Enjoying Ornithology

Citation preview

lUiuiMnI TCT DAVIC^^H

Enjoying Ornithology DAVID LACK F.R.S. This book includes popular articles, broadcast talks and a few more specialized studies by a professional ornithologist who enjoy his bird-watching as much as any arn . a * e ".[' The longest section is concerned with the author's pioneer studies of bird migration °V the new technique of high-power radar, in the last few years, radar studies have shown that the migrants that are seen give a highly misleading picture of what is passing overhead, and the new findings have transformed our views on the distances for which birds tiy and the heights at which they migrate; our views have been greatly modified on ho they find their way and the weather conditions in which they set out. Other articles concern some distinguished British ornithologists of the past, hints on how to undertake research, contributions stimulated by the Darwin centenary, and . finally some light-hearted essays, including a n ornithological examination paper, the first bird-watching Olympic and the description of a new species of swift, as yet unseen. The pook has been written primarily for enjoyment, but those who study birds seriously • Will find new and stimulating information. fhe many illustrations by Robert Gillmor, 10ne of Britain's leading bird artists, exactly : catch the spirit of the text, and the two in combination should provide enjoyable and fewardlng relaxation forthose who study and ; enjoy bird-life. pr David Lack, F.R.S., is Director of the I gdward Grey institute of Field Ornithology and current President of the International Ornithological Congress.

PRICE

30s net IN U.K. ONLY

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DAVID LACK

Enjoying Ornithology

Ilhistrated by Robert Gillmor

M E T H U E N & CO LTD 11 N E W FETTER LANE • LONDON EC4

First Published 1965 © 1965 David Lack Printed in Great Britain by Ebenezer Baylis and Son Limited The Trinity Press, Worcester, and London

Contents Preface Acknowledgements PART ONE

1 2 3 4 5 6 7 8 9

page 7 9 •

MIGRATION

Enjoying Ornithology Migration in a Pyrenean Pass The Significance of Migration Watching Migration by Radar Migration at Minsmere, Seen and Unseen The Height of Bird Migration Radar Films of Migration over Eastern England Radar Evidence on Migratory Orientation The Summer Migration of Lapwings Studied by Radar

13 31 40 49 56 64 72 100 123

PART TWO • INTERLUDE

10 Swifts at Home PART

11 12 13 14

THREE

139 • SOME BRITISH

British Pioneers in Ornithological Research Bird Artists The Edward Grey Institute, Oxford B. W. Tucker (1901-1950) PART FOUR • D A R W I N I A N

15 16 17 IS

ORNITHOLOGISTS

153 175 178 183

EVOLUTION

Darwin's Finches of the Galapagos The Darwin Centenary, 1858-1958 Mr Lawson of Charles T. H. Huxley and the Nature of Man

193 201 205 209

PART FIVE • E N T E R T A I N M E N T S

19 20 21 22 23

An Ornithological Examination Paper page Old Brecks or New Forests? A Vision of Rome, I960 An Undiscovered Species of Swift Robins for Christmas Appendix: Answers to an Ornithological Examination Paper Index

225 235 238 244 248 253 259

Preface The talks and articles brought together in this book were written for enjoyment, and for those with a general interest in natural history rather than for ornithological specialists. Professional scientists are often blamed for restricting their findings to technical papers in learned journals, to which they may reply that time spent in writing for a wider group of readers is time lost from the research which is their main job. The dilemma is real, and the present collection, of work already given elsewhere, is offered as a partial answer. I have been studying and writing about birds for thirty-six years, for seventeen unpaid and for nineteen as my profession, but always, I trust, as an amateur, and while the present writings come from my professional period, they are intended for other amateurs. The opening chapter may be regarded as introductory, as it shows how, in my view, the study of birds is best enjoyed. The first and longest section concerns my research on migration, which has not previously appeared in book form. It starts with what, up to now, has been my most exciting day as a naturalist, the discovery of birds and insects migrating through a high mountain pass. This led to a general consideration of the significance of migration, and then I was unexpectedly given the opportunity to study it by radar. The technique of high-power radar for bird-watching is so new, and has so changed ideas on migration, while at the same time it is so inaccessible to the ordinary naturalist, that in this, but no other, section I have included some more technical work. After an interlude on Swifts, there is a section concerned with the achievements of various British ornithologists. In the next section, my interest in Darwin's finches of the Galapagos Islands led me on to an assessment of Darwinism in relation to the nature of man and to a 7

PREFACE

growing admiration for T. H. Huxley. The final section consists of some light-hearted darts, but aimed seriously. This book may also, I hope, repay some of the debt which I, like all other British naturalists, owe to the Royal Society for the Protection of Birds (now at Sandy Lodge, Bedfordshire). This society has successively and successfully combated the threats to bird-life from the plumage trade, game-preservation, egg-collectors, the spread of suburbia and, in these last days, toxic chemicals. It has done this through promoting new Acts of Parliament, through education in the widest sense, through the purchase of sanctuaries and, in recent times, through scientific study. But while the society's work becomes ever more effective, the need for it is ever more pressing, so it will receive all royalties from this book.

Acknowledgements I am extremely grateful to Robert Gillmor who, in his illustrations, has so exactly and delightfully caught the intention of this book. I am also grateful to H. E. Axell, J. L. F. Parslow and J. Wilcock who shared with me the work and writing in Chapter 5, and to Dr E. Eastwood who similarly shared in Chapter 7. I must also thank Dr Eastwood and the photographic section of the Research Laboratories of Marconi's Wireless Telegraphy Co., Great Baddow, Essex, for the still photographs reproduced in Chapter 7 and for loan of the films from which the text drawings in this chapter were made. Finally, I am extremely grateful to the editors and publishers of the following journals for permission to reprint here the articles which originally appeared in their pages: for Chapter 1 Bird Study and the British Trust for Ornithology, for Chapter 2 John K. Terres and J. B. Lippincott Co., for Chapter 4 the Listener and the British Broadcasting Corporation, for Chapters 5, 13, 20, 21, and 22 Bird Notes and the Royal Society for the Protection of Birds, for Chapters 6, 7 and 8 British Birds magazine, for Chapters 9, 11 and 14 the Ibis and the British Ornithologists' Union, for Chapter 12 the Nezv Statesman, for Chapter 15 the American Scientist, for Chapter 16 the Glasgow Herald, for Chapter 17 the Scientific American ( © 1953 by Scientific American Inc. All rights reserved), for Chapter 19 the New Naturalist and for Chapter 23 the New Scientist. I am also grateful to the British Broadcasting Corporation for permission to print here two broadcast talks, in Chapters 3 and 10, which have not previously been published. Chapter 18 has also not appeared before. It is based partly on my book Evolutionary Theory and Christian Belief published by Methuen, and three other chapters also summarize material that has appeared in 9

ACKNOWLEDGEMENTS

books, namely Chapter 10 {Swifts in a Tower, Methuen), Chapter 15 (Darwi?i's Finches, Cambridge University Press), and Chapter 23 (Robin Redbreast, Clarendon Press). T h e chapters are printed here as originally written, except for occasional omissions and for the alteration of a few words in the light of later discoveries or for greater clarity. A few of the papers were originally accompanied by references to scientific papers by others, also omitted here, but they can be found by those interested in my original publications.

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PART ONE

Migration

h

1

Enjoying Ornithology Prefatory

Note

This address was prompted by the many questions I receive on how to start research, and I must apologize for the long delay in writing it down. Now that it is written, I am told that it may give two undesirable and unintended impressions that were absent, so I am informed, from the address as delivered. To counteract these, I would stress at the start, first, that I do not wish to imply that all ornithologists ought to do research, or that it is a waste of time to watch birds in other ways, or, and especially, that the ornithologists who do research are superior to those who do not. 'Now there are diversities of gifts', and research should be only for those inclined for it, as it is but one of the ways of enjoying bird-life, though a highly rewarding one. Secondly, the address was delivered from floor level, not from a pulpit. In proffering advice to others, I do not wish to imply that I think myself above the need for it. Indeed, with R. E. Moreau working in the next room, I am lucky to receive more criticisms than most others can get. But in thirty-one years of publishing research, seventeen as an amateur and fourteen as a professional, I have made many mistakes, An address to the British Trust for Ornithology's Regional Representatives and others at Cheltenham, in March 1956, reprinted from Bird Study 7 (1960) 13

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and my aim here is to pass some of this experience on to others, realizing, I trust, that I am still only too subject to fall into many of the pitfalls that I describe. The address is printed substantially as it was given, but with minor additions and corrections, while the second section (a simple example) was omitted from the address itself, being intended for beginners, not regional representatives. Research is merely a term for finding out something, or to put it more accurately, something previously unknown. It may be something very simple, for instance that the Rock Pipit is a regular passage migrant at the local sewage farm, or that the Yellowhammer tends to lay a smaller clutch in the autumn than the summer, or it may be the propounding of an elaborate theory based on twenty years' observations and masses of statistics and tables. In any event, it is a delightful pastime, one of the most delightful of all pastimes. Further, this pleasure is within the reach of all ornithologists, being easier technically, though harder morally, than most people think. D o not suppose that it is something which should nowadays be left to the p r o fessional, for in this field the amateur has as many advantages as the professional, though they are different advantages. Almost always research starts with the simple and often it ends there too. If in your garden, you happen to see a Spotted Flycatcher displaying in a way that you have not seen before, you record the event as accurately as you can, and as soon as possible after you have seen it, but do not worry too much about recording while it is happening, for if you try to do this, you may easily miss what happens next. It is not hard to train oneself to remember facts for long enough to record them afterwards. The next step, of course, is to try to interpret the behaviour. Was a second bird present? If so, was it likely to have been a male (which suggests threat display) or a female (which s u g gests courtship), or was the bird merely alarmed at your presence? Interpretation may be hard on the basis of one observation, and further, as small birds move fast and you were n o t expecting the occurrence, your description of it was probably 14

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not very accurate. The next step is to consult The Handbook of British Birds or some equivalent work to see whether the display has been recorded before. It probably has, but it may not have been, or it may have been wrongly described or interpreted (even in the 'Handbook', which, after all, is merely a summary of all previous observations such as yours). If it is undescribed, look under related species. Try, for instance, the Pied Flycatcher. If your observation really seems new, the next step is not to write straight off to an ornithological journal with a note for publication, but to try to see the Spotted Flycatcher do it again. Next time you will probably see it much better and will have a clearer idea of the circumstances in which it occurs. The need for repetition is one of the essentials of research, and this warning is needed as much for the advanced worker as for the beginner. Not long ago, an experienced worker sent a long paper to one of the ornithological journals describing a season's work on a particular bird problem, and next year he had to send another paper reversing all his earlier conclusions. Only after trying to see it again, send a note to a bird journal, and then the editors, with the help of consultant staff and books, can usually see if it is really new, in which case they will probably publish your note. Incidentally, do not head it 'Unusual display of a Spotted Flycatcher'. 'Unrecorded' it might well be, but it is extremely unlikely to be something unusual in the life of the bird. (In the 'twenties and 'thirties a whole series of notes appeared in British Birds headed 'Unusual display of Hedge Sparrow'.) There comes a stage in the development of many a birdwatcher when he (or she) has seen and knows well the regular birds of his district, and when, through suitably planned holidays, he has seen nearly all the species he is likely to see in Britain. Further, he may well have chanced on one or two rare or unrecorded happenings and have published short notes on them. But he knows that they were due to luck and will not happen often. So he wonders what to do next, and this stage is critical. He may, of course, take up a different hobby, or he may 15

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marry and get tied to the kitchen sink, or he may cease to develop further as an ornithologist but retain his interest at the existing level, quietly seeing and enjoying birds for the rest of his life. But there are others who wish, or think they wish, to go further, and it is usually at this stage that they come to the Edward Grey Institute or the British Trust for Ornithology and ask 'How can I do research?' What such questioners evidently want is a subject suggested for them. But this is the one question about research which is almost impossible to answer. That is because research is such a personal and individual matter. What fascinates one person bores another. It is absolutely essential that research should remain a pastime, even if it becomes a profession. T h e dullest, and saddest, of all papers are those by the professional scientist who has lost his enthusiasm. But this problem does not afflict the amateur, since if he ceases to be excited by birds, he simply turns to something else. It is important to remain excited by research if only because, as already mentioned, repetition is essential, and you cannot, or at least will not, repeat observations if you are bored. So even if you follow a research topic suggested by someone else, your heart will probably not be in it; it will remain his problem, not yours. Further, particularly if the problem is at all difficult, it should live with you all the time, just turning quietly over in your mind, whether you are catching the morning train to the City or bathing the children. T h e proverbial absence of mind of the Victorian professor was due to this absorption in his problem. (The modern professor is a full-time administrator, and quite different; his is one of the few occupations that usually leaves no time for research.) The choice of a subject for research is also personal in that it must suit your own limitations, of both person and place, and only you really know what these are. The problem is different for the town and the country dweller, for one who likes climbing trees, for one who is somewhat deaf, for one with a taste for gadgets, and so on. The problem also depends on whether you get your free time in the early mornings, or at week-ends, or on holidays, and on whether you have a car or bicycle. 16

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Actually, most of those doing research on birds, both amateur and professional, were never troubled by how to start. They were so busy just watching and enjoying birds, and in recording what they saw, that their watching became research before they realized it. For if you are the kind of person who likes research, your observations will themselves suggest problems to follow further. Advice is valuable, but in the later stages rather than the first. The same of course applies in professional zoology. One professor told me that, if a student comes to seek a place under him to do research but does not know what to study, he strongly advises him to take up a different career. So if you feel the need to ask the question 'What could I do research on?', seek within yourself as to why you have asked that question. And if, after that, you still want to do research, then start by helping others, trapping and ringing birds, or filling in Nest Record Cards, or joining a B.T.O. inquiry. If you have the research nature, one of these lines will soon suggest something for you to do on your own. One recent author confessed that his childhood aim had been to become a great naturalist. It is not surprising that he actually became a businessman, because he should have been interested in the birds, not in himself. M y own research started by accident when, at school, I regularly visited a Nightjar's nest and found that one day the male instead of the female brooded the young. I supposed the female had been killed, but next year found that the same thing happened at all my early nests (which shows the value of repetition), so I concluded that the females were laying again elsewhere and that the Nightjar must be double-brooded, though the textbooks said it was single-brooded. This was the first time I appreciated that statements in bird-books might be wrong, and it led me on to a general study of the Nightjar. Nearly all other ornithologists that I have asked started their research in the same sort of way, by accident, i.e. by bumping into an unexpected detail which puzzled or excited them. It is, of course, important to recognize that the detail is unexpected, and for this one needs some knowledge based on reading and also, B

17

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once again, to repeat the observation to find out more about it. It may be worth adding that the greatest of all biological discoveries came by accident. Darwin did not think out the theory of evolution from first principles, nor did he set off on the 'Beagle' in order to discover this or any other biological theory. He was simply a naturalist-collector, but when lie found a unique group of finches in the Galapagos, he wondered about their origin. Years later, when T . H. Huxley first read the Origin of Species, he remarked 'How extremely stupid not to have thought of that!' Quite so, but no one did 'think of that' until a naturalist saw some drab but unexpected finches. The difficulty of a research project may be raised again if, having completed some first study, you move house or j o b , and so have different surroundings or are free at different times of the day. Even with the confidence and enjoyment of a completed paper behind you, the change can be very disturbing. One's first thought is to continue as before, but this is hardly ever satisfactory, because the new circumstances are too different, and what came easily before is now almost impossible. Just before I went to live in D e v onshire, I had concentrated on heathland birds, and vainly tried to continue with them there, though the nearest heath was fifteen miles away and I had no car. In fact my n e x t research again came by accident, when I trapped and ringed woodland birds round Ringed Robin the back door, solely to amuse and instruct my school pupils, and found several ringed Robins entering the same trap, which made me wonder about their territorial habits. While, however, it may be fruitless to try to continue in the new place in the same way as in the old, and while it is essential to get to know the new area well, ideas for research seem rarely 18

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to come by wandering vaguely about wondering what to do. At two different periods in Oxford, when in need of new ideas, I wandered about Wytham woods for days at a time, but in neither case did any good ideas come. I have usually found that new facts or ideas come unexpectedly, not when one's mind is empty but when it is positively engaged in other matters, and because the mind is engaged elsewhere, the new ideas usually have to force themselves on my attention before I appreciate their value (i.e. I am very slow in the uptake). Another reason that it is so hard to advise others starting research is that, if a research project is sufficiently obvious to be perceived beforehand, then it may be scarcely worth doing. It is the unexpected that is so rewarding, and so enjoyable. This comment applies primarily to the naturalist, and not the experimental zoologist, who must plan carefully in order to test preconceived ideas. But he has the duller job, and it is for us naturalists to find the unexpected. As a result, we have more blank times than the zoologists, but perhaps greater rewards too. Although wandering vaguely about one's environment rarely leads to new ideas, wandering discursively about the bird literature can do so. One should read extensively, in the bird journals rather than the bird-books, and always for enjoyment, not out of a sense of duty. New ideas are far more likely to come when one is reading with enjoyment than when one is ploughing studiously through a laborious tome recommended by a wellmeaning acquaintance (a true friend would not suggest such a thing). Either the tome really isn't worth reading, or you are not ready for it, and so are spoiling it for later. T o conclude this section, research is so individual a matter that it is almost impossible to give advice about starting it. If the start has not come naturally from your bird-watching, and if the remarks I have made bear no fruit, then at least you can help the research of others in the ways I have suggested; and if this does not appeal, why worry? Why not just enjoy watching birds? In addition to these general remarks, a few hints may be given as to suitable subjects for research. These fall into two 19

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groups, those suitable for the home district during the workingyear-and those suitable for the holidays. For research at home, it is essential to have your problem close at hand, preferably within a few minutes of the house, because otherwise far too much time is wasted in getting to and from the place of observation. While some people have tried to study all the birds in a particular habitat, this is rarely productive, and good homeresearch has usually entailed either the study of one species, or the study of a particular activity in a group of species. If you decide to take up a particular species, and this is one of the most enjoyable of all studies, you must love your bird. After all, you will probably live with it for years, and if you don't love it, you may soon get bored with it, as few of us can maintain a purely intellectual interest. Some men could be made happy by almost any woman, but others are extremely choosy, and the same applies to bird-watchers. Most of us, I suspect, are choosy. Needless to say, the excitement of rarity soon palls, and there is everything to be said for studying a common species, for then one nest-failure does not mean disaster, and there is plenty of opportunity to study variations in behaviour. It is also valuable to have a resident species, which one can watch throughout the year. If it can be trapped and colourringed, so much the better, and mist-netting has made this possible for most birds now. There is a special pleasure, as well as scientific value, in recognizing particular individuals. Having said this, a wide choice remains, and it is up to you whether your love is quiet and mousy or gay and bedizened, whether she possesses a graceful neck or powerful claws, whether she utters wild cries or social chatter. On one further point, which often causes worry, I think there is no need to fear, and that is that you may have chosen a bird that is already being studied by someone else. One is, of course, frightened that the someone else may come first to one's choicest discoveries, but each person's interests, way of work, and surroundings are so different that this doesn't seem to happen in practice. Such, at least, has been my experience, and I have found, on the other hand, that at a later stage, the other 20

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worker's knowledge added to mine has produced discoveries which would not otherwise have been made by either of us. The only way in which this situation can lead to trouble is if you decide from the start that the other man is a rival and enemy, which may lead to unhealthy competition and premature publication. If, instead, you take the line that whoso loves my bird loves me, you will have rewarding co-operation. T h e other good home-subject is to stud)' a particular activity in many species. The obvious one is migration, perhaps at the local reservoir or sewage farm, in which case do study all the members of a group, for instance all the waders or all the ducks, and not just the rare ones. And don't be afraid of the blank day. In a series of regular visits, the day with no birds can be just as significant as the day with many, that is, if you are interested in research. Remember, too, that there are many other subjects than migration. P. H. T . Hartley's pioneer studies on the places where birds feed began as a spare-time occupation round his home, and after a happy interlude doing the same as a professional, he is now once more continuing them as an amateur. The holiday problem is quite different. At home, you have a narrow choice of places and species, and only a little spare time each da}' or week, but you may be able to continue for years. In the holidays, on the other hand, you have wide choice as to place and season and much time each day, but a very limited number of days; though you can, of course, return in a second year. It pays to choose an unconventional place and season, and to avoid the popular bird-resorts at the popular seasons, because crowds of other field-glasses disturb both the birds and you. Further, unless you are very strong-minded, you will probably be distracted by the report of the latest rarity a few miles down the coast. Distribution in an unworked area, and migration, are perhaps the most rewarding holiday problems, and in the choice of them, wide reading and discussion with others is a great help. Study of a particular species is usually unsuitable, because it needs much longer than a few weeks. If you have children with you, your choice of place and season is, of course, much more limited, but it is still wide enough to 21

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allow many possibilities, and I speak as one whose holidays regularly combine bird-research with building sand-castles. On holidays, as always, look out for the unexpected. It was on a holiday devoted to Nightjars that, by chance, I saw Swifts going out to sea at dusk, and this provided a stimulating holiday problem for several further summers. Finally, while I have been concerned here with field ornithology, many other ornithologists have done valuable sparetime research by keeping birds in captivity, or by studying bird-skins in museums, but I will not elaborate on these subjects here. I hope this next section will not sound too like a sermon, but while research is possible for anyone interested in birds, it is a discipline, and certain sacrifices have to be made, especially in time, for the cost in money can be negligible. Further, certain qualities have to be developed. The first, perhaps, is enthusiasm, which may be taken for granted in all bird-watchers, but it has to be sufficiently sustained to carry one through the blank days and much repetition. Persistence is essential. Humility is equally to be stressed, the more so as it is out of fashion; indeed, when has it not been out of fashion? T h e old word for research, and perhaps a better one, is 'learning'. As T. H. Huxley said: 'Sit down before fact as a little child, be prepared to give up every preconceived notion, follow humbly wherever . . . nature leads, or you shall learn nothing'. Next there is courage. W e are ready enough to go out in all weathers, to scale a steep cliff or to cross a turbulent sea, but are we equally ready to learn simple statistics, or to read German, or to make a gadget? Let us not be put off by any surmountable difficulty, though at the same time recognizing our unavoidable limitations and conforming our research to them. Finally, and perhaps most important, there is integrity, which is as essential for the simplest as for the most difficult research. Probably all scientists start as the servants of truth, but not all end there. The desire to be the first to publish a new theory, or to complete a book by the contracted date, or to 22

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come in from the cold, or to fill in more Nest Record Cards than anyone else, can easily lead to hurried, unchecked and slipshod observations, though none of them need do so. A particularly difficult phase comes when one has enough observations to think one's idea is right but twice as many are needed to prove it. At this stage it is often best to try to catch oneself out rather than to confirm one's idea. Charles Darwin always noted with special care the observations pointing against his views, because he found it was these that he tended to forget. Faulty observations may, of course, be detected by a later worker, but the real reason for accuracy is not that you may be found out, but that you may not. Your paper may remain the last work on its subject for many years and be constantly quoted. Even a careless mistake in writing down one ring-number may result in a recovery being reported from the wrong species, and so may lead to distortion in another worker's views on migration. One further temptation, the desire to see the unusual, does not afflict the research worker nearly so much as it does the rarityhunter, who is always biassed against the probable. For in research a 'new' observation has normally to be repeated before it is of value. Some persons think that another quality, intellectual brilliance, is needed for research, but this is a mistake. If you doubt this, you have only to read through a few volumes of any bird journal. Extremely valuable research can be done with no greater mental effort than that involved in filling up Nest Record Cards, while intellectually brilliant people sometimes do bad research through letting their ideas run far ahead of their facts. Of course, a brilliant intellect can help, so can keen eyesight or hearing, skill in climbing trees or making gadgets, but none of them is essential. What is essential is to conform our research to our limitations. Bad research, when not due to hurry, comes especially from people who have published in a field in which they have not trained themselves to walk, and are incapable of walking. But there are many fields, far more than enough to suit every type of ability and disability. Fortunately, as we do all this for enjoyment, not ambition, we 23

