small pine, the hen following and perching on a nearby pine while he was building. But, like the other, this hen also rejected her mate's lead and built the nest in a small umbrella-topped pine about 50 yards away. How

76 Pine Crossbills vividly these crossbills reminded me of the snow buntings, Rusty and Diana, in 1964. 'Rusty had chosen a particular spot in the scree field to which he repeatedly, but unsuccessfully, tried to lead Diana. Then, after he had failed to lead or drive her to the place of his own choice, Rusty started to build.' While seeking and assessing possible nest-sites, the hens often seem excited, nervously stropping their beaks, false preening and fluffing out their feathers, and sometimes making slow downward pecking movements above cones or spines. Ross also met with the same great individuality or perversity. 'Sometimes a pair will haunt a tree for days, apparently testing the site, then begin building nearby in a tree they seem to have ignored. Sometimes a cock may be seen sitting in a suitable spot and the hen will take up the stance after he leaves, then a week later the nest may be built there.... On 30 March 1938, a female crossbill was seen to bring in a stick, place it on a branch where she had been noticed sitting for a day or two.' COMMON CROSSBILL

I have a few observations of the way in which common crossbills select their nest sites. In East Anglia one hen built a nest in the fork of a tree where I had previously seen her brooding. Other pairs use different methods. On 14 March 1936, Edgar Chance watched a loudly singing cock in Surrey and on the 15th he saw the female 'shuffiing like a brooding hen in the actual crotch in which the nest was ultimately built.' On 28 March, Eddie Lees, then climbing and collecting for Chance, lifted out the four eggs in a net at the end of an extending stick. Chance found that they were already about five days incubated. In Hampshire Gosnell sometimes watched pairs selecting their nest sites. 'In and out of the tree they go, creeping about the branches like tiny parrots, yet always returning to the same spot, calling loudly the while. At last the hen breaks off with her powerful beak a small twig from the nest tree, and when once this is fixed in position, no more time is wasted and the building proceeds rapidly.' RED CROSSBILL

In 1952, L. Baily watched three pairs choosing their nest-sites. On 25 January, a pair was seen moving through some young pines, the cock often singing softly. 'The female kept out of sight, working the inner portions of the tree. Shortly, both birds disappeared from the top of a 26 foot yellow pine. After a lapse of a minute, the male flew to the terminal tip and sang strongly, the female departing down the hill. Momentarily leaving his perch, the male reappeared and resumed his song with a dead pine needle held in his bill. Two minutes later he placed the needle at his feet and flew off, presumably to join his mate.' Unfortunately these observations were incomplete.

Nest 77 At a second nest, every few minutes the cock would fly into a densely needled pine, each time stopping at a particular place on one of the horizontal branches. There he sang and called loudly before whisking out and down the ridge to where the female was known to feed. 'Never had we heard a male sing with such energy without being on the most conspicuous perch available. Though the performance was repeated time and time again, the female never came near the spot. On March 5, however, a nest was well under construction at that very location.' Baily later watched the complete process at a third nest. 'The male, having defined his territorial boundaries, joined the female and- both birds began a silent search of the lower branches in the area. Starting at the outer extremities of the limbs, they worked towards the trunk, pausing here and there to pry at pieces of bark or to rest motionless for a minute or two. Only on occasion a barely audible communication note was detected. Finally the female, which had consistently taken the initiative, stopped on a horizontal fork canopied with dense needles. There the male, on some unheard signal, came and fed her.... Following the ceremony, the pair became vocal, exchanging communication notes, then both departed out over the forest, giving the travelling call.' The crossbills subsequently built in the fork where the cock had fed the hen. NEST BUILDING

Although a cock pine crossbill has a latent ability to build, he seldom employs it. In the flock cocks and hens periodically break off the twigs of larch or pine, flying away with them in their beaks. The hen then sometimes flies away and almost immediately returns or, twig in beak, she flies a larger circle before going back to the flock when she soon drops the twig. I have not seen cocks making such long flights, but I have watched one, chipping excitedly, pursue a hen which had a twig in her beak. At other times cocks or hens cut or wrench off twigs, drop them, and then often preen or fluff or carry out other tension-releasing actions. The breaking and dropping is thus not unlike the action of a warbler which lifts the toys with leaves before she starts to build. I have original notes on the nest-building of over 30 pairs, but have only seen four cocks carrying material to nests in which their hens actually laid eggs (Appendix 3). On 25 March 1936, a pair was behaving abnormally. I had first seen a cock follow his hen when she had dropped down below a steep bank. A little later I picked him up singing on a tree about 100 yards away, where I saw him feeding the hen. About a quarter of an hour later he flew down to some brushwood where the hen broke off a few twigs which she at once dropped. Then the cock went down to the ground and flew away with a beakful of grass to the tree where I had first seen him. The hen immediately rose and followed him. I saw the cock arrange the grass in the nest which I could now see near the top of the tree. Meanwhile, the hen had

78 Pine Crossbills perched high up on it, first singing softly and then, astonishingly, giving a loud greenfinch-song, much like a cock's territorial song. After placing the grass the cock departed, but twice returned with twigs in his beak and once chipped sharply while she was building. The hen stayed on the tree top. In the end this eccentric crossbill almost finished the nest, but the hen did not lay in it. The cock, in mixed red and green plumage, was possibly a young bird which had mated with an old hen which could not attain full breeding condition. I tried to follow up the pair, but they moved away and I could never again locate them. Some pairs have peculiarities. On 2S March 1936, a hen which was taking twigs to her partly-built nest appeared to find long ones difficult to manage. Some she held crosswise in her beak, others she carried to a large stump 'where she broke them to a more suitable size. The cock fed nearby, standing just above her while she was breaking off twigs lower down in the tree. Suddenly he also started to snip off twigs which he instantly dropped, and then polished his beak on a broken stump. Around Dulnain Bridge, Winifred Ross noticed that the cock, 'assisted in the rough work of laying the foundation twigs, breaks them off and either offers them to the hen or places them there himself.' However, she found that the cock was less skilful in placing twigs than was the hen, which often rejected the male's twig or changed its position. One hen took a twig from her mate, allowed it to drop, and then perversely flew down to retrieve it. On 7 March 1933, she watched a hen working on the platform of a nest which had possibly been started on the previous day. 'The cock was singing on the point of the next tree, but stopped and accompanied her each time she left for new sticks. After an hour he began to assist, both birds breaking off the larch twigs and returning to the nest together. The hen always did her share first, while he watched, and she often gave the structure a kind of poke after he had placed his stick. This procedure was continued on the Bth.' Ross also saw other cocks periodically carrying in twigs, but noticed that the hen alone shaped and lined the nest. 'The male usually accompanies her to the ground where she is gathering grass, moss, or wool and stands close by while she is picking lichen from tree, but he hardly ever picks any himself, or if he does he drops it at once.' After the hen has started to build, the cock usually closely attends her, often singing quietly on the nest-tree or on one close by, and when she is looking for nest material he frequently flies just behind her. A pair of building crossbills are now usually quiet and almost furtive in their flights to and from the nest. You often only hear the loud rustle of their wings and then the chittering of the hen as she sits on the nest platform or in the cup while she is arranging the twigs or adjusting the lining. However, if a trespassing cock, a mated pair, or a quarrelsome surplus group, alight near the nest or, if they pitch near the hen, the cock usually starts to toop angrily and then attacks and supplants the intruders. The more passive hens often

Nest 79 avoid involvement in these noisy brawls and tack tack displays, but the dominant and aggressive sometimes fly over to attack and oust rival hens. From afar you may frequently hear the angry chatter. Almost always, hens select fresh twigs which they sometimes seem to find difficult to obtain. You now watch them flapping their wings and sometimes losing their balance as they tug at or cut off suitable twigs from pine, larch, or birch, which they them sometimes carefully trim to the desired size. At times the hen tugs hard but has to abandon the twig she sought. Head downwards, like gymnasts, they tug mightily and then fly away with great flapping of strong wings. Some find almost all the things they need near the nest or occasionally on the nesting tree itself. But I have sometimes watched one fly over 100yards with a twig hanging from her beak or perhaps held across it-One busy hen flew in with two twigs simultaneously and another flopped down from branch to branch to recover a twig which she had carelessly dropped onto an outflung branch. Another unorthodox hen arrived with a twig and some grass in her beak. Particularly when starting to build, hens are often nervous, making downward billing movements when they have dropped twigs. The cocks usually fly backwards and forwards behind their building mates, frequently perching on the nesting tree or high up on one nearby. At other times, when the hen is merely making short flights to and from the nest, the cock sometimes stays put, but continues to watch her movements. At 13.33 on 16 April 1964,in my favourite small wood in Easter Ross, I heard a cock tooping and seven minutes later saw the hen carry a twig to a nest on an upflung branch 20 to 25 feet up a small pine. Between 13.40-14.05 the hen brought in five twigs. Twice the cock escorted her, once pitching on the nest tree and once on one 20 yards away. In these twenty-five minutes he also once fed his hen. While on the nest the building hen continuously cried sip-sip-whee-sip-sip and she occasionally chipped quietly. Meanwhile the cock sang a soft rhythmic tip-tip-tip. A nervous bird, he sometimes twisted his neck and sat rather stiffly upright with his wings sleeked.Twice he also crouched forward in threat posture. Before flying, cock and hen drew in their feathers, but they never flicked wings or tails. Once the hen cut off a twig near the top of the tree where the cock was singing. Just after she starts to build, a hen tends to reach the nest by different routes, although she often puts down below it and then gauchely flutters upwards. After a few visits, however, she often comes and goes in a set routine. A few hens are eccentric. One carried in large blobs of lichen which hung from her beak like a beard, and sometimes also one or two twigs. How strange and comical she looked I The hen which retrieved the twig from the branch under her nest was exceptionally clumsy, often halfstanding up and flapping her wings on the nest. Ross observed the building routine of a hen which had been on a particular branch for a day

80 Pine Crossbills or two. 'She worked alone, almost using exactly the same route for entering along a branch and afterwards flying off the nest uttering a low chirrup. The male was sitting on the tip of a tree and took no notice of her. After a number of visits she uttered a single sharp note, and he at once flew with her. They did not return for half an hour, when he also brought a twig and continued to assist her all next day.' While building the foundation the hen also collects lichen, particularly fluffy lumps of Usnea barbata, from branches or trunks of nearby trees, and on occasion from the nesting tree; and she flies up to 200-300 yards, or sometimes more, for grass, heather, and moss for the egg cup. Once, however, I saw a hen drop down below the nesting tree where she broke off a few sprigs of heather and then flew up from branch to branch and so back to the nest. Pine bark is usually ripped off nearby trees, but I have occasionally seen a hen fly quite far with some in her beak. A cock also occasionally gathers bark. On 13 February 1974-Knox watched both birds taking bark from a lime tree and carrying it to a nest which was subsequently deserted. The cock usually escorts the hen on her longer flights to collect grass, moss or feathers from the ground, sometimes perching high up on a tree or settling on stump or fence a few feet above her. He is thus well placed to challenge and drive away any cock that may approach her. After the hen has picked up the material, she flies nestwards rather slowly with the cock usually following and calling quietly just behind her. These nest-building flights are quite characteristic, the two crossbills flying more hesitantly than during normal movements. You now sometimes watch strange sights. I particularly remember a vivid crimson cock balancing rather awkwardly on a strand of barbed wire barely a foot above his mate which was removing a piece of string from the wire immediately below him. I have also seen a cock guarding his mate while she tore some sheep's wool off a patch of heather. A hen pine crossbill raiding a chicken run for feathers in the garden of a croft or cottage is another exciting sight. Twittering persistently in the presence of the guarding cock, the hen hops along picking up and apparently selecting feathers. While collecting these bits and pieces hens often seem agitated, frequently making the downward pecking movements which I have described. On 15 April 1942 one did this when she failed to shift a tough flake of pine bark; and she was so excited that she continued to make these peculiar movements of head and neck as she flew away without it. . A building pair sometimes trespasses on another's territory. On 26 March 1942 a cock was escorting his hen who was picking up grass about 150--200 yards from their half-built nest. On their way back the cock settled on a pine top which was evidently within the defended territory of the neighbouring cock which immediately flew over and ejected him. Yet the disputed tree was only 50 yards from the nesting tree on which he now settled and started to sing.

Nest 81 After the platform has been built, the hen starts to make the cup which she smooths and shapes, moving round and round, pressing down with breast and belly, adjusting moss and grass with her beak, and often raising and flapping her wings to balance herself. While shaping the egg cup she also sometimes briefly broods in it. For instance, on 15 April 1941, I watched one suddenly begin to brood tail up for at least three minutes. She was then quiet and passive until she again started to build and adjust. The nests, which are often strongly but rather loosely built, start with a foundation platform of fresh and carefully prepared twigs (usually pine, larch or birch) and a superstructure of grass, straw, moss, lichen and sheep's wool, and are lined with finer grasses, moss, sheep's wool, rabbit's or mountain hare's fur, sometimes red or roe deer's hair, a few flakes of pine bark or some pine needles, and occasionally dead leaves, or a little string or waste paper. Hens also usually add a few feathers, particularly those of domestic fowl or of forest birds like ring dove, capercaillie, and black and red grouse. Sometimes you may watch a hen moving round and round the cup, apparently carefully placing the feathers where she wants them. At others she stands on the rim to drop in a feather before flopping down into the nest. While turning and rotating to smooth cup and lining, hens often chitter urgently and persistently, a characteristic series of calls which occasionally run into a quite sweet and distinctive nest-song. In this phase, often calling softly, the cock usually waits on a nearby tree until the hen flies away. After the first egg, steady building usually ceases, but a hen sometimes adds a few feathers to a nest containing a single egg. Now, however, the building and brooding drives possibly clash or compete. Hens usually build in spasms, each seldom lasting longer than half an hour, but they sometimes carry in material intermittently for over three hours, with intervals for meals. Some build quite fast; between 11.03-11.12, for example, one hen cut, carried and arranged eleven twigs in her newly-started nest. I have watched hens begin to build soon after dawn. Then, with the cocks roosting outside the territory, possibly in their special feeding trees, hens sometimes build alone, silently cutting and carrying twigs from trees close to the nest. I have watched a hen build late in the evening, but this is less usual. Hens often build and line their nests in 9-12 days, but those built in February and early March may take longer to complete. One laid her first egg 22 days after she had carried in the first twig of the platform. Others build and line their nests and then allow them to lie empty for a week or more. Replacement nests, however, are usually finished in quicker time. One hen built and lined her nest in 4t days and most have them ready within a week. Earlier nests tend to be more stoutly constructed than the replacements which are sometimes shallower and more loosely built. I have notes of the positions of 197 Scottish pine crossbills' nests, all but four in Strathspey and Easter Ross. 116 hens built well out on a lateral or

82 Pine Crossbills horizontal branch (58-8%); 66 in or close to the crown (33-5%); and 15 (7.6%) beside or close to the main trunk or stem. These nests were all placed from 8 to 70 feet above ground (Table 2). In Strathspey one nest was in a larch, all others in Scots pines. At Fairburn crossbills occasionally nested in larch or spruce, and a nest in Sutherland was in a Douglas fir. PINE CROSSBILL

In Fenno-Scandia, Valeur, Olsson and others saw only hens building the nests. Valeur remarked that 'the nest is built entirely by the female, the male singing from some nearby perch while she is so employed and joining her whenever she calls to satisfy her hunger.' Most hens built 'in the hours immediately after sunrise', and none appeared to do so after mid-day. Spjetvill watched one pair building in 1968 and two pairs in 1971. At all three of these nests the cock sang loudly close by while the hens were fashioning the cups. Olsson watched hens gathering moss and withered grass from the ground and pulling lichen off branches. In a nest which he carefully analysed he found many thin twigs of Norway spruce and pine, moss (Hylocomium and Drepanocladus), lichens (Alectoria, Usnea and Parmelia furfuracea), grass and a few dead leaves, inner bark of juniper, dry needles of pine and juniper, animal hair and vegetable fibres, feathers, and some elk's hair. In another nest c. sphagnum was the dominant moss. In the Kandalashka and Lapland State Reserve, our Soviet colleagues recorded that the cock helped to select the nest-site and that he escorted and frequently fed the hen while she was building. There pine crossbills periodically copulated during the building phase. The foundation platform of the nests was made of dry spruce twigs and the superstructure of straw, moss iDicranum sp.), wood lichen (Parmelia physodes), and bark and inner bark of willow, aspen and birch, with an inner layer of straw and moss. The egg cup was lined with willow down, elk and reindeer hair, mountain hare's fur, and a few feathers, particularly those of magpie and willow and hazel grouse. A few nests contained parts of a smoked fish's skin. In winter nests there was much wood moss, and plenty of straw in those built in spring. In February 1959 these observers also watched hen pine and common crossbills removing oakum from grooves between the beams and walls of farm houses in the Lapland Reserve. Most nests were built on spruce and only a few on pine. Of 21 pine crossbills' nests on spruce trees, twelve were placed against the trunk in the top third of the tree, four against the trunk half way down or lower, and five on lateral branches. Of the three nests on pines, one was sited beside the trunk and near the top of the tree, a second positioned similarly but much lower down, and the third was in a fork. Pine crossbills' nests were built rather higher up the nesting trees than those of spruce cro ssbills, which, in tum, were noticeably higher up than two-barred crossbills. In all, 18 pine crossbills' nests were at heights of 6t to 50 feet

Nest 83 (average 23 feet) above ground; 12 common crossbills at from 10 to 40 feet (average 21 feet); and four two-barred crossbills from to 20 feet (average feet). These pine crossbills, therefore, apparently never nested as high above ground as a few of ours do in the old Caledonian pinewoods. Winter nests tended to be thicker and more sturdily constructed than those built in spring. R. T. Smith and H. Ostroznic also noticed this practice in the curoirostra groups in Dumfries.

7t

6t

COMMON CROSSBILL

Cock common crossbills seldom build or carry material to nests, but Hinde (1955) recorded that a cock in one of his aviaries built a complete nest 'except for the lining, without help from the female.' However, none of the captive pairs in Hinde's aviaries reached full breeding condition. This particular cock, therefore, was presumably able to develop his latent building drive without the hen taking over and supplanting him. In the wild, cocks do occasionally take a small share in nest building. I once saw a Breckland cock break off and carry a twig to a nest, but hens alone built at eight others. Scattered through the literature, however, there are a few records of building cocks. In 1910, for example, Harry Witherby and James R. Hale watched cocks carrying in a few twigs. On the other hand, L. R. Flack and John Robson, who between them have found about 300 nests in East Anglia, have never met with a building cock. Flack writes, 'I have never seen a cock building and have no suspicions that they do so. The building of a nest is done by the hen alone, usually followed everywhere by a noisy cock. When gathering the small twigs for the foundations of the nest, the bird is very selective about choosing the right one, which she breaks from dead branches of Scots pine, usually from a tree close to the one in which she is building. On the other hand, if there are larches close by, they seem to prefer dead twigs from these. I have never seen the bird gather twigs from the ground, but obviously mosses and grasses are taken there. The birds, however, will fly some distance to chicken runs to gather feathers.' In Hampshire, Gosnell, who occasionally watched a cock carry in feathers, also describes pairs raiding chicken runs, the cock on guard and the hen hopping about and picking up the feathers. 'House sparrows seem strongly to object to the removal of "their feathers", and the hen crossbill has to run the gauntlet of their angry pecks.' Gilroy beautifully described the nests and building behaviour of crossbills in the Suffolk and Norfolk groups. 'Early nests often appear to take a very long time to construct, especially in the initial stages. One may come across a pair of birds apparently feeding quietly, when quite suddenly, the hen will creep to the end of a branch, clip off a dead twig, with her strong bill and fly off with it, the motion of her wings being extraordinarily loud and rustling. She can be easily followed to the nest, and the operation

84 Pine Crossbills watched perhaps half a dozen times, whee she will just as suddenly stop and do nothing more for the rest of the day. After the foundation and the outer rim of dead twigs are put together, building proceeds a little more quickly. Moss and grass are collected from the ground, often from the same spot; repeated journeys are made, the hen being invariably accompanied by the male, who takes no part, however, in the actual building of the nest. Most nests, too, contain as a portion of the lining thin strips of the outer bark of the elder, and it is interesting to watch the hen crossbill peeling the elder twigs with a considerable amount of care, and quite oblivious even of the near presence of an intruder. Occasionally feathers are added, but not many; and the nest when complete, although somewhat loosely put together, is singularly compact and even imposing. The nest of the crossbill is quite unmistakable even in May, when many greenfinches are nesting in similar situations....' I wonder, however, what Gilroy would have made of the extraordinary nest now in the Elveden Estate Office Museum. This consists of masses of thin wire, presumably taken from an old fence. In East Anglia the nest is usually placed in a fork near the end of a lateral branch at any height from 15 feet upwards, or less often near the very top of a tree and close to the trunk. Here the crossbills particularly favour a lower but dependent branch dropping at an angle towards the ground. All the nests found by Flack were in Scots pines, but W. Rolph of Lakenheath recorded three in larches. One nest was so low down in the tree that the eggs could be inspected by gently pulling down the branch. In 39 common crossbills' nests in Norfolk and Suffolk 26 (66.6%) were on lateral or horizontal branches; 9 (23.1%) in or close to the crown; and 4(10.3%) near the main stem or trunk. I have never seen a pine crossbill raiding an old or deserted nest of another forest bird for moss or feathers, but in 1962 E. Chance saw aNorfolk hen tearing out part of an old mistle thrush's nest which was a few yards from the tree on which she was building.

CHAPTER 9

LAYING SEASON, CL UTCH AND EGG I have found pine crossbills nesting in Strathspey in all months between February and June, but never found nests or recently fledged broods in late autumn or early winter. Ross (1948), however, met with 'young birds at all stages of development between 15 March and 29 November' but, without greater detail about calls, locations and food it is best to record these notes without comment. In Strathspey, most early breeding years synchronised with large populations and good cone crops, when a few pairs bred in February. Here our pine crossbills usually nested earlier in bumper cone years, with the exception of 1940 when there was only a moderate breeding stock which nested remarkably late. By feeding her the cock helps the hen to form her eggs. Winter sunshine assists him by partly opening rich and well-filled cones. However, this probably only marginally affects early breeding. On the other hand,a poor crop may inhibit breeding by denying the hen the necessary reserves. The annual mean date for full clutches has varied considerably. Between 1935 and 1942, it fluctuated in Upper Strathspey from 12 March in 1936 to 21 April in 1940, with an average of 1 April for the eight years (Table 10). At Fairburn, between 1900-07 (no records for 1906 and incomplete data for 1902) the mean date for full clutches varied from 27 February in 1903 to 11 April in 1900, with an average date of 19 March. Of 169 nests recorded in northern Scotland 46.1% of the hens completed their clutches in March, 37.2% in April, and 11.2% in February. In Fenno-Scandia, December and January nests are exceptional. In a sample of 48, 48.9% of the pairs nested in April, 34% in March and 12.9% 85

86 Pine Crossbills in May (Table 3). In Finland, Hilden considers that apart from food, the slight differences in breeding seasons between pine and common crossbills is an ecological distinction. In all seven nests which he and his friends found close to Helsinki, the eggs were laid in April, probably because the pine cones open later than spruce. The most detailed records for the laying season of crossbills in USSR are from the Kola Peninsula. In good spruce cone years a few pine crossbills lay in August, most of their broods flying in September. But parents are occasionally still feeding flying young in late October. In these years, however, crossbills do not nest between November-January because there are only 1!-7 hours of daylight. Towards spring, then, as the spruce cones shed their seed, the crossbills depart to districts with better cone crops, as Kirikov also discovered in the South Urals. In the Kola Peninsula a good pine cone crop alone does not attract wintering crossbills as these seeds are not generally accessible until late February-March onwards. In these years the pine crossbills arrive in March, common crossbills in April, and two-barred crossbill even later. Pine crossbills then nest from mid-May onwards, common crossbills from the end of May, and both continue breeding until the end of August, with all fledglings on the wing by the end of September. In these years the two-barred crossbills nested in the Lapland Reserve from mid-June to late August, but they do not breed there as regularly as the other two species, probably only settling on the Kola Peninsula when spruce and larch have failed in the north-east regions of European USSR. In years when good crops of spruce and pine cones synchronise here, both pine and common crossbills, by exploiting the spruce, nest successfully in high numbers from February-March until mid-May. Later the crossbills feed on pine seed until the end of August, but only a few pairs succeed in nesting. Breeding populations and numbers of pine crossbills in this region thus depend on the availability and abundance of spruce or pine seeds. This results in a difference of 20-45 days between the start of winter nesting in different years. In 1959,when there was a bumper spruce crop and a good pine cone crop, the common crossbills began to lay on 2 February, pine crossbills on 22 February, and two-barred crossbills towards the end of March. On the other hand, in 1966, with a good spruce crop and an average yield of pine cones, all three species commenced nesting in the second half of March. The winter-spring nesting of the twobarred crossbills, therefore, is more regular and less erratic, usually starting in the last ten days of March. REDPOLL AND SISKIN

Crossbills are not the only finches whose laying season is partly controlled by the richness and availability of conifer crops. In Fenno-Scandia, for example, redpoll and siskin seldom breed before mid-May, but in years

Laying Season, Clutch and Egg 87 of bumper spruce seed, Swedish observers have found them nesting in March and April with deep snow on the ground and the thermometer down to -20°C. In Strathspey I have also found that siskins and Scottish pine crossbills both sometimes nest exceptionally early in years of heavy pine cone crops (Table 15). COMMON CROSSBILL

In parts of their range common crossbills breed in every month of the year, their ability to withstand a cold and severe climate enabling them to breed whenever there is a good cone crop. A rich seed crop, rather than mild weather and daylight, is thus the main trigger. Some common crossbill populations in northern Europe and North America are special. In Finland, for example, Haapenen (1966) found that in some of the large mixed spruce and pine forests the crossbills occasionally nested in spruce from late summer until early May and then from late May to July in pines. In these forests, therefore, crossbills sometimes bred in every month of the year. Other groups have even stranger patterns. In the larch-pine forests of the Southern Urals, the crossbills exploited the cone crops of both trees. When good crops occurred the local crossbills had two separate breeding peaks; in April-May in pines and in August-September in larch. In some years nesting was restricted to the pines and in years when both trees were barren or fruited poorly, the crossbills moved on or the few that stayed failed to breed. The Tien Shan race has evolved yet another different rhythm. The special spruce growing there has a four-month coning season, which results in the crossbills breeding from late summer to early autumn. In North America, Niedrach and Bailey found that the populations in the Rocky Mountains of Colorado also had a long and quite unexpected breeding season. In December these birds exploit the seeds of different conifers in the lower hills and then move up to the higher ground where the cone crop islater. This produces a laying season lasting from December to June on the low ground and another from July to September on the higher slopes. In the sitka-spruce plantations of southern Scotland, common crossbills have also recently nested continuously from August to April. There are different patterns in England. After the great irruption of 1909-10 groups of crossbills colonised and have continuously nested in East Anglia, where invading groups have periodically reinforced small resident populations. In Breckland crossbills have nested almost entirely in planted pines where their breeding season sometimes extends from December to June, but their main breeding season lies between February and April, with March as the peak month (Table 3). On the heaths and commons of southern England, where the few resident crossbills usually nest on older and more scattered pines and on the fringes of large woods, the breeding season is

88 Pine Crossbills later, with almost as many nests found in April as in March, and very few as early as February. The small groups in the New Forest and on the Dorset Heaths have much the same pattern. Of 25 nests located between 1960-64, thirteen clutches were laid in March and twelve in April. In Ireland, where there are no longer any indigenous pines, but many plantations, irrupting crossbills have possibly nested in Tipperary from 1838 onwards and irregularly in other counties, particularly after invasions from northern Europe. The laying seasons of the Irish crossbills differ markedly from those of the Breckland groups. Here, in a sample of 43 clutches, 39.5% were recorded in April, 34.8% in March, and 20.9% in May. Only a few nests have been found in February. CLUTCH-SIZE

Although crossbills depend less on weather and climate than almost any other finches, the availability of cone seed is all-important. Table 4 analyses the clutch-size of pine crossbills in upper Strathspey and Easter Ross. In the Highlands, in years when large populations synchronise with bumper cone crops, some early nests contain five eggs. In a sample of 19 February nests located in Easter Ross and Upper Strathspey, two hens (10.5%) produced these large clutches. In March, when 80 out of 174 hens completed their clutches, the mean clutch size was 3.78. In April 66 hens produced rather larger clutches, averaging 3.9 eggs, with 12.6% containing five or six eggs as against 5.1% of such large clutches in March. What is the cause of this rather unexpected finding? I suggest that by April and late March the cones are beginning to open and discharge their seeds. This enables the crossbills to extract seed more easily and thus build up the reserves needed to produce more eggs. On the other hand, by late April and early May the crossbills must work harder as many cones have shed their seeds. The small sample of May nests, therefore, shows a smaller average clutch. The relationship of clutch-size to laying season in common crossbills groups in other parts of Britain, Ireland and northern EUrope make an interesting comparison (Table 3). In East Anglia, for example, there is the same trend, with a greater proportion of clutches of five and a larger mean clutch in April than in any other month. In Ireland, where the crossbills nest rather later, May produces the largest clutches. In Fenno-Scandia a smaller sample of 44 nests shows the same tendency, although more data are needed. In the Lapland Reserve and at Kandalashka, 40 pine crossbills nests all contained four eggs--a most surprising result-but no monthly analysis was given. Thirty two nests of common crossbills and 12 of two-barred are also all said to have contained clutches of four. Table 5 analyses and compares clutch-size in Scottish pine, pine and common crossbills in various regions and countries.

Laying Season, Clutch and Egg 89 REPLACEMENT CLUTCHES

In years of good cone crop, hen Scottish pine crossbills are able to replace lost clutches. The new nest is then built and the first egg of the fresh clutch laid sometime between the 7th and 11th days. A nest with one egg on the 8th day is most usual. One hen produced three consecutive replacement clutches.but others seem capable of only one ortwo (Table 6). Replacement nests may be close by, or as much as 200 yards away. DOUBLE BROODING

In Scotland pairs of pine crossbills are normally single-brooded in spring. The long dependence of the young crossbills on its parents clearly militates against the production of second broods. However, I watched a hen, which was feeding fledged young, build a second nest but she did not finally lay in it. Another pair with flying young established a territory but did not build a nest. Without colour banding, however, it is impossible to determine whether some nests found in summer are due to late pairings or to hens whose mates and young have previously joined flocks. In parts of USSR, in particular, pine and other species of crossbill have two or more breeding peaks related to different cone crops at different seasons. Some of these hens are thus likely to produce two or more clutches within the 12 months period. However, they are unlikely to be mated to the same males. COMMON CROSSBILL

In the Forest of Ae some pairs of common crossbills reared two and possibly three broods in 1967-68. Here, Smith and Young made a most exciting discovery. The three flying young of an earlier brood often flew in with the cock when he was feeding the hen on her second nest. One youngster-possibly a male--also frequently pitched on the nest in the absence of his father when he begged and was then fed by the sitting hen. Another of these fledged juveniles also fed the young in this second-brood nest. These unusual adaptations may assist some groups to increase rapidly (Plates 14 and 15). EGG

Scottish pine crossbills' eggs are seldom beautiful. Most have greenish or off-white ground colour but are blotched, speckled and sometimes streaked with deep red, orange red and sometimes by black or sienna blobs, speckles and blotches. A scarce but lovely variety has a pink flush ground colour and red rose blotches; but I have only twice found clutches of these lovely eggs. Most of the speckles and blotches are concentrated on the heavier ends, although I once found an egg, in an otherwise normal clutch, in which the large end was almost immaculate and the small end heavily marked. Jourdain gives an average of 100 Scottish eggs 21.64 x 15.9.