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usually find a suitable field for ourselves naturally and intuitively, without any effort, though there are exceptions. The one essential is sufficient time, time to make field observations, time to think about them, and time to write them u p ; and this necessarily means time taken from other things. Some sacrifice is needed, of the annual holiday, of week-ends, or of the early mornings. Eliot Howard, it will be remembered, p r o pounded his territory theory on the basis of early-morning watching before going to his business in Birmingham. W e have time to spare if we really want it. While, as I have stressed, advice from others rarely helps for the start of research, it is invaluable for research in progress. It is then that it pays to seek out the experts, and also to talk to anyone else prepared to listen. For not only does one receive valuable advice from others, but in telling others of our discoveries, we often find new ideas forming; that we did not know we had, and which might not have come to the fore but for the stimulus of a listener. Inquire into both the theoretical and practical aspects of your subject, read extensively, and do not be afraid of trying new techniques, or tackling a paper written in German, or of looking at a bird in new ways. If you are studying a particular species, try to enter as much as possible into its way of life, and if your friends start saying that you are becoming very like a Rook, or a Grebe, or whatever species it is, you are progressing. It is also valuable to have definite views, a bias if you like to call it that, or better, a hunch. T h e person with vague views rarely comes to definite or important conclusions. But there is also the opposite danger, of sticking too long to a view because it is your dream-child, in the teeth of contrary evidence; we have all seen examples of this — in other people of course. For many, but not all, aspects of research, numerical data are a great help, whether it be the number of waders each day at a sewage farm, or the number of visits paid to a nest by the parent birds in three hours. The great Eagle Clarke once saw 'large flocks of Skylarks and a small number of T r e e Sparrows' passing the Kentish Knock lightship. If you went there n e x t 24

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year and saw 1,005 Skylarks and 16 Tree Sparrows in one hour, did you see more or fewer than he? Counts help not only for comparing your findings with those of others, but for determining the influence of particular factors, for instance the influence of the weather on migration, or on feeding visits to a nest. Further, they may reveal the unexpected. When my wife and I counted the number of feeding visits to Swifts' nests, we found, as expected, that broods of three were fed more often than broods of two, but it was not until we analysed the figures, some months afterwards, that we noticed that the difference in feeding-rate came mainly in the afternoons, when the parents of broods of two took more time off. In counting, it is important to continue for long enough. If, for instance, you are studying a coasting migration, do not merely count the number of birds passing in five minutes and multiply by twelve, but count for the full hour. It is, however, possible to overdo counting, but this is usually when it has been undertaken for reasons that were not properly thought out beforehand. In some types of field work, experiments can also be valuable, but only at a late stage. It is no good trying to change the circumstances of a bird's life until you know thoroughly what its normal circumstances are, and if you try to do so, the experiments may be extremely hard to interpret properly. So do not experiment for the sake of experiment, but in order to find a better answer to some question suggested by previous observations on the natural life of the bird. W h e n counts or experiments have been made, their interpretation is greatly helped by simple statistical analysis. As most bird-watchers seem both icmorant and afraid of statistics, let me stress two points. First, statistical analysis is not a magic way of converting bad observations into good; it should be used only for sound observations. Secondly, statistical analysis is not difficult in the forms in which most bird-watchers need it, not nearly so difficult as learning to type, or to speak French, or to climb trees. It involves merely simple addition and multiplication and knowledge of what formula to use, the last, of course, being the tricky point, but there are several 25

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simple books written for those with no previous knowledge of statistics and with no special ability in mathematics. Just as you can switch on the light without any knowledge of electricity, so you can use statistical tests without knowing why they w o r k ; but you must know the right switch. While, too, most ornithologists do not use statistical tests often enough, a few, having cleared the hurdle, use them too often, or state their results with a degree of precision that is absurd for the data involved. Like other forms of showing off, this is irritating for others. The aim of statistical tests is to show whether a difference that you have found, based on sound observations, is likely to be a genuine difference or due to chance. In short, statistics stop you from deceiving yourself. But remember that if you find a difference between two sets of figures, and a test shows that this difference is not statistically significant, it does not necessarily mean that there is no real difference. It might mean this, but on the other hand, it might mean that the difference was genuine but you had not yet collected enough figures to prove it. So this may help to show you how much longer to continue recordiner. Another common mistake is to suppose that if two variables are correlated statistically, e.g. a weather factor with the number of migrants, that the one is necessarily the cause of the other. There may well be a third variable that you had not thought of which is correlated with both. Hence care and great common sense are needed in interpreting statistical findings. For instance, in autumn there is more westward migration across the North Sea with easterly than with westerly winds, and a test showed that this difference was statistically significant. But it does not necessarily follow from this that the cause of this relationship was the wind-direction as such; it might have been cold, or anticyclonic weather, both of which are usually linked with easterly winds in autumn. W h i l e , too, the tests needed for most kinds of ornithological research are simple, there are traps, especially in choosing the right p r o cedure. If you are in any doubt, consult an expert, and there is 26

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always the chance that he will work out your results for you, as he usually has a calculating machine, and sometimes a girl assistant, to do the laborious part for him. Finally, in the midst of your field observations, your wading through marshes or sitting in hides, your counts or statistical tests, take time off to think. As that great detective Hercule Poirot once said to his assistant, 'You are always urging me to physical activity, Hastings. You wish me to measure footprints, to analyse cigarette ash, to prostrate myself on my stomach for the examination of detail. You never realize that by lying back in an armchair with the eyes closed, one can come nearer to the solution of any problem'. 'I don't,' Hastings replied. ' W h e n I lie back in an armchair, one thing happens and one thing only.' Do not wait too long after completing your field work before writing it up for publication, or you may have grown too stale on it. Nor, on the other hand, complete the writing-up hurriedly, or with work still in progress, or you may have to correct your paper after it has appeared in print. (But it is often valuable to write up each season's work in manuscript, so as to clarify your views before the next year's work.) Some workers start to write a paper with a blocked-out scheme and neat sub-headings, but others just start writing, without a set plan, letting the paper take its natural form. I prefer the latter method, since I do not seem to know in advance the most suitable form for a paper. But if I have tables or diagrams, I complete these first, and build the paper round them. T h e title should be short but informative. Such phrases as 'Preliminary observations on' or 'with special reference to' are best omitted. In the paper itself, avoid jargon and technical terms, especially those fashionable at the moment. For instance, a professional ornithologist considering the factors influencing migration wrote of 'increasing environmental temperatures and longer photo-periods' when all he meant was 'warmer and longer days'. Also, do not quote verbatim from your fieldnotes, which gives a spurious exactitude. Descriptions should 27

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be rewritten as shortly as possible, in the light of later knowledge, and should be generalized. Again, do not include your original field numbers. A reader is not usually interested that some action came from 'male 132', particularly as you will not have mentioned most of the other individual birds by number, or by their combinations of coloured rings. T h e title and subheadings of tables and diagrams should make each intelligible to the reader without his having to refer to the text. A reader often studies them separately, and further they may have to be printed on a different page from where you discuss them in the text. Refer, and refer fairly, to the views of others, especially if they have anticipated your findings. It is normally sufficient, and best, to summarize their views in your own words, together with a clear reference; and direct quotation is desirable only where you differ strongly from them. If you criticize them, be not only fair but generous, remembering that 'we are as dwarfs mounted on the shoulders of giants, so that we can see more and further than they; yet not by virtue of the keenness of our eyesight, nor through the tallness of our stature, but because we are raised aloft on that giant mass'. Before offering your manuscript to a journal, have it read by at least two friends. If possible, one of these should have specialized knowledge, so that he can correct your scientific errors, while the other should not, so that he can see whether you have made yourself intelligible to general readers of the journal. In my experience, the main value of a critic is to say what is wrong, and not to try to put things right, which involves him in far greater labour that will probably prove useless to the author anyway. Usually, it is only the author who knows what he wants to say. And if your critic attacks one of your conclusions that you are sure is right, do not think him foolish, but see why you have expressed yourself so badly that you have not convinced him. By the way, not everyone makes a good critic, and only trial will show which of your friends can help in this respect. And the editor of Bird Study has asked me to say that he hopes you will study the advice to contributors normally published in each number of every bird journal. 28

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Finally, if you have spent many hours in the field, do not squander them b}7 careless writing afterwards. Moreover, you owe a debt to your fellow ornithologists. Do not suppose that a paper that is easy to read has been easy to write. Until very recently, I found that I needed about ten complete re-writings of each paper before I had got it into a simple clear form, though now, after thirty years of it, I find that sometimes only half a dozen drafts are needed for a short paper. After this, of course, the paper goes to critics and is again completely rewritten, and much of it may be changed yet again after editorial comments. There is no need to envy the few' fluent persons who write their papers in one or two drafts, as this does not give most of us enough time to ponder on our conclusions. Probably others, like myself, get many of their ideas only as they write. So the writing-up is really part of the research itself, and it can be just as exciting, as a new idea takes shape under our pen or typewriter. (Learning to type, if only on two fingers, is a great help.) If the writing of ten or more drafts sounds tedious, remember that for the amateur there is only one possible standard: the best. W h y should we take this trouble? Dr Tinbergen's view is that 'a rational explanation may make people understand in a way, but cannot make them share the joy. W e bird-watchers feel that the steel-and-concrete environment we are creating all over the world satisfies only part of our habitat demands. But just being in our ancestral habitat does not entirely satisfy us; sight-seeing soon bores us; we want to do something. And I strongly feel that our bird study is sublimated hunting. All aspects of hunting: habitat selection, stalking our quarry, trying to outwit it, and finally experiencing intense satisfaction in getting what we want. I know through introspection that scientific bird study gives me exactly the kind of experiences and satisfactions as I once found in hunting seal on the Arctic ice'. That, at the least, may explain the instinctive origin or motive (one avoids technical jargon like 'motivation'). But man is not made solely of instincts, and perhaps we may give the last word to that Norwich doctor, Sir Thomas Browne, who 29

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was also one of our first amateur bird-watchers: ' T h e wisdom of God receives small honour from those vulgar heads that rudely stare about and with a gross rusticity admire His works. Those truly magnify Him whose judicious inquiry into His acts and deliberate research into His creatures, return the duty of a devout and learned admiration'.

Pied Flycatcher-

Migration in a Pyrenean Pass The most memorable days for a naturalist combine grandeur with novelty, the beautiful with the rare or unexpected. As a boy, such experiences came to me through seeing for the first time a new kind of bird. Then as a student, I happened on the courtship of the European nightjar, which was not only a lovely sight, and partly undescribed, but opened to me a whole new world - that of bird behaviour. As I grew older, such memorable days became much rarer, for though the beauty was still there, the unexpected had gone, and most of the big rewards came gradually through persistent observation. But there was one much later occasion, just after my fortieth birthday, when in lovely autumn weather amid superb scenery, a deeply impressive spectacle was combined not merely with the knowledge that no one had written of it before, but that one of the puzzles of migration was solved. This happened on 13th October 1950. There had been much dispute in the past as to whether From Discovery edited by John K. Terres (J. B. Lippincott Co., Philadelphia, Penn.) (1961), a volume in which each naturalist contributor was asked to describe the most memorable event in his life. 31

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migrating songbirds cross or avoid mountains, and recent Dutch research had suggested that even low hills were avoided by migrant Chaffinches in autumn. This gave my wife and me the idea that the Pyrenees might provide a barrier which no small migrants would cross. For these mountains, rising to 10,000 feet, extend continuously from east to west across southern France, from the Mediterranean on one side to the Atlantic on the other, with only one small gap about three miles wide between their western edge and the sea. W e predicted that through this gap we might see funnelled a huge stream of southward-moving migrants. T o test this idea, we visited the area in October, since in western Europe most of the visible migration of finches and other birds occurs in this month. Now October is outside the holiday season, particularly in France, where nearly all the hotels close on 30th September, and this is undoubtedly one reason why what we saw was previously unknown. First, we felt that we ought to make quite sure that there was indeed no migration through the high mountains, so we arranged a short visit to Gavarnie in the High Pyrenees. T h e village of Gavarnie is near the head of a long steep-sided valley running from the plains southward into the heart of the mountains for some twenty miles, and it ends in a huge cirque, a semicircle of vertical precipices between 4,000 and 5,000 feet high. On 13th October, we left the village of Gavarnie at first light, when it was very cold, and climbed the western side of the valley by a steep winding path. T w o hours later, we had climbed into the sunlight and could look down on the valley of the cirque, which made a magnificent scene, the giant grey precipices still in shadow, and a thin waterfall tumbling over their full height to start the little river Gave, which ran through alpine meadows and stunted beechwoods, the leaves of which had turned a rich brown. No one was in sight, nor, so late in the year, were any domestic animals in the meadows. We now continued south-west along a narrow path up a subsidiary valley towards the Port de Gavarnie, a pass about 7,500 feet above sea-level and only some fifty yards wide, at 32

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the divide forming the boundary between France and Spain. The climb, chiefly through bare meadows and at the end over scree, took another two hours, and in this time we saw hardly any birds, though when the sun had warmed the rocks, a few Griffon Vultures and a Lammergeier soared off from their roosts on the cliffs above us. Nor did we see any people until, just before we reached the head of the pass, a man in priest's clothing, his cassock tucked into his trousers, appeared from the Spanish side at a rapid run, cut the hairpin bends of the track by sliding down the steep scree slopes with his stick between his legs, gave us the curtest of nods as he passed, and rushed on towards France. W e reached the bare top of the pass at 11 a.m., and as we did so, a party of Goldfinches fluttered past us and dropped down on the other side into Spain. W e had so convinced ourselves that there would be no migration that this came as a great surprise. But it was soon clear that a moderate migration of small birds was in progress. W e had not seen it on the way up because the birds kept much higher up the slope until they were funnelled into the narrow pass at the top. It was now a bright sunny day, with a chill wind from the west-south-west in the face of the migrants, which made them fly low. W e settled in the shelter of a tall rock at the top of the pass, looking back down the valley, toward France, with field-glasses, notebook and pencil, to observe and record what passed. In the next three hours we counted, in all, some 200 Goldfinches, 400 Chaffinches, 100 Linnets, and 30 Serins. These small finches were known to leave northern for southern Europe at this time of the year, but it was not previously known that they cross the high mountains on their way. There were also a few Meadow Pipits, W h i t e Wagtails, and Skylarks, making in all nearly 800 small birds in three hours, a modest movement compared with what one might see in the plains, but impressive for the mountains. W e probably counted almost all the birds that came through, for the pass was extremely narrow and the migrants flew low, many of the finches skimming only a few inches above the c

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Wood Pigeons ground. Indeed, because our silhouettes were hidden by the rock at our backs, the birds were often just above our heads, and we felt that we could have stretched out an arm to catch them. A few individuals seemed to lose heart on the steep final ascent, settling on the boulders a few feet below the top, then calling anxiously, until with more excited calls they rose to join another party coming over. Chaffinches were particularly prone to alight, and gave repeated alarm calls, the rocky slopes evidently being too unlike their native woods. In the same connection, we were interested to see that the pipits, wagtails and larks, which are birds of open country, flew decidedly higher than the finches, usually from six to twenty feet above us; they were evidently more at home there. Nearly all the birds came in small flocks of five to twenty individuals, and very few flew singly, such single birds being particularly inclined to alight near the summit. It should perhaps be added that all the birds really were migrating. None of these species are resident at the Port de Gavarnie, all flew in the same direction, south-westward from France into Spain, and their steady progression looked very different from the usual daytime flight of the species concerned. Flocks of Wood Pigeons started passing at noon, and in all we saw 500 of them, together with a few Stock D o v e s . Hence 34

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they were nearly as common as the finches, but we saw much less of them because they came through in a few large flocks. Also most travelled high, crossing the pass several hundred feet above our heads, but one flock of about 300 came through extremely fast and low, some even hitting the rocks with breast and wings, in panic from a pursuing Peregrine Falcon. The falcon was resident in the valley and doubtless subsisted on migrants at this season. T w o Sparrowhawks, presumably migrants, also came through. So did a few Griffon Vultures, all flying south-west, but as they are resident there, we do not know whether these were migrants. T h e steady passage of small birds at so high and bleak a spot was, it ma)' be supposed, sufficient treat for one day, for not only was the sight impressive, but we had established beyond doubt that small songbirds migrate through the High Pyrenees. Yet as it happened, birds were the least spectacular migrants that day, and just this once in our lives, we were more excited by the insects. Butterflies of several kinds were travelling steadily over the pass in the same direction as the birds, their number gradually increasine; during: the hours that we were there. The commonest were Clouded Yellows, their sulphur-yellow wings with broad black tips contrasting with the grey rocks. Even brighter were the Red Admirals, with nearly black wings set off by a red band and white flecks. This second species was at first scarce but later became as common as the Clouded Yellow. There were also a few Pale Clouded Yellows, and a very few Bath Whites, a small delicately coloured white species. The butterflies flew

Clouded Tellows and Red Admirals

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steadily up to the top of the pass, across and over it, and then down into Spain, keeping head to wind like the birds, but flying even lower, most of them only a few inches above the ground, which made them hard to see more than a few yards away. Ornithology being our business, we did not have time to count the insects, but at a guess, butterflies were passing at a rate of at least one hundred, and possibly five hundred, an hour. By butterfly standards this is evidently a small movement, but at the place in question it was exhilarating to see. W e also saw one Hummingbird-Hawkmoth, which was presumably on migration, though we did not actually see it cross the pass. When we arrived, dragonfiies were passing in numbers about double those of the butterflies, but an hour later they were much more abundant, and in the second half of our visit there were probably about ten dragonfiies to every butterfly. Whenever we looked at right angles to the stream of insects, we could see at least six and sometimes twenty dragonfiies in the air at once. They may well have been passing at a rate of several thousand an hour, but as they flew closer to the ground than did the butterflies, and were much less brightly coloured, this may have been an underestimate. W e had not expected them, and anyway were mere bird watchers, so we had no collecting apparatus. But we realized that entomologists would surely want to know the species involved. So eventually I took off my shirt and found that I could drop it on to a few of the most tired dragonfiies at the top of the pass, after which we packed them in our sandwich wrappings, so as to bring them home for identification. There were two forms, both of the same size and appearance, much the commoner having a red body and the other a grey one, and they turned out to be the male and female respectively of Sympetrimi st?-iolatum. P r e viously, this species had occasionally been seen m i g r a t i n g in the plains, but not through mountains, and the fact that we could catch such normally rapid and wary insects with a discarded shirt may help to show how exceptional the scene was. Even this was not the end, but it was not until we had been at the pass for over an hour that we realized that another insect 36

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was migrating in larger numbers than all the other insects and birds put together. This was a little hoverfly with a black and yellow striped body, and it was immensely common, there being at a rough guess at least twenty times as many as there were dragonflies, and perhaps a hundred times as many. The hoverflies, like the dragonflies, flew steadily up to and over the pass, keeping their heads to the wind, but they flew even closer to the ground, and that was why, together with their small size, we at first did not even notice them. Shortly before we left at 3 p.m., the whole surface of the pass, at about ankle-height above the rocks, was a shimmer of iridescent light, due to the reflections of the autumn sun on a myriad tiny wings. Once more, it seemed essential to collect some specimens. But everyone who is familiar with the rapid flight and changes of direction of a hoverfly will realize how impossible that seems with only the aid of a shirt. Like the dragonflies, however, the hoverflies were flying slowly and steadily forward, without their customary rapid darts, so it was not, after all, difficult to add a few to our collection in the sandwich papers. They turned out to be of one species, Episyrphus balteatus. In order to reach the village again before dark, we had to leave the pass in mid-afternoon, and it was striking how, as soon as we were about a hundred feet below it, all traces of the migration of insects and small birds had gone. Only the highflying pigeons could still be seen, and several more large flocks came over us as we descended. In conclusion, I add some general comments on our observations. W e saw finches and other small birds crossing the Pyrenees in various other places that autumn. Clearly, high mountains are regularly crossed by small birds, and unknown to us then, further observations were being made at this time in Switzerland to the same effect. The Dutch observations concerning the avoidance of hills have turned out to have a different and complex explanation, which need not concern us here. W i t h regard to the butterflies, those that we saw belonged to species that were already well known to migrate northward in Europe in the summer, but up to that time it had been widely 37

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believed that their movements were due to over-population in the south, and that though the individuals concerned might live for a short time, some even breeding, all were destined to extinction, and that there was no return. Yet it might on general grounds have been suspected that natural selection would not allow so self-destructive a habit, and shortly before our visit, Dr C. B. Williams had argued on these lines, and had collected scattered records of southward flights in autumn, especially of Red Admirals in England. Our visit put the existence of regular return flights beyond reasonable doubt, especially as on other days we saw more such southward flights in various parts of the mountains. Since bird migrants regularly fly north in spring and south in autumn, the idea of a return passage in butterflies did not surprise us so much as it did most entomologists. But there is this important difference, that whereas in birds the flights at both seasons are performed by the same individual, in nearly all butterflies each is undertaken by a different generation. Thus the Red Admirals and Clouded Yellows that fly north in spring die after breeding, and it is their offspring that return south in autumn, and their grandchildren that fly north once more in the following spring. Only in the American Monarch Butterfly is the same individual known to make both journe}^. That dragonflies might also make regular seasonal migrations, north in spring and south in autumn, had not previously been suggested, and our visit made it evident that they behave like butterflies in this respect. But how rarely does one see anything really new in nature. Soon after our return to Oxford, we read how the Oxford classical don, W a r d e Fowler, saw dragonflies travelling through the Swiss Alps in September, and a Swiss observer had also seen hoverflies, but the significance of their short reports was not appreciated. Hence while hoverflies were occasionally known to appear in masses, migration in the sense of a directed movement was not merely unknown but unsuspected in this group of insects; yet at Gavarnie they were the most impressive migrants of all. So the chief discoveries that day concerned the insects, and my most memorable day as an ornithologist was the only S8

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occasion in my life when these lesser creatures took precedence over birds. But I was bird-watching at the time, and the chief discovery was, after all, that insects migrate like birds, so birds played a key part in the story; anyway, no entomologist would have been so stupid as to climb the high mountains in October. Finally, of course, it was the picture as a whole that was so impressive, for, omitting the putative priest, the procession through the pass included creatures ranging in size from Griffon Vultures to hoverflies, all moving steadily in the same direction.

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3

The Significa?ice of Migration In the autumn in Britain many of the birds that nest with us in summer are starting on their way soutli. W h y do they make this annual journey? Many animals, including birds, move about in their search for food or breeding places, but m i g r a tion is obviously much more than a purely local movement, involving as it does the annual shift of whole populations for hundreds and often thousands of miles. As the huge scale of migration is often not appreciated, let me start with a few examples: first, a particular case. T h e Wheatear is a small bird which nests on sandy heaths and rocky moors. It breeds in Greenland, Iceland, r i g h t across northern Europe and northern Asia, and well into Alaska; each autumn the whole of this population migrates to Africa. T h e Wheatears breeding in Greenland have a sea crossing of several hundred miles, while those breeding in Alaska j o u r n e y westwards for more than the length of Asia, travelling in all some 7,000 miles, twice every year. A broadcast talk in September 1952 40

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Now consider the Palaearctic region as a whole, that is Europe with Asia north of India. Of nearly 600 species of birds breeding in this great region, some 40 per cent leave it entirely for the winter, migrating to Africa, India or South East Asia. I do not mean that only 40 per cent of the species migrate, for many others travel for several hundred miles within Europe or northern Asia. T h e 40 per cent are the long-distance migrants; and it may be doubted whether they could exist in Europe or palaearctic Asia if there were no warmer lands to the south to which they could retire for the winter. As a third example, consider only the song-birds, which are less powerful fliers than most other types. Of the 68 species that breed in Britain, some 22 spend the winter in Africa south of the Sahara, crossing both the Mediterranean and the great desert belt twice every year, in journeys of over two thousand miles each way. Clearly there must be some strong reason for so many species of birds to undertake these long and often dangerous journeys every year. W h y do they do it? At one time, it was thought that bird migration originated in the Ice Age, the birds of northern lands being driven south by the ice and later returning through a sort of ancestral tradition. But this view has been given up. For the Ice Age was much more complex than was at one time supposed, with several intervening warm periods. Also, the fossil record shows that various kinds of birds, which today are typical migrants, were already in existence in the Oligocene Age, that is to say some thirty times as long ago as the start of the Ice Age. Hence birds were probably migrating a very, very long time before the Ice Age began. Another objection to the Ice-Age theory is the great diversity of migration as we find it today. It is not just a north-inthe-spring and south-in-autumn affair of birds in the North Temperate regions. Thus some European species migrate not north and south but east and west, while in the Ural mountains, the Capercaillie even migrates north into a colder region for the winter, as suitable feeding places lie that way. Again, some birds make not merely two, but three, migrations each year. 41

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The Starlings nesting in Switzerland leave this dry area in late summer and migrate north-west to the marsliy plains of Holland, returning after a few weeks to Switzerland, and later leaving on a second migration to spend the winter in North Africa. Various ducks, also, which are flightless in the moult, migrate after breeding to remote islands or lakes, where they moult in safety and later migrate again to their winter quarters. Moreover, bird migration is by no means confined to those regions covered by, or near to, the ice-cap in the glacial periods. In particular, quite a number of tropical birds migrate. One of the rollers, for instance, breeds in Madagascar and migrates each year after breeding to the Belgian Congo, some 1,500 miles away, and migrations of similar length occur in other tropical species in Asia, America and Australia. Further, though migration is commonest in birds, it is also regular in various other groups of animals. W h a l e b o n e whales migrate in summer to the cold polar waters rich in food and retire for the winter to warmer tropical w a t e r s ; but, unlike birds, they breed in their winter and not their summer quarters. Various seals and bats also migrate for long distances. Some fish, such as the Tunny, migrate like birds from one main region to another and back later, while others, such as the Mackerel, have restricted spawning grounds from which they migrate outwards in various directions. Some species of fish migrate quite as far as birds, Eels, for instance, coming from the Atlantic south of the Bermudas to English p o n d s ; but Eels differ from bird migrants in that each individual travels each way only once in its life, from the Bermudas to England as a

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small fry and back again some ten to twenty years later as a large fish. Among invertebrate animals, movements from deep water to the coast and back again are found in crabs and other shore animals, while the cuttlefish spends the winter south of England and migrates each spring into the North Sea to breed. But the most spectacular invertebrate migrants are insects. Red Admirals and Clouded Yellow Butterflies, for instance, reach us each spring by a northward flight from the Mediterranean region, and there is a return flisrht south in autumn. But these butterflies differ from migrant birds in that, after they have bred with us, it is their offspring which migrate south, these in turn breed in the Mediterranean region and their offspring make the northward spring flight. Hence each journey is made by a new generation, and breeding occurs in both the summer and the winter quarters. Large migrations have also been seen in European dragonflies and hoverflies. But to observe insect migrations on a large scale one should visit the tropics, where they are far more extensive than in cooler climates. Migration, then, takes rather different forms in different types of animals, but in all it is a regular, seasonal, large-scale movement of a population from one main region to another and back again later in the year, the animals breeding in one of these regions, but not normally in both. Apart from the length of the journey involved, true migration is difficult to distinguish from purely local shifts of habitat at regular times of the year, in search of food or breeding places, which occur in many types of animals. But migration is normally distinct from another large-scale movement, emigration, found in such creatures as Lemmings, since emigration occurs at irregular intervals, the animals move outwards in various directions from a centre of over-population, and usually they do not return there. Coming back, now, to the question of why migration occurs, the commonsense view is that birds such as Swallows and warblers, for instance, leave us in autumn because winter is on its way and food is becoming scarce. But at the time when the birds actually leave us, their food is still plentiful, and a bird's 43

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mind is of such a nature that it cannot know in advance that winter is coming. Nevertheless, the commonsense view is partly r i g h t ; the problem has been confused because the apparently simple question 'Why do animals migrate?' is really two questions, with different answers. First, there is the question of the ultimate value or significance of migration in the life of the species; why has it been evolved? Secondly, there is the question of its immediate cause; what makes the birds (or the whales or the dragonfiies) actually set off? Thus, although our Swallows and warblers are not short of food when they leave in A u g u s t and September, so that food shortage cannot be the immediate cause of their going, food shortage in winter may still provide the ultimate reason for the evolution of migration in these birds. For if Swallows tried to stay here through the winter, they would almost certainly starve to death, whereas any that migrated to Africa would have a greater chance of survival. Migration, like so many other habits of animals, m u s t be a product of natural selection. It occurs on far too big a scale not to be of survival value to the animals concerned. On this view, a southward migration in autumn has been evolved by those of our birds that have a higher survival-rate if they m i g r a t e than if they try to stay the winter, and conversely a resident habit has been evolved in those species which, like tits or w o o d peckers, can find food here in winter, and for which the dangers of migration probably outweigh those of staying for the winter. In some of our native birds, such as the S o n g - T h r u s h , part of the population migrates and the rest stays with us, which 44

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suggests that the dangers of migration and of winter hardship are about equal. Supporting this view, a higher proportion of Song-Thrushes migrate from the north of England, where the winters are more severe, than from the southern counties where the winters are milder. These proportions are liable to change as conditions change. Thus in Finland, the proportion of Chaffinches and Goldfinches that remained for the winter gradually increased during: the mild winters of the nineteen-twenties and thirties, but now, after the severe winters of the nineteenforties, an extremely small proportion remains, presumably because nearly all those with a resident habit were wiped out. I consider, then, that a southward migration has been evolved by those species which, through lack of food, survive less well if they remain witli us for the winter. But food shortage cannot explain their return in spring. W h y do not our Swallows and warblers remain for the summer in Africa? This is a harder question to answer, but I would suggest that a northward migration has been evolved by those species that leave more descendants if they come north to breed than if they stay in the south. T h e northern lands provide favourable breeding conditions for many species, and in general the birds that nest there raise larger families than their tropical relatives. Hence this view seems reasonable, though admittedly it is unproven. T h e argument that migration is a product of natural selection can be applied with equal force to other animals. For many years, it was supposed that the northward spring flights of Red Admirals and Clouded Yellows to this country led merely to the death of the butterflies concerned and of any offspring they produced. It was therefore thought that these northward flights were either a by-product of over-population in the south, or a vain attempt to extend the range of the species into lands that could not support them permanently. But the migrations of butterflies, like those of birds, are on far too big a scale to be thus pointless. Some of the large movements have been compared with snowstorms. Butterfly migrations are particularly frequent in the tropics, and when Dr C. B. Williams, the authority on such movements, was living in East Africa, he 45

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saw some butterfly migration on 11o days in the year, that is on nearly two days out of every three. D r Williams argued that such movements must have survival value; and that if the northward spring flights to this country merely resulted in the extinction of those taking part, the migratory habit would have been eliminated from the species. W o r k i n g from this a priori argument, he organized an intensive search for the corresponding southward movements in autumn, and these have now indeed been found. In this country they are not nearly so conspicuous as the northward spring flights, but they occur regularly on a scale large enough to support the view that butterfly migrations, so far from being pointless, increase the survival-rate of the populations concerned. M o r e o v e r , as my wife and I discovered in the autumn of 1950, these return southward flights are much more prominent in the south of Europe. W e saw not only butterflies, but also dragonflies, and millions of hoverflies, pouring south through the high passes of the Pyrenees. Migration is not accomplished without loss. Each autumn, rare warblers, wading birds and other species wander offcourse to Britain. Indeed, the sport, as distinct from the science, of ornithology is largely concerned with the observing and recording of these failures in the struggle to survive. But such straggling provides raw material for natural selection to work upon, and occasionally it results in the successful establishment of a new home for the species. T h u s a hundred years ago the Black Redstart was a rare vagrant to Britain, but p r e sumably because conditions favoured its survival the numbers wintering here gradually increased, until now Black Redstart the species is a regular 46

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visitor to the south coast. Indeed in recent years it has even stayed to breed. I could give similar examples from other species which show that migration routes and winter quarters do not remain fixed but change gradually as conditions change. While the Ice-Age view of the origin of migration is wrong, we can be certain that, during the glacial periods, the pattern of migration was greatly changed, and it has been changing gradually ever since. T o say that migration is a result of natural selection, though fundamental, does not in itself explain how the birds come to set off at the right season of the year and how they manage to arrive in the right place. This brings up the second question involved in why birds migrate, namely what makes them set off when they do. I said earlier that our summer migrants normally leave us before the start of winter, and they likewise return shortly before the time when they can raise young. This anticipation of conditions is a characteristic feature of migration both in birds and the other animals that migrate. The advantage is so obvious, and the fact so familiar, that we forget how astonishing it is. How do the Swallows in autumn know that winter is coming? How, also, do they know when to leave Africa so as to arrive here in spring? How do the Salmon or the dragonflies know when to set out? The fact is, of course, that such animals do not know the ultimate reasons for what they do. A similar problem of timing arises over many other habits of birds and other animals, particularly those connected with breeding. Some of these habits are known to be regulated by hormones, chemical substances in the blood whose production is stimulated both by external changes, as in day-length or temperature, and by the internal state of the bird itself. Probably the impulse to migrate is linked with one or more hormones, but the details are uncertain. I might add that the impulse does not arise suddenly. The migrant bird spends several days before it leaves in feeding hard and putting on fat. Migrating insects also put on fat before setting off. They are then in a condition to migrate, but, in birds at least, they do not actually set off until the weather is suitable. They usually start only in 47

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settled anticyclonic weather, so the further problem arises of how this is recognized. Finally, there is the great problem of how the m i g r a n t s find their way. A Homing Pigeon is seeking its way back to a place it already knows, but a young bird (or a butterfly) on migration is setting off for a region where it has never been before; and in most species, the young are certainly not guided by the adults. How do they know what direction to take, and how do they know when they have got there? T o say that they do it by instinct is merely to classify, not to explain, w h a t has long been a mystery. All that the term 'instinctive* means in this connection is that the behaviour is innate or inherited, not learned by experience. It does not explain how the birds do it. Electrical and magnetic influences can almost certainly be ruled out. Recent experiments show that one m i g r a n t bird, the Starling, takes its direction from the bearing of the sun, and that it is able to allow for the changing position of the sun at different times of the day. This problem of direction-finding, in day and night migrants, in animals that m i g r a t e by flying and in those that swim, is a subject in itself. I hope, however, that I have said enough to show that the successful evolution of a migratory habit involves first a timing mechanism, so that the bird puts on fat and sets off" at the right season of the year, secondly an ability to recognize suitable weather conditions for the flight, thirdly a sense of direction, and fourth a sense of distance travelled, all of these being innate, so that they are efficiently developed in a y o u n g bird or an insect setting off for an unknown destination w i t h o u t guidance from others of its kind. Only under these circumstances will the animal reach the right place at the right time. T o say, then, that migration is a product of natural selection should increase, not lessen, our astonishment and admiration.

48

Watching Migration by Radar As I speak at this moment, on an October evening, there are probably thousands of larks, starlings and thrushes crossing the North Sea from the Continent into England. At least, they will be doing so if the weather is not too bad. But if you were to go outside in the dark some night and stand on the shore in Suffolk or Norfolk, you almost certainly would not see or hear anything of this great movement. At dawn, there may be birds in the fields that were not there the day before, perhaps including Redwings or Fieldfares from the far north, and you might be able to see more flocks coming in from the sea, travelling a few hundred feet above the water. But if the birds were flying much higher than this you would not see them. So the watcher on the ground is left wondering whether he may not be missing most of the traffic. T h e migration of birds is a challenge to the imagination, especially when it involves small land birds crossing several hundred miles of sea. And until now, almost the only way to A broadcast talk in October 1958 D

49

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Redzvi?ig study it has been to look round after the night to see if any new birds have come in, and to watch in the early m o r n i n g to see what may still be travelling. Actually, from this very incomplete evidence, quite a good picture has been built up of what happens, but it is based largely on inference, and there have been arguments, sometimes heated ones, as to just how m i g r a t ing birds behave when they fly across the sea. N o w , suddenly, speculation can be replaced by direct observation, for m i g r a t i n g birds can be detected and tracked for a long time by highpower radar. Let me go back a bit. In the war I was concerned with the early-warning chain of coast-watching radar stations. So soon as these began to use a wavelength as short as 10 cms, the operators often reported echoes out at sea in places w h e r e there were definitely no ships or aircraft. These echoes sometimes gave rise to air-raid warnings and also, since they usually moved at about 30 knots, caused E-boat scares on the convoy routes. For some time their cause remained a inystery, but eventually a biologist, D r Varley, established that they came from large seabirds. And after much opposition, chiefly from physicists, who could not credit that feathered objects reflected radar rays, this view came to be accepted. 50

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RADAR

The next stage came six or seven years ago, with the development of new radar sets of much higher power, on which the display was sometimes covered with small echoes, called 'angels' by the operators. These 'angels' were at first thought to be of meteorological origin, though no one could find anything in the air to correspond with them. They were commonest in the spring and autumn, commonest in the early part of the night and again in the early morning and, which was most disturbing, they did not drift with the wind but moved through the air at some 30-40 m.p.h. Of course the answer seems obvious as I have put it here. But it was in fact only recently that a Swiss biologist, working with British radar equipment at Zurich airport, proved that 'angels' were the echoes from small birds on migration; almost immediately afterwards, an English meteorologist made the same discovery working independently. Even now, physicists seem reluctant to accept this explanation, the two chief difficulties being, once again, the difficulty in believing that feathered objects reflect radar rays, and, perhaps more important, that the 'angels' are so numerous. But the agreement between the occurrence, speed, and direction of angel echoes on the one hand and migrating birds on the other is far too good to be due to chance, and I personally am convinced that nearly all angel echoes come from birds. Now the latest radar sets are still more powerful, and can follow even small birds for fifty and sometimes over a hundred miles, and through the courtesy of the Royal Air Force I have recently been allowed to study migration at their stations. May I say what a privilege it has been to see this wonderful sight and to use this powerful instrument, which opens up a new field of study. Once people get used to the idea that radar really does track migration, the first comment usually is: 'Oh but I do not see how you can do much with it, because I do not suppose you can tell what kind of bird is giving the echoes'. That is true, but it matters less than might be supposed, because enough is known about British birds to say what kinds are likely to be migrating at different seasons of the year, and in fact, when conditions are 51

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favourable, most or all of the possible species seem to migrate at the same time. And to set against this disadvantage, radar does three things that could not be done before. First we can now measure the amount of migration taking place during every hour of every day and ever}' night throughout the year. Secondly, we can plot the directions taken by the birds, including when they are far out at sea. Thirdly, we can find the height at which they travel. To take the height question first, most migrations seem to take place at around 2-4,000 feet, at least over the sea. Occasionally echoes come from over 10,000 feet, but this is exceptional. Now a height of even 2—1,000 feet is enough to mean that the birds are out of sight of watchers on the shore or in ships, so we were right to wonder whether the ornithologist was not, in fact, missing most of the traffic. Further, when the birds travel lower, it is often due to abnormal conditions, so that the bird-watcher on the ground or on a ship may even g e t a misleading picture of what is happening; for instance, the birds may be moving in a different direction close to the ground than higher up, of which I have seen several examples. I have just finished analysing the records, compiled by the Research Branch of Fighter Command, for migration t h r o u g h out the year as observed at a radar station in East Anglia. This shows that birds cross the North Sea in every month of the year, though few do so in January. T h e biggest movements of all occur eastwards in March and April, not only by night but also by day. This came as a surprise, because Norfolk ornithologists see almost nothing of them. T h e reason is this. The small land birds concerned usually migrate at a moderate height above the land and rise on reaching the sea, but those coming from the Midlands towards north Norfolk first meet the Wash, which they treat like the sea and rise high, and thereafter they do not come down again, so that all of this huge eastward migration passes over Norfolk too high to be seen from the ground. Eastward departures continue throughout May, and then, already at the beginning of June, before the last of the northern birds have left, others are returning west 52

WATCHING

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BY

RADAR

into England, chiefly Lapwings from the Low Countries. There is something of a gap in August, only a little movement in September, except with east winds, and then the winter visitors arrive in big numbers between October and early December.* It has recently been shown by German workers that migrating birds kept in cages try to fly in a fixed direction, the direction in which they should be migrating, which they recognize through the position of the sun by day and stars by night. But what happens when migrants are flying over the open sea with a cross wind? Until now the answer was not known, and there has, in fact, been heated argument over whether the birds drift with the wind or not. Radar gives the answer. First let us consider the possibilities. Suppose I was in a boat on the shore waiting to push off for a land the direction of which I knew but which was over the horizon, so that I could not see it. The crudest way of navigating would be to wait for a following wind and then to push off, hoping that the wind would not change when I was half-way over. Since, in autumn, birds usually set off with a following wind, it was possible that they used this method. Secondly, I might take a compass with me, and this would give me my heading all right, so that I ought to arrive safely, unless there was a cross current. But I would have no way of telling whether I was drifting and, if so, how far off course. Only if I were given other instruments, such as a chronometer and sextant, could I find my true position and adjust my course accordingly. Well, what do the birds do? Radar shows that, provided the weather is fine, the migrants head in a constant direction over the sea, both by day and by night, and this, combined with the German experiments I mentioned, makes it clear that they navigate by the sun or stars, and do not need landmarks. But, and this is important, if there is a cross wind at sea, they make no allowance for it, and their course is the resultant between their constant heading and the direction and speed of the wind. * The picture for August and September was greatly modified after this was written. It was later found that there are big movements of small night migrants in August and September.

53

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Now in spring they freely set off with cross winds, so that their eastward course varies between north-east and south-east, which means that a bird leaving, say, Norfolk, may make its landfall anywhere between Belgium and Denmark. But the results of bird-ringing indicate that it still gets home safely, so it must have some other means of knowing its true position; so it looks as though it can use this other means only when it is on the ground. This other means is at present a mystery. That is what happens in fine weather, and birds do not n o r mally start migrating unless it is fine. But one day last April it was fine at the start of the evening and later fog and rain set in. At this point many migrants were already some fifty miles out over the North Sea. Previously they had been heading rather north of east, but now they seemed unable to hold a steady course and kept changing their direction. This was presumably because they could no longer see the stars. Under such conditions they evidently mill around all night, gradually drifting with the wind, and it is after such nights that they land up, exhausted, on islands and headlands, giving delight to many bird-watchers, for such drifts often include rarities. Now many such drifted migrants caught and marked on Fair Isle and elsewhere have since been recovered in their normal haunts, suggesting that, though drifted, they can re-orientate themselves later. By good fortune, radar detected such a r e directed movement last April. At the end of March there had been an unusually large drift of Continental night migrants into England with south-easterly winds. A week later, to my immense surprise, I started to track a southward migration down the North Sea. Now a southward migration in April is almost unheard of. The radar suggested that some of the birds concerned were landing on the north Norfolk coast and when I went there, I heard that a further arrival of Continental species had taken place. Radar showed that these birds had come, not from the Continent, but from northern Britain. Clearly, they were the birds that had drifted over a week earlier and were now re-directing their course back home. Well, that is only a sample of what is being discovered by 54

WATCHING

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radar about bird migration. I am sure there is going to be a lot more. Indeed, I would regard this as the most exciting ornithological event in many years. I expect most birdwatchers will still prefer seeing a rare bird, and good luck to them, but this new instrument may help to explain how the rare bird got there.

55

Migration at Minsmere, Seen and Unseen During the first part of each morning in the spring and autumn of 1960 and 1961 and in the spring of 1962, H. E. Axell made regular counts of the migrants travelling along the coast at the R.S.P.B. Reserve at Minsmere, Suffolk. Simultaneously, a team from the Edward Grey Institute, Oxford, made radar observations on the migrant birds travelling high on a broad front over Suffolk. A comparison of the visual and radar records had not been planned at the time, but proves highly informative, showing in particular that the visible migration provides a very misleading idea of what is happening overhead. The use of radar to track birds is still suspect among some ornithologists, particularly on the grounds that the species producing the echoes cannot be identified. It may therefore be recalled that the grandfathers of these same ornithologists held a similar prejudice against the use of field-glasses, on the partly correct grounds that sight records were untrustworthy; on their view identification had to rest on shot specimens. Eventually, helped by the increasing experience of those using them Written with H. E. Axell, J. L. F. Parslow and J. Wilcock, in Bird Notes SO (1963)

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and by improvements in optical design, field-glasses were to produce far more new information on migration than the shotgun had done. Radar, similarly, is producing much new information which could not be obtained through f i e l d ^lclSSGSj and with increasing experience, the problem of identification is not nearly so serious as might be thought. The size and speed of the echo provide valuable clues, and in eastern England so much is known about the seasons when the various nocturnal and diurnal migrants travel that identification is often reliable to the group, and occasionally to the species. T h e birds seen coasting past Minsmere were chiefly Meadow Pipits, Linnets and Goldfinches, with in the autumn of 1960 many Siskins and some Redpolls. They travelled between 10 and 200 feet up, flying lower against strong than light winds, starting at first light and continuing until mid-morning. In autumn they occurred between mid-September and the end of October and in spring between the end of March and mid-May. As these birds, particularly the Linnets, often fly along the coast merely to feed, we considered a coasting migration to have taken place only when at least 100 birds travelled along the coast in one direction on the morning in question. Radar showed that between mid-September and the end of October, in the first part of the morning, there was often a broad-front movement heading rather east of south over Suffolk and out to sea, consisting of small echoes typical in size and speed of those from small passerine birds. Presumably these came from the same species as those seen coasting south, and no other explanation can be suggested for them. (Migrants arriving SSW from Norway may sometimes have joined the coasting birds, but the morning arrivals detected by radar were mainly of warblers in September and thrushes in October, so had nothing to do with the coasting movements and we have therefore left them out of account.) The radar and visual observations have been compared in Table I. The first row of figures shows that, out of the 19 autumn mornings studied in which there was a following northerly wind, a broad-front southward migration was 57

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detected on 13, but a southward coasting movement was seen on none, while on three mornings (with three others in 1.959) there was actually a small northward coasting movement of between 100 and 170 birds. On the 6 mornings when no movement was either seen or detected by radar, the weather was disturbed and presumably unsuitable for migration. The second row of figures, for opposed southerly winds (but omitting very light winds), is in marked contrast. A broadfront southward migration was detected by radar on only 2 out of the 35 mornings, and on both of these the wind was only just over our arbitrary limit of 9 knots for very light winds. On the other hand, on both these mornings and on 11 others when no movement was detected by radar, a southward coasting movement was seen, and on three occasions it exceeded 1,000 birds. No northward coasting occurred. The third row of figures, for extremely light southerly winds, is again in contrast. A broad-front southward migration was detected by radar on 18 out of the 20 mornings, and on the other two, together with 12 when a movement was also detected by radar, southward coasting was seen, which on 7 occasions exceeded 1,000 birds. No northward coasting occurred. What do these results mean? First, it is evident that the birds seen coasting give, by themselves, a highly misleading picture of the migration. For solely on this basis, one would have to conclude that pipits and cardueline finches move south in autumn only when the wind is opposed; indeed, with a northerly wind what little movement there is seems to be back north. Radar shows, however, that the high broad-front southward movements, which are probably the main departures, occur either with a following wind or with an extremely light head wind, and not at all with a moderate or strong head wind. T h e difference is that, with a following wind, the birds migrate high, are spread out on a broad front, and on reaching the coast put straight out to sea, hence they are not normally seen by an observer on the coast using ordinary field-glasses; on the other hand with a moderate or strong head wind, the birds fly too 58