90 Pine Crossbills The eggs laid by pine crossbills in northern Europe and USSR are similar, but are said to have bolder and blacker markings than those of curoirostra (Jourdain). Scottish pine crossbills' eggs are also smaller than those of pine and common crossbills although different groups or populations of curoirostra may produce eggs of differing sizes (Table 7). Kokhanov and Gaev found that two-barred crossbills' eggs had a rosecoloured tint. In the Breckland groups of curoirostra there were two generally distinct types of eggs in the 1930s--a large dull egg with purple spots and a thinner bluish egg, smaller and of a greenfinch type. These greenfinch-type eggs were the only kind found in East Suffolk in the late 1930s, but from 1946 onwards hens laying this kind of egg no longer appeared in the Suffolk groups. After the 1966 invasion, however, five hens which laid in or before February 1967 produced these 'greenfinch eggs', thus suggesting the possibility that they were laid by the same groups as those which had temporarily settled in the 1930s (Robson, pers. comm.). Even if a hen does not brood steadily on her first or second egg, or if she fails to sit on an incomplete clutch at night, few eggs are broken by frost or snow as they are remarkably resistant to cold. In Strathspey, although I have sometimes had to clear snow from the nest cup, I only met with four frosted nests, two containing single eggs and two with two eggs. In April 1905, a late nesting season at Fairburn, Gilroy found three nests, each with three eggs, which a sharp frost had split and broken, and on 23 February 1907 George Lodge also found nests with two frost-cracked eggs. In East Anglia, on the contrary, frost not infrequently destroys common crossbills' eggs, possibly due to earlier laying there, to different brooding adaptations, or to less resistance. Laboratory tests might be useful. LAYI:NG

After her first egg a hen pine crossbill usually lays daily, but two hens missed days between their second and third eggs. I have also recorded blank days in the laying of greenfinch, siskin, redpoll and linnet. There are few observations of the egg laying routine and behaviour of other finches. Before laying her third egg a hen siskin turned round and round in the nest cup; and I subsequently saw her preening herself almost continuously. Chaffinches regularly lay their eggs in the early morning and greenfinch, linnet and bullfinch also usually lay early in the morning (J. H. Owen, pers. comm.i. I twice climbed to Scottish pine crossbills nests in the dusk, before the

hen had started to lay, flushing her from or near the nest. I do not know, however, whether these hens were sitting or merely roosting in the tree beside the nest. It is difficult to discover how and when finches lay their eggs. Two hen pine crossbills laid their second eggs at some time between

Laying Season, Clutch and Egg 91 7 and lOin the morning. At another nest the third egg was laid between 07.30 and 08.30; I had checked the nest at the earlier hour. A fourth and final egg of another clutch was deposited between 08.17 and 09.20. Laying in the afternoon is abnormal but I have one record. On 13April 1937 I climbed to a nest just before noon, finding it empty and the crossbills absent. At 12.59, while watching siskins, I suddenly heard a crossbill chittering and found the cock tooping loudly near the nesting tree. As I approached the chittering died down but the cock still called periodically. At 13.32,he fed the hen at the nest. Then both crossbills flew off. I now climbed the tree and found that the hen had laid her first egg.

CHAPTER 10

BROODING High up on the nest the hen sits tightly as she waits for her mate to arrive. All now depends on his obtaining enough seed to satisfy her needs and his own. Now, with the hen seldom quitting the eggs, the well-drilled team is put to a severe test. The partnership between the lovely cock bird in his scarlet guardsman's tunic and the little green hen is all important. At night the hen pine crossbill sometimes sits on an incomplete clutch. By day she frequently covers the first egg, but seldom starts serious brooding until the second or third. Before the start of steady incubation, cock and hen sometimes feed at some distance from the nest, to which they periodically return. On 31 March 1935 the crossbills were absent between 14.25-16.07 from a nest containing a single egg. I then saw them return and twitter to one another. The cock sang quietly and fed on birch catkins, but the hen did not visit the nest. While sitting fitfully on an egg or two, some hens chitter intermittently or sing quiet nest songs and their mates may then feed them on or off the nest. Cocks now often sing or call the hens from eggs. On 26 March 1938, after one had peremptorily called off his hen, she flew over a clearing and pitched high up on a larch, where she flicked her wings to invite him to feed her. Then she fluffed herself and flew back to the nest on which she chittered loudly. A minute or two later she flew away with the cock. I now climbed the tree and found that there was one egg in the nest. In this pre-brooding phase pine crossbills often behave unexpectedly. On 22 March 1935 the pair was absent from a nest containing two eggs. At 16.20 on the 24th there were three eggs; the hen had evidently missed a day between second and third. Then, while I waited, the green hen-like

92

Brooding 93 cock pitched silently on the nest tree, and the hen started calling shrilly on the nest. At 16.27 the cock perched on the nesting branch, but the hen left immediately and started calling excitedly. Although much less demonstrative, the cock now sang and fluttered his wings in display flight about 100 yards off. Soon the hen returned and the green cock sang loudly when a strange male intruded. On the next day the hen was steadily brooding four eggs; the cock fed her at 14.17 and 16.01. On 25 February 1936, a pair in Abernethy Forest had a different pattern. At 13.15, the cock tooped excitedly; five minutes later I saw the hen fly out of a clump of pines and start to feed on the cones. At 13.45, there was frantic twittering and I then saw the cock feeding the hen on a nest about 30 feet up. Five minutes later it flew away, leaving the hen sitting on two eggs. She was still brooding at 16.15. I saw the cock feed her. She still had two more eggs to lay. In April 194Q another hen was brooding on two eggs, her first day of incubation. At 12.03, she squeaked on the nest, but the cock ignored her. At 12.45, however, he flew in and immediately ousted a trespasser but, although the hen was chittering and rapidly flicked her wings, he did not feed her and soon departed. A neighbouring pair then arrived and started to feed on the nesting tree itself. I saw the hen stand up over her two eggs and preen, but she did not attack the intruders. However, at 13.10 the cock chased them away, but waited half an hour before returning to feed his mate. Immediately afterwards the hen silently left the nest and the cock followed her over a steep bank. The two crossbills were now away for 26 minutes, and the hen fed near the nest for five minutes before returning to her eggs. The cock then flew off but at 14.30 he flew back to oust the intruding pair. The sitting hen chittered and solicited but he again ignored her. Ten minutes later she sang a sweet nest song and the cock again ejected the trespasser from the nesting tree. Yet, just previously, the hen had been feeding almost beside him on a tree about 20 yards awayl At last, at 15.13, the cock fed the brooding hen which had been singing on the nest and then she left and was away eight minutes. At 16.05, she raised her tail almost vertically, flapping her wings to balance herself while excreting over the nest rim. After this she fidgeted continuously, occasionally standing up, spreading her tail, and preening. This pair produced many surprises. After the next meal at 16.24 the cock stepped onto his mate's back and walked over her, an action which seemed to upset her as she promptly left the nest. Meanwhile, the cock waited for half a minute on the nest tree before following her. Seven minutes later both returned but he immediately flew away. Until 17.33,the cock was away from the territory, thus allowing the neighbours to alight quite close to this nervous and fidgety hen. Between 12.05 and 17.33, the cock thus gave his mate three meals at intervals of 102, 88 and 71 minutes. In these 5! hours the hen had also thrice left the nest for spells of 31, 8 and 7 minutes and her two continuous

94 Pine Crossbills brooding sessions had lasted 65 and 68 minutes. She then had two eggs. A pair watched in 1938 behaved differently. She laid her first egg on 17 March and was brooding two eggs on the 18th. At 12.35, she left the nest, first defecating and then drinking at a bum. Several minutes later she returned remarkably quietly and the cock then fed her. I then assumed that she had started to sit. On the 19th, however, I waited two hours without seeing either bird. The three eggs were wet, cold, and looked deserted. In the afternoon of the 20th, however, she was brooding and had evidently waited until laying her fourth and last egg before beginning steady incubation. On the other hand, two hens watched on 30 March and 9 April in that year did not begin to brood steadily until a day after they had completed their clutches. Most hens begin incubation on the second or third egg in a clutch of four, on the second of three, and on the third or fourth of five. This irregular start to incubation is difficult to explain. Even on the same day of the same year different hens have different patterns. Depending so much on a single food, one might expect the hens to incubate from the first egg onwards in poor seed years, thus killing off the younger chicks and helping the oldest to survive. On the other hand, if the hen started to incubate from the first egg, the cock would be forced to feed her and himself for extra days. In poor seed years a longer period of steady incubation would also be more exacting for the hen, compelling her to leave the nest at times to feed herself. PINE CROSSBILL

The few observations on the pine crossbills' brooding adaptations in Fenno-Scandia suggest similar irregularities. In Norway, Valeur recorded that most hens brooded steadily from their first eggs, but that others sometimes left incomplete clutches uncovered during exceptionally severe weather. For example, on a day showing 110 frost, a hen was off two fresh eggs for over 14 minutes. In Ostergotland, Olsson also found that three hens started steady brooding on their first egg. On the other hand, Spj"tvill concluded that a Norwegian hen did not start to incubate steadily until she had finished laying. Before this the eggs were cold when he had flushed the hen which, he concluded, was merely protecting them from frost. Russian observations in the Murman region were different. There hens apparently sat from their first eggs onwards, but they brooded more closely in colder weather. During warmer weather they sometimee left their nest for short periods. COMMON CROSSBILL

Most hen common crossbills intermittently cover their first eggs, but do not brood steadily until the second or third in a clutch of four. L. R. Flack tells me that, 'the female sits on the nest from the first egg onwards,

Brooding 95 although she is not then seriously incubating. This covering particularly happens when the crossbills are nesting close to house sparrows which sometimes rifle or interfere with crossbills' nests before or after they contain eggs.' In Dumfries, on the other hand, Newton found that some common crossbills brooded steadily from the first egg and that the clutch hatched asynchronously. There are thus some inconsistencies in the brooding adaptations of common crossbill as in pine crossbill. SCOTTISH PINE CROSSBILL

After the hen has started to brood steadily, the cock regularly feeds her, usually on, but occasionally off, the nest. He must now feed himself and also obtain extra seeds for the hen in feeding areas which are often anything from t to 1 mile away. Only rarely does he tackle cones on trees close to the nest. After feeding his hen he usually flies far away. Here is a typical picture. You suddenly hear a cock chipping in the distance and the brooding hen instantly becomes alert, stretching up her head and neck and starting to flick her wings and squeak almost like a mouse. Even if other crossbills are flying over, or have settled on the trees, the hen usually recognises her mate's voice from afar. As the cock flies in, the hen becomes increasingly excited, quivering her wings more and more rapidly. The cock now pitches on a tree from 50 to 100 yards from the nest, and then sometimes starts flicking his wings and tail and usually tooping excitedly. After a few minutes, however, he generally quietens down and stops calling and flicking his wings. Then he may fly in an inverted arc between two tree tops, landing on one which is nearer to the nest, and here he usually demonstrates again. Finally he is silent, but perhaps shows inner tension by a few emotion releasing actions. You may see him suddenly sleek his plumage before he flies to the nesting tree, often rustling rather noisily from branch to branch until he reaches the nest. Standing on the rim or on a twig beside it, he now gulps up seeds which are usually contained in a blob of mucus. Meanwhile, quivering and twittering and with open beak in what seems to be an agony of excitement, the hen receives the seed which he thrusts into her beak or he gulps them up into his own beak from which she takes them. These meals usually last one or two minutes, but the quantity of seed which the cock provides varies greatly. I have counted as few as six and as many as 24 gulps. After he has fed his mate the cock may flutter up to the top of the tree or to the end of the nesting branch, where he often calls softly or briefly sings a quiet sub-song, and then perhaps chipping sharply he bounds away. For the next few minutes the sitting hen continues to chitter and quiver her wings; but she soon settles down, sometimes bends down to arrange or change the position of the eggs, and then she licks the tips and insides of her mandibles with her powerful tongue. A few cocks have different routines. On 18 March 1942 a most unusual

96 Pine Crossbills

cock sang. softly for 20 minutes, almost beside the nest, without attempting to feed his hen. At 15.20 on the 21st he also sang and tooped on a larch for 10 minutes before flying over to his nest. An hour later he also tooped for 20 minutes and sang on this larch for 10 more minutes before visiting his exceptionally undemonstrative hen who did not chitter or flick her wings while he was feeding her or when he was singing on the nest tree. However, the cock chuck-chucked while giving her the meal. A pair watched in Easter Ross on 28 April 1974 also had an unusual pattern. Sometimes the cock was extremely noisy when visiting the nest, although he never seemed to flick wings or tail. At other times he arrived and fed the hen without a single call, and how nervous he seemed after feeding her; false feeding, pulling and pecking at his upper breast, nodding his head and periodically pecking between the spines. The nest was in the crown of a tall spindly pine which was thick and bushy. The cock sometimes stood on a twig above the nest, bending right down over the nest as he fed the hen below him. At 17.28 I saw something that I have never seen before. As the cock threaded his way through the foliage the hen stepped out and sidled past him through the branches. This seemed to upset him. After a minute he worked up to the top of the tree, where he chipped a few times, nodded his head and then flew away. The hen stayed off for 10 minutes and the cock did not return with her. I could not see whether he fed her when she was away. Most cock pine crossbills provide their sitting hens with seven to ten meals daily, usually feeding them on the nest, but occasionally on nearby trees. A few cocks are erratic in their visits, but most feed their mates at intervals of t to 2t hours. If a cock is long absent the brooding hen often starts to call loudly and, if within earshot, he may go to the nest and feed her. Some hens, however, fly offto feed, defecate, exercise, and occasionally drink, in the absence of their mates. They then come off at intervals of t to 3t hours, absenting themselves for one to ten and occasionally up to 17 minutes. However, a hen seldom voluntarily quits her eggs more than four times in anyone day, but if the cock is neglectful she silently steps out of the nest and flies to an adjacent tree where she sometimes feeds herself for 10 to 20 minutes and usually flies quietly and directly back to nest and eggs. On 12, 17 and 18 April 1938, for example, three different hens left their nests for spellsof three to fiveminutes, briefly tackling cones on pines close by before returning. On the other hand, two pairs nesting in the same Easter Ross wood in consecutive years had unusual routines. At 11.30 on 3 May 1967 the cock landed on a tall pine where he quietly chipped and tooped. Ten minutes later the hen left her four eggs and the cock fed her high up in a tree. At 11.47 she returned to her nest and, to my surprise, the cock again flew over to feed her. At 11.50, he sang nearby and again sang between 14.15-14.25, but he ignored the persistent chittering of his sitting hen. For a further 20

1 Cock Scottish pine crossbill. A close-up study. Rothiemurchus, 1946 . John Markham

2 Top: a haunt of Scott ish pin e cros sbills in the C airngorms. Gl enmor e, Inverness-shire. John Markham. Bottom: habitat of pin e crossbill. O stergorland, Swed en. Viking Olsson.

3 A study of a cock com mon crossbill. Surrey, 1973. Frank Blackburn.

4 Hen comm on cro ssbill with bui ld ing material. Surrey, 1973. Frank Bla ckburn.

5 The p ylo n hid e a t a Scottish pine crossbill's nest in a forest clearing. R othiemurchus, June 1952.]. T . Fisher.

6 T op: the first kn own photogr aph of a cock Scottish pine cros sbill about to brood egg s. Phot ogr aphed by th e auth or fro m J ohn Fisher 's pylon h id e. R oth iemurchus Forest, Inverness-shire, June 1952.]. T. Fisher and the author. Bot tom: hen showing neck-raised fear posture. R othi emu rch us, J une 1952. ]. T . Fisher.

7 P air of Scott ish pine crossbills at th e n est. H en with raised beak beggin g for food. R othiemurch us, June 1952. ]. T . Fisher.

8 H en Scottish pine cross bill brooding on a nest in a Scots pine. R othi emurchus, June 1947 . Eric j. H osking.

9 Pine crossbills. A beak study ! Co ck left, hen ri ght. Ostergotland, Sw eden. Viking Olsson.

10 Female pine crossbill feeding youngster . Pine seeds and secretion can be seen between th em . Ost ergo tlan d, Sweden. Viking Olsson.

II Top: cock about to feed young wh ile hen begs on th e edge of the nest. Rothiemurchus, June 1947. Eric]. Hosking. Bottom : cock Scottish pin e crossbill feeding hen on the rim of th e nest ; chick showing below . Rothiemurchus, June 1947. Eric j. Hosking.

12 A cock Scottish pine crossbill feeding a fledgling which has left th e nest. Rothiemurchus, 1946. John Markham.

13 Top: nearly fled ged young p ine crossbill s. No te th e latrine on th e ed ge of the nest. Os te rgo tland, Sw ed en . Viking Olsson. Bottom : young Sco ttis h pine cros sbills cr ouc hi ng in a nest near th e top of Scot s pine. H er e th ere is no special latrine. D eeside, Aberdeen , IO April 1974. Alan Knox.

14 (Above) T op: fled ged yo u ng co m m on crossb ill of an ea rl ier b rood begging while th e h en feeds ch icks in the seco nd nest. On h is retu rn to feed th e hen , th e coc k a ttacked an d chased the juven ile. Ae For est, Dum fr ies, 7 M ay 1968. j. F. Young. Bottom : a remarka ble phot ograph of a juvenile common cross b ill feedi ng the ch icks of a seco nd bro od in th e n est. The fledged young of the ea rlier brood accompanied th eir fat her whe n h e was visiting th e h en and chicks at the n est. Ae Forest, Dumfries, 8 May 1968. j. F. Young.

15 (Opposite) Top: fled ged young co m mon cross b ill wa its for food while h en is brooding young. Ae Forest, Dumfri es, May 1968 . R . T . Smith. C entre: juven ile com mon cros sb ilI waits for food while h en is feeding n ewl y h a tch ed ch icks. Ae Fo rest, Dumfries, May 1968 . R . T . Smith. Bottom : coc k co m mo n crossb ill feeding fled gling ou t of the n est. Dumfries, 1968 . R. T. Smith.

16 T op : yo ung male pin e cros sbi ll drinking. Ostergotland, Sw ed en . Viking Olsson. Bott om : male com m on cross bill drinking at pool. Surrey, 1973. Frank Bla ckburn.

Brooding 97 minutes he kept up this intermittent singing and then flew to nest and gulped up some seeds for his excited mate who kept calling after he had gone. Still remiss, the cock did not return until 17.12 when he waited three long minutes before feeding his noisy chittering mate. This time his mate had fasted for nearly 2t hours. Seventy minutes later the hen left the nest and the cock arrived immediately, both birds tooping angrily in chorus. Then, after feeding her, the cock escorted his mate to thenest from which she had been absent for 15 minutes. And that was her last meal of the day. Between 11.30-18.45, he thus fed the hen only five times, at intervals of seven minutes, two hours, 58 minutes, 2t hours and t hours. The hen was off nest at 11.40 for seven minutes and at 18.25for t hour. On 7 May he fed her at the nest at 12.50 but gave her nothing more until 15.17 although twice singing on trees nearby. At 16.05 a group of non-breeding common crossbills arrived with the tenant cock who did not visit the nest. The eggs did not hatch. Between 12-14 April 1968, I watched an extremely quiet pair in the same wood. At 17.05 on 12 April, I saw the hen leave her nest when the cock first fed and then surprisingly supplanted her from a tree top. Nervous and frequently fluffing her feathers, this hen stayed off her eggs for t hour. At 18.20, she abruptly flew from her nest, fed quietly on the nesting tree, and then slowly worked down from branch to branch where I saw that she was catching insects. Soon afterwards she joined a non-breeding group for a few minutes before returning to the nest. On the 13th this pair again behaved abnormally. At 17.03 the hen came off the nest, but the cock escorted her back to it and then fed her. While she was on trees nearby she frequently fluffed herself and showed signs of an emotional clash. On the 14th, D. Macdonald and I started to watch at 15.55. Nine minutes later the cock pitched silently on a tree top and the hen then departed so quietly that we almost missed seeing her. After a lapse of 10 minutes the two crossbills returned in silence, the hen flying to the nest at which the cock gave her many gulps of seed. This hen also failed to hatch her eggs which disappeared within the next 10 days. What caused this unusual behaviour? In 1967 the cone crop in this wood was poor and it was only mediocre in 1968. Probably these two cocks were finding it difficult to obtain enough seed to maintain themselves as well as the extra food needed to supply their mates. In 1967 groups of invading common crossbills were on the ground, but none apparently bred. PINE CROSSBILLS

There is also great variation in the brooding patterns of pine crossbills in Fenno-Scandia and USSR. At nests in Ostergotland, which Olsson was watching, the hens alone brooded, their mates feeding them every 2 to 2t hours. However, when these cocks were not away foraging they usually stayed on tree tops close to the nests where they maintained contact with

98 Pine Crossbills the brooding hens by calling weak descending see-see-roe notes which were apparently only used near the nest. Several times brooding hens called loud gyps-gyps to incite their mates to go foraging. The cocks then flew away to feeding woods which were half a mile or more away. At a pine crossbill's nest in Norway, on 2 and 4 April 1968, SpjtStvill found that the cock fed the hen fairly regularly at intervals of 42 to 150 minutes, with an average 85 minutes between meals. In Finland, Hilden and Linkola recorded that the cock pine crossbill brought food to his mate roughly every 2! hours, the seed having been collected from trees about 1 km. from the nest. They also noticed that the cocks only took the more accessible seeds between the opening scales near the tops of the cones. The crossbills thus dealt with each cone much more rapidly than in winter (Hilden 1974). Our Russian colleagues' careful description of this behaviour closely resembles our own observations on the Scottish pine crossbills. In these mixed pine-spruce woods the hens apparently seldom left their nests during incubation. However, a low flying aeroplane scared one hen off her eggs, but she was back on the nest within a minute. While foraging for their sitting mates, the cocks worked alone or in groups of up to five. Unobtrusive and seldom singing, they busily stripped cones until their crops were full and then flew off calling to visit the nests. The Russian observers also noticed how the hens instantly distinguished their own mates' calls, even when they were flying with a group of others and that they then started calling when the incoming cock was 50-100 metres away. COCKS BROODING

Normally the hen Scottish pine crossbill alone and entirely broods and incubates. However, I have records of four cocks temporarily sitting on eggs in the absence of their mates. On 21 March 1936 I watched the slimmer and smaller cock-bird arrive while his hen was calling a deep zoop-soop on a tree top. For seven or eight minutes both birds called on pine trees and then the hen flew to the top of a pine about 150 to 200 yards from the nest. To my astonishment, the restless cock, after repeatedly flicking his wings and moving from tree to tree, fluttered down onto the nest and two eggs which the hen had just left. When I climbed the tree the cock left immediately and the hen perched close to me. Two other cocks briefly brooded full clutches when their hens were off eggs. In 1952 I actually photographed one of them just as he was settling on the nest (Plate 6). I believe, however, that these unusual incidents were forms of displacement behaviour, the cocks reacting unexpectedly to the absence of hens. My fourth experience is less easily explained. On 28 March 1935 I was astonished to see a scarlet cock pine crossbill flutter off the nest to which I was climbing. Calling angrily, he then settled on a tree a

Brooding 99 few yards away, where he was soonjoined by the hen. Cock pine crossbills, therefore, appear to have a latent brooding drive. A few other finches also probably share this tendency. Eric Hosking watched a cock hawfinch briefly sit on eggs while the hen was feeding and B. H. Ryves and I have seen cock chaffinches covering eggs for a few minutes while their mates were away. There are other birds in which cocks only exceptionally brood. 'In the absence of the hen, a cock blackbird may go to the nest and stand over it, sometimes even crouching in the nest cup.' Other cock blackbirds are known to sit persistently if the hen is long absent or has been killed (Snow 1952). There are similar records scattered through the literature. BROODING BEHAVIOUR

While brooding, some hens are restless, almost continually changing position, raising and flapping their wings, and frequently adjusting the rim or pecking and probing in the floor of the nest. They also often raise and lower their crown feathers, sometimes in emotional stress, and at others possibly to allow air to cool their heads. Ectoparasites often irritate the brooding hen which then nibbles under her wing and pecks at her breast and flanks. Forever alert, she often snatches at flies or other small insects which are flying past or settling on the nest. However, one hen carefully inspected but seldom snapped at the occasional wood ants which had crawled up the tree. In hot weather the hen often opens up and possibly cools the nest-lining. In fear situations she raises or stretches her neck, often also making up and down billing movements. Other hens brood much more passively. At three nests I found that the hens were brooding at night; this is likely to be the usual pattern. Some cocks roost in the crown of the nesting tree or in one close to it. Small piles of droppings under these perches suggest that they may regularly use the same trees. Others roost in their feeding woods, only starting to visit their hens and nests in the early morning. One cock flew into his territory and fed his mate for the first time at 06.33. After his final visit to the nest at 16.55 he had not returned before I left in semi-darkness at 19.30. NEST HYGIENE

At night, and occasionally by day, a brooding hen excretes over the edge of the nest, sometimes depositing conspicuous white faecal capsules on its side. Before doing this, she rears up and rapidly flaps her wings to balance herself. However, some hens keep their nests much cleaner than others. On 28 April 1940, I watched a hen, then brooding four eggs, flyaway with a white capsule in her beak. This is unusual behaviour, but I once saw a hen pied wagtail do the same. She suddenly emerged from a hole in a dyke, a white sac at the end of her bill, and flew away with it. Yet she still had eggs in her nest. At Fairburn, in April 1905, Gilroy noted, 'the birds

100 Pine Crossbills take no care to remove excrement, and even when the eggs are quite fresh the nest is filthy.' This is certainly not the general pattern. Indeed pine crossbills on the Kola Peninsula are apparently exceptionally hygienic. During the period of incubation no trace of droppings were found on or beside any of the nests. The observers considered the possibility that cocks disposed of the hens' faeces, but could discover no direct or indirect supporting evidence. HATCHING-SPREAD AND INCUBATION PERIODS

As steady incubation commences so irregularly, the hatching of all the eggs in a clutch is sometimes well spaced. In Scotland all the eggs in four nests were hatched within a space of 24 hours, eight within 48 hours, two over a period of three days, and in one clutch containing five eggs there was a difference of 3t days between the hatch of the first and the last egg. The shell of each egg is chipped for under six hours before the chick struggles out of the shell. In Scotland the last egg in six different clutches hatched out at some time between the 13th and 15th day of brooding, giving an average measurement of 13.2 days. In Sweden Olsson estimated incubation periods of 14, 15 and 16 days respectively at his three most closely investigated nests. 'These calculations were based on observations which indicated that true incubation (as opposed to brooding) took place from the laying of the 1st egg.' At one of these nests the four eggs hatched over a period of three days. At a nest in Norway, Spjt>tvill estimated an incubation period of 15 or 16 days from the appearance of the first egg and either 13 or 14 days for the last egg; and, on the Kola Peninsula, the eggs hatched on the 14th or 15th day and once on the 17th day. It is not clear, however, whether the Russian measurements applied to the hatching of first or last eggs. Apart from the egg which hatched on the 17th day, the brooding period of each egg is likely to have been approximately 13t to 1+t days, which is roughly the same as that of the Scottish pine crossbills. EGGSHELL DISPOSAL

Scottish pine crossbills have more than one method of dealing with hatched eggshells. I watched two hens half stand to bend down over their nests while breaking up and eating shell fragments. One did this while the chick was still wet, the second waited until it was dry. A third hen flew about 30 yards with a shell in her beak, then pitched on a tree and transferred the shell to her foot before eating part of it. A fourth landed on a pine top and there let the shell drop from her beak. Possibly I had disturbed her. However, I have also twice found large pieces of hatched shell within 30 to SO yards of nests with young. Crossbills and other finches, however, possibly sometimes eat eggshells because they are in need of

Brooding 101 extra calcium. Shells carried away and then dropped may be disposed of as if they were faecal capsules. I have not seen a cock eat or carry away an eggshell. At two nests addled or infertile eggs disappeared shortly after the chicks had hatched. At one of these nests, beside which Eric Hosking had built a pylon hide in 1947, two eggs hatched and the third disappeared at about the same time. But I have never actually watched what happens. At a couple of other nests I found infertile eggs lying under small nestlings. DESERTION

In my experience, few hens have deserted their nests through human disturbance after laying has started. In 1936, however, a hen which I had flushed from four eggs laid a fifth and then abandoned the clutch. In the same year a second hen deserted four eggs after she had twice been disturbed soon after brooding had started, and a third abandoned a fresh clutch after putting a claw through an egg. Ross records a squirrel eating one of three eggs and leaving half of the eggshell on the nest rim. 'The crossbills removed the shell on the 25th, but though two eggs were left she did not lay again.' She also noted that some hens did not desert nests if only one egg had been taken. It is not clear, however, whether this observation applied to human predators, natural predators, or to both. On 7 March 1936, while leaving her nest, a hen dragged or lifted an egg onto the rim. As I wished to discover how she would deal with this situation I waited until she was back on her eggs and then re-climbed the tree an hour later. The sitting hen was evidently aware of the egg as she once made 'billing movements' above it. However, when I placed it on another part of the rim she ignored it. The egg thus later became cold and abandoned, the hen then possibly treating it as a droppingwhich she failed to remove. Brooding hens are amazingly tame and sit fantastically close on the nest. Sometimes you may touch and handle them. I particularly remember one which pecked at my fingers when I lifted her off and I can still see her fluttering all around me and even landing on my fingers. She had a pungent resiny scent. Kokhanov and Gaev had the same experience, but suggest that common and two-barred are even bolder and tamer at the nest than are the pine crossbills. This is a rough sketch of the way pine crossbills behave from the time that the hen lays her first egg until she has dealt with the last of the hatched eggshells. Every day is crowded with incident and fascination. You will never have a dull moment while waiting under the pine or sitting on a branch or hide close to the nest.