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low over the land to be detected by radar and on reaching the coast turn along it, so that a concentrated stream passes within easy view of the observer. W i t h a very light head wind the position is intermediate; some of the birds fly high on a broad front out to sea, so are detected by radar, while others turn and follow the coast, so are visible. These findings are not new, for the same conclusion was reached earlier for the autumn migration of the Chaffinch by Dutch workers, who used field-glasses of very high power to detect the high broad-front movements. The puzzle remains why, with northerly winds, any Linnets and Goldfinches should coast northward in Suffolk in autumn, especially as radar shows that their fellows are simultaneously proceeding southward on a broad front high above them: but the numbers coasting north are very small. It used to be thought that the movements of pipits and cardueline finches along the East Anglian coast in spring consist entirely of British summer visitors on their way further north. This may, indeed, apply to some of them, but others are evidently on their way to Norway. For in April 1961, I saw several coasting parties of Linnets and Goldfinches, together with occasional hirundines and wagtails, break away from the coast and put out to sea N N E , proceeding in this direction until lost to sight. This happened on days when either northward or southward coasting movements were in progress. Further, radar shows that, in April and early May, there are two diurnal movements of small echoes northward on a broad front over East Anelia, one N N W towards northern Britain and the other N N E in the direction of Norway. Hence in Table I, both these movements combined have been compared with the coasting movements (but the result is similar for each analysed separately). The lower half of Table I shows that, in spring, a northward broad-front migration occurred on 29 out of the 35 mornings with a following southerly wind, and also on 6 of the 11 mornings with a very light opposed northerly wind, but on none of the 6 mornings with a moderate or strong head wind. On the 59

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other hand, northward coasting was not seen on an} - morning with a southerly wind, but it occurred on IS of the 18 mornings with a northerly wind, on 7 occasions involving at least 1,000 birds. These results are effectively the same as for the autumn and can be explained in the same way, i.e. high broad-front migration with following or light winds, and low coasting movements with a head wind. But 'wrong-way' coasting was much commoner in spring than in autumn, occurring southward on 21 out of the 35 spring mornings with a southerly wind, on 4 occasions involving over 1,000 birds. Indeed, in three successive springs H. E. Axell saw, in all, about 17,000 birds coasting south as compared with 31,000 coasting north! Nevertheless, the birds coasting south are evidently part of the northward migration, for they involve the same species between the same dates as those coasting north on other days, while I, as already noted, saw some birds coasting south which broke away and put out to sea NNE. Further, radar observations are available for 21 mornings when there was southward coasting, and show that on none of them were any higher migrants travelling south, while on 16 of them, including the four involving over 1,000 birds, the birds high overhead were moving on a broad-front in nearly the opposite direction, N N E over East Anglia and out to sea. At least some of the southward coasting can be explained by supposing that the birds cross East Anglia on a broad-front heading NNE and then, instead of putting out to sea, turn east along the north Norfolk coast; but as the coast turns southeast and later south, any birds that continue to follow the coast are forced to fly south-east and later south. A similar response to a turning coast has been inferred for the autumn movements of Devon Chaffinches, and in them also the birds may eventually head almost directly away from their presumed destination. For the birds discussed here, the most critical area is probably north-east Norfolk, since it is here that the coast first turns away towards the south, and it seems significant that it is here that some birds coasting south have been seen to break away 60

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and set out northward over the sea. Very possibly the turning along the coast of birds which should have put out to sea is only part of the explanation of the southward coasting in spring, and further observations are needed. In any case, however, we suggest that the southward coasting is purely temporary, and that by next morning many of the same individuals may well be proceeding northward in their 'proper' direction. It may be added that between 2nd and 6th April 1960, H. E. Axell saw about 15,000 Starlings coasting south at Minsmere against the wind. Both radar and visual observations show that Starlings, unlike the other species discussed here, migrate east, not north, in spring. It therefore seems likely that those seen coasting south had previously travelled east on a broadfront over East Anglia but checked at the coast and turned south, into the wind. Radar showed that high broad-front departures eastward, which presumably included Starlings, occurred on two of the morning's concerned, but not on two others, while on the last no radar record was made. Summarizing, the field observations at Minsmere might suggest that, in autumn, pipits and cardueline finches migrate southward exclusively against the wind, while in spring, about two-thirds of them travel north against northerly winds while one-third travel south against southerly winds. But radar reveals a far more reasonable picture, that high broad-front migration, south in autumn and north in spring, occurs either with a following wind or against a very light head wind, and not against a strong head wind. Evidently the coasting birds are an unimportant fringe of the high broad-front movements, and we would guess that they involve only a small proportion of the migrants. T h e reader may wonder whether, in the light of these findings, further observations on visible migration are not a waste of time. But this, we consider, is far from the case. Apart from the great enjoyment to be obtained from being on the coast at dawn and in watching migrants on the move, we consider that, especially outside eastern England, much more needs to be learnt about when the different species of migrants travel, and 61

/

TABLE I Relation between visible coasting passage at broad-front movements detected by radar o

Seen northerly wind (following) southerly wind (at least 10 knots) southerly wind (v. light)

Seen southerly wind (following) northerly wind (at least 10 knots) northerly wind (v. light)

Number of autumn m SSE movement on radar coasting S coasting N none co 0 3(+S) 7

12

0

0

0

6

Number of spring m NNE or N W movement on radar coasting N coasting S none co 0

16

13

0

0

0

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what sort of numbers are involved. Also the visual observer sees low-flying migrants that are not detected by radar. The only warning we would give is that the visual observer should not conclude that he sees all, or even a representative sample, of the actual migration, for what he sees may even be in the opposite direction to the migrants overhead. Finally, British ornithologists do not }'et seem to have tried the visual technique pioneered by the Dutch, and recently elaborated by the watchers for trans-Gulf migration in Louisiana, in which the observer lies on his back and looks through a securely clamped telescope or high-power field-glass pointed directly upward, by which means high broad-front migrations that were previously unsuspected have been detected and identified.

Goldfinch

6

The Height of Bird

Migi'ation

Migrating birds cannot be seen when they are high above the ground by day, even with military optical equipment, and means have not yet been found for accurately assessing the height of night-migrants seen by a telescope against the face of the moon. Moreover, small birds, and even large ones, are extremely hard to see from a fast-moving aircraft. M o s t records of birds seen from aircraft have been below 4,000 feet though large birds occasionally, and small birds very rarely, have been observed at around 10,000 feet above the ground. Only with the new technique of radar has it become possible to obtain a true assessment of the height of migration. By this means, Sutter found that nearly all morning movements in Switzerland occurred less than 800 metres above the ground, though occasionally up to 1,300 metres. On morning and evening movements above Hertfordshire, migration was commonest at 2-3,000 feet, frequent up to 5,000 feet and very infrequent above 10,000 feet, the highest birds being at 13,000, 14,000 and 16,000 feet, while records of a similar nature were obtained above Worcestershire. From British Birds 53 (1960) 64

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MIGRATION

At intervals from October 1958, I have through the courtesy of R.A.F. Fighter Command obtained many heights for bird migrants over Norfolk and over the North Sea off Norfolk, by means of a new, much more powerful and more accurate height-finder than those previously in use in Europe. It was operated in conjunction with a plan-position display on which bird-echoes are readily recognized, and I am confident that all the echoes on the height-finder here attributed to birds in fact came from them, most from passerines and some from waders. On both types of equipment, wader echoes are larger than those from passerines and are further recognizable on the planposition display by their faster speed and by their manner and times of occurrence. Because of its high power, the new heightfinder is specially useful for recording parties or even single birds at great heights. However, where echoes from passerine birds are numerous, as is normal at low heights, they merge with each other and cannot be counted separately. Further, birds flying close to the ground are not usually detected by radar. Hence the mean height of passerines could not be assessed, though it was possible to calculate this for some wader movements because of their widely spaced echoes and the fact that none was low. In late October and early November 1958, with light winds, there were big westward arrivals in Norfolk, from the direction of northern Holland, of birds which had obviously left the Dutch coast during the night or the first part of the morning. The echoes were characteristic of passerine birds of moderate size, and the commonest species were probably Starlings and Chaffinches. Many Blackbirds also arrived in Norfolk in this period, but whether westward from Holland or south-westward from Scandinavia, or both, is not certain. On the westward movements, all the echoes were normally at or below 3,000 feet above the sea during the morning departures, and this also held during some of the nocturnal movements, though on other nights they were frequent up to 4,000 feet. Early on one morning there was a gap between the last nocturnal departures and the first morning ones, the birds that left Holland during the E

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Blackbird arriving,

Norfolk

dark extending to 4,000 feet but those that left by day reaching only 3,000 feet. In late October and early November 1958 there were also south-westward arrivals in the early morning, presumably of night-migrants from Scandinavia. T h e echoes were again typical of moderate-sized passerine birds, and the commonest species were probably Redwings and Fieldfares and perhaps also Blackbirds. During these movements, heights commonly extended to 7,000 feet, with a few at 8-10,000 feet and one at 11,000 feet, and similar heights, again including one at 11,000 feet, were obtained during one small evening arrival from the same direction, presumably of birds that left Scandinavia around dawn. Hence the Scandinavian migrants travelled higher than those from Holland, but further study is needed to determine whether this was because different species, chiefly thrushes, were involved, or because the Scandinavian birds had travelled for 400 instead of 100 miles over the sea. Many height-records were also obtained when the same species of winter visitors left Norfolk in late March and the first half of April 1959. Although a mean height could not be 66

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obtained, it was possible on seven mornings to determine the most frequent height: three times this was around 2,000 feet, once 2-3,000 feet, once around 3,000 feet, twice around 4,000 and once around 5,000. Hence if, as seems almost certain, these were the same species that arrived in Norfolk on October mornings, they tended to travel higher in the spring. This view is supported by the fact that in Norfolk much more diurnal migration is low enough to be visible in autumn than in spring. Of over 700 individual height-records on spring mornings in 1959, about three-quarters were below 4,500 feet, but the true proportion must have been decidedly larger, owing to the merging of echoes at lower heights. On half the mornings watched, there was at least one bird as high as 9,000 feet, and I obtained a few records at 10,000, 11,000 and 12,000 feet, but some, and perhaps all, of these birds might have been individuals that set off during the night and had not yet descended. In the same period of the spring, at night between 20.00 and 21.00 hours, echoes were usually so crowded that it was not possible to assess the most frequent height, though almost certainly this was at or below 5,000 feet. Occasionally echoes extended in a dense mass up to 9,000 feet, while on nearly half the nights watched there was at least one individual at 13,000 feet; the highest bird was at 14,000 feet. Hence the birds travelled rather higher by night than by day in spring, and decidedly higher by night in spring than by night in autumn. I obtained many more height-records during the first three weeks of September, 1959, these being on very small nightmigrants, presumably warblers, flycatchers and chats. Each night there was a big departure, heading SSE over the land, of birds giving very small echoes, and by 21.00 hours, the highest individuals had usually reached 10,000 feet, twice 13,000 and once 14,000 feet above the ground - heights comparable with those obtained on the larger passerine species departing eastward in spring. As in spring, mean heights could not be obtained, but most individuals were below 5,000 feet. Around sunrise each day in September, there was also a regular arrival of birds from the sea giving very small echoes 61

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and heading about SSW, these presumably being warblers, chats and flycatchers that had left Scandinavia during the first part of the night. On sixteen mornings watched, most echoes were below, and perhaps well below, 6,000 feet, but each day a thin scattering of echoes extended fairly uniformly above this up to at least 15,000 feet, while on seven mornings the greatest height was 19,000 feet and on two mornings it was 21,000 feet. With an exceptionally large arrival on 14th September, at 06.00 hours, I recorded 13 individuals at 19,000 feet, 9 at 20,000 feet and 3 at 21,000 feet, while one hour before midday, when the movement was still continuing, though less densely, there were at least 5 birds at 19,000 feet, 2 at 20,000 feet and 3 at 21,000 feet (which must have been different individuals from those seen five hours earlier). I devoted only a short time each morning to heights, and since in these periods I recorded 30 birds at or above 20,000 feet, this cannot be very unusual; indeed, there may possibly have been some above 21,000 feet, since I made no special search to find exceptional birds. T h e weather throughout the period of these watches was fine and anticyclonic with moderate north-easterly following winds, that is, it was typically favourable weather for migration at this time of the year. (Since this was written, it lias been suggested that the highest birds on these arrivals might have been small waders, such as Dunlin, from Scandinavia, and with this I agree.) On September evenings in 1959 I also obtained heights on larger wader-type echoes travelling west. These birds had evidently left the Dutch coast in the late afternoon and early evening. Probably most, if not all, were Lapwings, which are often seen coasting west in north Norfolk at this time of year, but during one movement, with a sudden shower, I heard Curlew calling overhead in the dark. Typically, Lapwing and Curlew migrate in compact parties, in which the individual birds are so close to each other that each party would give only one echo on a radar display. But the individual echoes were sufficiently far apart to allow the height of each p a r t y to be estimated separately, and hence a mean height could be calcu68

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lated. Whereas in passerine movements the height-records were normally spread fairly uniformly over a number of thousands of feet, in each wader movement nearly all the echoes were grouped within some two thousand feet of each other, thus giving a different pattern on the display, in the form of a band of echoes with sharp boundaries both above and below. On one occasion nearly all the records were around 3,000 feet and on another at 5-6,000 feet (mean 5,800 feet), while on the two days when the largest totals were recorded, the mean of 104 echoes on 14th September was 4,700 feet and of 42 echoes on 17th September was 3,500 feet. These differences in mean height on different days were statistically significant. Above the main block of echoes there were a few rather higher ones, which on some days extended up to 8,000 or 9,000 feet, while once there was one at 11,000 feet. Only once did I obtain height-records of small migrants, presumably passerines, similar to those regular in Lapwings. In the early mornings in April 1959 there was often a northwestward movement of birds giving small echoes, arriving in east Norfolk and Suffolk from the southern North Sea, presumably small passerine night-migrants from Belgium. On the early morning of 3rd April 1959, but on no other occasion, 75 out of 93 heights obtained on this movement were at 4,000-4,500 feet, 10 more were around 5,000 feet and the rest a little higher, while none was below 4,000 feet. Hence the height-echoes formed a concentrated band. The meteorologist at an airfield in the area reported a bank of fog, the upper limit of which was estimated to be at 4-5,000 feet, and the northwestward immigrants evidently continued their flight inland just above this. Sutter recorded similar movements above fog in Switzerland and, like me, did not otherwise observe a sharp cut-off in height-records when passerine birds were involved. Most migration occurs a very few thousand feet above the earth's surface, and this was the height to be expected on general grounds, for in most areas it is high enough to keep the birds clear of a rise in the terrain and above ground mist. But one would not expect migrants to climb higher than necessary 69

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for their safety, since climbing involves the expenditure of energy. Further, at high altitudes their efficiency might be reduced by the lower oxygen pressure and by cold. In addition, the wind is stronger higher up, and since migrants do not normally wait for a following wind, a strong wind must in general be disadvantageous. Finally, once a migrant is aloft, it is advantageous for it to maintain a steady height, since any altitude lost must be regained. Hence, the first question suggested by the present observations is how migrants maintain their height. The experience of airmen indicates that it is extremely hard to maintain a constant height by visual means under any conditions, and particularly over the sea and at night. It may therefore be wondered whether migrant birds depend on purely visual means, or whether they may have other means of telling their altitude, and perhaps even a special adaptation for this purpose. The present observations suggest that, whatever means may be used, migrating Lapwings assess their height above the sea at night more precisely than passerine winter visitors to Britain, while the latter are less variable than the smaller passerine summer visitors to northern Europe. Incidentally, if migrants can maintain a fairly constant height, one wonders what they do in those areas where they meet a mountain barrier, such as the Pyrenees, which rise within a few miles by over 10,000 feet. Secondly, man experiences discomfort from the reduced oxygen pressure above about 12,000 feet, and he is seriously incommoded in his muscular effort at 20,000 feet, where it is also very cold. Yet the latter height was occasionally attained by very small Scandinavian night-migrants. D o these migrants suffer from high altitude like man, or have they special adaptations? It should be stressed, however, that only a very small proportion of migrants occur at such heights. Thirdly, the occasional occurrence of small passerine nightmigrants at 20,000 feet raises the possibility of whether some of the rarities which reach Britain in September have arrived at this height. Since the wind is usually stronger higher up, they would drift faster higher up than lower down. This, however, 70

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is speculative, and it should be added that with easterly winds and anticyclonic weather, when most eastern rarities occur in Britain, the rise in wind-speed with height is not usually great up to 20,000 feet.

Radar Films of Migration over Eastern England At intervals from August 1958 to January 1962 inclusive, the Research Laboratories of Marconi's Wireless T e l e g r a p h y Co. Ltd near Chelmsford have taken films of a radar display by time-lapse photography and many of these provide a clear record of bird migration. T h e radar station was at Bushy Hill, Essex, and when migrants flew high they could usually be tracked between north Norfolk and south Sussex, as well as in a small part of the Pas de Calais. M o s t of the area covered was over the land, but it included a small part of the N o r t h Sea east of Suffolk and Essex, the Thames estuary, the Straits of Dover and a section of the English Channel south of Sussex. The films analysed here, omitting a few on which it was impossible to see whether or not birds were m i g r a t i n g , covered 1,463 hours, mainly in separate periods of about t w o hours each around sunrise or sunset, with a very few in the middle of the day, and 33 continuous 24-hour records. Including the From British Birds 55 (1962) with E. Eastwood

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l. Southward movement over southern England and the Channel, with snow to north. 11 a.m. on 9th January (see fig. '2).

2. Westward movement, mainly from Cap Gris Nez. '2.00, but continuing strongly over land. Dense departure SSW from East Anglia, moderate one SSE from north-west. The three movements passed through each other in the centre of the area. All were at short range, indicating low altitude.

Fig. 5. 3rd February 1959, 09.00 hours. Anticyclone in North Sea, dry, cold, with easterly wind. Departure W from Continent started well before first light, with peak around sunrise. Reached Kent and Sussex earlier than Essex or Suffolk because of shorter seacrossing. Birds coasted W S W to Cap Gris Nez, where concentration put out to sea W S W between 08.00 and 09.00, turning gradually W in Channel and later W N W , chiefly after passing Beachy Head, and so in to land. Later in the morning the W N W turn came further east, so that most birds were flying in over Beachy Head, and yet later over Dungeness. A similar turn W N W was seen off North Foreland, and later in the morning by some of the birds off Essex and Suffolk.

Fig. 6. 9.4.-th February i960, first part of morning. Fairly settled weather with very light southerly wind. The typical picture in early spring: (i) big return departure E of British winter visitors, (ii) moderate arrival N N W of British summer visitors, most prominent to west but also north of Calais, and (iii) moderate passage N N E over Pas de Calais, Straits of Dover and Kent. This diagram is compressed somewhat in time since, in the area covered, the departure E occurred earlier than the arrival N N W .

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Fig. 7. llth March 1959, 10.40 hours. Depression off north-west Ireland, cold front moving north-east over area as indicated by cross-hatching, S wind ahead of front and SW wind behind it. Very small movement north of east in Norfolk and dense departure from Suffolk coast a little north of east, birds presumably flying too low over land to be detected but rising high at coast, or starting from coast after earlier concentration there. No bird-echoes detectable near front, but behind it in Sussex a moderate E movement, some turning SE along edge of front but many disappearing into it.

Fig. 8. 9.2nd March 1960, morning. Anticyclone over Baltic, SE wind. Big departure slightly north of east, also big movement S, in part over sea to east. A southward 'reversed migration' is rare with a southerly component in the wind.

Figs. 9 and 10. VMh March 1959, 07.00 and 10.30 hours. Depression west of Ireland, cold front moving east as indicated by cross-hatching, wind SE ahead of front and SW behind it, widespread fog over northern part of area in early morning. Between 05.30 and 07.30 in south of area there were the three typical spring movements, (i) E, (ii) NNW and (iii) NNE, but in East Anglia extremely few birds were moving E and none in the other directions, presumably because they had been grounded by fog. Over the sea off East Anglia there was an area (shown dotted in Fig. 9) where all directions were random and migrants were presumably disoriented in fog. Movements

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(1), (11) and (m) faded rapidly between 08.30 and 09.OO as tbe cold front moved across, but between 08.30 and 10.SO there was a movement SSW over the sea off Suffolk and Essex, presumably due to the birds disoriented earlier returning when the fog dispersed. Behind the front, a N E movement started at 11 .OO and was dense over the whole area in the afternoon.

Fig. 11. 1*/ April 1959, 08.00 hours. Rather disturbed weather with W S W wind. Moderate departure E over land and sea, and marked coasting movement E N E to South Foreland and smaller one to Dungeness, with concentrated departures from these headlands.

Fig. 12. 20th April 1960, morning. Anticyclone, light N E wind to east, hardly any wind in centre of area and light wind, N W at surface, to west. Five separate movements, the two main ones being 'reversed', as typically with N E wind, namely arrival W from Holland and departure SSE over land and out to sea from Sussex. At the start there was also an extremely small movement N N E over Norfolk, during most of the time a small movement N N W from the coast north of Calais, and near the end a very small movement E to the west.

Fig. IS. 3rd June 1960, noon. Anticyclone with very light NE wind. A small pre-breeding departure NNE over England and Pas de Calais, presumably of arctic species, occurred simultaneously with a moderate postbreeding arrival WSW from the Low Countries, presumably of Lapwings. Also very small movement E in Channel. In Straits of Dover the Lapwings as usual changed from WSW through W to WN W, while the birds moving E turned ENE in Pas de Calais.

Fig. 14. 9th June 1959, morning. Transitional weather with westerly wind. Departure over land mainly between ESE and SE. Gradual change in direction of this movement in southern North Sea between ESE off Suffolk and SSE off Belgium, individual birds changing at different times, so it was hard to be sure what was happening. Species unknown.

Fig. 15. 2lst August 1958, 23.00 hours. Somewhat disturbed weather, with light SE wind in southern North Sea. Three small movements of presumed waders and/or gulls. One SSW from Wash had almost ceased by 23.00, another SW over Straits of Dover and Pas de Calais still continued, the third came in west over Norfolk and gradually changed direction from W to SW and eventually S.

Fig. 1G. 24M August 1059, 21.00 hours. Anticyclonic weather with W N W wind. Between 19.00 and 124.00 a small movement of wader-type echoes SSW across Kent, Sussex and Pas de Calais, some of them coasting \VS\V to Cap Griz Nez, also a very few SSW over East Anglia. From 20.15 a huge departure of very fine warbler-type echoes over land slightly east of south, the outlines of the Essex and Sussex coasts seeming to advance out to sea like a wall, as indicated by the dotted lines. Around !2.'J.30 a small W arrival of wader-type echoes. (Also, between 01.00 and 05.00, local disorientation, associated with fog, iti Sussex, and no further seaward departures took place from this area during this time.) Fig. 17. 2.6th September 1961, early night. Transitional weather with high pressure to the east, a light southwesterly wind west of East Anglia, a light south-easterly wind in Belgium, and a south wind in between. Small eastward departure (locally SE or ENE) from eastern England, very small movement W from France south of Cap Gris Nez, and small but clear-cut reversed migration N N W from coast between southern Belgium and Fas de Calais.

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Fig. 18. 6th October 1959, morning. Anticyclone in southern Scandinavia, SE wind. Small movement SSW off Suffolk and Essex, presumably from Scandinavia, and dense morning departure westward from Holland and Belgium, presumably mainly of Chaffinches. The presumed Chaffinches over North Sea flew either W or between W N W and N W , giving the impression of two distinct movements, but probably this was merely due to individual birds making the change from W to nortli of west at different points on their journey; after reaching East Anglia most flew north of west but some still W. In the eastern Channel and over Sussex, all flew between W N W and N W . In addition, a thick band coasted W S W to Cap Gris Nez, and put out to sea as a concentrated stream which gradually changed direction to W and then W N W ; this concentration was still easily noticeable far inland over Kent. 82

F i g . 19. 13/A October 1959, morning. Anticyclone over Scandinavia and Germany, small depression over northeast England, wind variable but N W to north. This shows the three main autumn movements: (i) departure SSE over land, in this instance chiefly to the west of the station, (ii) small S S W arrival from Scandinavia, and (iii) W arrival from Low Countries, the birds on the last movement as usual proceeding W N W or N W from France south of Cap Gris Nez. In marked contrast to the position in Fig. 18, there was no coasting movement to Cap Gris Nez, and no concentrated departure from it.

Fig. 20. 24//; November 1959, early night. Transitional weather with S W wind. Over England a big departure E and a fairly big departure just east of south, and over Pas de Calais a small movement S W . These movements started at dusk, the one E consisting of moderate-sized echoes similar to those when thrushes are on migration.

Fig. 2 1 . nth December 1961, midafternoon. Anticyclone centred over Germany, light south-easterly wind. Moderate arrival W into East Anglia, changing direction at east coast from slightly south of west over sea to slightly north of west over land. Also small SSW movement, presumably from Norway, over southern North Sea and Pas de Calais.

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shown in Fig. 1, and that for 9th January, with snow clouds moving rapidly down from the north, in Fig. 2. On 7th January the first birds left the south coast at 11.40 and the migration was densest at 12.30. On 9th January some had already left the Essex coast before 09.00, but on the south coast the first ones left Sussex at 09.30 and Hampshire at 09.45, after which a mass of echoes proceeded across the English Channel to France, the movement being densest around 10.30. D u r i n g this period, and especially in the late morning and early afternoon, snowclouds moved rapidly southward over eastern England, and the films gave a dramatic impression of the birds fleeing before them. The large size of the echoes was again typical of Lapwings, and it is possible that, while those on 23rd December had been Continental Lapwings moving west towards Ireland, those on 7th-9th January were British-hatched birds heading for Iberia. Ringing recoveries show that movements of both types occur in the area. The next radar records show that for six mornings with south-westerly winds between 10th and 23rd January 1959 there were small N N E or, less commonly, N N W movements, and there was also a small eastward departure on the 23rd. But on 24th and 25th January the wind was north-westerly and birds departed south, whereas on 26th-28th January, with south-easterly winds, there were very small westward and extremely small N N W movements. This well illustrates how rapidly the 'hard-weather' and return movements may alternate at this time of the year. The last hard-weather movements of 1958-59 occurred with easterly winds from 31st January to 4th February inclusive. There were no southward movements, but on all these mornings there was a westward immigration from the Low Countries, the largest of these, on 3rd February, being shown in Fig. 5. This was already in progress at a low density when the radar record started at 06.30. From 08.00 onward, concentrations of echoes left the Pas de Calais, and other birds presumably set out from Belgium and southern Holland, but, because the sea crossing is much longer from there, birds were 84

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not dense in the southern North Sea off Essex and Suffolk until after 10.00, and the density of arrivals was still increasing there when the record stopped at 11.45 a.m. On the mornings of 5th-9th February 1959 inclusive, in anticyclonic weather, very light easterly winds and widespread fog, there was hardly any movement, but what there was came west. The next sizeable movement was N N W with a south-easterly wind on 10th February. There was scarcely any movement during the following four mornings, when fog was again widespread, but with south-westerly winds a moderate eastward departure and a very small NNE movement took place on 15th February, and another moderate eastward departure and a small N N W arrival took place next day. The record for the morning of 23rd December 1959 is in marked contrast to that for the same date in 1958 already described, since in 1959, with a south-westerly wind, there was a small northward movement. The next radar records in this second winter were for the period from 15.00 to 17.00 hours on 5th, 6th, 8th and 12th January 1960, during a cold anticyclonic spell with northerly winds. On 5th January with a northwesterly wind, the tracks of the birds were between SSE and south, but on the following evening, with a very light northwesterly wind, the main movement over Norfolk, Suffolk, Essex and the Thames estuary was SSW, though there was a small movement SSE to the north-west of the station, over Huntingdonshire. On 8th January, with a north-easterly wind, there were two movements, SSW over Suffolk, Essex, the adjoining part of the North Sea and Sussex, and SSE to the north-west of the station, over the country around Huntingdonshire. There was also a small W immigration from the sea. On 12th January, with a N N W wind, the whole movement over East Anglia was again SSW, but there was also a small W immigration from the Low Countries, where the wind was easterly. On the next day, from 10.00 onward, the radar record covered 24 hours. At the start the wind was south-easterly, by 18.00 it was easterly, and before midnight north-easterly. The hard-weather movements were spectaular. All were detected 85

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only at about 40 miles, this unusually short range suggesting that the birds flew low, but within this range the echoes were very dense, so that Figs. 3 and 4, for the morning and evening respectively, do not give a true idea of their impressiveness. T h e biggest movement throughout 13th January was a westward immigration from the Continent which continued over England. It was already fairly dense at 10.00, increased in density until midday and remained dense throughout the afternoon, but had markedly declined by 19.00. Soon after this there were no further arrivals over the sea, suggesting that it had been a purely diurnal departure from the Continent. But the movement continued fairly strongly over England until 23.00 and at a low density until 04.00, after which it was not detected. In the latter part of this time it was mainly to the west of the station, whereas during the day it had been especially to the east of it. The main direction over the sea and over East Anglia was due west, but, as is usual with westward immigrations, it was about W N W over the Straits of Dover, Kent and Sussex. In addition, there were a number of remarkable changes in direction locally and temporarily over the land, two of which are indicated by dotted arrows in Fig. 3. At times for half an hour or more over a small part of the land many birds moved northwest and once even due north, while in other small areas at other times, and occasionally at the same time, many birds moved W S W or even south-west. T h e s e were probably birds avoiding localized snow-showers, and it accords with this view that such movements occurred only during daylight. Alternatively, they might have been birds temporarily disoriented by snow and blown down-wind by strong gusts, but one might then have expected them to be more erratic than they were. Throughout the day on 13th January 1960, the only movement was west (disregarding the local changes in direction). But at 18.00 the first signs were noticed of a second big movement, SSW from Suffolk, which built up rapidly in density between 18.30 and 19.00 and was densest from 21.00 to nearly midnight, after which it declined for several hours, increased rapidly again from 07.00 and stayed high until the end of the 86

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record at 09.30. While this movement was densest over Essex, Suffolk and south Norfolk, it also occurred over the Thames estuary and in Sussex. It was not detected over the North Sea to the east of Suffolk and Essex, and if this was not merely because the birds flew too low, the movement presumably originated from East Anglia itself, and was not an arrival from Scandinavia. It seems significant that it started when the south-easterly wind shifted more to the north. Assuming that the movement emanated from East Anglia, it involved both nocturnal and diurnal departures. On the morning of 14th January, it could be seen that the movement continued SSW from Sussex over the English Channel. T h e third movement, with tracks between south and SSE, was always smaller than that SSW, remaining small from its first appearance at 23.00 until the end of the record at 09.30. It came, as usual, from the land to the north-west of the station, and its first appearance so late in the night suggests that it may have been a departure at nightfall from much further north in Britain. Part of it came over the station itself and in the morning some of the birds were sufficiently far to the east to cross the Thames estuary. T h e next record, for 19th January 1960, with a southwesterly wind, showed a very small N N E movement, but next day, with a north-westerly wind, there was a fairly small southward departure, with tracks SSE, and a smaller departure E. On this day, therefore, a 'hard-weather movement' occurred in one direction and a 'mild-weather' return movement in another. Similarly, with a very light north-westerly wind on 25th January, there was a small 'hard-weather' departure just east of south and a large 'return' movement E, and with a W N W wind on 4th February there was an extremely small southward 'hard-weather' departure*and a moderate return one eastward. No records were made in midwinter 1960-61, when the weather remained mild. But there were records between 07.00 and 17.00 each day from 14th to 21st December 1961, during a cold dry spell in anticyclonic weather. The westward immigrations followed the usual pattern. When the wind was from 87

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between SE and N E in the Low Countries, as it was on the four days from 16th to 19th December inclusive, there was a moderately large immigration, the birds heading due west over the sea east of East Anglia, but W N W between the Pas de Calais and south Kent and Sussex, while the movement was sparse at 07.00 but increased rapidly in the late morning and readied its highest density off East Anglia early in the afternoon. This movement was observed only when the wind in the Low Countries was easterly, except for a small trace with a light northerly wind on 20th December. The other main movement was of birds heading SSW, chiefly over the North Sea east of East Anglia, but with a small continuation over the land. This movement was densest over the sea from the start of the record each day at 07.00 until 09.00, but usually continued until 17.00. It was moderately large on 14th and 15th December, small on the 16th, 17th and 18th, and negligible thereafter. T h e birds concerned had presumably set out on the previous night from southern Norway, where the wind was light southerly but temperatures were near to freezing. After the temperature rose there by several degrees, there were negligible further arrivals. After a very brief milder spell, the weather was again extremely cold and dry from 24th to 28th December 1961 inclusive. T h e next radar record was from 13.30 to 17.00 on 29th December, when a wave depression just west of Cornwall brought mild south-westerly air over the southern English counties, though from about Norfolk northward it remained cold with N E winds and full overcast. On Boars Hill near Oxford that evening, Skylarks were heard calling excitedly in the fog, as if disoriented on migration, while at intervals in the first part of the night, by which time snow had spread down from the north, one Skylark repeatedly flew up to a lighted window of my house, as if to a lighthouse. I concluded at the time that Skylarks must have moved south during the day away from the snow to the north, until they were disoriented by the fog at dusk. T h e radar record shows clearly, however, that from 13.30 until nearly 16.00 there was a steady northward 88

Plate 2. Uadar Display zcith Migration in Progress

l. Southward departure of summer residents. < .» p.m. on 2Kb August (see iig. 16).

•2. Westward movement of Chaffinehes. 8 a.m. on 6th October (see fig. 18).

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arrival (actually NNE) across the English Channel and the southern counties up to as far north as Northamptonshire and Suffolk, also over the Straits of Dover and the North Sea off Essex and Suffolk. There was also a very small movement N N W over Kent and the Thames estuary. These northward movements ceased before 16.00, and in the next hour all bird-echoes over the Midlands north of about Oxford were disoriented. Most of the echoes were large, probably from Lapwings, but Skylarks presumably behaved in the same way. This is a striking and unusual instance in which the habit of moving north in winter when the wind is southerly brought the birds into severe wintry conditions. It also shows the danger of inferring the direction of migration from observations on the ground without the help of radar. Northerly winds became established over southern England on the following afternoon, when birds presumably moved south, but no further radar records were available until the afternoons of 1st and 2nd January 1962, on both of which there were moderate SSW and small SSE departures, the echoes being detected only at short range, indicating that the birds flew low. On the morning of 3rd January, with a light northerly wind over eastern England, there was another small SSW departure, and also a fairly small westward arrival from the Low Countries, where the wind was light easterly. The remaining records cover 11 mornings and two nights between 8th January and 5th February 1962, and almost throughout this period the wind was south-westerly and the temperature mild. No westward or northward movements were recorded, but eastward return movements took place on nine of the 13 occasions, N N E movements on seven and smaller N N W movements on six. Summarizing these records for three winters, primarily for the daylight hours, *hard-weather movements' occur in three directions over eastern and southern England and the adjacent seas. The most conspicuous arrivals by day come west from the Low Countries, particularly between Suffolk and Kent, with appreciably less into Norfolk; and the direction of the southern 89

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fringe of the movement, from the Pas de Calais, is W N W not west. This movement is densest at around 09.00 off southern Kent, but at about midday off Essex and Suffolk, where the sea crossing is much longer. The birds continue west over the land by day and night, and most of them presumably reach Ireland. (The records were too sparse to show the extent of nocturnal westward departures from the Low Countries in winter, but they do occur.) The second movement is slightly west of south, the main departures from East Anglia itself being in this direction by both night and day, while in one winter there were also SSW arrivals over the North Sea, evidently from Norway. These birds are presumably heading for Iberia. Thirdly, there are small SSE departures, chiefly by night, and chiefly from some part of Britain north-west of Essex. Finally, there are corresponding return movements, respectively east, N N E and N N W . All these movements were usually small but about one-fifth of those west, east and SSW were of moderate size, as was one N N E , while one westward and one eastward movement were large. This is in marked contrast to the spring and autumn, when movements of moderate size are normal and large ones frequent. The scale on which densities are recorded depends in part on the range at which birds are detected, and hence on the height at which they fly. Part, but only part, of the reason for the low apparent density of these winter movements is that the birds fly lower than in spring or autumn, and some of the southward movements by day were particularly low. These westward and southward movements in winter are traditionally termed 'hard-weather movements', and the term is justified, both because they occur in cold not warm weather, and also because their function is to bring birds from an area where food is extremely sparse, owing to frost or snow, to an area where it may be more plentiful. Further, it has long been realized that such movements take place only in periods of hard weather, and that in winters without any cold weather the birds concerned do not move out. Finally, as shown by the present records, return movements occur as soon as the weather ameliorates. 90

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This being accepted, however, an important qualification is needed, because the westward immigrations from Holland and Belgium were virtually restricted to days with a wind from between north-east and south-east, and did not occur on days, however cold, with a wind from between north-west and north. Likewise, the southward emigrations from East Anglia occurred solely on days and nights with a wind from between north-west and north-east, and not on occasions, however cold, when the wind was from between east and south-east. Since both northerly and easterly winds are cold, both the southward and the westward movements were restricted to hard weather, but during the periods of hard weather, each occurred only when the wind was within about 45 degrees of the heading of the birds. Hence neither movement took place in all types of hard weather. These findings suggest that the winddirection may be used as a 'signal' by the birds for setting out, and this is supported by the fact that return northward movements occurred with winds from between south-east and southwest and return eastward movements with winds from between south-west and north-west. This dependence on wind-direction leads, as already described, to the curious situation that, with a north-westerly wind, birds may leave southward on a hardweather movement at the same time that others move eastward on a return movement. A corresponding phenomenon, though on an extremely small scale, was observed with a southeasterly wind, when some birds moved westward on a hardweather movement while others returned northward. Once also, on 29th December 1961, the 'signal' proved highly misleading, bringing the birds returning northward into an area of heavy snow. There was one important exception to these findings: birds left southward from southern Norway against a light southerly wind in mid-December 1961. At this time the weather in Norway was cold, and when it turned warmer, hardly any more birds left although the wind was then northerly. This suggests that, at least in this area, temperature itself may also influence southward departures in winter, and that birds may at times 91

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leave against the wind when it is cold (and perhaps provided that the wind is light). Coasting movements by day with concentrated departures from headlands are shown in Fig. 11 from South Foreland and in Figs. 13 and 18 from Cap Gris Nez. This phenomenon is now too well known to need discussion, though it is pleasing to confirm it by radar. Much more unusually, for one hour during the first part of the night on 24th February 1959, there was a concentrated line of bird-echoes moving eastward close to the Sussex coast, with a particular concentration where the line ended at Dungeness. There was a light westerly wind and full overcast, so it is conceivable that migrants may have been attracted by the lights of the coastal towns and of Dungeness lighthouse, but this is speculative. On 16th February and 1st March 19(50, during big eastward movements, many Starlings migrated eastward directly from their roosts at sunrise, forming concentrated bands of echoes on the display, and at least on 1st March they were tracked well out to sea. At 16.30 on 5th January 1960, just after Starlings had entered their roost in north Kent, a big southward movement began over the land, and this included a concentration from the area of the roost in question, presumably due to Starlings migrating directly from the roost a few minutes after entering it. More remarkably, on the night of 24th-25th March 1959, when an eastward departure continued all night, a concentrated group of echoes formed suddenly at 02.45 near Brighton, Sussex, and travelled at nearly 60 m.p.h. over the land slightly north of east, eventually putting out to sea from Kent. A second concentration formed near Dungeness, Kent, at 03.10 and moved in the same direction out to sea, while further concentrated bands left the Kent coast flying E at about 04.00, 04.30 and 05.20. Between midnight and 06.00, the wind 900 metres above Crawley, Sussex, the nearest recording station, blew from 220 degrees at 24-30 knots, so the airspeed of the birds concerned was probably around 30 knots. This figure, taken in conjunction with the concentrated departures, suggests that the birds may well have been Starlings migrating directly 92

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from their roosts. It was previously known that Starlings may migrate from their roosts at sunrise or just after dark, and though it might be supposed less usual for them to leave in the second half of the night, the full moon on 24th-25th March perhaps had some influence. It is hard to suggest any other species that could have been involved, and ducks, in particular, can be ruled out because they fly much faster than 30 m.p.h. and there are no large expanses of open water where they might have collected near Brighton or Dungeness. W h e n the films studied here were projected, the bird-echoes normally moved across the screen in one of several directions. Occasionally there was an illusory appearance of randomness when echoes were sparse and moved in several different directions, but each held its individual course. This situation, which occurred chiefly in winter with a very light wind and very few echoes, was sometimes hard to distinguish from a disoriented movement, in which the individual echoes changed direction at random. Disorientation was, however, easier to recognize by time-lapse photography than by personal inspection of a radar display as it was going on. Adding the present records for 11 afternoons to the 279 for the morning or evening, disorientation was recorded on only 22 out of a possible 290 occasions, just over 3 per cent of the 1,463 hours observed. Further, in all save two of the 22 instances, migrants were disoriented in only a small part of the area observed, and when the time for which disorientation occurred was multiplied by the fraction of the area affected, the proportion of disorientation was only between 1 and 2 per cent. Actually the proportion of disoriented migrants was even smaller, since disorientation hardly ever occurred during big movements. It should be remembered, however, that most of the present observations refer to birds over the land, and nearly three-quarters of them to the hours of daylight. Migrants do not normally start out in full overcast over the land, and when they encounter it there by day they probably tend to alight, or to fly low, orienting by successive landmarks. In fact, of the 17 observed instances of disorientation during daylight, 14 were 93

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restricted to birds over the sea, and in the three exceptions the area of disorientation over the land was very small. Tliere were also five instances of disorientation at night, four over the land and one over the sea. If the present observations had included more at night or more over the sea, disorientation would doubtless have been recorded more frequently. On every occasion when disorientation was recorded, the British Daily W e a t h e r Reports showed that tliere was fog, total cloud or rain in the affected area. This accords with the usual view that migrants cannot navigate when sun or stars are obscured. Disorientation occurred at all seasons, and was most frequent in winter, doubtless because full overcast is commonest then. The only instance of widespread disorientation, affecting the whole Thames estuary, occurred on the morning of 2nd December 1959, when fog was widespread in eastern England. This occurred with a south-westerly wind, so the birds concerned had probably left the land during the night flying east. Another instance when all the observed migrants were disoriented, but the area concerned was not large, occurred on 29th December 1961 over central England, as already discussed. Fig. 9, for 24th March 1959, shows that in the early morning the three typical spring movements, east, N N W and N N E , occurred in the southern half of the area covered; but hardty any migration was detected in East Anglia, where the weather report showed that fog was widespread, while off-shore there was a fairly large area in which birds were disoriented (indicated by dots). Between three and four hours later, as shown in Fig. 10, a front moved over the land from the west, nearly all migration over the land stopped, and the fog over the sea evidently dispersed, while from the area where birds had previously been disoriented there was a movement S S W . From the positions of the movements shown in Fig. 9, it seems most likely that the birds that had earlier entered the area of disorientation in the North Sea had previously been travelling N N E , so the subsequent movement S S W was probably a reversed movement of these migrants when they were again able to orient themselves. 94

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There was a similar incident on the morning of 15th April 1961. During the previous night there had been movements east and N N E over the land and sea, but from 04.00 until 08.00 the birds at sea off Suffolk and Essex were disoriented. Afterwards two movements occurred away from the affected area, one just north of west and the other nearly due south, these presumably being the reversed movements of migrants that had been travelling respectively east and N N E before they became disoriented. T h e films demonstrated four types of change in direction in daylight at a coastline. First, migrants coming from inland and proceeding out to sea may temporarily turn to follow a coastline if it runs in nearly their standard direction, as shown in Fig. 11. Secondly, in a strong cross-wind, migrants may maintain their heading when following a coastline, or when flying low over the land, but are drifted off-course once they get over the sea, as I observed on an earlier occasion by visual observations on migrating Starlings in North Devon. A film for the morning of 6th October 1961 showed the same point. Despite a strong SSE wind, some migrants held to the coast W S W from southern Belgium to Cap Gris Nez, but off Cap Gris Nez, and also off intermediate points along the coast, the tracks over the sea were between north-west and N N W , these presumably being the resultant between the birds' westward heading and the strong SSE wind. Chaffinches or Starlings were probably the species involved. The change in direction at the south coast shown in Fig. 1 may similarly have been due to the migrants concerned being able to correct for drift by the north-westerly wind over the land, but not over the sea. Thirdly, as shown in Fig. 21, birds coming in over the sea a little south of west changed direction to a little north of west after crossing the East Anglian coast; this is regular in autumn in this area, but its significance is not known. Fourthly, on the morning of 19th October 1961, there was a strong southward movement over the North Sea, but birds coming close to the east coast of Suffolk turned almost at right angles to head in to the land, though once they were over the land they resumed their 95

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southward direction; this also is regular by da)- in this area. A similar phenomenon was observed in diurnal migrants heading south-east from Dungeness, which turned due east to cross the French coast south of Cap Gris Nez on 16'th June 1959. Three types of change in direction in daylight due to bad weather were also recorded. T w o of these have already been mentioned, namely occasional reversed movements after disorientation at sea, and the turning of birds over the land probably to avoid snow showers. Thirdly, and rather similar to the last instance, when birds migrating eastward over Sussex reached a cold front, some turned south-east alone: its western edge, while others disappeared, because they either descended or were obscured by rain echoes, as shown in Fig. 7. More complex changes in direction over the sea were repeatedly observed by day in birds moving westward, especially in those crossing from Cap Gris Nez towards Kent or Sussex. A particularly clear instance occurred during the hard-weather movement on 3rd February 1959 shown in Fig. 5. At 08.00 birds coasted W S W to Cap Gris Nez and continued W S W out to sea in a concentrated stream, but by degrees they changed to west and then, mostly when a little west of Beachy Head, to W N W , so that they gradually came in over the land. Individual birds made this turn towards the north at different points, so it was not purely a response to the sight of land. Further, as the morning continued, the average point at which the birds turned from west to W N W shifted gradually further east, so that around 09.30 most crossed the coast near Beachy Head and around 10.00 near Dungeness, while at 10.30, when there was no longer a concentration leaving Cap Gris Nez, the birds moved W N W directly across the Straits of Dover. On the same morning, birds on the same movement flying over the southern North Sea towards north Kent also turned from west to W N W , which brought some of them more quickly over the Kent coast but meant that others which, had they continued straight on, would have reached the N o r t h Foreland, turned away from it into the Thames estuary, thus considerably delaying their landfall. Others made a similar turn off the East 96

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Anglian coast. The species concerned in the movement on 3rd February are not known, but they may well have been Lapwings. The same type of behaviour was observed on 19th December 1961, and in particular there was again a progressive eastward shift during the course of the day in the position at which most of the migrants turned towards the north. Between 08.00 and 09.30, the stream leaving Cap Gris Nez came over England mainly rather west of Beachy Head, but between 09.45 and 12.45 at Beachy Head, and between 13.30 and 16.00 at Dungeness. A turn from W S W to W N W somewhere off Cap Gris Nez was also observed on short films for 4th February 1959, 20th December 1961 and on four occasions in June. Lapwings are the only species known to move west in June and are also the most likely species to have been concerned in the hardweather movements in winter. A very similar change of direction occurred in the same area on the morning of 6th October 1959, as shown in Fig. 18, in this case involving a much denser movement of much smaller echoes. From the time of year and from visual observations in October, it is reasonably certain that Chaffinches were involved. This was a dense westward movement on a broad front, but it included a concentration moving W S W along the coast to Cap Gris Nez, where many birds put out to sea W S W , turned gradually west in the Straits of Dover and eventually W N W over Kent. The concentration was so great that, despite the many other bird-echoes present, it could be followed as a thick band on the radar display far across Kent. As the morning continued, this band gradually shifted further north in Kent, indicating that the migrants made their northward turn progressively earlier in the course of their flight. Further, the same turn was made by other migrants over the southern North Sea, giving the impression in some areas that there were two distinct movements, one west and the other between W N W and N W ; but the birds were evidently all part of one movement, different individuals making their turn at different points. This behaviour needs further study, but it suggests that the change in the direction of migrant Chaffinches from W S W in Holland G

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to W N W in southern England is primarily innate, and secondarily influenced by the sight of land, particularly in the Straits of Dover. A similar change in direction off Cap Gris Nez, presumably in Chaffinches, was briefly observed in three other films for mornings in late September and the first half of October, but not in some other westward movements in the area at this season. T w o other instances of a change in direction when in sight of the coast occurred on consecutive mornings in late January, when birds which were moving N N E tlirough the Straits of Dover turned north, and in some instances N N W , off north Kent. This brought some of them over the land, but took others round the North Foreland into the T h a m e s estuary, so this also was not a simple instance of birds heading in to the land. Likewise, on one morning in February, birds leaving east from Sussex turned north of east near Cap Gris N e z and so made a later landfall than they would otherwise have done. Again, birds on an extremely small movement due east in the English Channel on 3rd June 1960 turned E N E near the French coast, at the same time that others coming in the opposite direction turned from west to W N W off the English coast. All the movements described in the last four paragraphs occurred in daylight among migrants in sight of the coast, and although none of the birds headed directly towards the land, they were presumably influenced by seeing it. T h e evidence suggests that the migrants in question had a strong tendency to maintain an innate heading or 'standard direction', but that they also had a tendency, usually weaker, to head towards the land; the resultant tracks were a compromise between the two. It accords with this view that on four occasions when the movement could be studied over several hours, the birds changed direction progressively sooner after their start as the day continued. This can be interpreted to mean that their tendency to migrate on their innate heading weakened, and their tendency to head for the land strengthened, as their u r g e to migrate declined. A change in direction of a different nature, of g r e a t e r extent 98

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and probably out of sight of land, occurred on 9th June 1959 and is shown in Fig. 14. From dawn onward, birds of unknown species left the Suffolk coast ESE and gradually turned southeast, then SSE, and finally south, as they proceeded across the North Sea, so that they eventually made their landfall in southern Belgium. Finally, only two instances have been noticed of a change in direction at night, both of them over the land. Once in the first two hours after midnight in late June, migrants moving E N E over the land some miles south of the Wash gradually turned east while crossing Norfolk, and eventually ESE before they put out to sea. Once in the first part of the night in late August, large but relatively slow-moving echoes, perhaps from gulls, came in west over Norfolk and turned very gradually in a great arc over the land until they headed south (Fig. 15). In conclusion, these films have revealed much that is new about migration over eastern England, especially about the conditions in which hard-weather and return movements take place in midwinter. In many instances the species of birds producing the radar echoes can be inferred with reasonable probability, while in many others they are not known. Much more remains to be discovered.