CHAPTER 11

YOUNG CROSSBILLS Young crossbills stay longer in the nest, and become fully independent at a much later age, than those of any other small birds breeding in Britain. When the first chick has hatched, and the hen has disposed of the empty eggshell, the cock's behaviour may subtly change. After he has visited the nest and seen a nestling, he, sometimes twitters softly on a nearby tree before he flies off to his feeding ground. But there is no inflexiblepattern of behaviour. Some cocks continue their routines without any noticeable change, possibly because they have not yet seen their first-born. For the first few days, however, cock Scottish pine crossbills still continue to supply the hen with food for herself and brood. In the Murman region some actually step up their efforts, providing brooding hens with up to a dozen instead of 7-8 daily meals. On 2 May 1940, while I was watching a hen hatch her second egg, the cock fed her at 13.02 and then flew to a tree about 50 yards away, where he tooped quietly for a few minutes, although a cock siskin and a pair of chaffinches were feeding almost beside him. He then departed, but at 13.40 he arrived silently and again went to the nest to feed the sitting hen. Then, at 14.40, he sang for five minutes just east of the nest before rather furtively visiting and feeding his mate. He then flew strongly, right away from the wood. I continued to watch the nest. At 15.40, I saw the hen rear up and excrete a capsule over the rim, but she continued to fidget and brood rather uneasily. Twenty-five minutes later she suddenly flew off, but after seven minutes the cock, who returned with her, escorted her to 102

Young Crossbills 103 the nest and gulped up seeds which she took from his beak immediately she had settled down. He then noisily ft.apped and rustled to the top of the nest tree and bounded off to a favourite pine about 50 yards away. On this day there was no clear pattern. On 13 April 1939, a pair with a nest with 3 eggs, two of which were chipped for hatching, had a different rhythm. For 20 minutes the cock tooped loudly before he ft.ew down to feed the hen. In the early afternoon of the 14th both cock and hen were absent when I climbed up to the nest but, twittering softly, the hen arrived a few minutes later and went onto the nest where there were now two nestlings and one still unhatched egg. The cock did not show up. In Glenmore, in May 1960, I watched a nest where the first of five eggs had just hatched. The cock tooped and demonstrated in three different parts of the wood, continuing to do this for over 10 minutes before feeding the hen on the nest. Afterwards he ft.ew far away. His excited behaviour indicated some kind of inner clash; he had possibly only recently seen the almost naked chick. In the first week after the chicks have hatched, the cock works extremely hard to provide food for mate and brood as well as feeding himself. This sometimes results in his passing on enormous meals which may take several minutes in the giving. To obtain all this seed he attacks the cones of his richest feeding trees which may be half a mile or more from nest or brood, or he may exploit well-eoned trees in his own nesting territory. Richness and availability of the cone seed probably partly determine the different feeding rhythms of various cocks. On 10 March 1936, for example, I spent several hours watching a hen brooding three chicks and a single unhatched egg. Here the cock fed his mate at 14.05 and 15.25. I could see the hen quivering her wings and heard her chittering while he was feeding her. After the second meal the cock sang a full territorial song, tooped excitedly, and ft.icked wings and tail when another pair settled about 50 yards from his nest. This particular cock was regularly ft.ying over half a mile to the fringe of the large wood where he habitually fed. These sketches indicate the great difference and individuality of cock pine crossbills during the period of hatching. For about five days the hen broods her chicks for much of the day, as well as at night. Periodically, however, she brieft.y leaves nest and brood but seldom for longer than 20 minutes. The hen usually appears to know where to find her mate as he often returns with her and then feeds her after she is again brooding. In this phase the hen carefully tends her chicks and eats their faeces. Afterwards she gulps up a kind of seed paste with which she feeds the brood. Sometimes, however, a hen half rises and stands up in the nest to allow the cock to feed the nestlings and to consume their droppings. In a year when pine seed is scarce, the crossbills have to work extremely

104 Pine Crossbills hard. In June 1947 Hosking watched a cock call his mate off her two small chicks and recorded that she was then away for over two hours. At noon the next day the hen was covering the nestlings which periodically appeared under her, stretching up their necks and opening their large maws. But she apparently had nothing to give them. At 13.00 the cock settled on the edge of the nest and the hen stood up, quivering her wings and begging with up stretched head and open beak (Plate 11).The cock duly fed her and then both birds bounded away. Half an hour later the hen came back, creeping mouse-like through the thick foliage. As she stood over her small blind chicks, they continuously raised and opened their beaks, but she did not feed them. At 14.20 there was another incident when the cock went to the nest and the hen rose up and solicited. This time he fed her and the nestlings, leaving the hen to brood them. The hen now arranged the chicks and also prodded in the floor of the nest. However, another three quarters of an hour passed before she fed the chicks a large quantity of seed paste and then settled down to brood them. For the next hour she continued to brood, then the cock arrived and the hen flew off with him. On her return, after an absence of 50 minutes, she threatened and ejected a cock chaffinch which had settled on the nest tree. There was no further action of note until 18.15 when the cock fed the hen but not the chicks. Thereafter, the hen stood on the rim of the nest, prodding the chicks to eject their droppings which she then ate. The cock's partial failure to obtain sufficient seed possibly led to the failure of this nest. The two chicks inexplicably disappeared without trace. When you watch crossbills at nests with small chicks, the unusual or unexpected often happens. On 12 April 1941, at a nest where the hen was brooding three nestlings of about six days old, I saw the cock drive away a rival after a noisy scuffle in which the two scarlet birds sang screeching songs and grappled claw to claw. This affray upset the tenant cock which returned to the dead pine top from which he had launched himself against the trespasser. Here, for nearly 10 minutes, he sang, called, and flicked his wings before going silent and starting deliberate up and down beak movements above the spines. He then flew over and fed the sitting hen on a well concealed nest high up a tall pine. Before he had finished, however, the hen stood up and allowed him to feed the nestlings, one after the other. How fascinating it was to see the hen rise and push back her head and breast and the cock bending down to feed the nestlings. Three days later a small group of unmated cocks and a probably surplus hen arrived with the pair in their nesting territory. Calling noisily, the unmated birds then settled on trees about 25 yards away and waited until the pair had fed their brood. This time the cock visited the nest first, but the hen quickly joined him and fed some of the chicks from the other side. This done, the hen settled on the nest, brooded the chicks for a few minutes, and then prodded their rears and ate their droppings. Twittering softly, the

Young Crossbills 105 cock waited until the hen had finished and then both flew away, with the mateless group in noisy pursuit and at least one cock singing loudly. This spare cock, or possibly another, also accompanied the pair on their next visit. The male crossbill was again the first to feed the brood, the hen flying to the nest a minute later. Meanwhile, the stranger sang loudly while he waited and then, ch,pped loudly; the three did not fight, but both cocks chipped persistently on adjacent trees before the territory-holder visited his nest. Other pairs drive off unmated cocks or small mixed groups. On 17 March 1942, for example, a pair with young attacked a cock party which had started to feed near the nesting tree. Twice the hen flew 50 yards to evict one of them and later she and her mate attacked them. But this fighting apparently upset their feeding rhythm. Both parents left but returned a few minutes later. I then saw the cock feed the chicks which gaped and squeaked shrilly. Still nervous, the hen twisted her head from side to side and made frequent passes at spines before going to the nest. Neither parent carried off droppings but they might have eaten them while they were at the nest. For about five days the cock feeds the hen almost entirely, while she is brooding the almost naked and helpless chicks. Thenceforward she more frequently leaves the nest and goes foraging with her mate. In this phase some pairs have a rough routine, the cock twittering continuously on a nearby tree while the hen feeds, tends and broods the chicks on her short visits to the nest which usually last only about 15-30 minutes. The two parents then fly quietly away together. For at least 10 days the hen continues to carry out brief brooding sessions by day, and almost continuously at night. In 1946, indeed, I met with two hens which stayed with, and possibly sheltered, the young at night until they had left the nest, but this is untypical, After the hen has fed and warmed the chicks, and has joined the cock, the two birds usually fly rather slowly and quietly to favourite clumps of trees. In this middle period the interval between meals lengthens from] to 1t hours. On 16 April 1941, for example, a pair fed a fortnight-old brood at roughly t to hourly intervals. These chicks were standing up and flicking their wings, although I could hear them giving no cries during meals. This cock also preceded his hen to the nest, but she always followed immediately and then together both fed the young from opposite sides. After the parents had flown away, the young crossbills continued to flick their wings in the same way that a brooding hen so often does after the cock has fed and left her at the nest. On 17 April 1941, IO-dayold chicks failed to gape when I shook the branch or tapped the rim of the nest; but they did so when I lightly touched their heads with a pencil. I noticed, however, that this did not induce them to quiver their wings. The pair at this nest had a slow feeding

106 Pine Crossbills rhythm. I started to watch at 15.50 but the parents did not arrive until 17.03 when they first called softly and attacked cones on a nearby tree before visiting the nest. These chicks rapidly flicked their wings, but were silent while being fed. Here also cock and hen stood on opposite sides of the nest and fed their young simultaneously. Afterwards the cock cleaned his beak on a broken branch but he did not carry away droppings. Like so many pairs, these two birds were quiet and almost furtive at the nest and in flights to and from it. These characteristic feeding flights often enable you to recognise pairs which have young in the nest. The two parent crossbills now flyjust above or between the tree tops, seldom calling loudly unless a predator disturbs them. Cock and hen occasionally fall out. On 24 April 1941 I saw an instance of this. An intruding pair settled on the tree on which the tenant cock was scolding and demonstrating, just before going to his nest. Ignoring the fury of the territory holder, the stranger cock unconcernedly fed his own mate. This evidently needled the tenant, who immediately flew over and ousted his rival. Then he re-directed his attack onto his own mate which he now jostled from an adjacent tree top; and he called noisily for several minutes before feeding his brood of large young which were continuously uttering quiet itics while waiting for their meal. But this rage did not last long. A few minutes afterwards I watched this cock and hen drinking at a small puddle under the tree. He had quite recovered and sang quietly on an upturned pine while his hen was at the water. Other pine crossbills feed their broods with fair consistency and regularity. On 1 May 1969 an Easter Ross pair, with young about 10 days old, visited their nest almost hourly. At 15.05 I saw the cock feed the young and also, possibly, the hen at the nest. Before flying away he stood nervously on top of the nesting tree, plucking at his breast and making flight-intention movements. On his return, precisely one hour later, he tooped loudly and the hen appeared almost immediately. Both birds then flew into the nesting tree and flew south together. The cock had again been nervous, nibbling and crackling at cones, before flying over to the nest. My crossbills returned at 17.05; exceptionally quiet, they merely twicked softly before dealing with their young. The next meal was at 17.55 when, chipping quietly, both settled on an adjacent tree. Within a minute they had fed the chicks and had departed. The same routine followed 50 minutes later, the cock tooping softly before he and his mate provided the brood with a meal which lasted a couple of minutes. These birds worked almost to the clock. At 19.40 each fed the chicks in tum, but this time the cock waited for the hen on a tree across the clearing and, when she had finished, he flew off with her. I continued to watch the nest on 5 May. At 18.40 the cock arrived first. Both parents made nervous feeding and flight intention movements and gave subdued calls. This time they arrived from the east but flew north

Young Crossbill» 107 after feeding the nestlings. The hen had arrived first, but the cock soon joined her. Their next visit was marginally later. At 19.45 the cock, who again came first, perched 50 yards east of the nest and waited for five minutes until the hen arrived. She was now the first at the nest and then waited until the cock had fed the chicks and returned to the tree on which he had perched. In all the visits on 1 and 5 May, these crossbills fed their brood at 50 to 65 minute intervals, but I never saw either bird carry away droppings, although they might have eaten them at the nest. While brooding young the hen often stands up or steps onto the nest rim and begs when the cock arrives. By this means she is usually successful in inciting him to feed her, but he sometimes seems confused, turning agitatedly from the hen to her brood. After the cock has passed the seeds to the hen she usually delays before gulping up some of the softened seed to the chicks. For instance, at 12.50 on 18 March 1942, the hen that I was watching suddenly stood up and fed her lo-day old chicks although her mate had not visited her for at least 20 minutes. I have had many other examples of this behaviour. It is quite exciting watching the reaction of the hen to the approaching cock. She flicks her wings, chitters and bends forward and afterwards feeds the chicks by means of a right-left, right-left head turning routine. PINE CROSSBILL

In Sweden, Olsson described how two pairs of pine crossbills dealt with their young. At the first nest the hen only briefly left the chicks in their first week, but a second hen abandoned her feeble three-days old nestlings for an hour 'in almost freezing conditions', and three days later she was away for It hours on a cold dull day when the thermometer was registering 2°C. 'When she returned the young were so chilled that they seemed to be dead. They were quite motionless and not even the slightest breathing movement could be seen from the hide. The female tried to stimulate them to gape, but they did not react at all. After she had brooded them for only seven minutes, however, they recovered and fed quite normally.' This was apparently an exceptionally neglectful hen. On that same day she again left her young uncovered for 75 minutes in a cold drizzle. In 1944, Valeur had the same experience at a pine crossbill's nest in Norway, this hen quitting her newly-hatched chicks for 10 minutes on an even colder day with the temperature -16°C. Young pine crossbills, however, have a quite remarkable ability to withstand severe cold which would quickly destroy almost any other unadapted small bird. This enables them to survive in a bitter climate. In North Trondelag in 1968, SpjtStvill recorded the behaviour at a pine crossbill's nest in which the eggs hatched between 10-12 April. On the 19th two chicks had their eyes open while the eyelids of the third had begun to part. One chick, the smallest of the trio, was the least active at

108 Pine Crossbills meals. This pair visited the nest at intervals of 45 to 75 minutes, with the cock bird usually the more attentive. Between 12.00-17.00 he fed the young five times at 12.20, 13.35, 14.50, 15.45 and 16.30; the hen gave them meals at 12.35, 14.20 and 16.20. These birds, however, did not synchronise their visits, but arrived independently. A few days later the hen had become as attentive as the cock, and towards the end of the fledging period, she visited and fed the young more frequently than he did. This suggested that the hen's feeding impulse was relatively weak when the young were small, but that it became stronger as the chicks grew older and larger. Possibly she had first to build up her own strength and inner resources before concentrating on collecting food for the nestlings as well as for herself. The behaviour of the parents had again changed on 20 April when Spj«Stvill was ringing the brood. Both now flew rather nervously around nearby tree tops, but the cock did not try to feed the chicks throughout a watch lasting three hours. The pair continued like this on 22 April, the two brids avoiding feeding the brood until Spjstvill had hidden himself. However, the swollen necks of the young showed that they had recently been fed. Possibly, therefore, a predator had scared the parent birds. Nevertheless, the fledglings, now large enough to be left alone, were already depositing droppings on the edge of the nest. On the 28th the parents had resumed their earlier routine which they maintained until the young flew. This pair had a consistent rhythm. The cock fed the young first while the hen waited on the nest tree or on one nearby. When he had fed the chicks he always perched beside the hen. She then fed the brood while the cock waited until she had finished. Both then flew off together. Only once, at 16.43 on 29 April, did the hen actually join the cock at the nest. So successful were the parents' seeding expeditions that the fledglings grew daily larger. At two nests in Sweden, only the hen fed the chicks for the first 7-8 days when they were still blind. 'If only the male had been away he would first feed her and then she the young, if both had been away she would first feed the young, then he would feed her and, as soon as he had finished, she would regurgitate the food just swallowed and give it to the young. These birds fed their broods quite instinctively, the female turning her head to and fro from nestling to nestling. In spite of this, the distribution of food at the third nest often turned out to be quite unfair. Several times close observations showed the female certainly divided her beak movements fairly, left-right, left-right, but often she did not succeed in regurgitating food more than every other time. With only two young, as in his third nest, this could result in one getting nearly all the food.' Sometimes the hen made many beak movements, without passing over any food. At two nests the cock did not start to feed the chicks until their eyes had opened on the 9th day; one of these cocks later became the principal food distributor, 'I

Young Crossbills 109

never saw the female give food to the young, even when she had followed her mate to the nest. From the 16th day onwards, he was responsible for every meal.' At the second nest, both parents were still feeding the fledglings on their 18th day and both were seen at the nest on the 25th. At a third nest the cock was last seen when the young crossbills were 16 days old and thereafter the female alone reared the brood (Olsson 1964). At Kandalashka, the Russian observers found that when the chicks hatched in March-April, winter months there, the hen seldom left the nest during the first 10-12 days of the chick's life, the cock providing the food which she distributed to the chicks. He now worked harder and fed his mate more frequently than when she was sitting on the eggs. On the other hand, routines and feeding rhythms at late spring nests were entirely different. On 31 May and 1 June a team continuously watched a nest containing 5 to 6 days old chicks throughout the 48 hours. On the 31st the hen was away from the nest for 6 hours 24 minutes and brooded her young for 61 hours, the brooding sessions lasting from six to 78 minutes. On 1 June her absences totalled just under six hours and her brooding spells of 5f hours varied from 50 to 109 minutes. On both days this hen brooded continuously from late afternoon or early evening until early in the morning. Whenever the cock visited the brooding hen she left the nest and allowed him to feed the chicks. The two birds then flew away to forage. When both returned together, as often happened, the hen fed and then covered the brood and the cock flew away. Before returning to the nest he had probably passed to her all the seeds that he had collected. In the last two to three movements of the day, however, both parents fed the brood. On these two days the feeding rhythms were not consistent. The parents had not apparently perfected their team work. On the first day they gave the young 14, and on the second day 22 meals. The Kandalashka observers also noted that on 13 April, at a nest with a well-grown brood, the first meal was given 2! hours after sunrise and the last three hours before sunset. This pair fed their young at intervals of 43 to 83 minutes (average 65 minutes). In Apri11966, after feeding her chicks, a hen pine crossbill ate some snow which was lying on the spruce and then went to the nest to give her fledglings a drink. I have never seen Scottish pine crossbills do this, although I have often watched them feeding broods with snow heavy on branches around the nest. In the Murman region, 12-14 days old fledglings ignored the calls of strangers, but could distinguish those of their parents at a distance of 30 to SO metres. NEST SANITATION

After the chicks have hatched, and the hen is still brooding by day and throughout the night, she defecates while off the nest, and also occasionally over its side. She also regularly eats the chicks' droppings until they are

110 Pine Crossbills

in their third week. As the nestlings grow older, she stands on the rim of the nest to prod their rumps until they eject their capsules which she then consumes or removes. Cock Scottish pine crossbills eat the faeces less frequently. Older chicks deposit faecal capsules on the nest rim, from which cock and hen at first remove them. After about a fortnight, however, regular nest hygiene is abandoned, the nest then becoming an almost solid mass of white faecal deposits, always an indication that the fledglings are maturing. Our Scottish pine crossbills, however, are highly individual birds. On 17 May 1946, for example, I watched a cock prodding a wellgrown youngster and then flying off with a white faecal sac which he promptly dropped from the pine top on which he settled. Three days later I saw a hen eat a capsule at another nest containing almost fledged young, and a third hen flew off with a capsule, and dropped it about 30 yards away. Dead chicks are sometimes left in the nest. In Sweden nest sanitation and the feeding of the young were linked. At a nest at which only the hen fed the brood, she ate all the droppings. As long as a hen is responsible for feeding the fledglings she alone keeps the nest clean. 'As soon as the male began to feed the young, however, he also ate droppings. When both had fed the nestlings, real disputes could raise between them over a dropping.' In these nests in Sweden the young began to deposit droppings on the edge of the nest from the 11th day onwards but, 'around the 15th day the parents' interest in the droppings began to weaken. Eventually one side of the nest, the twigs, and even the ground below, were sprinkled white.' On the Kola Peninsula, hens ate the excrement of the young for 10-12 days. At first these capsules, largely consisting of hard and undigested seeds, probably supplemented the food which the cock was providing. For the first few days cocks, which seldom saw the chicks while the hen was brooding them, had few opportunities of consuming their faecal sacs. Later they began to share in nest hygiene, although less regularly than their hens. A few cocks, however, started eating droppings earlier than others. At the nest with 4-6 days old young, watched continuously for 48 hours, the hen ate 23 and the cock six faecal sacs. On both mornings, after

Young Crossbills 111 the first meals, the parents ate the droppings. These observations show that parrot crossbills in Fenno-Scandia and our Scottish crossbills have the same remarkable individuality, Russia each parr evolving its own routine. However, nest hygiene is unlikely to be the only factor involved in the eating of the faeces. These droppings probably contain elements that the parents need. FLEDGING

. Just before the young leave the nest, the parents sometimes appear to mduce them to fly by reducing their meals, thus possibly starving them into leaving. However, there is no inflexiblepattern. I have seen pairs feed well-grown broods twice in quick succession. After the young crossbills are capable of flight they often stay in the nest for several more days, fluttering into the foliage, clambering along surrounding branches, even making short flights, and then returning. At 17.40 on 4 April 1942 I watched a cock and hen feed the three youngsters, which then quit the nest and fluttered through the canopy, using their strong beaks to creep through the branches. When doing this, they were nervous, often raising and stretching their necks in fear. And how awkward and clumsy they lookedI One youngster stood on a nest-mate's back. Later, when their parents arrived to feed them, the hen went in first and the cock followed. At 17.57 the cock again fed one of the fledglings, all three of which were now squatting on a branch outside the nest where they quivered their wings in solicitation. Three times I watched one youngster leave and then return to the nest. However, behaviour of this kind is more likely in broods reared in trees large and branchy enough to allow the youngsters plenty of room to move. At other nests I have watched parents calling softly on nearby trees, apparently avoiding feeding the young to induce them to fly. The parent crossbills sometimes imitate the twanging chittoo hunger cries of the young and give the sharp chit-chit flocking calls which possibly induce the fledglings to join theine Sometimes the young crossbills leave and flyaway from the nest, but continue to return and use it as a night dormitory. At nests to which noisy, fledged young have returned, the cock is often sometimes tooping loudly and continuously for 10 to 20 minutes and flicking his wings and tail in anger and agitation. On 30 May 1942, for example, two young flew over 100 yards from a nest in Forest, but the third stayed put. The hen was absent, but the cock s angry calls compensated for her absence. Previously he had tooped for almost 15 minutes before flying over to feed his three fledglings, one after the other. Calling loudly and insistently, cock and hen carefully guard broods which have finally abandoned the nest and are still flying rather weakly and clumsily. On 25 June 1938 I watched a pair escorting three fledglings which had recently left the nest and were about 50 yards from the nestinz

112 P'ine Crossbills tree. With excited calls and violent wing waving, one youngster suddenly hustled its mother out of the tree, catching her with its beak, thus upsetting her balance and almost forcing her to the ground. At other times I have seen hens jostle fledglings which appeared to be in danger. For instance, on 31 March 1936 one bumped a weak-flying youngster from the end of the branch, compelling it to flutter uncertainly in an inverted arc from tree to tree. Almost crashing onto a branch it beat its wings wildly to keep its balance. Just occasionally a fledged chick falls to the ground and is abandoned by its parents, and eventually dies because it is unable to rise and flyaway with its brood-mates. Hens sometimes also fly at their youngsters to induce them to move from one tree to another or from clump to clump. Spj,stvill met with similar behaviour in Norway. On 1 and 2 May 1962, when about 19 to 20 days old, young pine crossbills several times flew onto branches around the nest, the hen feeding on one of them about a yard away. Between meals, and while waiting for their parents to bring them food, the youngsters often stood on the edge of the nest where they flapped their wings and practised flying. Now almost full-grown they also sometimes stood up on the flattened nest and occasionally slept soundly with their heads under their wings, as Spj,stvill found both the fledglings asleep when he climbed to their nest in the dusk. The parents were then absent and nowhere to be seen or heard. At 16.30 on 3 May, the nest was empty, but the hen fed one fledgling on a pine 150 yards away. The other youngster was missing. FLEDGING PERIODS

Fledging periods vary considerably, but young crossbills stay longer in the nest than those of any other finch breeding in Britain. I have measured the periods spent by six broods in the nest; these were 17-18, 18-20, 22-24, and 23-25 days. The richness of the seed crop may partly determine ?ifferences, but is unlikely to be the only factor. Some young crossbills have fully developed primaries and are quite capable of flying before they leave the nest. Olsson recorded three fledging periods in Ostergotland, one of 19 and two of 25 days, and in Nord Trondelag the young left on their 21st or 22nd day. Kokhanov and Gaev found that fledglings in the Kandalashka nests finally quit them 22 to 23 (occasionally up to 25) days after the first chick had hatched. However, one youngster flew away from the nest on the 19th day but it had been disturbed. WEIGHT OF CHICKS

Young common crossbills also usually spend from 20 to 25 days in the nest, but in 1967-68 winter broods in the sitka forests of Dumfries took

Young Crossbills 113 longer. Smith and 0 stroznic (pers. comm.) tell me that the average fledging period of a young crossbill was 27-28 days in the nest. One apparently healthy brood, however, only started to fly when they were 35 days old. Olsson, who weighed the young daily, estimated that a large chick probably received about 2 gm of partly-digested pine seed (possibly about 3500 seeds) per day. At one nest a young bird weighed 39 gm on its 20th and 22nd day, but its weight had dropped to 38 gm on the 24th, the day before it flew, suggesting that the parents may have been reducing its food to induce it to fly. On the other hand, at Kandalashka, six young pine crossbills weighed 37 to 50 gm on their first and second days out of the nest, and common and two-barred crossbills fledglings 30 to 35 gm (4) and 25 to 28 gm (2) respectively at this age. BREEDING SUCCESS

I have insufficient records to compare breeding success of the Scottish pine crossbills in different years, but 41 observed nests produced 152 eggs (av. 3.7) from which 115 chicks (75.60/0) hatched and 71 (46.60/0) left the nest. This analysis, however, does not include nests which failed through human predation or interference. The data from Kola Peninsula are not directly comparable, as I do not know what proportion of the nests or broods that failed were due to human as opposed to natural predators. The winter breeding groups of curoirostra in Dumfries were even less successful. Only about 38% of the eggs laid produced flying young. In 1967-68 a sample in southern Finland also bred poorly. Over half the nests observed failed, some through severe weather but mostly by jays and other nest predators. Human disturbance was responsible for five desertions during the nest building and early brooding phases (J. Excell, et ala 1974). The young are probably better adapted to survive severe cold than continuous rain. In 1941 the last chicks to hatch died in two nests and at two others the entire broods vanished without trace. In 1940 two broods of well-grown young, and in 1947 yet another, disappeared. There was no question of extreme cold. All these broods were hatched in April or later. Early broods regularly face exceptionally severe conditions. How then do the young crossbills survive the extreme bitterness of arctic or subarctic winters or early springs? When first hatched the chicks are covered with light grey down which is up to 10-12 mm long on their backs and on the backs of their necks. In the course of research, Kokhanovand Gaev discovered the existence of a remarkable adaptation. The feathers on a young crossbill's head, nape and the upper parts of its body, are the first to grow. By the eleventh or twelfth day these exposed parts are thus fully feathered and protected, enabling the hen to leave them periodically and to go foraging with her mate. In pine grosbeaks and redpoll, on the other

114 Pine Crossbills hand, which normally nest in summer, the feathering grows simultaneouslyon all parts of the chick's body or first on its underparts. This explains much about a young crossbill's resistance to extreme cold. POST-FLEDGING PATTERNS AND BEHAVIOUR

Young pine crossbills leave their nests about 10 days before their beaks have crossed. Their parents, and sometimes other adults, then continue to feed them for several weeks after they are on the wing. The young thus depend on the ability of the parent birds to find and extract sufficient cone seed to feed them. Here are the details. For the first 10-14 days after the young have flown, parents and brood stay together as a family unit, sometimes in or quite close to the nest territory. In this phase cock and hen often leave the fledglings well concealed in the crown of a pine or perched on small twigs or branches high up and close to the trunk, where they are usually quite inconspicuous. Meanwhile, the parents tackle cones on trees about 50 to 400 yards, or sometimes more, away from them. The young are usually noticeably quiet, only uttering their twanging hunger cries when the parents quietly arrive to feed them at about half-hourly intervals or, in poorer seed years, perhaps a. dozen times daily. At the end of this period the family group often disperses, wandering from wood to wood and sometimes settling in clumps of trees up to a mile from the former nest. Often cock and hen now separate from one another, each attending to and flying with one or two of the noisily importuning fledglings. The two parts of the family group, which are soon independent of one another, then frequently team up with other family parties or parts of families, possibly with failed nesting birds, and with members of rump or surplus parties. You thus sometimes meet with groups of cocks with the juveniles from several broods. Parties of hens with juveniles, but without any accompanying cocks, are unusual. On 26 April 1971, for example, a fine red cock in Sutherland, which was one of a group of about a dozen, periodically fed two fledglings which were sitting silently near the top of a larch. Before and during their meals the youngsters vigorously flicked their wings and occasionally dropped down to a small puddle in the peaty ground under the tree. The cock group fed in a clump about 100 yards away. In this period of roaming and wandering, which Kokhanov and Gaev suggest lasts about 33 days, the beaks of the juveniles strengthen and develop, the ends of the lower beak growing and crossing over. But although they now commence to find and take their own food they are not yet fully independent and are frequently fed by their parents, and occasionally by other adults in the flocks. In years of high numbers, small groups unite and become integrated with larger parties while continuing their wanderings. However, you can always distinguish the presence of young birds in the flock by their unmusical hunger and importuning cries

Young Crossbills 115 and by their persistent begging and wing waving whenever the crossbills settle. Gradually, however, the young crossbill tackles and exploits cones on its own, but it still has much to learn from the experience of its adult companions.