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Orientation

Laboratory experiments on orientation in animals are proceeding so rapidly that this may be a useful time at which to review evidence on the orientation of bird migrants over the sea p r o vided by radar. This evidence requires local knowledge for its interpretation and, since even with local knowledge I have made mistakes in the past, I have restricted this paper to my own analysis of the data from East Anglia. These data came mainly from personal visits to a Norfolk radar station in March, April and September. In addition, I am extremely grateful to Dr M. T. Myres, J. L. F. Parslow and J. Wilcock of the Edward Grey Institute for their observations in the same area in October and November; to the Department of Scientific and Industrial Research for substantial grants to finance their work; and to H.Q. R.A.F. Fighter Command and the personnel of the Norfolk radar station for providing us with every facility on our visits. I am also much indebted to the Research Laboratories of Marconi's Wireless Telegraphy Co., who kindly lent me for analysis their outstanding films of a radar display in this area taken at intervals throughout the year. From British Birds 55 (1962) 100

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Nearly all the experiments on bird orientation have been carried out on non-migratory domestic pigeons but there have been a few important exceptions. First, Riippell (1944) caught many Hooded Crows on passage through Rossitten in East Prussia and displaced them rather south of west to Flensburg in western Germany before release. The ringing recoveries of these birds showed that both their wintering area and especially their breeding area had been displaced to a corresponding extent to the west. The same held for later displacements to the south-west in Germany. From this it was argued that Hooded Crows arrive in their winter quarters and return to their breeding grounds by travelling on a fixed bearing for a fixed distance; the factors determining; this bearing- and distance were unknown, but presumably had an innate basis. These results held for most adults as well as for the juveniles, but some individuals, mainly if not entirely adults, returned to their normal quarters. Perdeck (1958) carried out similar experiments on the Starling, another mainly diurnal migrant, which he caught in large numbers on passage in Holland, displacing them rather south of east before releasing them in Switzerland. He found that the displaced juvenile Starlings travelled in the same direction from their release-point as they would have taken from their place of capture to reach the normal wintering area in England; these birds returned to the same (displaced) wintering area in France in subsequent years, but the evidence was inconclusive as to whether or not there had been a corresponding shift in their northern breeding area. Displaced adults differed markedly from the juveniles in that they returned to their normal wintering area in England. Perdeck concluded that juvenile Starlings arrive in their winter quarters by travelling on a fixed bearing, whereas adults have true homing (or 'goal') orientation, based on previous experience of the area concerned. Kramer (1950, 1952) made the critical break-through in showing that a caged Starling in a state of migratory restlessness oriented itself by the sun. The fact that it did not head in the true migratory direction needs further study, but does not 101

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affect the conclusion that it used a 'sun-compass'. Shift of the apparent position of the sun by mirrors caused a corresponding shift in the orientation of the Starling. T o use the sun to maintain a constant heading, it is necessary for the bird to allow for changes in the sun's apparent position with the time of day, and Kramer's pupil Hoffmann (1953, 1954, 1960) demonstrated experimentally that the Starling possesses the necessary 'internal clock' (see also Schmidt-Koenig I960). This suffices to explain how a juvenile bird can migrate on a fixed bearing by day. Later, Sauer (1955, 1957, 1958) showed similarly that juvenile warblers obtain their bearing at night from the stars; this he tested both under the natural sky and in a planetarium. The other factor enabling a juvenile bird to reach the wintering area normal for the population to which it belongs is that causing it to cease migration after a while. Possibly the bird might react to the time for which it has flown, but whether in that case it makes any allowance for the wind is not known. Another possibility is that it might depend on an innate astronomical clue for its latitude. Sauer (1957) claimed that a Lesser Whitethroat in a planetarium changed its orientation from south-east to south when presented with the night-sky at the latitude of the Mediterranean, where it makes this change of heading in nature. He also had suggestive evidence that birds presented with the night-sky of their wintering area ceased their migratory restlessness. However, a Whitethroat taken thus to South West Africa, at the extreme southern limit of the winter range of this species, continued to head southward, though three Garden Warblers were nearly inactive. Hence further observations on this matter are needed, especially in view of the criticisms of Sauer's work by Wallraff (i960). One would also like to know why it is that, in autumn, caged migrants used for physiological experiments cease their migratory restlessness after a while; this might possibly be because they had been active for the time normally needed to reach their wintering area, but the situation is so unnatural that other explanations are possible. In spring, on the other hand, migratory restlessness is usually, though not always, maintained 102

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right through the summer until the moult (references in Lack 1960b). This might perhaps be because, in nature, migratory restlessness in spring is normally inhibited by breeding behaviour; alternatively it might be because the caged birds have had previous experience of their breeding area and are aware in some way that they have not reached it. Critical experiments are greatly needed. The factors enabling an adult migrant to return to its home area after displacement on migration are also quite uncertain. This faculty is presumably the same as the 'homing' of pigeons, and in this connection Kramer (1952, 1957, 1959, 1961) made the important distinction between the 'compass-sense' (which for the homing pigeon, as for the juvenile migrant, is based on sun or stars) and the 'map-sense', by which the bird is able, so to speak, to fix its position with respect to its goal so as to head in the correct direction after displacement. Matthews (1955) postulated that the sun provides not only the compass but also the sense of position, through variations in the sun-arc. Kramer (he. cit.) and his school (Schmidt-Koenig 1960, Wallraff 1960) rejected this view on the grounds that the necessary discrimination of the sun-arc in the brief time available would make too great demands on a bird's visual acuity, time-sense, and capacity to compare with past experience. Matthews (1961) replied that more time might be available than previously supposed if the initial directions taken by homing pigeons on release were due to 'nonsense-orientation' northward. Pennycuick (1961) produced a modified theory of sun-navigation, based on sun-altitude and its rate of change, but it is as yet untested and Schmidt-Koenig (1961) considered it to be contrary to some of the experimental evidence. While Kramer and his school concluded that the sun is not concerned in the mapsense, they freely admitted their inability to suggest an alternative explanation. In one of his planetarium experiments, Sauer (1957) shifted the night-sky to that appropriate, at the time in question, to an area far to the east, and reported that a juvenile Lesser Whitethroat then headed back west, instead of orienting to the 103

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south-east. This suggests that it obtained not merely its compass-direction but its map-position from the star-pattern. But the latter conclusion was challenged by Wallraff (1961). This was partly because of the diversity of Sauer's results. In addition, such a shift might be interpreted as a shift in time rather than space, since the star-pattern concerned would have reached the bird's home area some hours later; hence its internal clock might have been affected. Further a corresponding shift of the night-sky to the west produced no corresponding eastward heading by the bird. Sauer (1961) replied vigorously, but this point also should, I think, be regarded as unsettled. This is not, of course, to doubt Sauer's discovery that a night-migrant uses the stars for its compass-direction. Finally, Merkel and Fromme (1958) and Fromme (1961) placed Robins, mainly juveniles, and a few White throats, one of the species used by Sauer (1957), in circular cages out of all sight of sun or stars, and found that, when in a state of migratory restlessness, they oriented correctly south in autumn and north in spring. This orientation was lost, however, when the birds were placed in an enclosed steel chamber. It is desirable that this challenging result should be confirmed by other workers, since both Kramer and Sauer reported that their experimental birds failed to orient when sun or stars were obscured by cloud, or when a planetarium sky was diffusely illuminated with a weak light from the horizon without stars. Precht (1961), however, supported Merkel and Fromme because he found that Black-headed Gulls removed from their breeding colony and placed in a cage without sight of the sun tended to head in the direction of their colony (Precht et al. 1956). (Assuming that both Sauer and Fromme observed correctly, the contradiction might possibly be resolved by supposing that Sauer's birds had not really lost their map-sense, but that their migratory restlessness was inhibited because they could not use a 'starcompass', whereas Fromme's birds for some reason retained their migratory restlessness, perhaps because they never saw the stars; but this is highly speculative.) The experimental evidence is highly conflicting, so let us 104

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now t u r n to the facts revealed by radar in eastern England. First, r a d a r shows clearly that, both over the land and over the sea out of s i g h t of land, migrants normally maintain approximately s t r a i g h t tracks. T h i s holds both in daylight and at night, and with a wind from any direction. If experiments had not already s h o w n that m i g r a n t s have a sense of direction independent of l a n d m a r k s or of the wind, it would have been necessary to postulate one. Secondly, the b i r d s ' tracks over the sea remain straight at the change from d a y l i g h t to dark in the evening, as particularly observed in L a p w i n g s arriving from Holland, and at the change from d a r k to daylight at dawn, as particularly observed in small passerines and w a d e r s arriving from Norway. Presumably at these times the m i g r a n t s switch from a 'sun-compass' to a ' s t a r - c o m p a s s ' , or conversely. A change in the tracks was not, of course, to be expected, since waders regularly start on migration s o m e t w o h o u r s before sunset and continue during the night, so m u s t have an adaptation to allow for this change. Similarly, n i g h t - m i g r a n t s on a long sea-crossing must be able to fly on in d a y l i g h t , and Saint-Paul (1953) had earlier shown that at least s o m e passerine night-migrants can orient by the sun. T h i r d l y , m i g r a n t s flying sufficiently high over the sea to be detected by r a d a r d o n o t seem to allow for lateral displacement by a cross-wind ('drift' in the airman's sense), and drift is often as extensive over the land as over the sea. For instance, birds heading east from Norfolk in spring regularly proceed E N E or even N E w i t h a s o u t h e r l y component in the wind, and ESE or even S E w i t h a n o r t h e r l y component in the wind. Similarly the passerine i m m i g r a t i o n heading S S W from Scandinavia in Sept e m b e r , which reaches the sea off Norfolk in the early morning, there varies in direction between a little west of S W and a little east of south, according to the direction and strength of the local wind. (One qualification should, perhaps, be added. T h e r a d a r display reveals m i g r a t i n g birds over an area of some 60 miles in r a d i u s , and within that area the direction of migration w a s n o r m a l l y constant, but this is based on a general 105

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impression of the radar echoes, not on individual echoes tracked for a long way. Hence the possibility that individual migrants might gradually change in direction over the sea to compensate for drift is not altogether excluded, but it is extremely unlikely and the change could, at most, be slight.) Since radar detects mainly the high-flying migrants, the findings do not exclude the possibility that migrants flying low by day might correct for drift by the use of landmarks or seamarks, and this has, in fact, been observed visually over the land and occasionally over the sea (Lack 1959c, pp. 390-391; 1960a, p. 54). The normal absence of compensation for drift conforms with the view that, in migratory flight, birds travel on a direction fixed by their sun-compass or star-compass, in the same way that, with only a magnetic compass as guide, a man in an aircraft or a boat cannot allow for drift by wind or current. This suggests that the migrant can fix its position by its 'mapsense' only when it is settled, or at least that it finds it hard to do in flight and so does not normally attempt it. Fourthly, there were a few occasions when migrants over the sea flew at random; the headings at any one moment were in every direction, and when individual echoes were tracked they showed marked and irregular changes in direction. On all such occasions, total cloud or rain was recorded at one or more of the coastal weather stations nearest to the area of sea concerned. Presumably, the migrants were disoriented because the sun or stars were obscured and they could not use their suncompass or star-compass. It does not necessarily follow that their 'map-sense' was also upset, if this is used only when the bird is settled. But it certainly follows that the non-visual sense claimed by Merkel, Fromme and Precht is inoperative in flight. Disorientation on migration is rare. It was most easily detected on the speeded-up Marconi films, where it occurred on 8 per cent of the mornings or evenings studied and for 3§ per cent of the total hours watched; the proportion of migrants disoriented was much lower than 3 | per cent, however, since usually only those in part of the area observed by radar were affected at any one time. Similarly, at the Norfolk radar station, 106

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disorientation was recorded over part of the sea on about Si per cent of the mornings or evenings watched in four successive Septembers and on about 11 per cent of the mornings or evenings watched in four successive Octobers and Novembers, when full overcast is commoner. Over the sea, disorientation seemed about as frequent by day as by night. But it was not normally recorded over the land by day, presumably because migrants do not start out in full overcast, while if they later meet it over the land by day, they either alight or fly too low to be detected by radar. Tinbergen (1956) showed that diurnal migrants can hold their direction more or less constant in full overcast when they fly low over the land by day, presumably with the help of landmarks, but that they become progressively less accurate with time unless they can glimpse the sun later. Since radar for tlie first time provides an almost full record of migration in progress, it reveals the conditions in which migrants depart or are deterred from doing so. So far as orientation is concerned, two points are relevant. First, in both spring and autumn, by day and night, migration is much less in very cloudy weather. This is presumably because birds cannot use their sun-compass or star-compass in full overcast, and it is because they do not normally set out in full overcast (though they may fly into it later) that disorientation is, as noted above, so rare. Migration was not absent on by any means all the occasions when the nearest weather station recorded full overcast, but this could well have been because the sky was partly clear, or clear for some of the time, in part of the area observed by radar. Secondly, in autumn, by both day and night, migrants normally set out on migration only with a following wind within some 45 degrees of their heading, or when the wind is very light, and they usually start in settled weather. Since they avoid setting out with a strong cross-wind, drift is normally small in the area of departure, and, since they usually set out in settled weather, drift tends to be small later in their journey. On the other hand, in spring, by day and night, migrants often set out in a strong cross-wind and in fairly disturbed weather, so that 107

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drift is frequent and rather extensive. T h i s difference is most readily explained on the supposition that juvenile birds, on their first migratory flight to winter quarters w h e r e they have never been, cannot compensate for drift, so that if they are drifted a long way they do not reach the area to wliich their population is adapted and may end in an area w h e r e they cannot survive. Juveniles probably comprise about half the birds migrating in autumn. In spring, on the other hand, all migrants are returning to an area where they have been before and so they can presumably compensate for drift. T h i s interpretation fits with the displacement experiments on a variety of wild birds showing that they can home to their breeding area (summarized by Schuz 1952), and with Perdeck's (1958) finding that displaced juvenile Starlings do not reach their n o r m a l wintering area. It does not fit with part of Ruppell's (1944) results with Hooded Crows, which failed to reach their former breeding area after displacement, nor, for the opposite reason, with Sauer's (1957, I960, 1961) claim that juvenile warblers can correct for longitudinal displacement by bico-ordinate navigation based on the stars on their first autumn flight. It should be added that there seems to be more urgency about the spring than the autumn migration, and this may be a further reason why birds sometimes set out in less good conditions in spring. A further interesting point is that, while autumn migrants do not usually set out in strong opposed or cross winds, they migrate freely in strong following winds. This might possibly mean that a juvenile migrant does not depend on the time for which it has flown for its determination of where to end its migratory journey, since it will travel much faster with a strong following wind than with a weak following or weak opposed wind. This particular piece of evidence is, however, far from conclusive. Radar shows that, at night, departing migrants coining to a coastline normally proceed straight over it and out to sea without deviation in their tracks. Rarely, with an opposed wind and a nearly full moon, a little coasting was seen, but only when the 108

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coastline was close to their normal heading. The idea that night-migrants use 'coastal guiding lines' (Williamson 1955, pp. 181, 183) can be ruled out. In daylight, also, most migrants proceed straight over a coastline and out to sea witliout deviation, but with opposed winds or in disturbed weather a proportion of them not infrequently follow a coastline close to their heading, and the coasting birds may later leave in a concentrated stream from a projecting headland or sharp turn in the coast. A visual observer on the coast may see a misleadingly high proportion of migrants coasting, not merely because the coasting birds fly past him instead of across (Van Dobben 195S, p. 216), but also because many of those crossing the coast may be altogether above visual range. T h e idea that day-migrants are effectively 'guided' by coastlines to their winter quarters can also, I think, be excluded - except perhaps in the case of the Chaffinch, discussed later. (It may be noted in passing that the term 'guidingline' was not originally used in this definitive sense, cf. Van Dobben 1953, Lack 1959c, p. 386). After crossing the North Sea westward from Holland in autumn, diurnal migrants sometimes (but not by any means always) turn upwind along the Norfolk coast. With a northerly wind, the coasting stream in east Norfolk moves north, in north-east Norfolk north-west, in north Norfolk west, and on the east side of the W a s h south, so that, if an individual continues along the coast for the whole distance, it eventually turns through 180 degrees. I have discussed elsewhere (Lack 1959c, p. 386) why migrants might continue coasting beyond a marked turn in the coast. The initial tendency to coast upwind after a sea-crossing needs further study. More complex changes in direction were sometimes detected by radar when migrants were within sight of land by day, such changes being particularly marked on Marconi films covering the Straits of Dover. Birds departing from Cap Gris Nez W S W often turned west in the Straits or the English Channel and eventually W N W . This was not a simple response to the sight of the Kent coast, because the place where, on average, 109

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the birds changed direction differed rather markedly on different days and also at different times on the same da}', while different individuals sometimes differed at the same time. Sometimes, moreover, the birds continued changing towards N W when already well over Kent. Similar changes were occasionally observed near North Foreland, in diurnal migrants that had come NNE through the Straits of Dover and later changed to N N W ; and here also, the birds by no means always turned so as to reach land as quickly as possible. This suggests that a gradual shift in the standard direction of the migrants was involved; changes of this type with time of day have been demonstrated for the Chaffinch in Holland in autumn (Van Dobben 1953, A. C. Perdeck in discussion). The most elaborate changes in direction correlated with a coastline are those of the Norwegian Chaffinches, just mentioned, which pass through Holland in autumn. These birds leave southern Norway probably rather east of south, change to SSW in Denmark and eventually to W S W as they move south down the east side of the North Sea. After they reach northern Holland, some take off W S W for eastern England, but others continue along the coast to Cap Gris Nez, from which many leave W N W (Van Dobben 1953, Perdeck 1961 and in litt.). Others follow the coast south and west beyond Cap Gris Nez and presumably later turn north to reach England, as has been shown for the Starling (Klomp and Perdeck 1959). This movement brings the Norwegian Chaffinches to England by a short crossing of the North Sea. But the birds actually follow the coastline chiefly in adverse weather, particularly with a strong head-wind, and also in the latter part of the morning when the migratory urge is presumed to be waning, while adult males do so to a greater extent than females or juveniles (Van Dobben 1953, Perdeck 1961). In the early mornings in good weather, the birds fly high and are not directly influenced by the coastline, but their direction of flight still varies progressively round the North Sea in the way described. This suggests that, though their direction can be modified by sight of the coast, they are not directly 'guided' by 110

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it, and that the primary factor involved is a progressive change in the standard direction or innate heading. In this connection a Marconi radar film showed that, on a large westward arrival, presumably of Chaffinches, in early October, some of the birds far out in the southern North Sea off Suffolk had already turned NW, whereas others flew west or W S W here and changed to NW only after crossing the English coast. If the successive changes in direction have an innate basis, they presumably depend in some way on distance flown, but, once again, it is not known how the birds estimate this. The Norwegian Chaffinches just discussed seem exceptional in the extent to which they change their heading in the course of their migratory journey, some of them eventually through 180 degrees, from SE to N W . Smaller changes in heading occur in two groups of European passerine night-migrants that winter in tropical Africa. First, the Lesser Whitethroat, Red-backed Shrike and Lesser Grey Shrike leave western Europe about SE and change to south somewhere around the eastern Mediterranean; secondly, the great stream of warblers and flycatchers migrating S W and SSW in autumn through western Europe to Iberia must there change to east of south in order to reach any point in tropical Africa, where they winter (Moreau 1961). These changes presumably have an innate basis, and they are presumably made either after the migrants have flown for a given time or distance, or when they have reached a given latitude, as discussed earlier. Radar has revealed two further 'dog-legged' migrations. First, the vast majority of passerine night-migrants that breed in Britain leave in late August and September just east of south, not SSW; but, since ringing recoveries show that they later reach western Iberia with the main European stream, they evidently change their heading from a little east of south to well west of south somewhere near the southern border of France. The same birds must change again to east of south in order to reach their tropical wintering areas, as already mentioned. Hence they make two changes in heading in the course of their journey, and both presumably have an innate basis. Ill

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Secondly, many Knot reach Norfolk in August and early September on days when the wader migration tracked by radar comes SSW. As Knot do not breed in appreciable numbers west of the Taimyr peninsula, they presumably change their heading from nearly due west in the arctic to SSW before leaving Scandinavia. Similar considerations apply to a smaller extent to various other arctic waders.