CHAPTER 12

VOICE The calls and songs of Scottish pine crossbills are always heard at their best in large spring flocks. At this time, something is always happening. Scarlet cocks now sing from wind-blown pine sprays, or even with cones held firmly in their claws. Singing still more softly, others bend down to seed cones without troubling to remove them. Now and then a cock suddely sings a loud song that rises almost to a screech as it flies off the tree, with mantle fluffed, tail spread and beating wings, to supplant a rival or perhaps to chase a hen. In these grand assemblies the deep brick-red breasts of the older cocks, and the orange and mixed red and green of others, contrast sharply with the dowdier almost greenfinch-like hens, but both sexes sing many sub-songs which are always a delight to hear. A large assembly produces quite a chorus of sweet notes mixed with others more harsh and strident, and smaller groups a lesser volume of the same sounds. Winifred Ross heard the Strathspey crossbills singing well in November, January, July and September, as well as in the months of spring. 'The call of the flock becomes more melodious towards the end of the year until the real community singing which is one of the great events

116

Voice 117 of the season. December, January and February are the months it may be heard. The perfect conditions are a sunny, windless, slightly frosty day, when 40 to 50 birds of both sexes gather in a tree and the air is full of melody. There is a constant ripple, as of muted violins, to accompany the outbursts of song from individual cocks, several of whom may be singing at once, as they circle in the air, or land on the tip of a branch. Each individual may sing seven to 10 minutes, and the song has 2-4 bars of full round mellow notes. Each bar is different in time and accent.... A bird heard the same day in the community-singing called one sweet single note several times, followed by a 4-note bar of soft full notes, then the single note recurred; the whole song lasted four minutes. It is impossible to detail the variety of this exquisite performance. When the pairs have broken offfrom the community, the cock continues to sing but the music is broken into by call-notes, feeding-notes and warnings--all inclined to be harsh.' In the spring groups the cocks progressively sing more strongly and also produce several different songs. 1. The rather jerky and unmelodious 'greenfinch song', chip-chip-ch'P.gee gee-gee chip-chip-chip, probably the most significant, is rendered in

various emotional situations and in different patterns. While establishing or proclaiming a territory, with or without a hen, a cock often sings this song from a tree top-if alone, he may sing many consecutive songs from one or more trees. On 17March 1938,for example, a cock in scarlet feather sang 10 complete songs in each minute. He had probably failed to win a mate in the flock, and was trying to attract one. On the other hand, on 28 March 1936, a cock sang 14, 11 and 12complete songs in three consecutive minutes while his mate was feeding a few feet below him. This pair had not settled on a territory and indeed did not nest here or apparently in any nearby wood. The same day four cocks were singing intermittently on one tree. Two flew away, but their companions stayed and went on singing for the next fifteen minutes. All these four apparently vigorous cocks were still mateless and on the move. In other years unmated cocks, still members of a gypsy group, have isolated themselves and sung loudly. On 9 April 1941 seven sang, defended particular treetops, and periodically embarked on song flights. The song or rhythmic chip-chip of one cock provoked the others to sing, although there were no hens in the group. Three days later I again met with this small and irritable party in the same wood. The cocks were still fighting, singing, temporarily isolating themselves, and then regrouping. Once five were simultaneously singing in challenge within a distance of 100 yards. Cock pine crossbills sing loud songs in other contexts. When attempting to entice an already paired hen, a mateless, but sexually excited, cock sometimes bursts into song before spreading his tail, ruffting his mantle,

118 Pine Crossbills and flapping his wings like a starling. On 21 March 1938, for example, I watched a magnificent crimson unmated cock bird sing loudly and flap his wings before fluttering on slow deep wingbeats to pitch almost beside a mated hen. The paired male, however, promptly drove him off. On the 17th another cock had behaved in almost the same way, ending up on a branch and hopping after another cock's mate. But he was also quickly ejected. In my experience, this combination of singing and wing flapping is rather uncommon behaviour, but David Tuckwell saw it in his aviary. About mid-January, the cock, a common crossbill of foreign stock which he mated to a Strathspey hen, began to sing and by late February he was beating his wings and singing to her. Scottish pine crossbills sing less on trees close to their nests and brooding hens than common crossbills do in East Anglia, where Edgar Chance often recorded several cocks, singing simultaneously, almost beside nests in roadside territories. I had expected to find the same behaviour in Speyside forests, but quickly discovered that this seldom happened. However, in March 1942, I came upon a rather eccentric cock which, habitually, not only tackled cones on the nesting tree but, sometimes before feeding his brooding mate, sang there continuously for up to five minutes. However, our pine crossbill cocks seldom sing long or loudly near their nests, unless they are about to challenge rivals, when a brief snatch of greenfinch song suddenly gains volume and stridency as the singer embarks on an aggressive 'moth flight'. Olavi Hilden has also told me that pine crossbills in Finland sing much less freely than common crossbills during the brooding period. 'In 1967, when many pairs of pine crossbills were breeding close to my home, I seldom heard any song, except a very quiet almost silent sub-song, near the nest. Common crossbills, on the contrary, sing frequently and loudly before and during the breeding period.' Sometimes a cock uses a short greenfinch song to call the hen off a nest when she is sitting on one or two eggs. I often watched this in an old pinewood near Loch Garten. I have also seen a cock performing a 'butterfly' song-flight near a nest where the hen had started to sit steadily on the first of four eggs, and in Apri11942 I recorded another fly in figuresof-eight while he sang intermittent snatches of song above the pines. Cocks sing loudest in situations of challenge. For example, on 8 March 1936, one which was singing quietly suddenly erupted into a loud song when a gypsy party of cocks approached, but after they had flown away he again sang softly. While 'sailing' at a rival the cock sings a much harsher song which rises almost to a screech as they grapple. However, the

greenfinch song is partly a dispersion weapon, and one often used after the hen has lost a nest and the cock is establishing or re-establishing his territory and showing readiness to defend his mate against rivals. Flying over the territory of another pair, a cock may also sing a quick burst of

Voice 119 'greenfinch song' then momentarily changing the tempo of his wing beats. Down below the tenant singslik.ewise to challenge him. 2. From high up in a tree, cocks often give a rhythmic series of chips, a form of song which has many different and possibly improvised pattems such as chip-chip-whee-sip sip-chak-chak. Another cock may use soft tuptup-tups as a song.

3. There are several different forms of soft and melodious subsongs-tip-tip-tip-toohee-toonee-tip-tip-too-nee-quik-tjuik or sip-sip-sipwhee-whee-hoo-hoo-hoo-hoo-ha. Less complete renderings include a barely audible tip-tip-hoo-hee-too-hee. To me, the least complicated form of this sub-song is always nostalgic. It reminds me of a cock woodlark singing quietly on a stump or tree top close to a nest on some heath in Surrey or Breckland. Warbling or bell-like phrases also often mingle with subdued toop« and chips or, as a climax, a cock may chack softly and then abruptly utter loud aggressive toops. Cocks frequently sing these songs while guarding hens which are perched lower down or drinking at puddles in the peat. Hens also sing these and other murmured sub-songs, sometimes with rambling warbler-phrases. Both sexes often sing softly with their beaks closed. On 2S March 1936 a most unusual hen, which had temporarily reversed rOles with the cock, first sang softly while the cock was building and then sang a loud 'greenfinch' song from a tree top. Meanwhile, the cock gave muted 'greenfinch' songs. 4. Groups of cocks which have not reached full breeding rhythm sing quick siJuee-gees-siJuee-gees and have other short songs, like kak-kak-eeseeese, which they often utter from within trees but seldom from their tops. S. Zip-sip-crahoo-sip-crahoo-eese, with the final eese rising in pitch. I have heard a cock sing both the long and the shortened forms of this song close to his brooding hen. Other cocks give these songs while members of unmated groups.

6. In 'butterfly' or 'moth' flights, while attacking other cocks, or chasing or attempting to rape hens, cock pine crossbills often use a form of harsh strident song which rises to a screech. 7. The distinctive building and food soliciting chitterings of hens at the nest, occasionally run into rare but melodious 'nest songs'. There are many differences in the songs of individual cock Scottish pine crossbills, but the sonagrams suggest that these are more varied than those of the common crossbill 80 far recorded on tape; onlyone unit type( 3and 3a)

120 P,'-ne Crossbills is alike (Joan Hall-Craggs,pers. comm.). However, there is still much to be learnt. Cock Scottish pine crossbills sing all their songs in scarlet, redbrown, orange and green plumage. On 24 February 1968 a partly-moulted juvenile male curoirostra was also apparently singing his full song in the Forest of Ae. E. Simms, who taped and analysed the songs of common and Scottish pine crossbill, suggests that there are 'Four stages from the threshold of song to full song. The first stage is a series of chipping calls,jip-jip-jip, run together in a slow emphatic trill or from five to 10 J·ips, with each trill lasting about one second. There may be as many as 20 trills to the minute. At the second stage a ter-chee note is added to the jip-jip series and this indicates that the bird is at a song post. In stage three the song advances to double notes--jeeaa with some four to 10 of them at the same rate as in the first two stages. The fourth and final stage is the full song.... which includes the ter-chee phrases of stage two and this is followed by a warbled song like that of a redstart and some chipping notes.' A. W. Robertson (1954), who made such a full study of common crossbills in Breckland, only twice heard this full song, which he described very beautifully. On each occasion the cocks had beeen emotionally upset, one having lost his hen, the other his nest and young. 'In these songs the jip note was infrequent but the tree-yo teekadoo and terchee phrases cropped up regularly, as did another note remarkably like ee-cher of the great tit. Like beads these phrases were strung along a necklace of warbling which in power and clarity were the equal of a canary.' Simms also made a tape recording of the song of a cock Scottish pine crossbill. This, he said, 'included a number of phrases such as tip-tip-tip, tsee-tsee-tsee as well as a warbled tseeker-tseeker (Sonagrams 1-6). Robertson heard both sexes of common crossbill singing 'a subdued inward-warbling which once sounded like the song of distant linnets.' The sub-songs of the Scottish cocks which Simms recorded are rendered as 'creaking notes crrook-crook, yek-yek, ip-ip,yureek-yureek, and grrr-grrr and so on run together in an inconsequential way.' CALLS

1. The usual flight and social contact call of pine, Scottish pine, and common crossbill, is a loud penetrating metallic chip which is often fairly continuously repeated in flight. Crossbills use this call at different intensities in many situations. Common crossbills use loud continuous chips in sequence, in alarm or anger at the nest, and in other explosive situations. The chip is then faster, louder and more urgent than when the bird is in flight or calling, less agitatedly, from a perch. Both sexes use this call, but Scottish pine crossbills make less use of the call when they are angry or alarmed. However, a cock sometimes chips sharply and repeatedly to call his hen off an incomplete clutch. A cock or hen, also, frequently gives a

Voice 121 single chip or a series of chips immediately before leading its partner or flock companion from the trees on which they are feeding, to another part of the wood. On the other hand, before the pair or group is about to fly to a nearby tree, the leader often uses a quickening series of more conversational and less decisive toiks, A brooding hen may give a single or series of loud sharp chi;ps to call up a mate which has been slow to feed her. The Scottish pine crossbill's chip tends to be louder and fuller than that of the common crossbill, but strength and sharpness partly depend on the situation evoking it. However, the Scottish pine crossbill's chip is usually recognisable when both birds are calling simultaneously. After making recordings of both common and Scottish pine crossbills, Simms also recognised the difference in their flight calls, the common crossbill's 'ringing jip-jip being replaced in the Scottish bird by a deeper, coarser, more rounded tyoop-tyoop' (Sonagrams 7-7a). In Sweden, Olsson failed to detect any basic differences in the social contact notes of the two crossbills. But Hilden (pers. comm.) found that in Finland the flight calls could be identified: 'the pine crossbill has a deeper more metallic kip-kip-kip or kyp-kyp-kyp (written and pronounced in Finnish) whereas the common crossbill calls with a softer plit-plit-plit, with a distinct 1 sound.

2. The deep toop is the most important of the Scottish pine crossbill's calls and is possibly one of the signals which assists our resident birds to keep separate from common crossbill invaders. Cocks toop in alarm or anger, or excitement before flying to the nest to feed brooding hens; sometimes in flight, and in a wide spectrum of emotional situations in flock or group. The hen's rendering of this call is a more metallic but explosive soop which is separable from that of the cock. When three or more birds are challenging one another, or when two pairs are at odds in a group or on a territory, they produce a chorus of angry chattering taktaks. The deep toop sometimes occurs in a flying group and probably indicates excitement rather than a social contact signal. Chip is the main social contact call of Scottish pine and common crossbills. The excited tooping of a cock, before he alights close to the nest, indicates inner tension. The calls, often accompanied by agitated tail and wing flicking, are rendered with the beak closed. Sonagram lOashows the tek-tek alarm cries of a pair of curoirostra at a nest with young. In Norway, Haftom considered that, without sound spectrograms, he was unable to distinguish between the calls of the two crossbills, Other ornithologists in Fenno-Scandia and USSR have commented on the deep distinctive excitement calls of the pine crossbills. Professor Pontus Palmgren (pers. comm.) describes the call of pytyopsittacus as 'lower

122 Pine Crossbills pitched and more muffled than the call of curoirostra:' In Norway, Wilgohs and Hagen also record a deeper kop-kop as did Wheelwright in Sweden and Naumann in Germany in the 19th century. In Sweden, moreover, Olsson, who found no distinction between the social contact calls of the two species, describes 'a hard tsu-tsu, a stuttering alarm call (the u sound as in duck) apparently only used in danger situations as, for instance, when a jay was approaching the nest. Hilden also remarked on a common call of the pine crossbill, 'which is probably lacking in the common crossbill, a loud rapid redpoll-like dsy-dsy-dsy-dsy in long series; it is obviously connected with threatening in territorial disputes.' This call is possibly the equivalent of a Scottish pine crossbill's toop. In the Kola Peninsula, Kokhanov, who has had unique opportunities for studying pine, common and two-barred crossbills in the same habitats, tells me that pytyopsittacus and curoirostra markedly differ from each other, not only by appearance but also by calls. Pine crossbills have 'much lower, louder and harsher calls than common crossbills, This difference is particularly noticeable when both species are flying in mixed flocks.' Other British ornithologists besides Simms have remarked upon these vocal distinctions. The late Arthur Whitaker, who had much experience of crossbill-watching in Breckland, agreed that the deep toop was missing from the common crossbill's vocabulary. Another experienced ornithologist, I. C. T. Nisbet, reached the same conclusion. On 21 May 1961, he remarked that the call of a cock which he had watched in Wester Ross gave 'a low pitched choop choop choop or klomp klomp klomp' which was quite different from any notes that he had heard from the continental crossbills which he had recently watched in Suffolk. This call, however, was the same as that given by Speyside birds, and both the Speyside and the Wester Ross crossbills occasionally gave 'a higher pitched yip yip in addition.' Roy Dennis, who has studied common crossbills in England and on passage and in winter in Spey Valley, likewise considers that the deep toop of the Scottish pine crossbill is similar to that used by the pine crossbills which he trapped on Fair Isle. Cocks and hens have other anger and excitement calls. On 17 March 1941, for example, while fighting with a rival which was trying to entice his hen, a cock used a harsh angry .ip which was quite different from the usual toop. Besides giving their angry .oops, hen sometimes appear to change into a lower gear, then uttering loud deep and measured choks-choks which are not unlike the rattle of a blackbird. 3. While feeding or moving through the canopy or foliage, Scottish pine crossbills maintain contact with mates or group by an almost continuous subdued twittering wik-wik. These lower-pitched social calls differ a little from those of common crossbills, whose twittering peep-peeps sound

Voice 123 softer and higher pitched. These calls, however, serve the same functions in both birds. 4. While building, forming the nest cup, or arranging the lining, a hen often twitters almost continuously. On 5 March 1936, for example, a hen which was lining and rounding off her nest cup, produced a continuous twittered sip-sip-sip for seven to eight minutes. I also heard a hen calling softly just before she laid an egg; this may differ from the calls used in building. As excitement mounts, a building hen often interpolates a whistling whee into the chittering-sip-sip-whee-sip-sip-rDhee·sip-sip. 5. Nest solicitation. Flicking her wings above her back, opening her beak and sharply raising head and neck, a brooding hen usually starts chittering immediately she hears her mate flying towards her. She then continues this extraordinary shrill mouse-like squeaking and wing quivering during her meal and for one or two minutes after the cock has tl.ownaway. On still days you may hear this excited cbee-chee-chee or sip-s,p-sip when perhaps the nest is 50 or 60 feet up, and you yourself are at a distance of 30 or more yards from the foot of the tree (Sonagrams 8 and 9). H. Christiansen (1957) noticed, however, that the pair of common crossbills that he was studying were silent when the cock was feeding his sitting hen. 6. Courtship feeding. Cocks and hens are often silent during courtship feeding or they call so quietly that you hear nothing, although you sometimes see their beaks moving. I have watched this at a distance of 10-20 feet without being able to detect any calls. Occasionally, however, the hen gives a quiet and insistent chittering. R. A. Hinde (1955) described the courtship feeding calls of a hen common crossbill in his aviary as a low lilillillil (Sonagram 8a). 7. Copulation calls. Scottish pine crossbills often copulate without using any calls. Sometimes, however, both cock and hen twitter metallically before the cock mounts. Immediately before they meet, the hen sometimes interpolates soft whee-whee cries into the twittering. 8. Pivoting. During pivoting a cock common crossbill uttered a disyllabic call reminiscent of that of a goldfinch (Hinde). Ross also mentions hearing a cock giving a 'low moaning crooning sound as he sways to and fro,' but remarks that this was only audible at a range of two to three feet. I have not heard these calls. 9. Calls at the nest. Before feeding their hens, cocks occasionally toOl' or chock conversationally, using these calls without the depth and

124 Pine Crossbills vehemence evoked by more extreme emotional situations. If the cock is slow to feed her the hen sometimes utters a single deep chik or chuk, or gives these calls in a slow and deliberate sequence. A cock often gives a few dull wooden and unresonant chucks-chucks just before gulping up the seeds. These are slower, altogether different cries from the more familiar chip-chip or toop. On 16 and 22 June 1952 the cock twice imitated the chitoo of fledged young just before he fed his hen on the nest. However, this cock had a second mate which then had well-grown young in her nest. Less frequent calls are the nasal chows-chows or teoto-teotos given by hens disturbed at nests containing young. One also uttered a single explosive chick. I believe that these are cries of intermediate or less urgent excitement. 10. Ross described a hen giving a 'peeping plaintive cry when a squirrel was eating her eggs, a pathetic sound in its hopelessness; and a cock's high warning scream to the hen when the squirrel was in the tree'. I do not know whether these are distinct cries or variants. 11. When I lifted a hen off her eggs, and she had settled on my fingers, one hen gave almost inaudible ooks-ooks which I have never heard in any other situation. 12. Calls of parents and young. When they are 12-14 days old, fledgling pine crossbills recognise their parents' voices and start to call to them at a distance of 30-50 metres. They ignore the calls of strangers (Kokhanov). When about to feed fledglings just before they quit the nest, a parent Scottish pine crossbill sometimes imitates perfectly the insistent chitoo of fledged young and also uses the chit-chit-chit flocking notes. I took particular trouble to satisfy myself that the parent birds and not the fledglings were actually giving these calls. At the time that I heard the two parents calling in this way, large groups and family parties were on the wing nearby. Small chicks squeak shrilly, but older young give a trilling itic-iticwhile quivering their wings and begging to be fed. Just before they fly the young crossbills start to use the monotonous chit chit chittoos which are such familiar sounds in family parties and in flocks. Olsson heard young pine crossbills first use the typical social contact chip-chip when they were 16 days old. A little earlier he had heard the trilling cries. Young pine crossbills out of the nest give 'a begging chiterchiter-chiter-chit-chit-chit-chiter.' These are probably the same cries as those that young Scottish pine crossbills use when they are on the wing. Palmgren (pers. comm.) tells me, however, that the fledged young of pine crossbills have a call that is strikingly different from that of a young curoirostra. Tape recordings might be helpful here.

Voice 125 13. Flock calls. You often hear different excitement and social contact calls in post-breeding groups. The social contact chip, and sometimes the angry toop mingle with the monotonous chit-chit flock cries of parents with young and the rasping importuning cries of the flying fledglings. The young also occasionally use a twanging teumg-teumg which I have heard given by adults in groups without any fledglings. Scottish pine crossbills thus have a great variety of vocal signals. Social contact, aggression, courtship feeding, sex, nest-making, food solicitation, brooding, feeding, fledging and flocking, all having special cries which other crossbills recognise. Pairs and close companions are able to recognise one another's calls. A brooding hen picks up the cries of her own mate and usually responds to them long before she can possibly see him. Within a fortnight young pine crossbills likewise react to the voices of their parents and ignore those of others. When separated, homosexual pairs and small groups of cocks sometimes sing or call, responding only to the voices of close companions. Sonagrams 1-6, which follow overleaf, compare the songs of Scottish pine and common crossbills. The differences between the songs of the two species are obvious in the sonagrams. Sonagrams 7-12 compare the calls of the Scottish pine and common crossbills, and are captioned by Joan HallCraggs.

126 Pine Crossbills

SCOTTISH PINE CROSSBILL-SONG

Voice

COMMON CROSSBILL-SONG

127

128 Pine Crossbills

SCOTTISH PINE CROSSBILL-80NG

7. 0 Chipping Frequency range: most energy between 2· 5 & 4· 0 kHz thus higher than common crossbill. Duration ofsingle call ca. ·04 so a little shorter than common crossbill. Structure: ascent and descent X 2. The ascending parts of the call are brief like those of the common crossbill, but the descending sections have more concentrated energy, especially the first descent which is also oflonger duration than any similar part of the common crossbill call. This probably accounts for its 'fuller' sound. SCOTTISH PI NE CROSSBILL-CALLS

Voice

129

COMMON CROSSBILL-SONG

7a. Chipping Frequency (pitch) range: most energy between 1· 5 & 3·0 kHz. Duration ofsingle call ca. ·05 sec. Structure: very rapid ascent and descent X 3 resembling an irregular frequency modulation; this 'spreading out' of the total energy of the sound might account for its 'thinner' quality than the comparable call of the Scottish pine crossbill. COMMON CROSSBILL-CALLS

130

Pine Crossbills

8 & 9. calling and chittering on nest. Frequency range: most energy between 3·0 & 4·0 kHz. Duration ofsingle call ca. ·04 sec. Structure: Ascending calls with most of the sound energy at the top. The 'chittering' calls rather resemble these, but the 'chitters' are less regularly spaced and are also of slightly different pitch and structure. But the recording of the 'chittering' is rather too quiet to get a properly detailed sonagram.

10. cJ + tooping at nest. Frequency range: most energy between 1·5 & 3·0 kHz so a little lower than common crossbill. Duration of single call ca. ·05 so slightly shorter than common crossbill (IIa).

Voice

131

8a. Courtship feeding Frequency range: most energy between 2· 0 & 3·0 kHz. Duration ofa single call ca ·02 sec. Structure: slight ascent and longer descent; it looks like a version of the 'conversational' call (l1a), condensed in both time and frequency.'

lOa. Alarm calls of J and at nest. Frequency range: 1·5-3 ·0 kHz like the Scottish 'tooping.' Duration: the shortest call is about ·03 sec and the longest about ·05 or a little more.

132 Pine Crossbills

11.

0

tooping

12. 5j2 tooping Much more concentrated in pitch than conversational tups of common crossbill (1Ia). Thus a rounder, rather more pitched sound, though still too brief for us to perceive the pitch easily. In spite of this being a very slightly shorter call than the conversational call, most of it falls at around the same frequency band so, again, this should help to make the sound fuller and more intelligible (J .H.-e.). In the field the toopor :lOOp of the Scottishcrossbill is distinguishable from that of the common crossbill (D.N.-T.).

Voice

133

l l a, Conversational tup calls. Frequency range: most energy between I· 5 and 3·5 kHz. Duration ofa single call ca. ·06 sec. Structure: brief ascent and long descent j the energy is diffuse and the sound rather 'click 'like.

CHAPTER 13

NEST DIARIES I have found great joy in watching our pine crossbills at the nest and slowly learning a little about their brooding behaviour, but until 1939 I had never watched a nest throughout the hours of daylight of anyone day. In that year I was studying a group in an old pinewood, close to Loch Garten. Almost every day I was with them. I watched them disperse and mate, build, lay and brood, then, on 1 April, on the 9th day after the hen had started to sit, I decided to watch a particular nest for a whole day. Maxwell Hamilton, now an elder statesman of the Scottish Ornithologists' Club, kindly agreed to join me. On a frosty morning I cycled eight miles from Dorback and arrived under the nest at 05.15. It was then dark, but at 05.29 I could just hear the crossbill call as she left the nest, to which she returned after three minutes. Three-quarters of an hour later, in a stroll to warm myself, I watched another hen building in a tree less than 100 yards from my nest. Quietly and almost furtively she moved from pine to pine, tugging and snipping at twigs from trees close to her nest. Her mate never appeared; he was still in his roosting tree. As dawn broke I was listening to a curlew 'bubbling' on a moss outside the wood, but there was still no movement at my crossbill's nest some 10

134

Nest Diaries 135 feet up in the trees above me. Then, at 06.33, I heard a crossbill flying in from the north and saw him pitch in the nesting tree where he tooped excitedly before feeding the already squeaking and chittering hen on the nest. He stayed for less than a minute and then flew off along the same line. Almost as he went, a curlew sang again and I saw Hamilton wheeling his bicycle along the path. While we were synchronising our watches, a crossbill flew overhead, but our hen ignored it. Between 06.20-06.40, blackcock fought, sneezed and rookooed in a clearing, and at 06.59 another crossbill passed over us without our seeing any movement on the nest. The tenant cock arrived at 07.14; we had not heard him until he started his tooping. This time the hen flew to meet him. But, to our surprise, he now went straight to the nest and appeared to settle on the eggs. His unexpected action instantly brought the hen back, the cock immediately quitting the nest and feeding her on it. Without more ado he left as before. At 07.45 we saw a cock curlew chivvying another,the pursuer dipping and rising and almost hitting the trespasser as it flew over the moss. The next movement was at precisely 8 o'clock when two cocks anived together and the hen squeaked shrilly on the nest. We now found that the bird which had settled nearest to the nest was a stranger which the home cock quickly ejected. Without delay the owner then fed the hen and flew off to his feeding ground. He and the other cock had possibly fed and flown in together. Twenty-five minutes later a cock sang as he passed over the nesttree, but the brooding hen stayed mute. At 9 o'clock, however, our bird visited and fed his hen. This time he was extremely quiet, uttering only a few quiet chips and the hen shrilled less persistently. Twenty-nine minutes later, when the cock arrived, the hen quit her eggs and flew down to a small puddle in the peat for her only drink of the day. This seemed to upset the cock, but after three minutes he escorted her back to the nest where he fed her. He then tooped harshly and ousted two pairs which were quietly 'coning' about 50 yards away. For a few minutes there was a great explosion of angry sound while our cock bird was challenging and expelling the trespassers. He then flew away. This time the cock was absent longer, arriving at 10.55 before responding to the hen's plaintive chittering. After he had passed her some seeds, he pitched on the top of another pine and then departed. At the next meal, 11.37, the hen chittered less persistently, her hunger possibly less urgent; and we could see no movements at the nest. At 12.18, chipping loudly, a group of seven crossbills went bounding overhead, but the hen did not appear to respond to them. However, at 12.50, she suddenly slipped off the nest and began crackling noisily at cones on a tree about 50 yards off.While she was doing this, the cock anived with two others, which he quickly saw off his territory, On her coning tree, the hen flicked her wings and begged to be fed, but at first the cock seemed to ignore her. In less than a minute, however, she had gone back to the nest to which her mate followed,

136 Pine Crossbills feeding her for It minutes while she squeaked and beat her wings. Every time that the hen left the nest the cock appeared to be upset. This time he flew to one tree top where he stayed for at least a minute and then flew to another where he seeded some cones before going away. A cock crossbill sang at 13.02, but this was unlikely to have been our bird as he did not visit the nest and the hen did not call. I recorded nothing more until 14.31, when the cock tooped explosively for fully five minutes before quietening down and then feeding his noisy soliciting mate. A dozen crossbills, probably all cocks, rocketed through the trees and landed close to the nest at 14.55. For a couple of minutes three of these cocks fought, scuffled, and challenged in a flurry of angry sound and excitement. Then the whole flock lilted through the trees and far away. We still waited. The hen slipped off the nest at 15.37 and just afterwards we heard the cock calling loudly. Both birds moved away, the hen to drink at a puddle, but within five minutes she was back on eggs, the cock staying for a minute on the nesting tree before rustling down to feed her. This was the cock's last visit to his mate and nest, but at 17.05 a cock, possibly the tenant, settled on a nearby pine, tooping loudly before flying off. However, he ignored the nest and we did not hear any calls from the hen. We stayed until 19.36 when woodcocks were roding in the dusk, but we saw no more of our crossbills. Between 05.15 and 19.30, on that eventful April day, this cock crossbill had fed his hen at the nest 10 times, at intervals of t to It hours, averaging 61 minutes between meals. The hen left the nest five times, after brooding sessions lasting 1t to hours, staying off from one to six minutes. Twice she fed herself and once drank in a peat puddle about 50 yards from the nesting tree. The peak of this energetic cock's activity was between 06.33-11.37 when he visited the hen seven times in just over five hours, with an average 44 minutes between meals. This was possibly an unusually rapid rate of feeding in a year of moderate cone crop. From this and other experiences I had now learnt a little about the feeding and brooding rhythms of pine crossbills, but from the ground it was not always easy to interpret what was happening at the nest. I often climbed the nest tree, sometimes sitting on one of its branches or on a tree overlooking the nest. This widened my knowledge but was not entirely satisfactory as the crossbills were always conscious of my intrusion. However, in the great pine crossbill year of 1952 I had a new experience. On 8 June I found a nest by watching the cock feed his hen at a nest in a small pine in an isolated clump which had escaped axe and fire after the war. It was beside this tree that John Fisher built the pylon hide--a canvas tent placed on a platform held up by long and grotesque stilts. Here, between 12-22 June, we spent 53 hours of continuous wonder and excitement. What marvellous little birds these crossbills were I The cock was a little

3t

Nest Diaries 137 beauty, with a deep blood-red breast showing a few straggling green feathers. His wings, shoulders, and stout forked tail were darker, almost black they looked in some lights, and the mandibles of his large powerful beak were crossed right over left. How tame and confiding he was as we watched him through the muslin 'peep hole' of the hide. You could see him breathe and watch his every movement. From the ground the hen seemed to be wearing a dull green uniform, and her movements in the nest looked stiff and clumsy, but how different she really was when you were sitting beside her. Good light showed up so many subtle tints quite invisible from the ground. Nape, breast and mantle were greyish green, but her green crown was tinged with yellow and her tail dark brown. When the gentle westering sun lit her green mantle, her great beak shone and glistened and her eye lit up like some rare and precious jewel. We came to know her well. At times she yawned, dozed or slept, closing her eyes and sometimes half lying on her side; or she fluffed out her neck feathers and raised her hackles. Sometimes she preened most carefully, gently running the feathers through her beak or perhaps plucking a small feather from a flank. Most beautiful of all, I watched her brooding with the raindrops from a summer shower shining like bubbles of pearl on her green mantle. These raindrops she usually shook off, but once I saw her turn her head and with her long red tongue lick them off one by one. I greatly enjoyed watching and hearing the signals between cock and hen. Take 12 June. For over an hour of this stuffy afternoon she intently watched a wood ant which had crawled up the tree, and then she closed her eyes and fell asleep, looking almost dead or stuffed. Then she woke and languidly prodded in the bottom of the nest before falling asleep again. I was almost as drowsy as she was. Suddenly, and without warning, the cock started to twitter softly close by. At first the hen did not answer, but when he started his deep toops she began chittering and uttering a few soft and unresonant chuck-chucks. After a few seconds her mouse-like squeaking kept time with his deeper cries, and she abruptly raised her head and neck and started to flick her wings. Soon the cock was beside her, curiously jerking his head aside and gulping up seeds which she took from his mandibles, half turning with stretched neck to do so. Then, after he had finished feeding her, he wiped his beak on a twig, preened carefully, and was gone. Our hen usually started to twitter immediately she heard the cock call in the distance and then, with head and neck raised, she continued her shrill cries for one or two minutes after he had flown away. However, at 12.59 on 22 June, she took the initiative, chipping persistently to attract him. Once she stopped, gave a single explosive chip, and then went on as before. Suddenly alert, she half turned and I now heard the cock's excited toop some distance away. For a few more seconds the hen chipped excitedly