The two main migratory movements over East Anglia in spring are of winter residents departing eastward and of summer residents arriving from the south and heading N N W . But not infrequently with a cold easterly wind there is a westward arrival from the east, and occasionally with a cold northerly wind there is a southerly departure. Such 'reversed migrations' occur by both day and night, and though their existence was known earlier, they have proved to be much commoner in East Anglia than formerly supposed. Their survival value is obvious. But their occurrence presents a complex problem in orientation, as pointed out by Sauer (1961, p. 234), since night-migrants in spring respond to the spring star-pattern by travelling in the direction appropriate to the autumn. This phenomenon presents no particular difficulty, however, if the birds use the stars or sun purely as a compass. Similarly, small movements of passerines occur eastward from East Anglia with westerly winds at intervals throughout the autumn and, at least in October, these probably include reversed migrations, as the echoes resemble those from thrushes. Three ringing recoveries also demonstrate such reversed movements in this group. A Blackbird ringed at Spurn 112

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Point, Yorkshire, on 6th November 1954 was recovered four days later in Germany {Brit. Birds, 48: 492); another ringed on Fair Isle on 21st November 1958 was recovered in Norway ten days later (Brit. Birds, 52: 474); and a third ringed on Fair Isle on 14th October 1959 was recovered in Norway two days later (Brit. Birds, 53: 492). Also a Redwing ringed on Bardsey, Caernarvonshire, on 11th October 1959 was recovered in Belgium a month later (Brit. Birds, 53: 491), again an eastward movement, but not a reversed migration for this species. Another curious autumn movement, a small one restricted to nights in late August and September with a wind between N E and SE, is that of small passerine night-migrants heading west from Holland to East Anglia. Accompanying 'falls' at the east coast observatories indicate that typical Continental night-migrants, notably Redstarts and Pied Flycatchers, participate. As these species normally migrate SSW towards Iberia, this is not a true reversed movement, nor is it directly down-wind, and its significance is quite obscure. More typical reversed movements occur northward in autumn with southerly winds, but they are extremely sparse and rare in East Anglia. They are commoner elsewhere in England (J. L. F. Parslow in press), while much bigger northward movements with southerly winds in autumn have been demonstrated by radar in eastern U.S.A. (Drury, Nisbet and Richardson 1961). Radar has provided no evidence for the existence of 'downwind directed drift' by which Williamson (1952, 1955, 1959) supposed that migrants disoriented over the sea in full overcast descend low, reorient by the waves, and fly down-wind; but the negative is not conclusive, since if such flights occur they would probably be below radar range. Williamson considered this type of 'drift' a valuable adaptation enabling the birds to H

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escape from full overcast, and it is an essential part of this theory that the drifted birds (many of which would be juveniles) should afterwards be able to correct for their displacement by a redetermined' movement. In this connection, Williamson (1955) stated: 'it is already clear from a preliminary examination of a number of bird observatory records that drifted birds quite obviously have a faculty for accurate re-orientation, and are not 'disoriented waifs', as some students of migration have claimed'. This view accords with Sauer's (1957, 1961) claim that juvenile warblers can correct for displacement by bicoordinate navigation based on the stars, but not with Perdeck's (1958) finding that juvenile Starlings do not correct for displacement; however, the Starling usually migrates by day. The point is so important that I decided to examine the records, published annually in the 'Reports on bird-ringing' in British Birds, of probable Scandinavian night-migrants ringed at the British east coast observatories in autumn and later recovered outside Britain. The most spectacular was a juvenile Red-backed Shrike ringed in Northumberland in late August and recovered in Sicily a month later {Brit. Birds, 48: 496). This species normally migrates SE, however, and there is no

Red-backed shrike

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evidence that the bearing of Sicily from Northumberland differs from the normal heading in autumn of the population to which this bird belonged. On present evidence, therefore, this bird might well have headed in the same direction as before it drifted to England, without any correction for displacement. Better evidence comes from the many Robins ringed after the great 'fall' on the English east coast in early October 1951. Of six then ringed at Spurn Point in Yorkshire or Cley in Norfolk and later recovered abroad, one in the Gironde and two in Charente Maritime, France, were nearly due south of where ringed, but two in Minorca were SSE and one in Italy was SE; another ringed on the Isle of May, Fife, was recovered SSW in Portugal. One might perhaps conclude from this that three adults corrected for displacement by heading south-eastward to their normal wintering grounds, while four juveniles failed to correct and continued on their normal south or SSW heading, thus reaching a different wintering area. But other explanations are possible, for instance that two different Robin populations with different wintering areas were involved in the 'fall', so the evidence is quite inconclusive. After another Robin arrival in early October 1959, chiefly in south-eastern England, six recoveries were SSW of where ringed, in Iberia (Williamson and Spencer 1960). This might suggest that no change in heading occurred, but these birds may not have been drifted appreciably off-course to the west in the first place. A seventh Robin ringed on Fair Isle in the same period must have been drifted west, but, as it was later recovered SSW in Portugal, it may not have changed its heading on leaving Fair Isle. The other Scandinavian chats, warblers and flycatchers, which between them comprise the bulk of the September 'falls' at the east coast observatories, have provided very few ringing recoveries abroad. Of the species which normally migrate southwestward (i.e. omitting the Lesser Whitethroat), none of those ringed on the British east coast in autumn have been recovered in the same autumn appreciably east of where ringed. The most typical Scandinavian migrant is the Pied Flycatcher 115

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and, of the seven recoveries abroad in the same autumn, six were SSW of where ringed, five in Portugal and one at Cadiz, while one was south of where ringed, in Charente Maritime, France. Hence all seven were in areas regularly frequented by Scandinavian migrants on passage. But it is not known whether these ringed individuals were adults or juveniles. Nor is it clear whether they appreciably changed their heading after leaving England or whether they continued on the same SSW heading as before, while the one individual recovered south of where ringed might, presumably, have been drifted eastward in the Bay of Biscay by the prevailing westerly winds. Similar doubts attend the few recoveries of other drifted species. Clearer evidence for redetermined movements is provided by the Continental Redwings ringed in autumn on Fair Isle. These birds normally head south-westward, so they were evidently drifted off-course to Fair Isle and several have later been recovered in Continental Europe between south and SSE of where ringed (Goodacre 1960), presumably having corrected for this displacement. Similarly, Continental Song Thrushes ringed at British east coast observatories after presumed westward drift on autumn passage have been recovered on the Continent between south and SSW of where ringed (Goodacre 1960), though the changes in direction have been less marked than in the Redwings. In both species, however, the proportion of recoveries is so small that all may have been either adults returning to wintering grounds known from a previous year, or juveniles accidentally drifted back east by the prevailing westerly winds later in their journey. Hence the possibility remains open that the bulk of the juveniles did not correct for drift, but continued south-westward into the Atlantic and so did not provide any ringing recoveries. There is, therefore, no convincing, or even suggestive, evidence from the ringing recoveries that drifted juvenile migrants in their first autumn can redetermine their direction towards the normal wintering area for their population. This is, of course, a negative statement, and the possibility that juvenile migrants have this capacity is not excluded. If they have it, 116

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however, it would seem to require an extremely complex behavioural mechanism. The juvenile migrant must be able not merely to respond to a succession of star patterns, but by their means to compensate for lateral displacement away from an area of which it has no prior experience, all on an innate basis. One must beware of rejecting a hypothesis because it seems to ask too much of a biological mechanism, but it is legitimate in cases of this sort to ask that the evidence in favour of the hypothesis be strong, and as yet it is weak or non-existent. It may be added that if juvenile birds in their first autumn do not have the capacity to correct for drift, this might help to explain why nearly all 'rarities' (i.e. birds far beyond their normal range) are juveniles in their first autumn. Failure to correct for drift could not, however, provide the whole explanation of this phenomenon, as some of the rarities have come such immense distances that one must suppose that either their innate headings or their star-compasses were at fault. I earlier claimed (Lack 1959c, p. 394) that radar evidence supported the idea that drifted migrants later redetermine their course. This was particularly because, after big 'falls' of Scandinavian night-migrants in Norfolk with SE winds from 2nd to 4th September 1958, I detected by radar, on subsequent nights with westerly winds, eastward departures of small passerine-type echoes, which I postulated were the drifted birds returning to the Continent. Later experience has shown, however, that such eastward departures occur regularly from Norfolk in autumn with westerly winds and are unrelated to previous 'falls', so they are not, or at least are not mainly, redetermined movements. Unfortunately radar has not revealed the direction later adopted by the Scandinavian chats, warblers and flycatchers after autumn 'falls' in Norfolk, probably because they comprise so small a fraction of the migrants on any one September evening that their echoes are swamped by those from departing summer residents. I also (Lack 1959a, b, c) thought that I detected redetermined movements heading SSE in early April 1958, after big 'falls' of Continental migrants on the British east coast with 117

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south-easterly winds in late March. Moreover, the echoes heading SSE stopped at the Norfolk coast, where typical Continental species or subspecies were seen. I think there is no doubt, in this case, that the movements heading SSE were indeed of returning Continental birds. It was later suggested to me that it might be more correct to interpret them as reversed, rather than redetermined, movements, since the birds' heading was nearly due south. However, the main direction of Continental nightmigrants in spring is probably NNE, and so, if this held for the migrants in question, a movement SSE was not directly in reverse. I therefore think that these were true redetermined movements. As such, they present no particular theoretical difficulty in spring, as the birds are returning to a known goal. A more curious movement was often seen over the North Sea north of Norfolk on October mornings, by Myres in 1959 and by Parslow in 1960, though we did not appreciate its significance until Bourne and Myres (in prep.) saw similar movements off northern Scotland. With south-easterly winds over the North Sea during the night and morning, the radar display often showed around sunrise a moderate or large immigration heading SSW towards Norfolk, the echoes being typical in size and speed of those from thrushes. These echoes later decreased in density, while others became common which were of similar size and moved at similar speed, but which headed about SSE, and these usually reached their highest density around 10 a.m. A similar phenomenon was also seen with north-easterly winds over the North Sea, except that on two such occasions there was already a large immigration heading SSE at sunrise. On one of these last occasions, and on several mornings with a south-easterly wind when both SSW and SSE movements were detected, there was an arrival of Continental Redwings, Fieldfares and Continental Robins at the English east coast observatories. These were presumably the species detected by radar and, to judge from the size and speed of the echoes, thrushes greatly predominated. On none of these occasions were any echoes detected moving SSE over the land, but on quite a num118

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ber of them, including those when the whole movement over the sea was SSE, similar echoes moved SSW over the land. These observations indicate that, with easterly winds in October, Scandinavian thrushes heading SSW during the night change their heading to SSE in the first part of the morning while in flight over the North Sea. The direction of the change, through about 45 degrees towards the east, suggests compensation for drift by easterly winds. As such, however, it was not entirely effective, since with a fairly strong easterly wind, the resultant tracks were on some occasions due south and rarely west of south. Usually, all migrants travelling over the sea eventually changed to a SSE heading, and since it seems unlikely that all the birds on all these movements were adults, the behaviour in question presumably occurs both in adults and in juveniles migrating for the first time. Similar behaviour was not recorded during the frequent SSW immigrations towards Norfolk of Scandinavian chats, warblers and flycatchers with easterly winds in late August and September. This thrush behaviour might be explained in one of several ways. The possibility that the birds are compensating tor westward drift by bico-ordinate navigation after sunrise, though not excluded, seems unlikely. Pointing against it, the change always seemed to be from a heading of SSW to about SSE, irrespective of the strength of the wind and hence of the amount of drift, while over the land the birds changed back to a heading of SSW. As a second possibility, Tinbergen (1956) showed that Chaffinches migrating through Holland gradually alter their heading during the course of the morning from W S W to SSW and eventually SE; this behaviour is restricted to days with easterly winds (A. C. Perdeck in discussion). In contrast, however, the alteration in direction of the Scandinavian thrushes over the North Sea did not appear to be gradual, since, during the period of change on the mornings concerned, the birds headed either SSW or SSE, and not south; hence each individual presumably changed sharply. A third possibility, the simplest on the available evidence, is that the Scandinavian thrushes have a response while on migration such that, if they 119

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find themselves over the sea at dawn, they change their heading from SSW to SSE. But as such a change was not observed on the SSW arrivals with a westerly wind in the North Sea, this response is evidently evoked only if the birds are aware, in addition, that they have been drifted west. They might recognize westward drift either by reference to objects on the sea or by the later rising of the sun. On one occasion when there were south-easterly winds throughout the North Sea during the night, resulting in extensive westward drift, the wind was light S W off Norfolk next morning; yet the birds evidently changed direction to SSE, though reference to the surface of the sea at dawn would have indicated eastward, not westward, drift. Conversely, on two occasions with westerly winds during the night in the northern North Sea, so that there was no westward drift, there was a light easterly wind off Norfolk next morning; yet the birds did not change direction. Perhaps, therefore, they react to the later rising of the sun, but the relationship is not quantitative, i.e. they do not vary their heading in relation to the extent of their drift. Clearly, further study of this remarkable behaviour is greatly needed, and all the conclusions in this section are highly tentative. The relatively simple behaviour here postulated, namely a fixed change in compass heading in response to sight of the sea at dawn, together with awareness of westward drift, might well be a valuable and effective adaptation for birds liable to drift seaward into the Atlantic, or to overshoot their wintering grounds in Ireland. It is curious, however, that the Scandinavian chats, warblers and flycatchers in September do not show similar behaviour off Norfolk. But they have much further to travel, for whereas many of the Scandinavian thrushes spend the winter in Britain, the chats, warblers and flycatchers are on their way to tropical Africa. Possibly, therefore, these smaller species show a similar response further south in their journey, e.g. off Iberia. With easterly winds off northern Scotland in October, Bourne and Myres (in prep.) found, similarly, that Scandinavian thrushes often came in south-westward during the night, flew 120

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low over the sea after midnight, rose high at dawn, and then flew either SSW or south-eastward, and sometimes eastward or north-eastward. Evidently a similar phenomenon occurs here — indeed, this was where it was first recognized - and it appears to be more complex than off Norfolk, but the details have not yet been worked out. There are also corresponding movements in autumn off eastern U.S.A., where night-migrants may be drifted eastward into the Atlantic by north-westerly winds. Visual observations on the mornings after such movements show that many birds return westward to land (Baird and Nisbet i960), but, since British migrants in sight of the coast head directly towards it, visual observations may not show the true change in direction over the sea out of sight of land. The return movement has now been confirmed by radar (Drury, Nisbet and Richardson 1961), but such details as the precise westward headings of the birds over the sea, and whether any of them continue south-eastward by day, have not yet been published. The radar observations reviewed here provide no decisive answers to the questions raised by the conflicting experiments discussed at the start of this paper. Ultimately, the answers must come from critical experiments, but meanwhile the tentative conclusions suggested by radar may be summarized. In general, the radar observations fit best with the view that migrants in flight orient solely by a sun-compass or star-compass, since they do not, so far as can be determined, allow for lateral displacement by the wind (unless flying very low). On this view, a drifted adult migrant re-orients by its postulated map-sense only after it has alighted. Hence the occurrence of disorientation in full overcast might mean merely that the compass-sense is then inoperative, and it does not necessarily follow that the map-sense depends on sun or stars; it does follow, however, if the map-sense depends on non-visual means, that this is not used, and presumably cannot be used, in flight. The existence of reversed movements in spring and autumn may also be held to favour the view that the birds use sun or stars primarily as a directional compass, since otherwise they must sometimes use 121

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the star-pattern appropriate to one season of the year to navigate in the direction appropriate to the opposite season. Radar observations also fit best with the view that juveniles in their first autumn do not use bico-ordinate navigation, since it is otherwise hard to see why the wind conditions in which migrants set out are such as to minimize drift in autumn (when many juveniles are travelling), but not in spring (when all are returning to an area where they have been before). If, however, the juveniles travel on an innate heading, some other (innately based) factor is needed to determine when they stop, and since they set out freely with strong or light following winds, or with light opposed winds, this factor is not, perhaps, dependent on the time and distance for which they have flown through the air. It is also necessary to postulate for various species that the innate heading is changed during the course of migration. Indeed, various British night-migrants evidently change their heading twice on their way to Africa, while Scandinavian Chaffinches have a progressive change in heading through perhaps 180 degrees between Norway and southern England or Ireland. Finally, Scandinavian thrushes drifted westward by easterly winds in autumn change their heading from SSW to about SSE when in flight over the North Sea by day, but apparently return to a SSW heading after making the land. On present evidence this can be explained as a relatively simple response to the sight of the sea, and bico-ordinate navigation need not be invoked. Finally, I would stress again that the above conclusions are highly tentative and that the problems raised can be solved only by experiment. NOTE: The references cited by authors' names and years of publication in this chapter are set out in the original paper.

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The Summer Migration of Lapwings Studied by Radar Much the most prominent movement of bird echoes detected by radar over the southern North Sea in summer comes westward into East Anglia from the direction of Holland, and it is reasonably certain that it consists primarily of Lapwings. This movement was first detected each year in the last few days of May, and continues through June and July. From the end of May throughout June, Lapwings are the only common migrants seen moving west in north Norfolk. During special watches on the east coast of Suffolk in June and July 1955-57, I saw Lapwings arriving only once, in thundery weather, but other evidence shows that, whatever birds are responsible for these echoes, they normally cross the coast too high to be seen, and during the many days of my visual watch, I saw no other migrant coming off the sea flying west. It is true that Swifts, on weather movements not on migration, occasionally came in west, but they flew so close to the waves that they would From Ibis 104 (1962) 123

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probably have been below the radar horizon, while the kind of weather in which they travelled was different from that associated with the westward movements of bird echoes detected by radar. Further, on the night of l l t h - 1 2 t h June 1959, my assistant W. R. P. Bourne noted that the many bird-echoes moving west over the North Sea continued west over East Anglia up to a belt of frontal rain, far inland, where they seemed to be disoriented, and none were detected beyond the front. On the following morning, in part of the area where the front had been, there were many flocks of Lapwings which had not been there before. Again, on the morning of 15th July 1960, with a W S W arrival detected by radar, the only migrants that I saw arriving in a short watch on the east coast were six Lapwings flying WSW. My watches in 1955-57 showed that only one other migrant, the Curlew, entered Suffolk in appreciable numbers in June and July, but they first appear at the end of the third week of June, not from late May onward, and all those seen over the sea were flying south-west, not west, so this species can be ruled out. From late May until the middle of July, the Lapwings passing west in north Norfolk are adults, many, if not all, of which are moulting their primaries (R. A. Richardson, K. G. Spencer in litt.). It is evidently part of the summer migration of Lapwings from Scandinavia, Germany, the Baltic states, Poland and U.S.S.R. into Holland, which starts at the end of May and continues through June and July. The Dutch workers who discovered this movement apparently did not realize that it continues westward into England, and in the absence of recoveries of foreign-ringed birds in England in June and July, it is not possible to say from what parts of the Continent the English arrivals are derived. The radar evidence suggests that the passage into England is densest from Holland into Norfolk and Suffolk, but it also takes place from Belgium into Essex and as far south as Cap Gris Nez into Kent. The density is much sparser to the north than the east of Norfolk, but especially with a southerly component in the wind, some of the birds pass 124

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north of Norfolk and make their landfall in Lincolnshire or south Yorkshire. Also, in July 1957 a radar station in Yorkshire sometimes detected westward arrivals of the type discussed here, those by day reaching their highest density in the late morning and early afternoon, several hours later than off East Anglia, as was to be expected from the longer sea-crossing. Further study is needed to show whether these birds were the northern fringe of departures from Holland or whether, as seems more likely, some Lapwings cross direct from Germany to Yorkshire at this season. It is interesting that this return movement of Lapwings into East Anglia after the breeding season starts a week or two before the last northern waders have left East Anglia for their arctic breeding grounds. The occasions in June and July 1956, 1957 and 1959 when Lapwings were seen coasting west in north Norfolk (published in the Norfolk Bird Reports) were decidedly fewer than those when westward arrivals were recorded by radar, and Lapwings were sometimes seen passing on days when none were detected by radar over the sea. On many days, however, the passage detected by radar continued inland over East Anglia without any apparent decrease near the coast, and I concluded that on such days the birds crossed the east coast above visual range and did not descend or concentrate along the north Norfolk coast. On some other days, the echoes decreased or stopped altogether near the coast, presumably because the birds descended, after which they may either have continued low along the coast towards the west, or have alighted and resumed their passage a day or two later, when none arrived off the sea. These suggestions were confirmed in 1960 when, unknown at the time to M . T. Myres and me, who were watching by radar, K. G. Spencer {in litt.) kept a full record of the days in June and July when Lapwings moved west over Scolt Head, on the north Norfolk coast. Any Lapwings reaching Scolt Head from the east would probably have been in sight of land for some SO miles, so that, if they tend to fly lower over the land than the sea, they would have had roughly an hour in which to descend. The radar and visual records have been compared in Table I. 125

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This shows, in particular, that there were six occasions when a large passage was detected by radar over the North Sea and many Lapwings were also seen passing Scolt Head, on all of which the wind was opposed from between west and southwest; and 10 other occasions when a big passage was detected by radar but no Lapwings were seen passing Scolt Head, on all of which the wind was following, from between north-east and south-east. Particularly revealing, radar showed that a big passage continued all day on 15th and 16th July, and on both these mornings, with a wind from W S W , Spencer saw many birds passing, but later on both days the wind changed to between north and east, after which he saw only one small party flying very high down-wind. These findings fully confirm those obtained earlier for the eastward emigration of passerine birds from Norfolk in spring, in which, on the days when a big movement was detected by radar, many were seen coasting with opposed winds but few or none with following winds. The other categories summarized in Table I need no discussion except for one occasion on 16th June, with a big visible passage, as usual against the wind, but no movement over the sea recorded by radar. There had, however, been big arrivals on the two previous days, and probably some of these birds had alighted at the coast and continued their passage on 16th June. It should be added that the radar record for 1960 showed that, correlated with anticyclonic conditions, there were more westward movements over the sea against a west or south-west wind than in other years. Finally it may be stressed that, on the basis of the visual record, one might well have concluded that in June and July Lapwings migrate to Norfolk exclusively with west or south-west winds, whereas the radar record shows that in fact nearly all come with easterly winds. The radar echoes from the westward movement were usually of moderate size and fairly well spaced, never merging with each other as in the dense passerine departures of spring and autumn. The mean heading of this summer immigration was west or slightly south of west. With a northerly component in the 126

Lapwings wind the tracks were usually south of west, not infrequently W S W , while with a southerly component in the wind they tended to be a little north of west, though rarely as much as W N W . The Lapwings appeared to make no correction for drift by the wind, but the extent of their lateral displacement was always small, as the birds normally migrated with a partly following wind or a very light wind. By timing the tracks of the birds and allowing for the speed of the wind, W . R. P. Bourne on several occasions in June 1959 assessed the air-speed of the birds as roughly 35 knots, which fits well with migrating Lapwings. I obtained similar records myself in September movements of the same sort. By means of a radar height-finder, Bourne, Myres and I found that, over the sea, there was usually a mass of echoes up to 3,000 feet and sometimes 4,000 feet, with a few at 6-8,000 feet and rarely 10,000 feet or even higher. Hence at lower altitudes the pattern differed markedly from that of the westward Lapwing immigration in September, when nearly all the flocks were at 3-6,000 feet, with hardly any lower. On one night in July, when there was a big departure from the opposite coast both before and after dark, I found that those birds which must have left the coast by day travelled mainly at or below 3,000 feet, with extremely few ranging up to 7,000 feet; whereas of those which must have left after dark, quite a number were at 4-8,000 feet, i.e. appreciably higher. On one night in June with thunderstorms in the western part of the North Sea, all heights were at or below 2,000 feet. A continuous series of still photographs of a radar display was available for the summers of 1957, 1958 and 1959 and 127

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allowed the hourly variations in the density of migration to be analysed. In the western half of the southern North Sea, i.e. 2-3 hours after the birds left the Dutch coast, the echoes normally grew dense around sunset, were densest around 22.00 hours G.M.T. and decreased from midnight until about 05.00. They increased again from about 07.00 to anotlier high point around 09.00, and decreased again after midday to their lowest point at 14.00 or 15.00 when, even in movements lasting over several days, there was sometimes a complete cessation. Occasionally the morning pattern varied, with an increase in density between 03.00 and 05.00, but this was possibly due to an increase, not in numbers but in height of flight, with the coming of daylight. Occasionally also, there was no marked morning increase, while at any time the passage might be interrupted or diminished by the onset of bad weather. These findings indicate that, while departures sometimes occurred throughout the 24 hours, most of the birds left Holland either during an hour or two from sunrise onward, or during the two hours before and one hour after sunset. This differs from the pattern in most small passerine birds, which set out either around sunrise itself or soon after it has become dark. The evening passage of Lapwings, in particular, regularly started some three hours before it grew dark, which meant that many of the birds were over the middle of the North Sea when darkness fell. One wonders whether they then switched from solar to stellar navigation, but whatever method they used, there was no observable change in the direction or other characteristics of their passage. Birds flying close to the waves may be undetected by radar; but during my watches on the east coast of Suffolk during the summers of 1955, 1956 and 1957, with sparser records for the previous years, I never saw Lapwings arriving low over the waves, and the same held during four successive Septembers. In the late autumn, however, both J. L. F. Parslow and I occasionally saw Lapwings arriving against a strong head-wind flying so low that they were undetected by radar. It seems far more likely that Lapwings would set out in such conditions 128