138 Pine Crossbills before calling more softly as her mate approached. Then she was squeaking and chittering her mouse-like cries which ran into quite a sweet and distinctive nest-song. A minute later the cock was beside her uttering dull-sounding chucks chucks and nervously raising and lowering head and beak above the spines. The hen then raised her head and neck and began to flick her wings. To satisfy her, the cock gulped up 11 portions of seed, agitatedly scratched under his wing, and flew away. Our hen sometimes left the nest of her own accord or quit when her mate arrived. At 13.42 on 16 June, when the cock called, she stepped onto the edge of the nest and flew westwards. Surprisingly, the cock did not immediately follow but stood over the eggs for about a minute before bounding after her. After nine minutes the hen returned to the nest, where she shufHed and moved the eggs. The cock, now beside her, pecked at a spine and then passed over eight gulps of seed. I noticed that he occasionally gave the rasping chitoo calls which young crossbills give so persistently when begging to be fed. On this occasion the cock had called his hen off. At 17.50 on 20 June, on the other hand, 1 hour and 13 minutes after her last meal, the hen quietly left her eggs for 17 minutes, the longest of her various absences. Several times the cock settled on the eggs when his mate was away. At 16.38 on 13 June she came off when he was tooping on a tree about 20 yards away. He waited four minutes and then rustled over to the nest, where he settled down and brooded the eggs for almost a minute, even attempting to catch parasites while he was sitting. This was an even more unusual experience than that which I had watched at 18.35 on the 12th. That time our hen opened her beak and threatened the visiting mate. Then off she went and he stepped into the nest and crouched over the eggs, but never actually brooded them. Within half a minute she was back and he had started to call on a branch nearby. Once again she responded by leaving the eggs, !loop,·ng harshly and flicking her wings, and then she was covering her eggs again. I do not know what had caused all the upset. After he had gone she was not licking her mandibles as she always did after a meal. Sometimes the cock stood on the edge of the nest, or on a twig beside it, while he fed his hen, usually half turning his head away as he gulped up the seeds which he placed in her beak, or which she took from between his mandibles. These meals greatly varied in size. At 16.39 on 22 June he gave her 24 gulps, but at 13.59 on the 20th he had only managed five portions, the seeds passing between cock and hen in a sticky mucus stream. Although 1952 was a wonderful year for pine crossbills in Rothiemurchus, our hen only responded to the calls of her own mate, ignoring those of passing crossbills. On 22 June, for example, the hen clearly heard, but did not react to, the loud cries of passing crossbills at 14.08, 14.18, 14.19 and 15.02. Earlier in the day a stranger cock had sung quietly close to the

Nest Diaries 139 nest-a rhythmic sequence of chips and little flurries of gee-gees-but the brooding hen showed no interest in him. Occasionally, however, she turned her head to follow a flock flying overhead, but her mate was possibly among them. Whenever she heard the familiar call she became instantly alert, but waited before starting to call. Then she sometimes uttered quiet chip-chips until she stretched up her head and neck and began to squeak and chitter. Just occasionally I noticed that our hen appeared to recognise and tune in to her mate's calls as he flew overhead. She seemed to know when he was about to visit her. Twice within a minute I have seen her raise her head, but fail to beg or chitter, after she had heard a toop in the distance. Watching nests from the ground I had often seen hens fidgeting and shufHing about on the nest, but could never discover exactly what they were doing. In the hide I learnt much that was quite new to me. Every movement of the hen was now seen to have some meaning and purpose. I often watched her 'delousing', catching and eating parasites on her own body and in the nest. Sometimes she would dig hard under her wing pits, on her flanks and upper breast, or even on or under her tail. Her large and clumsy-looking beak was really quite a delicate instrument. How gently and easily she ran her feathers through it. I also saw her digging in the lining and floor of the nest, sometimes probably searching for parasites and at others possibly to air the eggs. She was certainly bothered and irritated by parasites. At the end of the fortnight she had a bare patch under an eye and another, about the size of an old sixpenny piece, around her cloaca. I once watched her rise suddenly as if an insect had bitten her, and she then pulled at her left flank and afterwards raised her head. I could sometimes see the little animals that she caught and nibbled. But I do not know precisely what they were. Apart from this exploratory probing and prodding, our hen was extremely restless, frequently loosening or spreading her tail and half-raising her wings. She often stood up and gazed intently at her eggs, and almost continuously changed her brooding position, sometimes describing t to t of a circle in the cup. She seldom sat continuously head to wind, even when a stiff breeze or near gale was making the stilts of the hide creak and groan and the canvas lash against its supports. She was skilful at catching flies, often snapping at those which had settled on the nest or were flying around it. Within four minutes, on 22 June, for example, she caught a couple of flies, snapped at two others, but ignored one which had settled on her back. She recognised, but usually ignored the occasional wood ant which had climbed up the tree in the warmth of the sun. Only once did I see her half-heartedly lean forward and snap her beak at one of them. Perhaps she did not regard them as good meat. I soon realised the importance of a crossbill's long flexible red tongue in

140 Pine Crossbills feeding and in emotional situations. Before and after the cock had visited the nest, this hen sometimes opened her beak and flicked out her tongue. Once I also saw her do this when a flock of crossbills was flying overhead. After her meal she licked her mandibles and then cleaned her tongue by passing it through them and she also used her tongue to catch parasites in the nest and on her own body. Periodically this ever-restless and always exciting hen turned and repositioned the eggs in the nest cup. She had special ways of doing this. Usually she half stood and looked down at them and then bent down and spooned them up with a shut beak. Once I saw her raise one egg, holding'it between the under mandible and the upper breast, then drop it into a new position. At other times she shuffled the eggs with her lower body, first half-standing and fluttering her wings to gain purchase. I saw her break off a spine and work it into the lining and lift, nibble, and then replace a small pine needle. Once she billed at a small twig and she ate a long stringy grass. I also saw her working at a small piece of wool attached to the rim of the nest and then make the motions of placing it under her, without actually doing so. Sometimes, when he was nervous or apparently agitated, the cock shifted from stance to stance before feeding his mate and he occasionally made those tension-releasing upwards and downwards head movements above the spines. The warm June weather probably enabled the hen to leave her nest more frequently than she would have done in late winter or early spring. We never saw her defecate over the side of the nest which, to the end, was entirely free of those characteristic white droppings. On hot days she often dozed or slept with her eyes closed and sometimes she panted, her back rising and falling in time with quicker breathing. I soon learnt a little about a crossbill's fear reactions. The hen knew the calls of hoodies, rooks, young rooks, and even black-headed gulls as those of enemies. Immediately she heard any of these calls she jerked up her head, stretched her neck, and sometimes made upward and downward head and beak movements. If suddenly alarmed, she would raise her head and neck and would peer over the nest if she heard movements in the heather below. High winds, which made the nest branch sway wildly, always seemed to frighten her. When the gusts lifted her tail or ruffled her feathers or ear tufts, she would crouch on the nest, sleeking her feathers and rapidly raising, lowering and jerking her head, or snaking it from side to side; and she then sometimes called single sharp and excited chicks. From time to time she raised her hackles, perhaps sometimes merely to cool her head. This raising of the crown feathers was certainly not always a response to an emotional situation. Usually she ignored or took little notice of other small birds, but on 15 June she lifted her head and looked hard at a pair of noisy chaffinches. Altogether our small team of observers spent over 53 happy and absor-

Nest Diaries 141 bing hours in the small hide on the stilts. Twenty-four times we watched the cock go to the nest, where he fed his mate at intervals of 89 to 159 minutes, an average of 103 minutes between meals. The little hen's continuous spells of brooding lasted 114 to 314 minutes (average 239 minutes) but, while we were watching, she left her eggs of her own accord 14 times, for absences lasting 1-17 minutes, an average of 4.8 minutes. Plenty was always happening outside the hide. Crested tits sometimes purred and bullfinches piped in the trees. On 14 June, two cock cuckoos noisily challenged one another and on the 18th a hen cuckoo bubbled nearby. In the clearing below cock wheatears sang and chacked, curlews yaked and oystercatchers held piping parties. Sometimes, late in the evening, a roebuck barked eerily. On 12 June, an unmated cock greenshank sang somewhere above the tarn and later gave his nostalgic triple calls and sobbing cries. There were really few moments without abiding interest.

CHAPTER 14

FOOD For many thousands of years, before the lairds and their foresters had planted larch, Norway spruce and exotic conifers, Scottish pine crossbills probably fed almost entirely on the pines throughout the year, but when the cone crop failed they are likely to have exploited birch, rowan and weeds. Now our crossbills regularly feed on larch on the outskirts of the old pine forests and sometimes resort to stands and plantations of Norway and sitka spruce and Douglas and Columbia firs, as well as to more subsidiary foods. A flock of crossbills feeding on the pine tops is always attractive to watch, the stout little birds rustle and scuttle through the dark green foliage, using wings and sometimes beaks to assist them. Deftly cutting or wrenching off cones, they turn them round and hold them in their feet while extracting the seeds. Or, looking like small parrots, they gymnastically remove the seeds without detaching the cones. Always active, they continuously hop or flutter along spindly branches with cones in their beaks to more secure lodgements close to the stem; but, however quietly they work, you always heard a loud crackling, silvery seed cases spiralling slowly in the sunlight, and a dull plop as the cones drop from branch to branch and so to the ground. In some years, single birds, pairs, and groups persistently feed on stands 142

Food 143 of larches before switching to the pines just before nesting. On 8 March 1938, for example, I watched a pair feed on larch cones for over an hour and a small group nearby also busily took larch seeds without detaching the cones. Time after time a single cock also snipped off larch cones at the extremities of thin branches and then sidled to firmer stances. By 17 March, however, these crossbills had almost forsaken larches in favour of pines. Mated cocks then selected favourite clumps from which they later obtained the supply of seeds needed to feed the brooding hens. In the period of preparation and courtship feeding, pairs often select special feeding trees, often those growing in isolation in sunny clearings or on forest fringes facing the sun. To these they often return, feeding greedily and scattering many partly-emptied cones on the ground below. These 'crossbill trees' are usually richly laden with cones which the sun has helped to ripen, thus helping the crossbills to extract seeds more easily, and are often situated in openings not far from the nesting tree. For example, on 23 March 1935, the favourite tree was an old bent pine which was about 200 yards from the nest. The discovery of a 'crossbill tree' is one of the clues for which the nest hunter is grateful. I met with the same feeding pattern in some of the common crossbill groups in Norfolk and Suffolk and the Norwegian ornithologist Ivar 0ye noticed the same habit in Nordmore. Laboratory and statistical tests would probably tell us whether these trees do produce richer cones than those which the crossbills visit more casually. We may then discover that they find what they need by exploration and by trial and error. In the U.S.A. there has also been some interesting research on the coevolution of the pine squirrels Tamiasciurus hudsonicu« and the conifers in which C. C. Smith (1968, 1970) showed the squirrel selects the particular lodgepole pines Pinuscontorta which give them the highest feeding rate. The cones on some trees in a squirrel's territory are thus left untouched while those on other trees are stripped entirely. P. F. Elliott (1973) also discovered that the squirrel'S preference for a particular type of cone was based on '( 1) width of cone, (2) the number of viable seeds per cone, (3) the ratio of total seed weighed to cone weight, and (4) the shape of the cone in relation to its attachment to the branch'. Similar research on cone selection of crossbills might show equally interesting results. It is now known that the nutritive value of spruce seeds in Finnish Lapland varies greatly from year to year. The proportion of crude protein has fluctuated from 9· 8% to 22% (Pulliainen 1973). Equally exciting was the discovery that there is apparently a north-south trend in the nutritive value of the seed. Spruce seeds from southern Finland contain about 29% more crude protein and are richer in phosphorous than those from Finnish Lapland (Table A). Cones from Lapland also contain many empty seeds. The lOOo-grain weight of spruce seeds originating from latitude 67°N in Sweden was about 2· 6 gms, They were thus about 1· 3 gms heavier than

144 Pine Crossbills seeds from the same latitude in Finnish Lapland. However, E. Andersson ( 1965) discovered that the l00o-grain weights of spruce seedsvary annually and regionally. In Finnish Lapland, therefore, a crossbill has to extract and consume many more seeds to attain the same level of nutrition. With this poorqualityof seed and the short hours of daylight, spruceforests in Finnish Lapland are clearly poor in marginal habitats for crossbills. Table A. Comparison of the analytical data of spruce seeds collected in northern and southern Finland (Pulliainen 1971). NorthernFinland SouthernFinland t-test S.D. Mean + S.E. S.D. Mean + S.E. Organic matter, % 97.7 ± 0.3 0.6 95.1 ± 0.1 0.3 8.13··· Ash, % 2.3 ± 0.3 0.6 4.9 ± 0.1 0.3 8.13··· Crude protein, % (N x 6.25) 14.2 ± 0.5 0.9 23.3 ± 0.5 1.1 12.82··· Digestible crude protein, % 8.9 ± 0.4 0.9 21.8 ± 0.5 1.1 18.43··· N free organic matter, % 83.6 ± 0.7 1.4 71.8 ± 0.6 1.2 12.55··· Crude fat, % 6.7 ± 1.1 2.1 35.6 ± 0.1 0.2 27.01··· Crude fibre, % 39.0 ± 1.0 1.9 22.1 ± 0.1 0.1 17.60··· P, g!kg 5.0 ± 0.5 0.9 9.3 ± 0.3 0.5 8.27··· Ca,g!kg 0.7 ± 0.2 0.3 0.4 ± 0.0 0.1 2.00. 10- .05 K,g/kg 7.9 ± 0.1 0.2 7.4 ± 0.2 0.4 2.08. 10- . 05 Mg,g/kg 2.2 ± 0.2 0.4 3.0 ± 0.7 1.3 1.16

In future the chemical composition as well as the quantity of seed must be assessed in studies of the eruptions, movements, numbers and breeding densities of crossbills (Pulliainen 1974). This research may also help to explain some of the problems of the non-breeding surplus. In poor quality seed years only the most efficient pairs are likely to be successful. In July-August 1971,for example, pine, common and two-barred crossbills all fed upon new and old spruce seeds, both on the trees and on the ground; but they shunned the new crop of pine cones, richer in nutrients, which were then available. The crossbills thus were not selecting the seeds for their nutrient value, possibly because it was more difficult to extract soft unripe pine seeds from new and resinous cones than to deal with the seed from a new spruce cone of different shape, size and structure (Pulliainen 1972). Table B. Analytical data of spruce and pine seeds collected in NE Lapland in 1971 ( % of dry matter) (Pulliainen 1972.)

Sample

Date of collection

Old spruce seeds New spruce seeds New pine seeds

March. 1971 29 July - 1 Aug. 1971 24 July - 6 Aug. 1971

Organic Ash matter 95.7 94.9 92.7

4.3 5.1 7.3

N total

K

Ca

P

Mg

3.47 2.84 4.02

0.835 1.711 2.879

0.072 0.071 0.146

0.948 0.724 1.041

0.420 0.215 0.171

The ripeness of the cones and the accessibility of the seed certainly seem partly to determine the speed with which a pine crossbill can feed. If the cones are firmly closed and contain few seeds, the feeding bird sometimes quickly detaches, tests, and drops many without taking a single

Food 145 seed. You now examine the discarded cones but find few beak marks. On the other hand, if the cones are opening and contain plenty of seeds, the crossbill deals with them more thoroughly. On 7 April 1935, a fair seed year, a cock spent three minutes on each cone, which he dealt with alongside the trunk. On 15 February 1936, with a heavy crop of cones on the pines, a pair fed for 22 minutes, almost effortlessly and continuously picking out seeds. Sometimes these two birds hung head downwards, at others, heads up and bodies parallel to the stem, they stretched up, looking almost like small woodpeckers as they extracted what they needed. At this time the hen already had her nest and was to lay the first egg within the next few days. The cock, who sang softly and twittered to her, once dropped down onto a low branch while she was taking grit from a moist and mossy patch. Both then stropped their beaks on a weathered root and flew back to their 'cone tree'. On 16 February, another pair disposed of a dozen cones in as many minutes, frequently licking the sides of their beaks. On this windless day I could hear the crackling when I was over 50 yards from the foot of the tree. Three mateless cocks also flew from tree to tree with cones in their beaks. Even in good seed years, however, the speed with which a pine crossbill deals with cones and the number of seeds extracted varies greatly. On 17 March 1974, Bruin and I watched an Easter Ross cock take six cones which it dealt with at a rate of 68 to 230 seconds, averaging 146 seconds per cone. Judged by the floating seed cases, he extracted 8 to 35 seeds from each, with an average of 16 per cone, thus obtaining about seven seeds per minute. This was a good example of a pine crossbill's rather irregular feeding rhythm in a year of good pine crop. They frequently returned to this clump of trees, which was close to a clearing and faced the south, and the ground was littered with discarded cones. In years when pine seed is scarce, groups of unmated cocks and hens, and also some mated pairs, fail to breed. Our pine crossbills then feed on other conifers as well as on pines. On 5 April 1959,for example, a group of unmated cocks in Easter Ross were tackling pine cones from which they took a few seeds without detaching them, two others were feeding on larch cones, and two on pine blossom. In 1971, a poor seed year in East Sutherland, a non-breeding pack fed on larch buds on 30 March and one cock tackled larch cones on a tree growing on the edge of the wood. In that April, pine crossbills and great spotted woodpeckers both appeared to favour larch rather than pine Our Scottish pine crossbills sometimes feed on small shoots of pine or spruce, as well as on cones and buds. Before doing this they often appear to be nervous, fluffing their feathers and making jerky beak thrusts into the spines. In spring the hens, which need protein to form their eggs, often persistently hunt insects, the cocks doing so less habitually than their mates.

146 Pine Crossbills On 8 March 1936, however, I watched a mixed flock searching for insects on the carpet below the pines. I also saw hens taking some kind of insect in festoons of Usnea barbata growing on the branches and trunks of pine and larch. On 15 March one hen searched and pecked at the forest floor and nibbled a capercaillie's skeleton and another carried a mountain hare's bone to the top of a pine. These birds evidently needed calcium. While searching for insects, hens often rip bark off old pines. On 12 April 1970, Adam Watson and I watched a hen doing this in Glen Tanar Forest; she also probed in the lichen. Later we watched another hen feeding open-beaked, for 10 minutes, on an old squirrel's drey some 25 feet up a pine where she was apparently consuming mouthfuls of tiny insects. Then the cock called her and they both flew away to another wood across the river. Winifred Ross also saw crossbills digging their beaks deep and 'extracting some form of nutrient' from lichen, and others searching under the raised bark of an old and rotten rowan tree. Rowans certainly do sometimes attract them. I have watched a hen carefully hunting their branches for insects while the cock perched on the top. I have never seen pine crossbills flying to the nest with insects in their beaks, but the proportion of animal food which they give their young is possibly larger than field observations suggest. In June 1963, Olsson watched pine crossbills feeding the larvae of the sawfly (Lophyrussertifer) to grown young. In his Rough Notes, Booth pictured parent crossbills with beaks full of insects, but I could find no supporting observations in his notebooks. Hens brooding on late spring or summer nests frequently snap at, and eat, any small flies that they can catch. They also hunt and eat ectoparasites on their bodies and those found in the nest lining. However, one hen seemed to ignore and seldom snapped at the odd wood ant which had climbed up the nest tree. After the pine cones have emptied, crossbills continue to find seeds in them and now also feed on the upright larch cones which almost always retain some seeds until they drop off the tree. On 13June 1969, a group of a dozen of our resident pine crossbills of mixed sexes were quietly removing seed from cones growing on the tops of recently burnt pines, and they also devoured pine blosson and searched for insects. In August, this group also tackled green pine cones but dropped many, apparently without extracting any seeds. In November, December and January, flocks and pairs feed on larch and pine, the richness and availability of the cones determining which they choose. On 9 November 1939, a good pine cone year, 11 Scottish pine crossbills had long spells of leisurely feeding, occasionally interrupted fy singing and fighting. Behaving almost like a pre-mating group, these birds, mostly cocks, moved to and fro between particular clumps and trees. In years of poor or modest pine seed, our crossbills seem to prefer larch

Food 147 in winter, particularly when haunting plantations in the valley or on the fringes of pine wood or forest. However, pairs and small packs remain in the pines. Around Dulnain Bridge, where immigrant curoirostra sometimes winter in large plantations of larch, Winifred Ross described a flock attacking birch cones, 'the sun glittering on the red cocks among the gold leaves and falling silver-winged seed-cases'. Unfortunately she did not distinguish between Scottish pine and common crossbills and gave no dates but she noticed that 'the larches were stripped when adjacent pines were untouched'. On 30 September 1933, however, an autumn when there was a poor crop of pine cones, two hens fed passively on a larch while the cocks fought for 10 minutes. Our native pine crossbills less frequently feed on unusual food than do the invaders. At Dulnain Bridge, possible immigrants fed on unopened rowan leaves and the weight of one group 'brought a bed of raspberries almost to the ground.' When conifer seed is scarce, continental common crossbills on passage make use of some unexpected foods, such as beech and oak buds, oak galls, thrift, seeds of oak and thistles, ivy and rowan berries and aphides. There are also many historical records of their robbing apple orchards. Scottish pine crossbills frequently visit keepers' or crofters' houses in woodland or forest clearings where they remove broken putty from the windows and often take grit from chimney stacks. How I love to see them tapping away at the putty which evidently contains something that their bodies need. In North America, Tordoff (1954) found that red crossbills need salt which they sometimes find in cattle salt-licks, in the litter from ice-eream freezers, and from that sprayed on roads to melt the snow. Red crossbills have also consumed 'material leeched out of cement, wood ash and urine stained snow.' DRINKING AND BATHING

Our crossbills love water. How thrilling to watch them drinking or bathing at a peat runnel or beside a burn or water saucer. Twittering continuously, they look like small parrots as they splash and drink. While they are doing this, one or several usually stand guard on a stump or tree and the thirsty birds often go to water in ones and twos. In a mated pair this kind of guarding is almost a ritual, either cock or hen guarding the other while it is drinking or bathing. Nevertheless, crossbills can be particularly confiding at these times. I have often stood almost beside them. One bird, or sometimes a pair, on occasions may cling to the gutter pipe of a house, dipping its head into the murky liquid. I have even seen pairs returning again and again to the guttering of a house where an auction sale was in progress with the auctioneer bellowing the odds. The Dumfries crossbills also drank from the rhone pipes of a farm and in

148 Pine Crossbills

puddles beside it. After over-night rain one also crept along a wet branch to drink the water drops hanging below it. On 30 March, after another day of heavy rain, a hen tore off and ate some wet lichen. So urgent is the crossbill's need of water that nesting habitats in Breckland are almost entirely restricted to roadside pine rows or to clumps of pines close to houses, where ditches and gutter pipes are the main source of water. However, Dawson and his colleagues (1966) discovered that when supplied with unlimited water in an aviary, red crossbills only drank about 22% of their body weight daily, about the same quantity as that taken by other small passerines of similar size. FEEDING PATTERNS IN OTHER CROSSBILL POPULATIONS

In East Anglia common crossbills subsist largely on pine cones. J. Robson tells me that spruce is scarce on the roadside where most of them feed, but that they feed on larch cones when available and may also exploit beech, alder and birch. One cock fed oak buds to his hen. In 1962 and 1963, quite large packs of invading continental crossbills lived in the Wytham Woods near Oxford, where they stayed from July-August 1962 until April 1963 without attempting to breed. These flocks preferred pine to larch in June, alternated between larch and pine in July and August, and largely favoured larch from the end of August to January. These different cone crops, however, were apparently insufficiently rich to bring pairs to breeding condition. Kirikov (1952) and Formosov (1958) have studied the food and feeding behaviour patterns of common crossbills in different parts of USSR. In his

Food 149 10-year study in the Southern Urals, Kirikov worked on the groups living in mixed pine and larch forests, where common crossbills subsisted mostly on pine in spring and larch in other seasons. In years when both larch and pine had good cone crops, the crossbills bred in April-May when the pine cones were discharging, and again in August-September when the larch cones opened. In years when the pine crop was good and the larch failed, the crossbills nested only in spring. When both trees failed, most of the crossbills departed leaving behind only a few non-breeders. Kirikov later found the same pattern in forests around Leningrad where the crossbills also bred twice annually in years of abundant pine and larch cones. These groups of crossbills thus used the pines in only two or three months of the year. Around Kostroma, Gorki, and Moscow, where there are many extensive tracts of pine and spruce, spruce cones start to open towards the end of March, most of the seed falling in the snow in April-May when various birds and rodents exploit them. At this season, however, the crossbills seldom join them, as the cones remaining on the branches are almost empty from late May onwards. On the other hand, pine cones which open later and lose their seeds more gradually are often rifled by crossbills and great spotted woodpeckers in late spring or early summer. Sometimes, however, the crossbills go to the ground to inspect the many strewn spruce cones, but they seldom make great use of them. In the autumns and winters of rich spruce cone years, the crossbills frequently drop cones containing anything from 45 to 150 seeds (D. Danilov, 1937).However, this is not as wasteful as it first seems. When the cones have fallen on moist ground, they close and usually become inaccessible to other birds, although squirrels and two species of mice do deal effectively with them. Despite these mammals, many cones still hold seed until the late summer in a year of heavy coning. This enables the crossbills to exploit the previously dropped cones and provides them with an important reserve of food during a famine of cone seed. Formosov also discovered that, whenever there is a shortage, the crossbills ate conifer and birch buds, and insects which attack larch cones. A rich flowering of larch buds, which form in the year before fruiting, sometimes induces flocks of crossbills to remain in forests with little pine seed, presumably in anticipation of an abundance of larch cones. Towards the end of winter and in the early spring of years of poor coning, flocks of crossbills are sometimes extremely excited, the cocks singing vigorously and staying in the dearth area as if they expected a heavy cone crop next autumn. Another local race of crossbill, on the slopes of the Tien Shan mountains in Soviet Central Asia, depends on the Tien Shan spruce Picea shrenkina, which drops its seed in late October and November. Thus, in 1955, after a bumper crop of cones, this entire crossbill population had paired off by late August or early September. On 2 September, Formosov found a hen sit-

150 Pine Crossbills ting and males shot had well developed testes. There, August and September are the only favourable months for raising chicks. In large pine and spruce forests around Kandalashka, pine, common and sometimes two-barred crossbills periodically nest in the same year. In years of good spruce cone crops, a few pine crossbills lay in August, the young leaving their nests in September. Kokhanov has seen parents feeding young in late October. Between November-January, however, crossbills are unable to nest because there are only 1t to 7 hours of daylight. Thereafter, all three species may feed on spruce cones from February-March until mid-May, then on those of pine until late August. The availability or abundance of spruce or pine seed largely determines the laying season. In 1959, for example, when there was a bumper spruce cone crop and a good crop of pine cones, common crossbills started to lay in early February and continued breeding until late July, with a peak period between 20 February-l0 March. The earliest pine crossbill laid about 22 February, and the majority between 21 March-l0 April, but some pairs nested thenceforward until the end of July. The small groups of two-barred crossbills began laying in late March and continued to nest until the last week in May. On the other hand, in 1966, with a good yield of spruce and a fair crop of pine cones, all three species started to lay between 1-10 March, the two-barred until late June, pine and common crossbill for about a month longer. In other years, when the spruce, but not the pine, had a good seed yield, pine crossbills nested in March-April and exceptionally in February. In years when spruce failed and pine had a good crop, pine crossbills bred later in May-June, and in years of good pine yield and a good autumn crop of spruce cones, they bred continuously from May to September. In some years both pine and common crossbills nested in late winter and early spring, with only slight differences in their laying seasons. In Scotland, Finland, Sweden and Norway, pine crossbills are not known to have these double-breeding seasons, and they generally nest later than common crossbills which have settled in planted pines (Table 3, page 233). FOOD OF PINE CROSSBILLS IN NORTHERN EUROPE

In Norway, besides eating the seeds of spruce and pine, the pine crossbills also attack larch and birch cones, mountain ash berries and the fruit of the dog rose. Hugh Blair watched adult pine crossbills and pine grosbeaks picking seeds out of horse droppings in Finnmark. A breeding pair which Spjetvill was watching in North Trondelag, in 1968, fed almost exclusively on pine seeds, but in early April he saw a group of five cocks tackling spruce cones. Snow (1952) also found that spruce and pine seeds were the main winter food of all three crossbills in arctic Finland.

Food 151 Olsson met a rather different pattern in Ostergotland, Sweden, where, in 1954 and 1963, the nesting pairs foraged entirely on spruce trees during incubation in late March and April, but thereafter fed their young exclusively on pine seeds, which were accessible by the time the chicks hatched. Before the young left the nest, each parent was opening about two ripe cones per minute, from each of which they extracted 10 to 20 seeds. In Finland pine seed is the staple food of breeding pine crossbills which nest later than the spruce-feeding common crossbills (Hilden, pers.

comm.s.

P. Juutinen (1952 and 1953) carefully analysed the crop contents of five parrot crossbills collected in North Karelia, Birds shot 8.6.1949 21.7.1947 31.7.1949 8.8.1947 20.8.1949

Sex juv.

?

Treewhere the birdwasshot

Quantity offood in the stomach

Pinus Larix Pinus

0.49ml 0.35ml O.17ml+0.Olml Curculionidae 0.40ml 0.23m1

Picea, Pinus Pinus

In June and July he found that pine crossbills were feeding on two-year old pine cones, with the exception of one group which was on larch on 21 July 1947. In August they fed on larch, spruce and fresh pine cones. In north-east Finland, where there were no cones on the pines in March-April 1971, common and two-barred crossbills fed almost entirely on the excellent spruce crop, avoiding a good crop of mountain ash Sorbus berries. In early March the two-barred crossbills ate spruce seeds which the cones had already discharged onto the branches. In spring and summer large flocks of pytyops;ttacus, curoirostra and leucoptera in roughly equal numbers, continued to exploit old spruce seeds both on the trees and on the ground. In July they fed on the new spruce cones but avoided those of the pines although pine seed is often regarded as the main food of curoirostrain]une and July. Allthree crossbills apparently had the same feeding behaviour but differed in selection of food. The differing proportions of invertebrate food was noteworthy-8.4% for pine crossbill, 27.8% for common crossbill and 2.6% for two-barred crossbill. Old spruce seeds, and this animal matter, possibly compensated for the richer pine seeds in the summerdiet of the crossbills. The larvaeof Gilpiniapolytomum andPrist,phora spp., both needle pests, was the main insect food (Table C). On the Kola Peninsula, where I have already described the food trees of the three crossbills, Kokhanov estimated that a pine crossbill usually took 3-4 minutes to each cone, from which it removed 6-20 seeds, an average

Table C. Food items consumed by crossbills in NE Lapland during the period 20 July - 11 August 1971. Frequency = number of crops containing the food item, no. = number of the food item in question. (Pulliainen 1972)

Loxia pytyopsittacus (15 specimens)

Food items

Freq.

Piceaabies, new seeds old seeds Araneida: Clubionidae, Clubiona sp. Xysticidae, Xysticus sp. Linyphiidae sp. Spider, leg Insecta: Hemiptera, Miridae sp. Homoptera, Psyllidae sp. Aphididae sp. Diptera sp. Empididae, Tachydromia sp. Hymenoptera, Pamphiliidae sp., larvae Tenthredinidae, Gilpinia polytomum Htg., larvae Pristiphora spp., larvae Ichneumonidae, sp., pupae

13 10

No.

350 124

-

-

Loxia leucoptera (8 specimens)

Loxia curoirostra (16 specimens)

Volume ml

0/0

17.5 8.7

61.2 30.4

-

Freq.

No.

14 11

626 89

2

2

Volume ml

0/0

31.3 6.2

60.3 11.9

+

+

-

1

1

+

+

-

1 4 2 1

1 46 2 1

+ + + +

+ + + +

-

1

1

1.0

1.9

4.9 3.5 +

8

31 6

11.6 1.8

22.4 3.5

-

-

4 2 1

11 3 1

1.4 1.0 +

4-

Freq.

6 3

No.

270 18

Volume ml

0/0

13.5 1.3

88.8 8.6 + + +

I

I

1

1

1

1

+ + +

4

4

+

+

2

2

+

+

2

3

0.4

2.6

Food 153 of about six seeds each minute. In these woods the pine crossbills is the only species able to deal effectively with the pine cones when they first open late in April and are still hard and dry. CROP

Kokhanov and Gaev measured the contents of 40 pine crossbills' crops, which held from 35 to 389 spruce seeds. However, few of these crops were full when the birds were collected and some seeds had already been digested. The capacity of the crop was then tested by filling several with spruce seeds taken from the crops of others. This experiment showed that, on average, a pine crossbill's crop when full could carry 1.90 gm or 350 spruce seeds, a common crossbill's 1.64 gm or 300 seeds, and a two-barred 120 gm or 220 seeds. They also estimated the amount of food needed to rear a young crossbill-294 gm or 105,000 seeds for a pine crossbill, 225 gm or 90,000 seeds for a common crossbill, and 182.8 gm or 65,300 seeds for a two-barred crossbill (Table 9). In Sweden, Olsson calculated that at each meal a pair of pine crossbills distributed about 2 gm of partly-digested pine seed, or roughly 350 seeds to a brood of well-grown young. This suggests that the brood alone might require 3500 seeds daily. Clearly, however, the young would need a smaller quantity of seed in their first 10 days. The parents also require many seeds to maintain their own health and strength. COMPARISONS BETWEEN FOOD OF PINE AND COMMON CROSSBILLS

Pine crossbills are better adapted to tackle the harder and tougher cones of the pine than are common crossbills, an inferiority particularly applying to fledged young. In Jutland, E. P. Pedersen found that immature common crossbills need 11-2 months before they are able to deal effectively with mountain pine cones, and Niethammer suggested that although common crossbills could extract seed from pine cones, pine crossbills were the more efficient in dealing with them. This is the nub of the problem. Where the two species compete in pine forests, the pine crossbill is likely to be more successful. In 1935 and 1936, however, Southern (1946) remarked that invading curoirostra groups near Oxford fed on hard green Scots pine cones in October and that they also stripped rows of Austrian pines with tough yellow cones in winter. However few, if any, of these invaders ultimately bred in this district. It must be remembered that, for successful breeding, the cock probably has to help to feed the hen before she can lay eggs, and that he must maintain her during incubation, and largely supply hen and brood when the chicks are small. He also has to feed himself. In poor seed years many pairs thus fail to breed. Common crossbills do exist and breed successfully in planted pines, but ecological competition with the pine crossbill is best compared in

154 Pine Crossbills traditional habitats and in years when pine seed is scarce. The successful breeding of common crossbills in Strathspey in 1936, and in Deeside in 1974, and probably in other years, happened in years of good pine cone crops and took place on the fringes of pine crossbill heartlands. In 1967-68, and in other years when there was a shortage of pine seed, pairs and groups of common crossbills foraged in woods where the Scottish pine crossbill were nesting, apparently without reaching breeding conditions. A similar situation has been noted in Finland (Hilden, pers. comm.i. FEEDING ON THE GROUND

Russian and Finnish observers have referred to crossbills periodically going to the ground in summer to exploit cones dropped and only partly emptied in winter, but this has seldom been observed in Scotland. On 22 March 1946, however, I watched a hen fly down and pick up a pine cone below the tree. This was, however, possibly one which she or her mate had previously dropped. In a long dry spell in April 1968, however, when the cones had started to open and shed their seeds, the common crossbillsfed on partly-emptied sitka cones which they had dropped on the ground earlier in the year. They also eagerly exploited ripe cones still hanging on wind-blown sitkas(SmithandOstronznic,pers.comm.).Knoxfoundthatcrossbillseasily picked up seed from the aviary floor. COMPARISONS

Although pine crossbills in northern Europe feed predominantly on pine cones, common crossbills on spruce, and two-barred on larch, the ecological niches of all three species do overlap. One or the other periodically exploits the cones most favoured by the others; but all three species have evolved beaks which are best adapted to deal with the cones of particular trees. A comparison between the feeding ecology of the twobarred crossbill and the siskin needs detailed study, but these crossbills are better adapted to open larch cones than are the siskins, The main breeding season of the two-barred crossbill, in March and April, thus seldom synchronises with that of the siskin which, also, rears late or second broods mainly on small insects rather than on conifer seed. FRUITING OF CONES

Svardson and Kiren have shown that spruce, birch, beech and oak all produce widely fluctuating seed crops in the same years, but all these trees usually have rich cone winters almost every third or fourth year. Warm sunny days in June and early July 'cause many buds to become flower buds, instead of purely vegetation buds, giving rise to shoots. This results in rich flowering in the following spring and many cones in the autumn'. After a heavy coning, however, the tree grows tired and is unable to respond to the same stimulus that might otherwise have initiated a good

Food 155 flowering. However, after a few years rest a slightly cooler and possibly less ideal warm spell in early summer may start the growth needed to trigger off a rich seed year. The Scots pine has a different pattern. Its cones do not ripen until the second autumn. Bumper cone crops on spruce and pine thus seldom synchronise. Pine crossbills in Scotland and northern Europe, therefore, are unlikely to enjoy rich crops of pine cones in years when common crossbills are exploiting a spruce bonanza. The crop of cones on the pines, moreover, fluctuates less dramatically from year to year, although the pine usually produces fewer cones in a year after a rich coning. The pine thus has fewer peaks and slumps. In Upper Strathspey in the 1930s and 1940s,however, there appeared to be a rough 3-year rhythm which helped to determine the annual breeding numbers of our pine crossbills in particular districts. In Finnmark, pine seed years were for a long time irregular and widely separated, with the trees infertile for 30-50 years. This resulted in few records of crossbills. In the early 1920s, however, meteorologists noticed that summers were becoming warmer and that the pines were responding with several heavy seed crops, although the few spruce remained inactive. Once the pine forests could support them, crossbills were not long in appearing. In the early 1920s small parties were seen on the Pasvik and in June 1927, a rich pine cone year, large flocks of pine crossbills and their young were recorded. Thenceforward there have been few crossbill years, but in the good coning of 1937 and 1958 pine crossbills again nested in Finnmark.

CHAPTER 15

COMPETITORS AND PREDATORS During their main breeding season few other animals compete with the pine crossbills for their highly specialised food and habitats. In Scotland and in northern Europe, invading common crossbills are their main competitors, but I have already described their ecological differences, and how the pine crossbills of Scotland have avoided dilution over the milennia. Between the Black Wood of Rannoch, and its outliers, and the mainly exotic conifer plantations of Dumfries and Kirkcudbright, there are now wide and largely unoccupied spaces between the two species--a rather similar position to that obtaining in parts of Norway and Sweden during the boreal post-glacial phase when spruce and the common crossbills had not yet settled. The future is thus uncertain but most intriguing. Of the other birds and mammals living in the old Caledonian pine relicts, great spotted woodpeckers, which are never really numerous, rifle pine cones much more effectively than the crossbills, but they rear their broods mainly on ants and insects. Particularly in winter and early spring, the pine crossbills and pied woodpeckers compete for cones, but the woodpeckers are too few for this rivalry to be serious or significant. In northern Europe, however, juvenile great spotted woodpeckers, which largely subsist on spruce and pine seeds from October to April, are competitors and often erupt in the same years as curoirostra. In 1909, 1930 and 1935, for example, when the pine and spruce failed in Finland, large 156

Competitors and Predators 157 numbers of curoirostra and great spotted woodpeckers passed through eastern Russia. In these years great flocks of curoirostra also reached Britain (Pynonnen, 1939, 1943). At such times, therefore, the woodpeckers probably seriously competed for cones with common and possibly pine crossbills in northern Europe. On 27 September 1966, for example, a great spotted woodpecker chased a pine crossbill from its feeding territory (Hilden 1974). COMPETITION BETWEEN COMMON, TWO-BARRED CROSSBILLS AND PINE GROSBEAKS

In Britain two-barred crossbills are such scarce vagrants that they can seldom compete with pine or common crossbills. On 17 February 1968, however, Ostroznic watched a common crossbill attacking and jostling a feeding cock two-barred crossbill. In F eburary-April1973 the feeding ecologyofcommon crossbill and pine grosbeak was compared in Finnish Lapland. The crossbills fed entirely on pine seed and the pine grosbeaks 930/0 on spruce buds and 7% on willow Salix buds. In this winter there were no mountain ash Sorbus berries and few seeds in the spruce cones. 'The pine seeds had a higher nutritive value than the spruce buds and the latter were more nutritious than spruce seeds' (Pulliainen 1974). These two potential competitors thus successfully occupied the same habitats without serious ecological risk (Table D). Table D. Analyticaldata (% of dry matter) of Scots pine and spruce seeds,and spruce buds collectedin the winter of 197'2/73 in the Vamotunturi fellterrain, northeastern Lapland. (Pulliainen 1974)

A'R, Organic % Sprucebuds Spruce seeds Scotspineseeds

2.9 2.8 5.9

qrude Digeltible matter, prottnn, crude protein,

Crude fat,

Crude fibre,

N total,

%

%

%

%

%

%

97.1 97.2 94.1

11.65 9.75 28.07

8.40 6.00 24.93

10.50 16.10 30.55

27.423.9

1.86 1.56 4.49

cs,

K, g/kg

g/kg

Mg, g/kg

6.29 4.60 6.62

4.30 0.80 0.86

1.12 2.46 2.60

Red squirrels are competitors for cones in the Scottish pinewoods, but we have insufficient knowledge of their numbers and fluctuations for a rational assessment. I have already mentioned the relationship between red squirrels and crossbills in parts of USSR, where in winter the squirrels exploit the cones which the crossbills had dropped earlier. This is also possible in Scotland, but I have had no hard evidence. Russian observers have noticed that red squirrels are much more efficient in clearing seeds from cones, and that the cones which they drop are of less use to other mammals and birds in times of scarcity. Crossbills are said to be better able to discover new feeding grounds than squirrels, to which they sometimes act as guides. A few other forest birds are possibly marginal competitors. Siskins, which often nest on the fronge of the old pine forest and in plantations, do

158 Pine Crossbills

not possess strong enough beaks to open closed and unripe crones. However, although they are not competitors during the pine crossbills' main breeding period, they are able to take seed from the opening cones while the young crossbills are being reared. When there is a good or bumper pine cone crop, as well as a good coning of spruce and larch, I have found that siskins tend to nest earlier than usual. They are also able to extract seeds from cones which crossbills have opened but have left on the trees. Crested and coal tits also take the seeds from opening cones. All these birds thus compete with young fledged crossbills, which largely depend on their parents in the first 4-5 weeks after leaving the nest, a time when their beaks are not sufficiently hardened to extract seeds from firmly closed cones. The other finches of the pine forest edges have different patterns of food ecology. Lesser redpolls are largely birds of the birch scrub, bullfinches of the juniper, and greenfinches of the forest fringe, where they feed on weeds and the seeds of woodland plants. In northern Scotland goldfinches are seldom present in pine crossbill habitats. Pine crossbills usually tolerate chaffinches, although they sometimes jostle cocks from the tops of trees, but this pugnacity is more likely to be due to psychological than to ecological competition. The status of a cock crossbill is indicated by his position on the tree. To him, height is important. Dominant cocks, which call, sing and display from the pine tops, possibly treat cock chaffinches as status competitors. In spring, however, when you are watching a cock pine crossbill and a cock chaffinch on the same tree, you are seldom likely to forecast their reactions to one another. One cock completely ignores a noisy chaffinch, a second toops, flicks his

Competitors and Predators 159

wingsand then bustles the chaffinch from his perch,but a third allows one

to sing only a few feet away from him. I have also watched cock chaffinches singing a few feet from brooding hen crossbills, apparently without arousing any angry reaction. Here are some field notes. On 25 March 1936, I watched three different cock chaffinches singing on the same trees as cock pine crossbills without any fighting whatever. On the 26 March, a cock pine crossbill sang loudly on top of a pine with a chaffinch a few feet below and a siskin feeding almost beside him. Both these he ignored. A few days earlier, on the contrary, both cock and hen pine crossbills flew at siskins, chaffinches and bullfinches, hustling them off perches high up on pine trees. In an Easter Ross wood, on 1 May 1967, I watched a cock pitch on a pine about 50 yards from his nest and the brooding hen, and there chip excitedly and flick wings and tail before flying at a cock chaffinch, which had flown in and started to call on this tree which was inside his own territory, Yet two days later this cock chaffinch twice landed on a twig almost beside the sitting hen crossbill without her reacting. I do not believe, however, that this casual rivalry with other forest finches is completely functionless. On 31 March 1974,for example, I watched chaffinches, greenfinches, redpolls, goldfinches and coal tits, all feeding rapidly on the seeds of opening pine cones in the feeding area of a pair of pine crossbills. In this year, when pine seed was abundant in this wood, the competitive forages of these finches was probably of little importance, but in a year of seed scarcity when the pine crossbills are hard pressed, it could have been more significant. As in territorial patterns, the extremes are decisive. In autumn the relationships of the different forest finches are interesting to watch. On 8 October 1969, a group of 30-40 siskins fed on larches along with smaller parties of pine crossbills. The cock siskins sang solo and in chorus while rifling larch cones and sometimes searching for insects in lichen on the branches. Small bands of chaffinches kept together in the larches where they hunted for insects on lateral branches, and one cock fluttered after a small moth. Claws in and head back, a coal tit ran up a larch, picking out insects in lichen and pushing its beak into crevices; and greenfinches and redpolls fed near the tops of exotic conifers. Siskins also

160 Pine Crossbills exploited the seed still left in partly discharged larch cones, but the crossbills often wrenched them off and hopped along the branches to forks where they rapidly seeded them. On this sunny autumn day, therefore, these different birds were all peacefully exploiting different niches in the same trees. The obvious is often elusive. In northern Scotland, man is undoubtedly the pine crossbill's most serious competitor. .For many hundreds of years he has progressively felled and sometimes burnt the old open pine woods and forests which our birds most favour. The many thousands of acres of planted pines have been an inadequate substitute for the pine crossbills, although they may soon be settled by groups of common crossbills. On the other hand, foresters have created new habitats for common crossbills on the dry heaths and brecks of Norfolk and Suffolk, and in the plantations of Cumberland and southern Scotland. The original colonisation of the Breckland, in 1910, stemmed from the earlier experimental plantations of Thomas Coke of Norfolk. PREDATORS

In northern Scotland red squirrels are the most serious natural predators. In years when there are high numbers of these colourful little mammals, they may sometimes destroy many crossbills' nests and broods. I doubt, however, whether their predation has ever significantly affected the breeding populations of pine crossbills. In 1936, for example, when so many pairs of pine crossbills bred in Upper Strathspey, I·found only two nests robbed by squirrels. These contained some fragments of eggshell in mussed nest-cups. Winifred Ross actually watched a red squirrel climbing a tree to rob a nest. She found that a crossbill deserted its nest even if the squirrel left some eggs untouched. In 1972, a red squirrel also destroyed and devoured a brood of young pine crossbills in a nest in the Loch Garten Reserve. In the late 19th century, Booth suggested that the predation by red squirrels had led to a scarcity of crossbills in particular locations. I greatly doubt this. The absence of nesting pine crossbills from a favourite habitat is usually caused by normal movements in search of better cone crops. Pine martens, stoats and weasels are other possible predators; but I have no proof. Hooded crows probably rob nests. I disturbed one from a nesting tree and later found that the eggs had gone and that the nest was slightly tilted to one side. Raising its head in fear, the brooding hen crossbill reacts nervously to the sight or calls of crows and rooks. Sparrowhawks occasionally take pine crossbills. In 1936, I found the remains of one on a sparrowhawk's plucking stump in an Abernethy pinewood, and that year disturbed a cock and a hen sparrowhawk close to crossbills' nests. On the other hand, D. H. Weir, who has examined scores

Competitors and Predators 161 of sparrowhawks' plucking stances in Strathspey, has never found the feathers of a pine crossbill on any. In 1967, however, while recording a radio programme in Rothiemurchus, he and John Amott watched a sparrowhawk chase and catch a continental crossbill which had been perching on a larch. Pine crossbills react nervously and tack angrily but rather quietly when a sparrowhawk or merlin fly near or overhead. On 24 April 1970 I also watched a cock twisting his.head from side to side when a merlin flashed over a Sutherland wood. Few though they are in most of the nesting habitats of our resident crossbills in northern Scotland, long-eared owls are other possible predators. However, I have had no proof that they or tawny owls have ever taken them there. PINE CROSSBILL

In Finnmark, Norway, the pine crossbills have little to fear from predators, at least until the young break the shell. Pine martens are scarce, and few squirrels are likely to be astir so early in the season; but Siberian jays and hooded crows are well known for their fondness for eggs and nestlings. Tengmalm's owls and hawk owls are never numerous and Lapp owls are not known to have killed crossbills. However, the merlin is a possible predator and the sparrowhawk undoubtedly a real menace. Yngvar Hagen includes six crossbills--none specifically identified-in this list of the sparrowhawk's bird bictims, Goshawks are scarcer and probably less deadly. Hagen mentions only one crossbill among 306 known bird prey of the goshawk (Blair, pers. comm.). In Sweden jays are likely predators. Olsson remarked that the pine crossbills called angrily whenever a jay approached nest or young. In some parts of the Soviet Union, predation is apparently high. Between 1958-67, predators destroyed 20 out of 24 (83.30/0) of the pine crossbills nests kept under observation in the Lapland Reserve and 13out of 16(80lfo ) at Kandalashka. Squirrels, corvids, and human interference were responsible. In these years 24 out of 32(7 5lfo ) of the common crossbills nests in these two districts also failed. This kind of predation is clearly more significant than any so far recorded in Scotland. PREDATORS OF COMMON CROSSBILLS IN BRITAIN

In southern Scotland and in England and Ireland, common crossbills have the same predators as Scottish pine crossbills and also some other enemies. Part of a continental crossbill was found in a hen harrier's nest in Galloway and the skull of another in a long-eared owl's nest in Rum. In Breckland, jays, magpies and carrion crows, as well as red squirrels, occasionally rob eggs and destroy broods. On 25 March 1922, for example, Percy Meeson noted that a jay had sucked three eggs in a nest at Icklingham and on 7 March 1939 he found another nest with broken eggs

162 Pine Crossbills which he considered was also the work of a jay. Little owls are other possible killers. H. A. Gilbert and A. Brook (1924) suspected that one had killed a brooding crossbill on its nest, but this was merely supposition. Breckland crossbills have some other unexpected nest competitors and predators. House sparrows sometimes rifle crossbills' nests, before and after the hens have laid their eggs. In 1967, for example, two pairs of crossbills built four nests in succession, all of which house sparrows pulled to pieces after the crossbills had laid. Another pair of house sparrows ejected a pair of crossbills from their nest and built their own on top of it. These competitors, however, are absent from the natural habitats of crossbills. EGG COLLECTORS

I have described some of the colourful characters who used to hunt for pine crossbills' nests in the Scottish Highlands and for those of common crossbills in East Anglia. Highly successful nest predators though these egg collectors have sometimes been, the sheer size of the Scottish Highland pine forests has ensured that their impact was relatively unimportant and always extremely local. However, between 1900-07 they robbed up to 100 nests in one part of Easter Ross and between 1935-39 took at least SO clutches of eggs in Spey Valley; but even this scale of predation is most unlikely to have affected the status of our wandering groups of native pine crossbills. In the 1920s and 1930s, roadside pines near Thetford, Brandon, Hockwold and Lakenheath, were regular haunts of weekend eggers. In 1923 Edgar Chance, Norman Gilroy and his son robbed 20 nests, and in 1924 Gilroy alone took a dozen clutches in one weekend. In the 1930s egg collecting was more widespread and still more severe. Between 7-28 March 1936 one collector took 11 clutches, and between 23 February and 14 April of that year another robbed 19 nests; and the second egger's bag was only his personal share of a much larger 'group loot'. Since the war, egg collectors have continued to work in East Anglia where they annually 'liberate' many clutches of crossbills' eggs; but most of the robbed pairs seem eventually to rear broods. Even in the years of really high egg predation in the fashionable egging districts, many crossbills have reared broods in nests that the collectors missed. I do not believe, therefore, that this been significant, but its persistence effectively destroyed any possibility of long-term research on the common crossbill populations of East Anglia.

CHAPTER 16

DISTRIBUTION IN SCOTLAND Since 1945 small groups of Scottish pine crossbills have bred in Sutherland, Ross, Inverness, Moray, Banff, Aberdeen, Perth, and possibly Argyll where they have been largely restricted to old Caledonian Forest relicts or to open and mature woods and plantations. The early literature is confusing. The Old Naturalists did not distinguish between resident pine crossbills and periodic invasions of common crossbills from northern Europe. This led to a false impression about the spread and numbers of our resident birds. Let me now consider distribution county by county. SUTHERLAND Around 1840 groups of crossbills settled in, but soon disappeared from, 'fir woods' around Rosehall. In 1848, Charles St John reported that they were 'becoming numerous' and in July 1868 Booth met with a large

'assembly' near Lairg, probably a group of irrupting continental birds. In the 1880s crossbills had deserted the woods near Little Ferry, but had returned by 1894, and were then 'common' in south-east Sutherland. 163

164 Pine Crossbills Between 1895-1969 Ian Pennie and Donald Macdonald knew of no authenticated breeding records, but a few pine crossbills are likely to have bred at least periodically. In 1970 I found my first Sutherland nest in a conifer wood near Rosehall. Since then pine crossbills have nested in at least six different woods. Common crossbills are also probably colonising. In 1974 I watched a mating party, containing two pairs and a single cock, courting in a large wood of old pines, spruce and other conifers in which pine crossbills periodically nest. In August 1974,I also watched a small group of common crossbills with fledged young in another mixed conifer plantation in the south-east of the county. A brood recorded at Altnaharra were also possibly curoirostra. The present status of crossbills in Sutherland is, therefore, fluid but most exciting. ROSS AND CROMARTY

There is more information for Ross and Cromarty. In 1854 Alexander Macdonald of Balnagown took eggs for John Hancock and later supplied clutches to Harvie-Brown and other collectors. On 17 January 1876, Sheriff Mackenzie shot a pair near Tain which had 'large stout bills and characteristics of the so-called parrot crossbills,' About this time, however, Booth mentioned that crossbills had deserted several former breeding haunts. In the early 1890s, Harvie-Brown remarked that crossbills were 'as common as ever and had spread inland to the glens and streams wherever the trees were suitable for nesting and food.' This is puzzling. Did groups of continental crossbills temporarily colonise new plantations or did our resident pine crossbills respond to this newly created habitat? Since 1945Scottish pine crossbills have not become established in the new pine and conifer woods which the Forestry Commission and private woodland proprietors have planted so freely. We do know, however, that at least from the late 1890s until the fellings of the First World War, large groups often bred near Muir of Ord. Old pines and mixed conifers in other parts of Easter Ross also provided much suitable breeding habitat. We know less of what was happening in Wester Ross. In June 1891, A. H. Evans found a pair breeding on an island on Loch Maree and in 1895 Hinxman and Eagle Clarke reported resident crossbills near Gairloch. The 19th century literature contains few other records. In 1952 I found two, probably three, pairs of pine crossbills with broods and a small non-breeding flockin a small wood in the north-east ofthe county. Between 1962-69 at least one, and up to three, pairs bred in this wood. Pairs were also present in 1970-73, and at least two pairs nested in 1974. In irruption years common crossbills sometimes feed there in summer and several pairs and a flock of non-breeders haunted the wood in spring and early summer 1967, but I have no proof of their breeding. Between

Distribution in Scotland 165 1969-74, pine crossbills have also nested in not less than six other woods in north-east Ross. Further south they also nest regularly in large mixed conifer woods, where non-breeding groups and flocks of continental crossbills sometimes winter in irruption years. Thus, Scottish pine crossbills now nest annually in Easter Ross, but from 1961, when I first started to work here, I have never met large breeding populations. For Wester Ross the literature is sparse. In 1938, The Handbook defined the Scottish crossbill's range as 'West to Loch Maree' and in 1953 Baxter & Rintoul could add nothing. In 1959, however, Steven & Carlisle referred to crossbills in the old pines around Loch Maree. There is also a little more recent data. In May 1936, Jack Robson watched a small flock near Garve, and in another year in the 1930sfound a nest in the now felled Inchbae Woods. On 21 May 1961, I. C. T. Nisbet watched a small but clearly identified group of pine crossbills near Shieldaig. Robson also reported pairs without eggs or young west of Garve in May 1964-66, and another pair near Shieldaig in May 1965.Pairs and groups of crossbills are sometimes to be found in the Beinn Eighe Reserve, where single nests were recorded in 1962, 1963, 1966 and 1970. In these years, too, other pairs probably bred. In irruption years large flocks of up to 50 birds also passed through the old pines. R. Balharry recorded these movements in the winters of 1962-63, 1966-67, and 1969-70, all years of continental invasion. In the last 20 years, however, I have no evidence of the massive breeding of pine crossbills. INVERNESS

The New Statistical Account mentioned that crossbills bred at Dyke, Moy and Kiltarlity, but gave no details. In June 1876 Booth hunted for crossbills around Erchless Castle, near Beauly, where the ground was 'thickly covered with the cones which had been thrown down'. He shot 'a green bird which proved to bea female and an orange-red cock'. I have read no other first-hand accounts. In 1935, Richard Meinertzhagen shot some Scottish pine crossbills near Beauly. The skins are now in the British Museum Collection at Tring. A few pine crossbills sometimes nest in the old pines of Glen Strathfarrar, and probably also in the 2000 acres Caledonian Pine Reserve in Affric Forest, where they are occasionally seen throughout the year (J. R. Riddell,pers. comm.). There is no continuous account of the Strathspey crossbills. In 1848, Lewis Dunbar took the first recorded nest and in 1889 R. H. Read described a hen uttering 'a continuous sharp barking kind of croak'-an excellent description of a hen pine crossbill's call of anger and alarm. In 1891 Harvie-Brown claimed that crossbills had arrived 'in successive waves' and that they were 'all over Strathspey and down Speyside as far up Badenoch as Kingussie, whilst the tributary glens of Feshie, Dulnain

166 Pine Crossbills and the minor stream valleys and wooded tracts are full of them'. Yet he mentions that few ornithologists had found nests. Is it possible that, as in Easter Ross, the Victorians sometimes confused passing curoirostra with resident pine crossbills? The lack of years and details makes analysis almost impossible. In the last 250 years the pine crossbills have lost many habitats through felling, and now are probably breeding in much smaller numbers and in fewer woods. In this century most of our pine crossbills have favoured the old forests of Glenfeshie, Invereshie, Inshriach, Rothiemurchus, Glenmore and Abernethy, and relicts of the old Dulnain Forest, west of the Spey. In years of high numbers they also nest in some outlying woods and older plantations. Before the 1920s, few ornithologists studied crossbills in Upper Strathspey, but thenceforward Willie Marshall's notes and those of visiting bird watchers and egg collectors have provided an outline. From 1925, pine crossbills have nested west of the Spey between Aviemore and Carrbridge where there are now far fewer old woods than in the 1920s and 1930s. They have also nested in Alvie Forest and often feed on old larches near Balavil. In 1936 crossbills nested close to Dalwhinnie, sometimes flying to larches above Loch Ericht, I do not know, however, whether these were resident pine crossbills or continental crossbills from the 1935-36 invasion. The wood in which they were nesting was not characteristic pine crossbill habitat. In the 1930s and 1940s our birds nested regularly, but in varying numbers, in large woods, clumps, and stands of pines between Nethybridge and Grantown-on-Spey and had regular breeding groups in pinewoods and plantations around Loch Garten. Some older woods, wind-breaks and plantations close to Nethybridge, Tulloch and Kincardine, and some open plantations outside Rothiemurchus Forest, often held breeding pairs. In 1935 and 1936 small groups nested in planted pines on the edge of Revack Moor, but the trees were felled in the 194Os. They also fed, but did not breed in, windbreaks in Dorback. West of the Spey they nested in the Old Wood of Curr and in mixed pine and larch plantations near Dulnain Bridge. In some years, as in 1935-36, groups of common crossbills wintered around Dulnain Bridge and in 1936 I found two pairs of common crossbills breeding there. In 1865, crossbills were allegedly 'common' in Glen Urquhart, but there had been an invasion of common crossbills in 1863. In 1882, 'they had been known to occur at intervals for many years, but lately had taken up their abode permanently, although they disappeared now and again for a short time.' However, they were then apparently breeding freely, as large flocks 'composed chiefly of young birds' were reported. An irruption had occurred in 1881. In February 1939 and February 1962, cocks were collected, but I have no breeding records. The Old Naturalists apparently never searched for crossbills in the

Distribution in Scotland 167 Great Glen, but old pinewoods in Glenmoriston, Glen Loyne, Glengarry, Loch Arkaig, Glen Loy and Glen Nevis all provided a most suitable breeding habitat. From 1970 onwards, John Currie has recorded Scottish pine crossbills between Glengarry and Fort William, particularly noticing the deep diagnostic calls and heavy beaks in several mixed family parties in Leanachan Forest. He also watched groups in Clunes Forest in July, but has not yet located any in the Old Caledonian relicts in Glens Loy and Mallie. The small groups watched in 1972 and 1973 could have arrived from the east along the Great Glen or from Speyside by way of Loch Laggan. ARGYLL

Steven & Carlisle (1959) were informed that a few crossbills periodically visited Ardgour Forest where the old pines are suitable for our residents, but I have no confirmed breeding records. In March 1971, a pair nested in new conifer forest in Knapdale. This is likely to have been common crossbill, but there is no evidence. In that year Tim Sharrock also found broods in Glenbranter Forest, where they were 'probably fairly common'. Significantly, Glenbrantar Forest consists largely of mature sitka spruce, typical of curoirostra groups in southern Scotland. Relict pines around Loch TulIa are other probable pine crossbills haunts in Argyll. MORAY AND NAIRN

In 1850,Hancock and St John found a brood near Findhorn, and in 1868 crossbills nested in the Altyre Woods, but early history is scarce. In 1895, Harvie-Brown gave the crossbills' breeding range as 'all over Strathspey and down Speyside, the valley of the Findhorn, Ardclach and Darnaway, Altyre, Brodie, Culmoney, the valley of the Nairn at Cawdor and Holm Rose, Forres, the Laich of Moray and the woods which crest the Brae o'Moray above the source of the Lossie'. Unfortunately, he gave no years or details which might help us to assess the proportion of resident pine crossbills against continental immigrants. The early 1900s are equally puzzling. In the British Museum series of 'Scottish crossbills' is a large-beaked cock shot near Elgin in January 1908; but several cocks obtained in Moray during the 1910 irruption lack detailed data. However, on 10 April 1910, H. MacGrath shot a cock at Carron, one of a pair which was probably breeding. This bird, which had a smallish beak, was probably curoirostra. In 1909-10, both species were together in some Moray woods during that great invasion, but we cannot now ascertain how many of each were breeding. The next 20 years are almost blank. On 12 April 1929, Willie Marshall saw a pair building at Blacksboat, and in the 1930s Scottish pine crossbills nested regularly near Castle Grant. Dr Roland Richter tells me that in the 1930s, and probably in the im-

168 Pine Crossbills mediate post-war period, Scottish pine crossbills nested in 'all larger pinewoods and also in smaller stands at Roseisle and Ardgye. About 1960, however, the crossbills became scarcer and they deserted larger forests like Loch-na-Bo and Speymouth, as well as the smaller woods. Culbin and Darnaway Forests then also held smaller groups and populations. In the late 1960s and early 1970s, however, resident groups had slowly built up, but Richter is convinced that there is no regular breeding stock of continental crossbills in the 20 x 10 km squares which he covered for the BTO Atlas. I can add a little more information. In 1953 pine crossbills nested between Forres and Dallas, and William Milne also found them breeding in Culbin Forest. This was interesting, as the great groups which had nested in Upper Strathspey in 1952 had departed before the end of that summer. There are also other records. In April 1966 D. Tuckwell watched a hen building near Forres, and B. Etheridge saw another building in Roseisle Forest. These records are of interest because the 1966 invasion only arrived in Scotland in summer. In 1971, T. Cooper found a nest in Culbin Forest, and D. Humphrey saw one near Craigellachie. M. Muttit, also, tells me that crossbills now breed regularly in Monaughty Forest. On 28 May 1972, Muttit saw a pair with young on the wing near Lochindorb and located pairs at Findhom Bay, and at Loch of Blairs in the spring of 1973. On 26 August 1973, a party of seven hens was also recorded at Loch Spynie. Thus, the larger forests and older plantations in Moray, now, probably carry a small regular breeding population of pine crossbills which move from wood to wood in different years. BANFF

There is little published information about crossbills in Banff. In 1845, the New Statistical Account for the Parish of Banff mentioned crossbills, and in 1864 they apparently bred near Huntly. The crossbill is also listed in an account of The Birds of the Cullen Woods, towards the end of the century. The later literature is almost equally unhelpful. In June 1946, however, Adam Watson watched crossbills feeding 'three or four fledged young at Foyte House, Banff'. In early July 1971, a hen and brood were seen feeding on a larch near Keith, and in 1972 a pair bred near Glen Rinnes Lodge, Dufftown, and a family party was recorded in Glenlivet (E. S. Bruce, pers. comm.i. It is not known which species these birds were. ABERDEEN

Pine crossbills have probably always nested in the old Deeside forests, but there are few early records. In 1769 Pennant saw 'pine grosbeaks flying about the great pine forests of Invercauld in Aberdeenshire; and I imagine they breed there for I saw them on 5 August.' Surely these were crossbills? I know of no records of

Distribution in Scotland 169 pine grosbeaks in summer, either in Dee or Spey, whereas the Invercauld pines are breeding habitats of Scottish pine crossbills. There are a few casual mentions of crossbills in Aberdeenshire, but few early breeding records. On 4 July 1821, some masons building a lodge near Gordon Castle saw crossbills feeding 'very familiarly' and believed that they heard young calling. However, there was a large continental irruption in that summer. In early spring 1865,Robert Cameron, a village dominie, watched flocks and later found a nest near Loch of Skene, which the hen deserted in a snowstorm. In 1863 there had been an invasion of continental crossbills. In 1866, a pair nested at Methlick and, in April 1893, George Muirhead took a nest with four eggs near Haddo House. No recent irruptions in either year. The later literature is equally sketchy. On 7 July 1935,Henry Boase saw a family party near Braemar and, on 17 July, G. Sandeman watched a similar group at Ballater. There is also a little unpublished information. Between 31 August and 12 September 1940, six cocks were shot near Ballater. Alan Knox, who has critically examined three of the skins in the British Museum Collection, judges that these were large-beaked Scottish crossbills. In July 1943, and in other years unknown, Bernard Tucker, who saw crossbills in many woods around Braemar, 'formed the opinion that they were mostly common crossbills,' but pointed out that in late summer these might have been continental immigrants. In July 1945, Adam Watson located two broods near Braemar and in 1946 a nest with small young at Birkhall. In June 1948, he also saw many flying broods in Glen Derry and, on 29 June 1950,watched parents feeding downy young in this glen. In May 1955, Bob Scott also watched crossbills feeding their young, which still showed traces of down. Watson remarked that these crossbills had larger beaks than the curoirostra which he had recently been watching in Norway. Their calls were not assessed. Comparison between records in these years suggests that groups of Scottish pine crossbills probably shuttled between Upper Strathspey and Deeside and, possibly, Lower Moray. From 1966 onwards, Watson and I have annually visited many of the Upper, Middle and Lower Deeside woods, where the crossbills had nested in the 1950s. Between 196Cr-68 we met with few crossbills, but in July 1969 I identified the calls of a small flock of common crossbills in Glen Quoich. From the winter of 1969 onwards, Deeside crossbill populations slowly built up, but I only distinguished the calls of pine crossbills in Ballochbuie in 1971 and Glen Tanar in 1972. In 1973, a pair of crossbills attempted to nest in Balmoral Forest, but their calls were not assessed. In April 1974, however, Alan Knox found two nests in Glen Tanar, where the cock at one, and the pair in the other, uttered the deep diagnostic Scottish

170 Pine Crossbills pine crossbill calls. Knox later found quite large groups of the large-beaked Scottish crossbills breeding in other parts of the forest, as well as a number of non-breeding flocks. He collected specimens which he identified by the size and shape of their beaks. Groups of continental crossbills, two of which he shot for comparison, showed the much thinner and distinctive beak which is most noticeable when the skins are laid side by side. These groups of common crossbills nested in planted pines in Glen Dye on the Aberden-Kincardine county march. In 1974 Adam Watson also reported a pair of crossbills with young at Ballochbuie but their calls were not noted. However, it is now certain that both Scottish and common crossbills have bred in at least two consecutive years in Deeside. KINCARDINE

In the irruption years of 1886-87 about 100crossbills frequented Drumtochty Glen, some apparently nesting. In October 1897, another irruption year, 30-40 again settled there, 'consuming all the larch cones as they went along'. In 1900 more flocks were recorded and in 1903 a pair nested 'on a horizontal branch of a larch about 50feet from the ground'. One of theyoung crossbills fell out of the nest. There are very few later records for Kincardine. In April 1943,Ian Pennie watched two pairs near Banchory and later watched a pair with two newlyfledged young in late April and early May. He also saw other crossbills at Tilquhillie on 29 March and 27 April, but had no proof that they had bred. The calls were not recorded. In the 1950s, crossbills bred in some numbers but there is no proof of species (A. Watson). Between 1966-68, numbers were low but flocks settled in mixed conifers near Blackball in the winter of 1969. This was in the second winter after the large 1966-67 continental invasion. N. Pirozzi caught and measured one of the cocks which wasclearly a continental bird. In 1972 there were still large groups, mostly non-breeding, in Kincardineshire, but in 1973 at least one pair reared young. In 1974, groups reared young in Glen Dye. There were also parties of non-breeders (A. Knox, pers. comm.). Scottish pine crossbills thus do not appear to breed regularly in lower Deeside, where recent breeding pairs, or groups, may have been common crossbills. However, both species were in Glen Dye in 1975. ANGUS

In May 1963-the summer after a continental invasion-a pair of crossbills nested in Kinnaird Park, Angus. PERTH

About 1779, crossbills started to nest at Dunkeld, 'since the larix (larch trees) on the cones of which they live has been cultivated' (O.S.A.). Don (1813) mentions that crossbills 'destroyed many cones in 1811 and 1812', and in 1839 hundreds were attracted to the Carse of Gowrie by an excep-

Distribution in Scotland 171 tionally large crop of larch cones. In 1810, and in the late 1830s, there were several large irruptions from northern Europe. In 1887 Booth, who often worked in Glen Lyon, mentions meeting 'a few small parties on two or three occasions in Perthshire ,. But I can find no detailed records in his MS notebooks. There was apparently no acceptable breeding record until 1902, when a pair nested at Bridge of Ericht and another at Rannoch Lodge. However, flocks, groups and occasional breeding pairs, possibly prompted HarvieBrown ( 1906) to assess the crossbills status in Perth as 'resident, abundant, and rapidly increasing in all mature woods and plantations'. However, he appears to have ignored all continental invasions, attributing this increase to a massive break-out from the forests of Spey and the woods of north-east Moray, Ross and Sutherland. It is now impossible to assess precisely what happened, but the crossbills which periodically nested and settled in the Perthshire larch woods were more likely to have been invading curoirostra from the continent, than a large mobile surplus of native pine crossbills spreading out from the northern and central Highlands. In Perth, as in other parts of northern Scotland, our resident Scottish pine crossbills were then, as now, probably breeding in the few old Caledonian relicts, or in a handful of old open pinewoods. Crossbills still breed in Perthshire. On 6 May 1966, Jack Robson watched a pair in the Black Wood of Rannoch, but Dr Valerie Thom tells me that they are scarce there and in other parts of the county. Crossbills have also bred near Dunkeld, Kirkmichael and Connel, but I have no evidence of species. However, D. R. Rose tells me that the groups he watched in late autumn or early winter appeared to be continental curoirostra. Only in old Caledonian pines in Glen Lyon and Rannoch, where the crossbills fed almost entirely on pine seeds, has he been able to identify the diagnostic calls of the Scottish pine crossbills. In newer plantations 'the birds exhibit the characteristics of continental crossbills and feed in plantations of spruce, larch and pine. I have not seen any Scottish crossbills outwith the area of semi-natural pine'. Between 1971-73, Charles Reed of Rannoch School, found eight crossbills' nests near Kinloch Rannoch in 15 to 20 years old spruce/larch and Douglas fir plantations. In 1971 he found four nests, and in 1972 and 1973 two nests in each year. None of these nests were high above the ground. 'The only call that I have ever heard is the metallic flight call'. These two interesting communications suggest that groups of common crossbills are possibly colonising newer conifer plantations outside the main breeding habitats of our native Scottish pine crossbills. DUMFRIES AND KIRKCUDBRIGHT

Large groups of common crossbills now rest in the sitka and Norway spruce plantations and new forests in Dumfries, Kirkcudbright and other

172

Pine Crossbills

Provisional map showing the breeding range on 10 km square grid of crossbills

Loxia from the B . T . D . / I . W . e . forthcoming Atlas of Breeding Birds in Britain and Ireland--data are for the period 1 9 6 8 - 7 2 .

Distribution in Scotland 173

Breeding range of Scottish pine and common crossbills in Scotland and northern England.

parts of southern Scotland, where they sometimes breed almost continuously from October onwards. A few birds have been critically examined and shown to be curoirostra. After the 1966 invasion numbers greatly increased, but groups of crossbills were already established in these plantations. These groups, however, do not nest in high numbers in the same woods in consecutive years, but move from forest to forest much as do Scottish pine crossbills in the Highlands and common crossbills in East Anglia. 1974 was a bumper season for them in Ae Forest (Newton, pers. comm.i. SOME CONCLUSIONS

We can only speculate about the 19th century distribution of crossbills in Scotland. In the years when Harvie-Brown and his correspondents were 'exploring' the Highlands, crossbills nested in far greater numbers than they now do. This was particularly applicable to Ross, Moray and Perth; but the Old Naturalists possibly failed to discriminate between flocks of predominantly non-breeding continental immigrants and the smaller breeding groups of native pine crossbills which were probably

174 Pine Crosshills always restricted mainly to the old pinewoods of the northern, northeastern, and central Highlands. In the second half of the 19th century, however, common crossbills of northern Europe possibly settled temporarily in large and mainly mixed conifer plantations in Ross and Inverness and in larches in Perth. The 1970s offer a most interesting comparison. Groups of curoirostra are now finnly established in the new conifer forests of southern Scotland and are already breeding in planted pines in lower Deeside, They probably now nest and may soon establish colonies in mixed conifers in Sutherland, Inverness, Perth and Argyll and also possibly in Caithness, Ross and Moray. We thus now have a second opportunity of studying and perhaps solving some of the problems which have greatly puzzled contemporary ornithologists.

CHAPTER 17

MOVEMENTS, NUMBERS AND POPULATIONS Common, pine and two-barred crossbillsperiodically erupt in great numbers from their breeding habitats in northern Europe; but partly because they are much more plentiful and widely spread, common crossbills make more frequent and dramatic breakouts. Differences in the food ecology of the three crossbills tend to prevent them nesting in the same location in the same year, but they often explode simultaneously. In 22 of the last 27 irruptions the proportion and numbers of pine crossbills in these invasions varied greatly (Newton 1972). In 1929, however, more pine than common crossbills arrived in Denmark, but this trend was reversed in the great 1935 invasion. In 1953 and 1962,pine and common crossbills broke out simultaneously and in the next spring many pine crossbills bred in Qstergotland. 1962-63 produced the only sizeable recorded influx of pine crossbills to Britain, when about 50 were noted on Fair Isle, and 20 in East Anglia and north Scotland, between October-May. In 1963, a pair of pine crossbills probably nested in Surrey (P. Davis 1964). Why do the larger pine crossbills seldom build up really large breeding groups and far fewer break out from their boreal pine forests? Surely because they are scarcer, have a more restricted breeding range, and large175

176 Pine Crossbills ly depend on the pine which has a more consistent crop of cones. Thus, pine crossbills usually adjust to local shortages by making smaller movements than the more bloated populations of curoirostra are periodically compelled to make. This probably explains why so few pine crossbills reach Britain, although some may be overlooked in the swarms of invading curoirostra. The pine crossbill is, therefore, a scarcer and less volatile species. Common crossbills sometimes invade Britain in great numbers. Between 1900-72 there have been 23 invasions, of which 17 have been large. In 1909--10, 1938-39, 1958-59 and 1962-63, crossbills arrived from northern Europe in consecutive years. The largest invasions have occurred in years when the spruce has failed over much of Fenno-Scandia and northern USSR, particularly in 1909, 1930, 1935, when immense numbers of curoirostra abandoned the boreal forests. However, spruce seldom fails so completely and simultaneously in so much ofN.E. Europe; most poor seed years are either local or, at most, regional. In some years, when the spruce failed, however, the common crossbills did not erupt and in others they began to leave before the new crop of cones had ripened. Some mass exoduses in consecutive years, moreover, evidently originated from different parts of northern Europe. For example, between 1900-70, spruce failed in 14 different years in Sweden, in only six of which there were eruptions of common crossbills; most of the emigrants originally came from Russian forests in three of the years. On the other hand, large flocks abandoned the Swedish forests in 1927, 1953, 1956, 1968 and 1962, all years of moderate spruce cone crop. Significantly, however, no 'break out' took place in bumper spruce seed years; all eruptions from Sweden occurring in years of poor or at most moderate cone crop. Eruptions usually start in July and August before the ripening of the new cones; but the common crossbills, which can possibly assess a new crop, often avoid eruptions by discovering new feeding habitats within their normal breeding range. Thus, eruptions probably occur when high numbers and shortage of seed synchronise and so trigger off the mass excitement which induces emigration. The arrival of swarms may then excite groups of pine crossbills if these have attained high numbers in these particular years. No one has discovered, however, what proportion of a particular population joins the exodus and why part fails to respond to the mass excitement, and stays behind to exploit what remains of the cone crop. Even in their peak years pine crossbills are much scarcer than common crossbills. In Kirkkonnummi, about 20 miles from Helsinki, for example, in 1966-67 when pine crossbills had their largest populations between 1964-74, Hilden counted only 27 birds on 2 January and 120n 27February in his 16 km transect. In the followingwinter, in the bestyear for curoirostra in the same period, he recorded 145and 110birds in these same months. The two species do not breed here in the same open pinewoods in the same year.

MOfJements, numbers andpopulations

177

BREEDING DENSITY

In years of high numbers Scottish pine crossbills often nest in loose groups. Two to six pairs then sometimes breed in small woods or in particular parts of larger woods, building their nestsfrom 50 to 400 yards apart (maximum density 6 pairs in a wood of 26 acres). The settlement ofa mating group in a particular wood probably leads to this high breeding density, but each pair defends its own 'core' territory, On the other hand, even in peak years, some pairs nest in isolation with nests a mile or more apart. Inyearsof small numbers most pairs are well spaced out, although two or three nests are sometimes found in a large wood. In 1960,however, a year ofmuch pine seed, five pairs in Rothiemurchus and Glenmore Forests were irregularly spaced, with their nests sited at intervals of 1 mile or more. In 1903, on the contrary, Stirling located two nests on the same tree at Fairburn. When found one nest had one and the other two eggs. Pine crossbills have similar patterns in Fenno-Scandia and U.S.S.R. In Norway 0ye, Valeur and Spjetvill met with small breeding groups with nests about 100 to 200 metres apart. In 1967 Hilden recorded three nests within 8 acres near Helsinki and Kokhanov and Gaev describe roughly the same breeding dispersion on the Kola Peninsula. Breeding density in curoirostra groups in England and Scotland varies greatly. In Breckland I oftenfound isolated and solitarypairs as well as small breeding groups. Robson has had the same experience, but emphasises the existence of groups containing 3-12 nesting pairs. In one year two pairs built nests on adjacent trees, but not simultaneously. Flack also recorded 5-7 nests in double rows of roadside pines near Brandon. All these nests were in a line of trees not more than 300 yards long. There are sometimes isolated breeding pairs on the heaths and commons of Surrey and Hampshire, but in March 1936--an irruption year--Gosnell located two nests with nests only 50 yards apart. Breeding density in the Dumfries groups varies. In 1967-68 G. Trafford (in litt.) told me that two nests were 100 yards apart, but that most were spaced at intervals of about 300 yards. In irruption years on the continent, density is sometimes much higher. In 1942, for example, 10 pairs nested in a 2-acre plantation of young spruce trees in Jamtland, Sweden (Svardson, 1957). NUMBERS IN RELATION TO CONE CROP

In Finland, Reinikainen (1937) and Haapenen (1965, 1966), discovered that common crossbill numbers are closely related to the spruce crop, and that in early autumn they tend to settle in woods and forests where cones are plentiful, and then breed there in the spring. As the spruce crop differs widely in different parts of Finland, there are great regional differences and fluctuations in the crossbill groups. Haapenen's research

178 Pine Crossbill» shows, however, that groups which have settled in pines fluctuate less significantly from year to year. There is a different pattern on the Kola Peninsula where pine and common crossbills sometimes breed in large numbers and two-barred crossbills at lower density. Around Kandalashka, many pine and common crossbills bred in the spring and summer of 1959, when there was a bumper crop of spruce cones and a good yield of pine. In 1962,with a good crop of spruce and a fair pine cone crop, and in 1966,with a fair spruce and a good pine yield, common and pine crossbills also nested in fair numbers. In this region, therefore, the spruce was evidently the most important food tree for all species of crossbill. None nested in 1960 and 1965,for example, when there was a moderate crop of pine cones but a scarcity of spruce seed. Here, however, where pine crossbills breed in all kinds of conifer forest, they nest later than curoirostra in good spruce cone years. In years of plentiful pine crop, and a good autumn seeding of spruce, however, they also nest from May to September. On these mixed habitats, therefore, the pine crossbills sometimes appear to be the most successful species. NUMBERS AND POPULATIONS OF SCOTTISH PINE CROSSBILLS

From 1934, I have studied Scottish pine crossbill populations in Upper Strathspey and from 1962 some groups in Ross, Sutherland and Aberdeen. I summarise records in Tables 10-14. Table 10 shows fluctuations of some breeding populations in Upper Strathspey between 1933-42 when I was working in the forests of Abernethy, Rothiemurchus and Inshriach. In the last nine of these years, I made roughly the same effort to find nests in my study areas. These estimates thus give a fair impression of the size of local breeding groups in nine successive years. I also show Willie Marshall's annual assessments of the Scots pine crop in Abernethy Forest, which are based on his field observations and the yield of seed in cones dried in the kiln at Nethybridge. Marshall classified the cone yield in three simple categories: (a) bumper, (b) fair, which includes moderately good seed years, and (c) low, little seed in the cones. Donald Carr, now Head Forester at Nethybridge, has also given me similar assessments from 1964 onwards. The Scots pine has an inconsistent coning pattern, but Marshall discovered that in a period of 30 years there were roughly 10 good, 10 moderate and 10 low seed years. Heavy yields, however, did not occur at regular 3-yearly intervals. This index applies to most of upper Strathspey, but is not always valid for woods in the lower Spey and the Findhom valleys, where cone crops were not always similar to those in upper Strathspey. Table 10 shows that the pine crossbillsnested in high numbers in the three seed years of 1933, 1936 and 1942, and in the fairly good cone years of 1935 and 1938,but that their breeding numbers were lowest in 1934 and

MOfJements, numbers andpopulations 179 1957, the poorest cone years in this decade. Table 11 covers a longer period in less depth and detail, but the records in the 1950s suggest a relationship between cone crop and breeding numbers. 1936 and 1952, with the largest populations, synchronised with bumper cone crops. In most other seed years, the pine crossbills also nested in high or fairly high numbers, with fewest breeding in years of the lowest seed yield. In two years only-1935 and 1936--pine crossbills bred in high numbers in consecutive years. In 1937few pairs nested in any of my study woods, in all of which the cones had failed. From 1966 onwards, when I was looking at crossbills over a much wider area, I never met with any really high-density populations in any part of the north or north-east of Scotland. In these years, moreover, the relationship between crossbill numbers and the cone crop was apparently less clear-cut than in the 1930s, 1940s and 1950s. The years 1968 and 1971, bumper seed years in upper Strathspey, did not synchronise with peak numbers of pine crossbills. In 1968, few pairs bred in Rothiemurchus; and I have no evidence of large breeding groups in other parts of upper Strathspey. In 1971, however, although the Strathspey forests did not carry bumper populations, pairs and small groups were recorded elsewhere, particularly in Sutherland, Ross, West Inverness, Moray and Aberdeen. In 1972, on the other hand, a poor year for cones in Abernethy Forest, a fairly high number of pairs bred there and in other Spey Valley forests, and in Affric, Strathfarrar, Moray and in Glen Tanar in Aberdeen. But I found fewer pairs in Ross and Sutherland than in 1971. Continuous felling of mature pines in the Nethybridge area, has possibly concentrated local groups of crossbills in parts of Abernethy Forest and its outlying woods, where the topmost branches of the old pines seldom fail to produce a fair crop of cones in almost every year (D. Carr,pers. comm.). The slow build-up of breeding populations continues. A fairly good seed year in 1974 synchronised with larger breeding groups in Ross, Sutherland, parts of Inverness and Aberdeen. Shall we soon meet with more breeding pairs, larger groups, and a more consistent relationship between numbers and cone crop, as in the 1930s, 1940s and 1950s? Table 12 which records the numbers of nests found on an Easter Ross estate between 1898-1907, possibly has a different pattern. In these years the proprietor and his keepers yearly attempted to find every crossbill's nest on the estate, but unfortunately he did not note the cone crop. However, the crossbills fed on spruce and larch as well as on pine. The mixture of conifers in these woods helps to explain the greater stability of the crossbill groups. After finding 23 nests in 1903, for example, the searchers located 16 in 1904. In this period numbers probably fluctuated, though apparently less dramatically than in upper Strathspey in the 1930s and 1940s.

180 Pine Crossbills Table 13 shows the numbers nesting in a small hillside wood of about 150 acres in north-east Ross where, from 1962-74, I counted the crossbills and roughly assessed the crop of cones. Here, too, there appears to be a relationship between numbers and cones. In the 1930s I watched crossbills in upper Strathspey only, and thus do not know where the nomadic groups came from in good cone years, or where they went in less productive years. But from 1945, while I was working in Strathspey, Adam Watson was watching crossbills in Deeside. Table 14 compares our records, which suggest that between 1945-55 the same large nomadic groups may have shuttled between the old pines of Dee and Spey. In 1950, large numbers of crossbills bred on Deeside, but few in Rothiemurchus where the pines produced little seed. In 1952, on the contrary, larger groups of crossbills nested than in any year since 1935. Hundreds of pairs then bred in upper Strathspey, but very few there or in Deeside in 1953. However, I discovered many in the older woods and plantations of the Findhom and lower Moray valleys, which were then enjoying a better cone crop than that in Rothiemurchus. Why were there so many large wandering flocks in the early 1950s? Have wartime and post-war fellings of old pinewoods, on both sides of the Cairngorms, deprived high density crossbill groups of vital living-space, thus compelling them to move further afield than in the past? Scottish pine crossbills are extremely selective in choosing breeding habitats, particularly favouring open and mature pinewoods in sunny places and avoiding closer canopied plantations even when otherwise suitable. In the 1940s many favourite breeding woods were felled in upper Strathspey. ERUPTIONS

Scottish pine crossbills erupt from their Highland breeding habitat in much the same manner as common crossbills leave the boreal forests. However, because their populations are smaller and usually restricted to pinewoods, they tend to make shorter journeys before discovering better cone crops in other parts of the Highland area. Our residents thus nest regularly somewhere among the older pinewoods between Sutherland in the north and the Black Wood of Rannoch in the south. Truly eruptive movements only take place, however, in years of the highest numbers. In most years, after breeding successfully in particular woods, the pine crossbills disperse and settle in autumn in adjacent or less distant forests or plantations, where the new pine or larch crop is superior to that left behind in their recent breeding haunts. These short journeys often enable quite large groups to disperse locally without any semblance of a classic eruptive movement. However, I do not know if any of our native crossbills, in years of peak populations, join the excited flocks of continental invaders which periodically pass through their breeding woods.

MOfJements, numbers andpopulat'ions 181 After breeding well for several years in different parts of their range, big populations sometimes build up and may then move further and more explosively. In the summer of 1936, for example, I often watched large noisy flocks on the move. Most of the pine cones had then shed their seed and could no longer support the swarms of crossbills, The excitement shown by these highly mobile flocks recalled those accounts of preeruption frenzies in boreal forests. By late summer few crossbills remained in Upper Strathspey and, in March and Apri11937, only a few pairs bred in the woods which had previously supported hundreds in the spring and early summer of 1936.Moreover, these few pairs nested exceptionally late, presumably because the poor cone crop delayed attainment of breeding condition. In spring 1938,however, fresh drafts, some only settling or dispersing in March or April, took possession of many former breeding woods, but I do not know whether these new settlers had bred or had been reared in these pines in 1936. It was the same story in 1952, when there were only slightly smaller breeding groups than in 1936.All through June I watched and listened to the noisy excitable groups lilting overhead. By late July almost all had gone from the old pines of Rothiemurchus. A particular pair of crossbills seldom seems to breed in the same wood in consecutive years. In the 1930s and 1940s,for example, I never located a single hen with distinctive eggs nesting in the same wood or forest for more than one year. Between 1964-67, however, an isolated pair probably nested annually in a small Easter Ross pinewood, where these two birds were often seen together in autumn and winter. The 'jizz' of the cock and the brooding behaviour of the hen were remarkably consistent. Different pairs held territories in this wood in 1967 and 1968. Other cardueline finches are, probably, likewise unattached to particular breeding habitats. In Sweden, for example, a banded siskin was recovered in breeding woods 120 km apart in consecutive breeding seasons and two marked mealy redpolls were re-eaptured in woods 280 and 550 km apart (Newton 1972). Crossbills are likely to have the same patterns, but we have no ringing returns to guide us. NUMBERS AND CLUTCH-DATES OF SCOTTISH PINE CROSSBILLS AND SISKINS IN STRATHSPEY

In northern Scotland, siskins (which feed largely on conifer seeds in early spring, and partly on insects in summer) share some of the pine crossbill's breeding habitats. In spring, however, siskins feed mostly on larch and Norway and Sitka spruce, and much less on pine cones. In summer, they rear the chicks of second broods mainly on small insects taken on birch and conifer. Their patterns of breeding dispersion also differ from those of the pine crossbill. Siskins often breed in small nesting clusters in clumps and plantations of spruce and larch, but in rich pine cone years many also nest in open pine woods where, in warm springs,

182 Pine Crossbills they frequently remove seeds from discharging or partly opened cones. In Czechoslovakia, Turcek found that siskins were unable to extract seed from unopened pine cones unless the crossbills had partly opened them and left them hanging on the tree. In northern Scotland, however, siskins successfully exploit pine cones, but they need the sun to assist them. In Table 15, I have compared breeding numbers of pine crossbill and siskin in the same years, and have recorded the dates of the earliest clutches of each species in the same pinewoods. The earliest siskin clutches were recorded in the bumper pine seed years of 1936 and 1942, the two years in which pine crossbills also laid earliest in my IO-year study. On the other hand, both siskin and crossbill were late in nesting in the poor pine seed year of 1937, but siskins then nested in fair numbers in some of the Strathspey woods which the large crossbill breeding groups of the previous spring had then almost deserted. There were also other inconsistencies. Siskin and pine crossbill both nested unexpectedly early in 1941, a year of only moderate pine cone crop. Although breeding populations of siskins are highly volatile, they seldom crash as suddenly and completely as do those of the pine crossbill, probably because the siskins depend less on a single cone crop. In almost every year, moderate to large breeding groups of siskins breed in parts of upper Strathspey, although the same woods are not always favoured in consecutive years. In any particular wood or district, therefore, there is a great annual variation in numbers. In northern Europe irruptions sometimes greatly inflate local breeding stocks. In the spruce seed years of 1935 and 1949, for example, very large populations reared broods in northern and southern Sweden where, much as in a crossbill irruption, the large groups which settled in autumn, in woods and forests heavily laden with spruce cones, nested there in the following spring and summer. Invasions from northern Europe may periodically swell native breeding groups in our Scottish forests, but I have had no acceptable evidence. NON . . BREEDING

In tables 10 and 13 I have briefly referred to the non-breeding rump, or surplus, which always appears to be a component of Scottish pine crossbill populations at all levels. In years of high and low numbers, and of good or poor cone crops, groups of unmated cocks in all phases of plumage constantly wander through the pinewoods, often invading or straying into occupied territories. Even in years of low breeding numbers, these parties often contain some unmated hens and non-breeding pairs. Single unattached birds--usually cocks--may likewise move from wood to wood where they periodically clash with breeding pairs. In my experience, however, mixed parties have almost always contained more cocks than hens, but on 26 August 1973, C. Gervaise watched a group of seven hens attacking green cones in a pinewood in Moray.

Mooemenu, numbers and populations 183 What are the causes of this phenomenon? It is impossible to determine the age of a hen in the field,but I have found cocks breeding in all phases of scarlet and of orange plumage. In both Scotland and East Anglia, moreover, cocks in green feather, indistinguishable except in the hand from that of mature hens, have sometimes bred successfully and without any apparent disadvantage. The males belonging to the non-breeding packs are thus certainly not all immature or incapable of breeding. Some males in these groups sing and fight vigorously and occasionally establish flexibleterritories to which they successfullyattract hens laterin the season. Here are a few thoughts about these most puzzling problems. 1. The crossbill's exacting breeding regime helps to explain the existence of non-breeding pairs and groups in poorer seed years. In the demanding environment of late winter and early spring, and virtually dependent on a single food, inexperienced or inefficient pairs (or those in which the males are poor providers) are likely to fail to breed, or will breed late. The large proportion of non-breeding birds in curoirostra invasions gives some support to this idea. In some irruptions in England, for example, a very small proportion of the invading population breeds, probably because the various cone crops are insufficiently rich or accessible to bring the majority into breeding condition. 2. In years, or sequences of years, of moderate numbers and good or fairly good coning, a greater proportion of the less efficient pairs is likely to breed. This is probably a factor in the rapid build-up of a previously depleted population. 3. The non-breeding surplus in years of peak or high numbers is less easy to explain. Is it possible, however, that the great excitement and social stimulation, so noticeable in the pre-breeding mating assemblies, which often results in good and early nesting, simultaneously triggers the start of eruptive excitement in lower status birds? This is speculation but, for a bird with such a fluctuating and specialised food, this would make ecological sense in years with exceptionally bloated populations. As we have seen, seed famines tend to follow the richest cone years. If every member of an exceptionally high population had bred, still larger numbers would be compelled to undertake even greater movements to avoid straining limited resources. 4. The excess of males over females in the non-breeding packs is possibly easier to explain. In all crossbills, the male is under great pressure as a provider throughout the protracted breeding period, from courtship feeding until the young can maintain themselves. Selective forces may thus ensure a small surplus of males as replacements, and possibly as

184 Pine Crossbills nurses or foster parents for the young crossbills in their first and most vulnerable month away from the nest. 5. At the regional level, periodic large-scale felling of old and specially favoured pinewoods, as during and after the two World Wars, probably leads to temporary movements of mobile packs which have lost important habitats. Scottish crossbills are clearly highly selective in their choice of breeding habitat. BREEDING NUMBERS AND POPULATIONS, 1965-74-

There are many difficulties in assessing the breeding numbers of Scottish pine crossbills. Even in years of large populations, the crossbills do not breed in many apparently suitable woods, although in others several pairs sometimes breed close together. Multiplication of small samples is thus likely to lead to many errors. Non-breeding pairs and groups are other sources of confusion. The frequent annual movements from district to district also prevent long-term comparison. Any population estimate is thus likely to be little more than an informed guess. Here, then, are my assessments for the last decade. SUTHERLAND

A few pairs bred in 1970-74, when nests or broods were located in at least seven different woods. I doubt, however, whether more than 15 pairs of pine crossbills have nested in Sutherland in anyone year. In 1974, I watched pairs of common crossbills and later located a mobile flock which contained adults and flying young. ROSS AND CROMARTY

Between 1967-74, I have had no evidence of large breeding populations in Easter Ross. In 1971, pine crossbills bred in at least four different woods. In other years there were many non-breeding groups and some apparently non-breeding pairs. 1974 was the best year, with a good scattering of breeding pairs, as well as mobile groups. Small groups nested in Wester Ross in 1966 and 1970, but pine crossbills apparently no longer nest regularly around Loch Maree or in the Beinn Eighe Reserve. No reliable information about breeding numbers in Shieldaig or in other Wester Ross woods. In Ross and Cromarty, up to 40 pairs may have nested in 1974, but this is only an informed guess. INVERNESS, NORTH OF THE CALEDONIAN CANAL

Small groups have nested in Glen Affric and Glen Strathfarrar, and probably around Fort Augustus, but I have had no evidence of large breeding populations during this period. Possibly, 25 pairs bred in 1972. Insufficient records for other years.

MOfJements, numbers andpopulations

185

EAST INVERNESS AND UPPER STRATHSPEY

The 1966-69 numbers were low or fairly low. There was an increase between 1970-72, with numbers fairly high in 1972 when T. Milsom watched breeding birds and broods in Rothiemurchus, Glenmore and Inshriach. On 18 July, he saw a flock of 40, mostly males, which he identified as Scottish pine crossbills. In July, however, the position was confused by an invasion of curoirostra. In all years there has been at least a small breeding population in upper Strathspey, about 10-15 pairs breeding in Abernethy Forest in almost every year (D. Carr). Groups shift from forest to forest, but numbers have never equalled those recorded in the peak years of the 1930s and early 1950s. I suggest that up to 80 pairs may have nested in the best years. WEST INVERNESS

Small breeding groups reported. In 1970-73, small parties recorded in Leanachan Forest, with 1971 the best year. Few pine crossbills in 1973 (J. Currie), Insufficient records to estimate population, but possibly up to 10 pairs. ARGYLL

The crossbills which nested in Knapdale and Glenbranter Forests in 1971, are likely to have been curoirostra. An estimate of breeding pine crossbills is quite impossible. MORAY AND NAIRN

Low breeding numbers in the 1960s but a few pairs nested in the larger forests. In the 1970s, numbers started to build up. Broods were recorded in woods and forests close to Forres and Elgin. A nest was also found near Craigellachie in 1971 and another at Lochindorb in 1972. I doubt whether more than 40 pairs have bred in anyone year. BANFF

No records of large breeding groups. A family party was seen at Keith in 1971 and a nest found near Dufftown in 1972. Possible maximum, 10 breeding pairs. ABERDEEN

Between 1967-69, Adam Watson and I found no breeding pairs, but in April 1970 met with two pairs in Glen Tanar, one of which had no nest. In 1972, there were pairs in Glen Tanar and in Ballochbuie Forests, but the numbers were at only a moderate level. In 1973, there were also a few birds; one pair nested unsuccessfully near Balmoral Castle. In 1974, Alan Knox located large groups in some of the Deeside forests, where he estimated that there were not less than 350 birds at the start of the year. Between 50 and 100 pairs may have bred there.

186 Pine Crossbill« Did these groups, by far the largest recorded during the last decade, contain elements of the fairly high breeding populations which nested in upper Strathspey in the poor seed year of 1972? This would be in line with experience in the early 1950s. In 1974, Knox also recorded curoirostra nesting in Glen Dye, Kincardine, and R. Rae found an autumn nest in Mar. PERTH

Small numbers have nested in the Black Wood of Rannoch, but the probable presence of colonising common crossbills prevents any reliable estimate. Valerie Thom tells me, however, that she has never met with large breeding groups. SUMMARY

Their erratic local and regional movements prevent reasonable estimates of breeding numbers. In the lowest years of the 1960s, possibly less than 100 pairs of our resident pine crossbills nested in the north of Scotland. In the 1970s, however, breeding groups have built up. The maximum estimates for anyone year in the different pairs of our bird's range are: Sutherland, possibly 15 breeding pairs. Ross and Cromarty, 40 pairs. Inverness, north of the Caledonian Canal, 25 pairs. East Inverness and upper Strathspey, 80 pairs. West Inverness, 10 pairs. Moray, 40 pairs. Banff, 10 pairs. Aberdeen, 100 pairs. Perth and Argyll, no estimate. This gives a total of 320 pairs. These maxima, however, did not all apply to the same year. The size of the terrain, the erratic annual movements of groups, many gaps in coverage, and the presence of curoirostra invaders, make a worthwhile population estimate almost impossible. In the late 1960s I had no evidence of any large population in any part of the Scottish pine crossbill's area. However, this is a resilient bird, capable of rapid recovery and increase after periodic slumps. In the best years of the early 1970s, allowing for many gaps in knowledge and a great deal of conjecture, it is possible that there has been a stock of about 1500 adult birds widely dispersed over north and north-east Scotland, but I must again emphasise the roundness of the figure. Clearly, however, it is disquieting to compare present numbers with the large groups containing hundreds of pairs which nested in upper Strathspey, alone, as late as the 1950s; but the recent recovery is promising and the large Deeside groups in 1974 give hope for the future of our bird.

CHAPTER 18

SPECULATIONS All my special-study birds have been quite different, and all have lived in quite different habitats. The dotterel and the snow bunting belong to the remote and misty high tops, the greenshank to wet and stony flows and a few forest bogs and clearings, and the Scottish pine crossbill to the old pinewoods and forests. Francis Jourdain had urged me to concentrate on a few species rather than drifting from one exciting experience to another. So, when I went to live in the Highlands in the 1930s, these were the birds that I chose. When I started to study crossbills in Scotland I was quite ignorant of their recent history. I certainly did not then know how fortunate I was with the Scottish pine crossbills in the 1930s, when I was able to watch them in really high numbers. Then, they probably bred every year at great strength somewhere in the Scottish Highlands, not least in the Spey Valley where I was working. In the 1960s, I never met with large flocks and breeding groups such as I had known from the mid-1930s to the 1950s. In those early years few were interested in our Scottish crossbills. I had almost to start from scratch. How strangely different were the pine forests of Strathspey from the pine rows and wind breaks where I had watched common crossbills in East Anglia.

187

188 Pine Crossbills I have now worked out an outline of the breeding pattern, but this still leaves many unexpected problems. Why do some of our birds nest in clusters in quite small woods, yet in the same year other groups disperse widely, the pairs breeding well apart and at irregular intervals? And why do these crossbills nest quite regularly in some woods and only occasionally in others? I have described many differences in . mating patterns, territoriality, nest-building, and in brooding, feeding and fledging rhythms, but these are almost insignificant problems compared with those posed by numbers and the regulation of populations. I have described the non-breeding surplus which exists at every level and I have speculated about its causes and mechanisms. Here the pioneer research in Finland is most helpful. In future studiesofbreeding and non-breeding populationswe must assess the quality as well as the quantity of the cone crops. We have much to learn about the signals which inhibit inter-breeding between the various closely-related species. In the wild these are clearly subtle, but they must be effective. In aviaries, pine and common, and common and two-barred crossbilIs have been known to interbreed and produce hybrids. In north America, Tordoff successfully bred from hybrids between common and two-barred crossbills. Yet in mixed conifer woods in northern Europe and U.S.S.R., pine, common and two-barred crossbills occasionally breed successfully in the same woods in the same year, all periodically exploiting the most favoured food trees of the others, but without any known significant interbreeding or hybridisation. However, all have distinctive calls, and differently shaped beaks and heads, which are likely to assist in maintaining the identity and separation of the species. In the future, many more aviary studies are required, but we must never forget that all these species are closely related and probably still emerging and evolving. Signals used successfully in the wild are not necessarily decisive when the birds are captive. Trapping and colour-ringing adults and chicks may help, but with birds so mobile and usually lacking continuity of breeding in particular habitats, we cannot expect quick results. However, it would be fascinating to discover the movements of groups in which the parents and families are divided. We might also learn more about a possible creche system in the post-fledging groups. Do hens sometimes leave their flying broods in charge of their mates, and other males, and later mate with different males to produce new nests and broods? This could be one system by which a population could rapidly build up. Without some method of marking, however, this is now almost impossible to prove. Another possibility is the pattern discovered in the Dumfries groups, where flying juveniles sometimesfeed the chicks in the second nests, and are themselves fed by the brooding hen. In some years this unexpected behaviour must lead to a rapid build-up in the population. Laboratory tests could throw light on the crossbills' selection of cones.

Speculations 189 As in squirrels, do the crossbills favour particular trees for the richness and accessibility of the seed? Are the cones near the tops of the old pines softer and their seeds easier to extract? Is this why a position near the top of the tree is apparently so important to the status of a dominant crossbill? Will experiments also help to explain why our Scottish relicts still avoid the newer pine plantations, although the groups of common crossbills, nesting in older planted pines in East Anglia, nest earlier and have a longer breeding season than any other purely pine groups in Britain and Ireland. Here laboratory tests, aviary studies and field observations are complementary. The Forestry Commission and private owners have greatly changed the content of conifer woodlands' in Scotland. In the new artefact habitats, with sitka spruce plantations now so prevalent around their redoubts, are we likely to discover Scottish pine crossbills breeding in the pines in spring and later in sitkas in autumn? And will the common crossbill invaders and colonists continue to explore and breed in mixed plantations on the fringes of the old pinewoods? We can only speculate about the evolution of these remarkable birds. Sometime in the distant past, a few members of small conifer seed-eating finches, like redpolls or siskins, possibly developed crossed beaks and not only survived, but discovered that their crossed beaks enabled them to extract seeds from unopened cones. Selective forces then gradually favoured the descendants of these individuals, and eventually evolved a new species which could exploit unopened cones inaccessible to the others. In this way, crossbills have occupied vacant niches, where they breed at times impossible to all other finches. I am lucky to have had this scarce and unusual pine crossbill to study. Whether, as I do, you regard our Scottish crossbills as relicts of the original stock of pine crossbills, the largest race of which now breeds in the forests of northern Europe and the Soviet Union, or as a distinctive largebeaked race of the common crossbill, or as a monotypic, but still emerging full species, this is a bird which has escaped dilution and whose fate and future depend entirely on the pine forests of northern Scotland.

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APPENDIX 1

Crossbill Taxonomy by ALAN G. KNOX Department of Zoology, Aberdeen University

The crossbills Loxia belong to the subfamily Carduelinae. Their closest relatives are the grosbeaks Pinicola and rosefinches Carpodacus, genera largely confined to Asia and North America. In Britain the closest breeding relatives are the Linnet, Redpoll and Twite of the genus A can this (Vaurie 1959, Desfayes 1971). Three species of crossbill are currently recognised: 1. Loxia leucoptera Gmelin, the Two-barred, or White-winged Crossbill, usually distinguished by its two broad white wing-bars. There are three subspecies: leucoptera and bifasciata (Brehm), normally breeding in the northern boreal forests of the Nearctic and Palearctic respectively, and megaplaga Riley, confined to parts of upland Hispaniola. 2. Loxia curvirostra Linnaeus, the Common, or Red Crossbill, with a largely Holarctic distribution, breeding widely through the coniferous forest zones. 3. Loxia pytyopsittacus Borkhausen, the Parrot Crossbill, with its normal breeding range confined to the boreal forests of the north west Palearctic, where its range lies within that of curoirostra.

The Common Crossbill has a long and complicated taxonomic history. This has mainly arisen because of the erratic habits of the birds. Because the conifer cones open in the early summer and shed their seeds, the birds depend thereafter on the next year's crop, and, following the end of the breeding season, they flock and start wandering. During these movements they often travel only short distances, but frequently, under certain environmental circumstances, they fly into areas normally unoccupied, or only irregularly occupied by the species. Some or all the birds may then settle down for at least one breeding season, or else return to the permanent range in the following spring. Many areas not continuously occupied by a particular race may be taken over by alternative races in subsequent irruptions. Thus, on examining breeding birds collected in one of these temporarily colonised regions over a period of decades, the population would appear to be highly variable and intergrade with breeding populations in other areas. This type of situation, along with confusion caused by different races wintering together, was first recognised by Ludlow Griscom (1937), who showed each subspecies to be more uniform than had been previously believed, that only rarely did two subspecies breed near each other, and this 'absolutely never' occurred in consecutive years. His work led to the recognition of eight subspecies in North America. In the

191

192 Pine Crossbills

Fig.A. Breeding distribution of Loxia curvirostraandL.scotica.Most boundariesaredynamic,and onlyanindicationof rangecanbegiven.Theextentto whichNewWorldrangesoverlapisnot known. 1Loxiac. minor;2grinnelli;3bendirei; 4benti; 5 strickland;;6mesamericana; 7 neogaea; 8pusilla;

minor: very small;

pus ilia:

short, thin bill;

large;

red males rare

heavy bill;

bendirei:

neogaea:

very similar;

dull brick red.

averages larger; males bright scarlet

benti: large; thin bill; males

dark; dull

Compared to this, curvirostre is very large and has a very heavy bill; males are paler, females are yellower, than neoqee«

rosy red; whiter

grinnelli.

large; heavy bill; scarlet

belly

mesamer.. icana: very dark

Fig. B. Loxia curoirostra;geographic variation in the New World. All subspeciescompared with neogaea; neogaea compared with nominate curoiroetra.

Appendix 1 193

9 curoirostra; 10 balearica; 11 corsicana; 12poliogyna; 13guillemardi;14mariae; 15tiamchanica; 16 altaiensis; 17 himalayensis; 18japonica; 19 meridionalis; 20 luaoniensis; 21 L. scouc«

nominate corvlrostre: larger;

slight cline

"ermakt"

japonica:

small; I pale, bright; whiter lower abdomen;

I

orsicana.

, alearica:,

tianschanica:

heavy bill; dull. females greyer

thin bill; pale; esp. sides of face and ear coverts; red males rare; both sexes yellowish

mall;sho heavy bill: Ie greye

bright red

guillemardi:

poliogyna: small; short, heavy bill; red males rare, orange; females grey

long, heavy bill; red males rare and pale; females grey

Loxia curoirostra; geographic variation in the Old World. All forms compared with nominate curoirostra.

194 Pine Crossbills Old World, Vaurie (1956, 1959) recognises thirteen subspecies, eleven of which are in the Palearctic (Fig. A). In both hemispheres many other subspecies have been proposed but are not currently valid. As some forms are represented in collections by only a few specimens of breeding birds of either sex, and since there is only scant knowledge of the precise breeding distribution over large areas of the species range, it is expected that there is much still to be learned about crossbill taxonomy. Although regarded by some authors (Griscom 1937, Meinertzhagen & Williamson 1953) as a race of curoirostra, the Parrot Crossbill is normally accorded full specific status. Vaurie (1959) recognises no subspecies. MORPHOLOGICAL VARIATION

Individual variation in the crossbills tends to be high; even males of neighbouring pairs can be quite different, sufficiently so to allow recognition of each in the field in many cases. Geographic variation tends to be 'random in type, with many isolated populations' (Vaurie 1959), and is summarised for the Common Crossbill in Fig. B. There are many intermediate populations and individuals, but with poor breeding samples available it is difficult to assess their importance. The Spanish birds, hispana Hartert, belong to this category, and there are other possible subspecies in, for example, Asia Minor and the Caucasus. The nature of variation within nominate curvirostra, even away from Spain and Asia Minor, is unknown. The birds which arrive in Britain during irruptions seem to vary from year to year, both in measurements (Davis 1964), and, perhaps, in habits (Moffat 1916). Both authors suggested that the birds may come from different parts of the permanent range in different years. There is some evidence that this might be the case, as curoirostra is clinal in colour and wing length from east to west across the U.S.S.R. (Vaurie 1956), and there is the possibility that it may be clinal in other features, or even show variation that forms regional mosaics. An additional or alternative hypothesis might be that the birds which erupt are physically different from those that remain behind (in Newton 1970), and that different components may erupt in different years. Measurements I have taken of birds collected in Sweden and Italy give slightly different averages (Fig. G). Assuming the samples to be representative of each population, the Italian birds, therefore, may have emigrated from some part of the main range other than Sweden, or they might represent eruption of only a biased sample of the whole population of Sweden (in this case, smaller birds). There might alternatively be another explanation, namely that there is a permanently resident population in Italy consisting of smaller birds; but field evidence for or against these alternatives does not at present exist. The most striking differences between the races and species are in the shape of the bill, In some, for example the Parrot Crossbill, it is deep and wide with a relatively short steeply curved culmen; in others, such as minor and himalayensis, the bill is more straight and slender. This variation has been correlated with the main food of the form concerned; all specialise on conifer seeds, but the different species of conifer have cones of differing strength, requiring more or less heavy bills to open them. Thus the main food of the Parrot Crossbill is said to be Scots Pine Pinus sylvestris; that of the nominate race of the Common Crossbill is

Appendix 1 195 Spruce Picea; and of the Two-barred Crossbill and the slender billed himalayensis, Larch Larix (Lack 1944a, 1944b, 1971, Ludlow 1944). The degree of ecological isolation claimed by Lack (1971) and others (for example Meinertzhagen & Williamson 1953) is, however, not always borne out by field observations. Svardson (1957) has said that the breeding of leucoptera in Scandinavia depends on the size of the Spruce crop, and Snow (1952) found the food of all three species in Lapland was seeds of Pine and Spruce. Dement'ev et al (1954) reported the winter diet of leucoptera in the Kola peninsula as exclusively Spruce, which it also ate in summer, with only occasional exceptions. PuUiainen (1971) collected leucoptera and curoirostra in Lapland in winter and found they had eaten only Spruce; in summer he collected all three species and found they also had been eating Spruce, although there were new Pine cones available (Pulliainen 1972). Juutinen (1953) observed curoirostra eating Pine (five cases), Spruce (four cases) and Larch (three cases). In the British Isles, Moffat (1916) noted Common Crossbills eating Pine and Spruce after different irruptions, and in England, where there have been breeding populations since the 1910 irruption (Witherby 1911, Parslow 1973), the food is almost entirely Pine, the cones of which they easily open, even when new (Southern 1945). These observations may have been made at times of food abundance and bear no relation to a possible situation of competition during scarcity. However, ecological isolation is not as absolute as some authors claim. PLUMAGE

The main variations in plumage are in colour saturation and frequency of red in the males (Fig. B). L. c. curvirostra and the Parrot Crossbill are inseparable on plumage characters. The Two-barred Crossbill may be told from the Parrot Crossbill or any race of the Common Crossbill by its broad white tips to the tertials, blackish remiges and retrices and black upper tale coverts (Griscom 1937). The white tips to the secondary- and greater-coverts are broad and distinct, but wing-bars are not restricted to this species. The tips of the coverts in L. c. curoirostra are sometimes found to be white or pale pinkish, sufficiently so to lead the unwary to misidentify the species in the field. Sometimes there are also narrow pale tips to the tertials. This type of variant was known at least as long ago as 1850 when it was originally described as L. rubrifasciata by Bonaparte and Schlegel. It is 'by no means rare', as Griscom reported, and the present writer is aware of several that have occurred in Scotland in the recent past. Since no specimens of L. leucoptera are known to lack wing-bars (although they would be difficult to detect), Griscom has reasoned that curvirostra evolved from an ancestor of leucoptera, and the wingbars in the former are throwbacks. THE SCOTTISH CROSSBILL

The Scottish Crossbill scotica and the English Crossbill anglica were first described as races of the Common Crossbill by Ernst Hartert in 1904. Both

were distinguished by their larger size and heavier bills, especially scotica, which, by Hartert's diagnosis fell as an intermediate between L. c. curoirostra and L. pytyopsittacus. In 1909 he accepted his anglicato be a synonym of L,c. curoirostra.

196 Pine Crossbill» Griscom (1937) re-examined the birds Hartert had called anglica arid found that, in his opinion, the type specimen belonged to scotica, which should therefore be called anglica, as that name had seniority (due to page priority) under the rules of nomenclature. This recommendation was never adopted; the B.O.V. (1938), after studying the bird in question, decided 'on the whole it agreed better with the English series (than Scottish birds)'. In his 1932 supplement, Hartert placed scotica as a subspecies of pytyopsittacus, a transfer not supported by the B.O.V. (1934) or Witherby et ale (1938), while Meinertzhagen (1934) agreed with Hartert, provided pytyopsittacus was valid. By 1956 circumstances had caused the B.O.V. to reverse their 1934 decision, but again this change had protagonists (for example Hollom 1960) and, more numerously, antagonists (for example Vaurie 1956, 1959, Voous 1960). Vaurie, who led the opposition, believed the intermediate nature of scotica's morphology was the only reason for the B.O.V. move, and argued that guillemardi, the Cyprus subspecies of the Common Crossbill, was similar to, or even larger than, scotica in shape and size, and that if scotica was to be placed in L. pytyopsittacus, then so should guillemardi, a situation, he pointed out, which had never been advocated by the B.O.V. (Vaurie 1956). However, morphology was not the only reason for their decision (Wynne-Edwards pers. comm.). They also took into account that the Scottish Crossbill 'appears to maintain its distinctive characters in the face of repeated widespread invasions of the Common Crossbill.. . . If this is the case, there can be no interbreeding between residents and invaders . . .' (Wynne-Edwards 1948). Therefore, with reproductive isolation, scotica could not belong to L. curoirostra, and should be moved to L. pytyopsittacus. V nfortunately, the B.O. U. later (1971) decided not to follow their own recommendation. Investigations by the present writer into the relationships of the Scottish Crossbill began with examination and measurement of over three hundred post juvenile crossbills belonging to pytyopsittacus, scotica, and nominate curvirostra from areas other than Spain and Asia Minor, along with poliogyna and guillemardi the other two well defined Palearctic races with heavy bills. The last two subspecies were easily recognised by the reduced frequency of red in the males, and the greyer females, while pytyopsittacus caused few problems with its large size and heavy bill. On the other hand, measurements of scotica and L. c. curoirostra, overlapped to an extent that rendered separation difficult, and necessitated a less straightforward approach. This technique has been described in detail elsewhere (Knox, in prep.). Basically it involved plotting the width of the lower mandible against the Index of Curvature! for each bird (treating the sexes separately) and marking which birds were collected within the known range of the Scottish Crossbill. This was taken to be the counties of Perth, Aberdeen, Banff, Moray, Nairn, Inverness and Ross, and assumes the race is sedentary (Witherby et ale 1938, Baxter & Rintoul 1953, Vaurie 1959, B.O.V. 1971). The resulting scattergrams showed the birds collected in the range of the

Scottish Crossbill (hereafter referred to as the Highland area) to be mainly (and to the exclusion of the other points) clustered around one end of the scatter, with 1. The Index of Curvature is a calculated figure representing the degree of curvature of the culmen; the larger the figure, the more steeply curved the culmen.

Appendix 1

197

index of curvature (-400) Fig. C. Diagram showing scatter of measurements of females designated curoirostra (squares) and scotica (circles). Open symbols: birds collected outside the "Highlands". All measurements of the two forms overlapped considerably, so preventing easy identification of many birds.

only a few points dispersed through the other end, reflecting, for the Highland birds, scotica at one end, and c. curvirostra immigrants as the isolated points among those representing the birds collected outside the Highlands (Fig. C). Because of the overlap in the clusters, it was necessary to compare all the measurements of each bird in turn with average measurements of two groups (for each sex) formed by subjectively dividing the total scatter into a 'scotica' group and a 'curvirostra' group. Each bird was assessed individually to see to which group it fitted best, and the measurements for each group then recalculated. It was probable that, even with this method, there was a small proportion of misidentifications. This method extended the known range of measurements of scotica to an extent that gave considerable overlap with measurements of c. curvirostra (Fig. D). On any single character, scotica was a poorly defined race, but when several features were considered together, identification was usually possible.P Thus, although intermediate between c. curoirostra and pytyopsittacus, scotica emerged as being considerably more like the former in morphology and, on that basis, belonged as a subspecies of L. curvirostra. 2. The type specimen of anglica was examined in this study, and found to be indistinguishable from scotica (as previously noted by Griscom); however, even though it fell as an extreme member of L. c. curoirostra, it was considered to belong to that form, as, apart from this bird collected in Hertfordshire, evidence that scotica leaves the Highland area was lacking.

198 Pine Crossbills

Fig.D, Percentageoccurrenceofsizeclassesin the sampleexamined.Femalesonly.Left-hand sideof vertical axis: scotica; right-hand side of vertical axis: curvirostra.

Where various types of crossbill have taken to eating Pine, and consequently have a considerably more reliable food supply than Spruce, the populations have become much less irruptive (for example L. pytyopsittacus), or even sedentary (L. c. poliogyna, L. c. guillemardi). The Scottish Crossbill is in this way similar to poliogyna and guillemardi, and this probably represents the only major nonmorphological difference between it and L. c. curoirostra. Otherwise the biology of the two forms is very similar and, even with their extensive vocabulary, it is generally difficult or impossible to tell one from the other by voice in all but a few notes. With such similarity between the Scottish and Common Crossbill, there would seem to be little doubt that they were conspecific; nevertheless, it is clear that scotica does maintain its characters in the face of frequent invasions, which have often given rise to breeding populations in Britain, the nearest well established one being in south-west Scotland. Despite the difficulties in detection, there are also one or two records of curoirostra breeding in northern Scotland.

Appendix 1 199

Percentage occurrence of size classes in the sample examined. Males only. Left-hand side of vertical axis: scotica; right-hand side of vertical axis: curoirostra. (For details of calculation of indices see: Knox, in prep.) n = sample size.

With a total population as small and as mobile as that of the Scottish Crossbill, any regular hybridisation with the Common Crossbill would lead to the identity of the race being destroyed. Therefore, it must be assumed that hybridisation does not occur, or it occurs so infrequently as to be insignificant, and, as the opportunity for hybridisation is probably presented with each irruption of Common Crossbills into the Highland area, reproductive isolation must exist between the two forms. The mechanism of this isolation is unknown; it might be competitive exclusion, with ecological or behavioural factors preventing the two forms breeding in the same forest, or differences in behaviour might inhibit the establishment of mixed pairs. Whatever the mechanism, isolation is effective, and the existence of opportunities for breeding together can scarcely be questioned, considering the frequency of irruptions of continental birds into the Highlands, and the fact that the immigrants frequently breed in several parts of Scotland, from which crossbills are absent at other times. Crossbills nest along Deeside every year, and in spring 1974 they were breed-

200 Pine Crossbills

Fig. E. Relationship between average wing length and bill depth for males of 17races of Common Crossbill (.), the Scottis Crossbill ( + ), and the Parrot Crossbill Insufficient data on three races of the Common Crossbill.