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after a hold-up due to bad weather near the end of the migratory period than near its start. Taking these various points into consideration, it is reasonably certain that the occasions in June and July on which the westward immigration was recorded by radar were the only occasions in these months when it occurred. This means that the radar record can be compared with the weather to determine the factors influencing the volume of migration (except that certain minor variations in the density of bird-echoes were probably due to variations in the altitude not the volume of migration). A conspicuous feature of the westward immigration in June and July has been its tendency to occur on several successive days followed by long blank periods. In 1959, for instance, it occurred on l Oth-15th June, 18th-25th June and 7th-1 Oth July, and in 1960 on I3th-l5th June, 17th-26th June (the longest period recorded) and 15th-16th, 20th-21st and 23rd24th July. Other movements lasted only a day or less. The term 'wave of migration' implies some inherent rhythm such that, once a migratory movement has started, it runs a course of set duration; but the present movements varied in length from a few hours to ten days. The variations are wholly explicable in terms of the weather, the birds tending to set out in anticyclonic weather with easterly winds, which usually persisted for several days; hence the term 'wave' is inappropriate. T o investigate the influence of the weather, I analysed the density of bird-echoes each morning and each evening on an arbitrary scale from 0 to 2 in relation to the direction and speed of the surface-wind, the temperature, and the extent of cloud, rain or fog, as recorded at Den Helder in northern Holland in the British Daily Weather Reports, using the figures for 06.00 for the morning movements and those for 18.00 for the evening movements. I also classified the general weather situation, whenever possible as anticyclonic or disturbed (with a depression or front), using a 'transitional' category as little as possible. Table II shows the paramount importance of easterly winds. The mean density of migration was highest with north-east and i 129

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east winds, somewhat lower with south-east and north winds and extremely low with a wind from any other direction. It is not quite true to say that there was more migration the closer the direction of the wind to the normal westerly heading of the birds. For there was at least as high a density of bird-echoes with north-east as east winds, and more than with south-east winds, while the density was also higher with north than south winds and perhaps with north-west than south-west winds. But these minor differences were probably due to other factors, as the weather tended to be less settled with a southerly than a northerly component in the wind. The possible influence of other weather factors has been summarized in Table III. In view of the marked influence of wind-direction, overall averages would have been misleading, and I have separated the figures for more or less following winds between north-east and south-east on the one hand and for more or less opposed winds between south-west and northwest on the other. To make the table more compact, I grouped the figures for the morning and evening, as there was little difference between them. The uppermost section of Table III shows that the density of migration was higher in anticyclonic than disturbed weather, the difference being proportionately much greater with westerly than easterly winds. In the most favourable conditions, namely an anticyclone and an easterly wind, some westward migration was recorded on all 41 occasions studied. In the most unfavourable conditions, namely disturbed weather and a westerly wind, some migration was recorded on only 7 out of 154 occasions studied, and then it was small. The wind-direction was evidently more important than the general situation, since the average density of migration was a little higher with an easterly wind and disturbed weather than it was with a westerly wind and an anticyclone. The second section of Table III shows that nearly all the movements that took place against a westerly wind occurred when the wind was light, whereas the wind-speed had no apparent influence with following easterly winds. The third section shows 130

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that t h e r e was less migration with cloud or rain. T h e fourth shows that temperature had no influence. T h e various w e a t h e r factors are linked with each other, anticyclonic w e a t h e r with light winds and little cloud, disturbed w e a t h e r with s t r o n g e r winds and more cloud, so that to determine statistically which of these factors have an influence on the amount of migration, it is necessary to use a multiple regression analysis, as set out in the following equation: d=iv+g—

0-00415— 0-018c— 0-0038£

w h e r e d is the density of migration in the units used here, s is the speed of the wind in knots, c is the proportion of the sky covered by cloud, including rain as total cloud, t is the temp e r a t u r e in degrees Fahrenheit, w is a factor for wind-direction, with a value of 0-85 for north, 1-23 for N E , 1-14 for east, 0-87 for SE, 0-59 for south, 0-43 for S W , 0-34 for west and 0-49 for N W winds, and g is a factor for the general situation, with a value of 0-477 for anticyclonic, 0-223 for transitional and 0 for disturbed weather. In this analysis, the only factors with a statistical significant influence w e r e wind-direction and the general weather situation. W i n d - d i r e c t i o n had the greatest influence, and it is evident t h a t the birds respond to wind-direction as such. That, when account has also been taken of the general weather situation, n o other weather factors had a significant influence m i g h t mean that the birds respond to the general weather situation as such, or to atmospheric pressure, but this by no means follows. It could well be that the birds respond to a combination of factors which includes wind-speed and cloud, and that, in the regression equation, these factors were covered by the t e r m for the general weather situation. T h a t wind-speed has an influence with opposed winds was strongly suggested by T a b l e III. T h e w e a t h e r had a rather different influence on the westward L a p w i n g passage in June and July from what it had on the eastward passerine emigration from Norfolk in March and April analysed earlier. T h e differences in question are partly linked, 131

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and they are differences in degree rather than kind, but some of them are marked. An appreciable Lapwing movement occurred on only 36 per cent of the mornings and 37 per cent of the nights studied, and there were long intervals without any passage. In contrast there was an appreciable eastward emigration on 74 per cent of the mornings and 84 per cent of the nights between late February and late April. Presumably the survival of Lapwings is not greatly affected by the precise date in June or July when they move from the Continent to England, hence they tend to wait for favourable travelling conditions. In spring, on the other hand, there is presumably strong survival value in the passerine emigrants establishing breeding territories as quickly as possible, and this is evidently the over-riding factor determining their departure, except in highly unfavourable conditions. Wind-direction had only a small influence on the passerine emigration in spring, but it was the factor with the greatest influence on the Lapwings in June and July. This may have been partly because the Lapwings wait for favourable travelling conditions whereas the spring emigrants press on. Also westerly winds, which are following for the spring emigrants, often bring rain and disturbed weather, which are unfavourable for travel, whereas easterly winds are usually associated with settled weather. Finally, other weather factors which have a negligible influence on the Lapwings in June and July have a marked influence on the spring emigration (notably temperature, while the incidence of strong winds and rain is higher in spring). This means that any effects of wind-direction will tend to be more often obscured by other factors in spring than in June and July. Anticyclonic weather strongly favoured the Lapwing movements in June and July, whereas the average density of the spring emigration was the same for anticyclonic as for disturbed weather. Once again, this might be partly because the Lapwings wait for the best conditions while the spring emigrants press on. A much more important reason is that in spring the beneficial effects (light winds and clear sky) and adverse effects (head-winds and cold) of anticyclonic weather 132

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tend to cancel each other, and the same applies to disturbed weather (strong winds and cloud, following winds and warmth) whereas in June and July in anticyclonic weather all the factors are favourable. Temperature had no influence in June and July, but a marked influence in spring. The spring can be early and mild or late and cold, and so the spring emigrants have probably evolved a response to temperature as a 'timing factor' helping them to reach their breeding grounds at the biologically appropriate time, but there is no such obvious biological advantage in a response to temperature in June and July. Lateral drift by a cross-wind was very small for the Lapwing movements in June and July, because the birds normally set out with a roughly following wind or a very light wind. But lateral drift was often marked in spring, since the birds often set out with a strong cross-wind. Finally, it may be kept in mind that in June and July the Lapwings set out in the same general weather situation, an anticyclone with easterly winds, as on their westward migrations in September and October and their westward 'hardweather movements' between November and early March. It is therefore possible that some of the responses of the birds to the weather in June and July may have been evolved primarily with respect to circumstances operating later in the year, but it would be very hard to test this view critically. T o conclude, radar allows for the first time an analysis of the weather factors influencing a particular migration, helped by the fact that in summer the Lapwings concerned do not normally travel below radar range, as they sometimes do in late autumn. But the visual observations on this movement give, by themselves, a highly misleading idea of when it occurs. It may be added that an analysis of the arrivals of Lapwings in September in relation to the weather gave closely similar results to those in summer, the birds normally arriving too high to be seen from the ground, travelling mainly with easterly winds or very light winds, and in clear anticyclonic weather, while the temperature had no apparent influence. 133

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T A B L E II Comparison of radar record of westward passage over North Sea with Lapwings passing west at Scolt Head, 8th June—9.5th Jidy 1960 Number of birds detected by radar visually

Wind-direction in N Norfolk

Number of instances

many many many few

many few

6

0

10

0

1

0

1

0

many few

0

0

3

3 24

6 l 10 l l S 12

W-SW N E , 2 var. NE-SE NW SW SW W - S W , 12 N W

Notes: 1. In the visual record 'many' means more than 10 distinct parties, often many more, 'few' means 2-6 parties, and 0 means none, or at most one small party. On 14th June Spencer counted 333 individuals in a typical half-hour and states that they passed at similar density on other days. During the two months, the average size of a party was 18 birds (limits 5-50), a figure based on 118 flocks counted. 2. Two mornings, 15th and 16th July, were included in both the first and third lines of the table, since early on with a W S W wind many Lapwings were seen, but later, when the wind changed to between N and E, none or extremely few were seen. 3. The direction of the wind was that over Norfolk, not that over Holland analysed in Table III. 4. The radar observations were nearly all by M . T . Myres, the visual observations by K. G. Spencer.

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TABLE

III

Influence of wind-direction in Holland on zvestzvard passage of Lapwings in June and Jidy

Wind-direction Number of days NE E SE S SW W NW N Total

28

Morning Mean density of movement 1-0

Number of days

Evening Mean density of movement

36

1-3 0-9

13

1-0

8

10

0-7

4

0-7 0-1

12

0-2

4

66

0-1

60

0-1

16

0-1

19

0-2

84

0-2

43

0-3

7

0-5

11

0-9

176

0-40

185

0-49

This table is based on all the available days in June and July 1956, 1957, 1959 and 1960. The weather records were those from Den Helder in northern Holland, the density of migration was on an arbitrary scale from 0 to 2.

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T A B L E IV Influence of various weather factors in Holland on zvestzvard passage in June and July With easterly winds W i t h westerly winds Number of Mean Number of Mean ( •asions d e n s i t y occasions densit General weather situation anticyclonic transitional disturbed Surface wind-speed in knots 2-7 10 15 20 25 Cloud 0/8-4/8 5/8-7/8 8/8 rain Temperature in °F. up to 54 55-59 60-64 over 64

41 16 42

1-3 1-3 0-8

43 31 154

0-59 0-31 0-04

23 32 20

0-8 1-2 1-1 1-3 0-9

23 68 53 47 37

0-40 0-27 0-16 0-07 0-03

1-2 0-9 0-6

82 92 S3 20

0-30 0-15 0-08 0-08

30 110 74 14

0-07 0-17 0-22 0-21

17 7 64 24 S 1

(1-0) (0-7)

3 24 38 34

1-1 11 1-1

Notes: 1. The term 'easterly' covers all winds between N E and SE and the term 'westerly' all winds between N W and S W . 2. The cloud record was missing on one day with a SE wind and one with a west wind.

136

PART T W O

Interlude

V

\J

10

Swifts at Home Swifts are wonderful birds, in my opinion the most remarkable of all British birds. Whether or not they are the fastest in the air, as often claimed, would be hard to test. But they are certainly the fastest for their size, and they are also the most aerial of birds, finding their food and nesting material on the wing, drinking and bathing from the air, mating on the wing, in which they are unique, and, perhaps most remarkable, often spending the night in the air. Yet until the last few years, less was known about Swifts than about any other common British bird. Gilbert White of Selborne, writing nearly two centuries ago, was still the authority on many aspects of their lives. That is because Swifts are so hard to watch. They are either dashing through the air or hidden in the dark inaccessible holes where they nest. And they spend such a short time with us, coming in May and leaving again in August for southern Africa. I admit that Swifts are dull to look at, sooty black all over except for a pale chin, whereas the more familiar Swallows and A broadcast talk in February 1957

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martins are partly white below, and smaller. And the Swift's harsh scream is much less pleasing than the Swallow's homely twitter, though to some it will recall still summer evenings in quiet villages. While, however, the Swift's scream is unpleasing, harsh, and unmusical, that is to our ears. Does it sound like that to a Swift? I got interested in this question because in Switzerland there is another Swift, larger than ours, the Alpine Swift, whose voice is a musical trill. It seems surprising that two closely allied species should have such different calls, so I asked Eric Simms of the B.B.C. Recording Unit if he could record the scream of our Swift and slow it down. W h e n this recording is played at about a quarter of the natural speed it sounds varied and exciting, and also, by the way, not unlike the trill of an Alpine Swift. So the notes of the two species are similar after all; it is simply that our bird trills so rapidly and at so high a pitch that we cannot hear it properly. It is reasonable to suppose that the Swifts themselves hear the details of these musical bubblings. My wife and I started to study Swifts eleven years ago in a village near Oxford where they were nesting in holes in thatched roofs. But all we could do was to put a ladder up to the holes and feel in for the eggs and young, or watch the parents outside. So we discovered very little. W e also saw Swifts nesting a hundred feet above the ground in ventilator shafts in the tower of the University Museum, but these, we thought, were inaccessible. We then heard that a Swiss schoolmaster had succeeded in getting Swifts to nest under the eaves of his house by putting up nesting boxes for them and this gave us the idea for a grand experiment. During the winter of 1947-48, we put ladders and staging inside the Museum tower up to the ventilators, and then replaced the ventilators by nesting boxes. When the Swifts came back next May, the tower was unchanged from the outside, but when the birds entered their holes, they found boxes instead of narrow wooden ledges. To our relief, they accepted the change, and since then the colony has risen in numbers, until we now have thirty-nine nesting pairs. 140

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In the second year of the study, we took out the wooden backs of the boxes and put in glass instead, so that, by sitting in the dark inside the tower, we can see what goes on in the boxes without disturbing the birds. Provided we keep quiet, and do not come suddenly too close to the glass, the birds do not mind us at all. The boxes also have lids, so that we can take out the eggs or young for weighing and measuring. This does not seem to worry the parent birds. You can put your fingers underneath a sitting Swift and take out one of its eggs, and usually it just sits quietly until you put the egg back again. In nature, of course, Swifts nest in holes in rocks, which no enemies could enter from the back, and evidently the birds have no adaptation to cope with this unusual circumstance. I wish I could give you an idea of the strange narrow world in the top of the tower where my wife and I have spent so much of our time. W e are one hundred and twenty feet above the ground, right under the tiles. There is no light, except for the little coming in through the entrance holes to the nesting boxes. It is very cold on a cold and windy day and appallingly hot on a sunny and still day. Except for the wind, and the chimes of the clock on Keble College, it is silent save for the sharp knock as a Swift enters its hole, followed by the faint twittering if there are young to be fed, or a harsh scream if an intruding Swift has entered the hole occupied by another bird. The parent Swifts usually come back to nest in the same hole as in the previous year. It has been proved by marking them. But there are sometimes fights, in which one tries to dispossess another. Most birds fight (if one may use the term) by song and display, and only if these threatening actions fail, which rarely happens, do the birds come to actual blows. But Swifts in their cramped dark nesting holes have neither room nor light for such refinements. If a strange Swift enters, the owner screams and stretches its wings, but if the stranger does not leave at once, the owner grapples with it, and the two stay locked together for up to five hours. It looks horrid - remember we can see it from a few inches away - as the two Swifts grip with their strong sharp claws and peck each other violently 141

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with their bills; soon the bird that is b e i n g defeated utters piercing cries and lies back motionless, as if n e a r death. But this is misleading. T h o u g h the claws of a Swift are sharp enough to draw blood from my finger, the birds g r i p each other on their scaley legs, w h e r e they do n o h a r m ; and the furious pecks are made with a beak so soft that it cannot hurt. Moreover the piercing cries and limp pose seem m e r e l y to be signs that one of the birds has had e n o u g h ; it is n o t really hurt and flies off strongly after being ejected from the hole. So the fights of the Swift are not so terrible after all, t h o u g h w e still dislike looking at them. Because it lives in a small dark hole, the Swift can also have no use for elaborate courtship, and the chief action b e t w e e n the pair is mutual preening, in which each bird passes its bill through the feathers of the other, especially t h r o u g h the feathers of the throat and neck. T h e birds m a t e on their nests, but also on the wing, as first described by G i l b e r t W h i t e . If you watch outside a nesting colony in late M a y , you will p r o b ably see many Swifts confusedly flying about, w i t h chases and screams. But occasionally, about a hundred feet above the ground, one bird flies close behind another, t h e l e a d i n g bird, which is the female, quivers the wings rapidly and then holds them stiffly out, the male comes up from behind and gently alights on her back, and the t w o then glide d o w n w a r d t o g e t h e r for a few seconds and then separate. Often t h e y a r e silent when doing this, sometimes there is a subdued scream. A n d that is all there is to it. T h e y make it look so simple, but g r e a t control is presumably needed on the d o w n w a r d glide, and as it is, the birds sometimes lose balance. F o r e i g n swifts of o t h e r species also mate on the wing, but no other kinds of bird are known to do so. Normally, Swifts do not alight on the g r o u n d o r in v e g e t a tion. This means, among other t h i n g s , t h a t t h e y collect all the material for their nests on the w i n g . Hence t h e y build chiefly on windy days, when much rubbish g e t s blown into t h e air. They take feathers, straw, the winged seeds of p l a n t s , and even a bus ticket or the wings of a white butterfly. T h i s m a t e r i a l is 142

S W I F T S AT HOME

stuck down to the floor of the nesting hole with saliva, which the bird dribbles out soon after coming in. It is this saliva, by the way, that forms the main ingredient of birds' nest soup, so esteemed by the Chinese. Some of the cave-nesting swiftlets of the Malayan region make their nests almost entirely of saliva, and these are industriously farmed at great profit. At the Museum tower, the Swifts lay their eggs at the end of May, the date varying somewhat from year to year. These variations seemed in some way due to the weather but we were much puzzled as to what the connection was, until we found that the weather exerts its influence after a lapse of five days. Thus if it is very cold in mid-May, laying begins five days after the weather has turned warm. Again, if after laying has begun there is a sudden cold or windy spell, laying ceases five days later, and it starts up again five days after the bad spell has ended. Presumably, it takes five days to form an egg inside, and once it has been started, the weather does not influence it. The white eggs, two or three to a clutch, hatch after two and a half weeks. The nestling is hideous; quite naked, with not even the small tufts of down that adorn a young sparrow or thrush; eyes shut; no movements except to grip with its claws and to open its large mouth for food; and with a grotesquely swollen abdomen due to the relatively enormous gut and liver. But this distorted monster is really a miracle of adaptation. And though to our eyes a chick - a pheasant chick for instance is a far prettier object, each is equally well suited to its way of life. The pheasant chick feeds for itself and is active from hatching, so has strong legs, good eyes, and a well developed brain, with down to keep it warm and, by its colour, to conceal it from enemies. So its prettiness results from the need to escape from enemies. A young Swift, on the other hand, is safe in its hole and is fed by its parents, so apart from holding on, its energies are devoted to turning insects into flesh as quickly as possible. There is a similar parallel between a lamb and a human baby. The pretty woolly lamb looks as it does in part because it is the natural prey of wolves, whereas the much less attractive human baby has merely to eat, grow, and hold on. 143

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T h e parent Swifts feed entirely on air-borne insects, which are common in fine weather but become e x t r e m e l y scarce if it is wet or cold. And then the y o u n g Swifts may have nothing to eat. But whereas the nestling of a T h r u s h or Robin dies if it starves for more than a few hours, a y o u n g Swift can survive for several days without any food, and for much l o n g e r if it gets an occasional meal. It is able to do this p a r t l y because, when food is plentiful, it stores up fat, on which it can draw later; and partly because, if food is short, it can slow up its rate of growth, so that any food it g e t s is used primarily for maintaining life. It has another remarkable adaptation. W h e n food is plentiful, one parent goes out hunting while the other broods the nestlings to keep them w a r m . But if food is very scarce, one parent cannot find enough, so both g o out, leaving the nestlings uncovered. T h e y then g e t cold and torpid, and may stay like this for several days. W h e n w e first saw such clammy objects we supposed they w e r e dying. But n o t a bit of it. After a few good meals, they once m o r e became vigorous, none the worse for the temporary suspension of their activities. None the worse, that is, except that they g r o w m o r e slowly and stay longer in the nest. In young songbirds, the interval between hatching and leaving the nest is nearly constant, but a young Swift may stay in the nest for anything from five weeks in fine weather to eight weeks if it is very bad. Despite these adaptations against starvation, nestling Swifts often die if bad weather continues for a long t i m e . I said earlier that the Swift lays a clutch of two or three e g g s , and one of the questions we studied at the t o w e r was the r e a s o n for this number. Our figures now cover m o r e than ten y e a r s , and show conclusively that in fine weather Swifts are able to raise three young successfully, but in bad weather at m o s t t w o and sometimes only one. Now if the summer is g o i n g to be bad, it is obviously more efficient to start with only t w o , n o t three, young, since then no food is wasted on a third chick which will later die. So in a bad summer two, but in a fine s u m m e r three, is the most efficient size of family for the Swift. T h e balance seems very even. Of course if Swifts could tell w h a t sort of 144

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summer it would be, they might adjust their clutch-size accordingly, laying two in a bad and three in a fine summer, but they, like us, have no means of knowing in M a y what the weather will be like in June and July. After it has g r o w n its feathers, the nestling Swift becomes more active. It repeatedly flutters its wings and, at a later stage, presses its wings down on the floor of the nest and raises its body off the ground. Near the end, it can hold up its body for ten seconds at a time. T h e reason for these 'press-ups' is probably to strengthen the muscles that will soon be used in flight. In the same way a human baby, in the weeks before it starts to crawl, lies on its back and repeatedly kicks its legs. D u r i n g its last days in the nest, the young Swift also spends much time looking out of the hole and one day, usually in the m o r n i n g before 10 o'clock, it puts part of its body out, perhaps withdraws it again once or twice, and then tips gently out and away. W e are so used now to the idea of instinctive behaviour that we cease to be surprised at it. But consider. Up to that moment, the y o u n g Swift has lived in a cramped dark hole, safe from enemies and dependent on its parents for food, its only knowledge of the outside world what it can see by looking d o w n w a r d through a narrow slit. It then flies out into the wide world, alone, having nothing further to do with its parents or brothers, flying without practice, with a long narrow wing, which is the most difficult sort of wing to control, finding all its food for itself, avoiding birds of prey, and migrating to South Africa, over six thousand miles away, probably in company with others as inexperienced as itself. It is hard to believe that the hideous naked nestling could in six weeks achieve so much; it seems fantastic; yet it happens every year. But Swifts, as I have already said, are remarkable birds. And one of the most remarkable features of their lives is the way, or r a t h e r ways, in which they spend the night. In most kinds of birds, roosting involves no special difficulty. At dusk they r e t i r e to thickets or holes, where they sleep securely, and come out at daybreak. But Swifts have such long narrow wings that K

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they cannot fly a m o n g bushes or o t h e r c o v e r ; indeed, they cannot launch safely into the air except by d r o p p i n g from a height, which gives them e n o u g h speed to continue. And to find a place to sleep which is both safe from enemies and has a clear drop in front is not easy. It is all r i g h t in s u m m e r , because the birds nest in holes in buildings or cliffs, and the colony comes back to the same place y e a r after year, so that they know where to g o , while y o u n g birds can find places by joining the old ones. But when the birds are a w a y from their breeding area, things become much harder. Actually, difficulties arise even in s u m m e r , especially during the great weather movements of Swifts, s o m e t i m e s involving thousands of birds, on the east coast of E n g l a n d d u r i n g unsettled weather. At first, these m o v e m e n t s w e r e described as migrations, but they occur even in the middle of the summer, when no Swifts could be m i g r a t i n g . N o w as I have already said, the air-borne insects on which Swifts feed are n u m e r o u s in good weather but become so scarce in bad w e a t h e r that the birds are in danger of starving. It has n o w been s h o w n that big summer movements of Swifts occur d u r i n g the p a s s a g e of a depression, the birds flying against the wind r o u n d the southern edge of the depression, and thus m o v i n g a w a y from bad weather into better weather; later they r e t u r n h o m e again. Recoveries of marked birds s u g g e s t that they m a y travel at least four hundred miles from home on such m o v e m e n t s . Indeed one Swift ringed at Oxford was n e x t s u m m e r c a u g h t in the air intake of a jet aircraft over D e n m a r k , five hundred and fifty miles away. Parent Swifts with e g g s or y o u n g could not afford to move away from home like this, and t h e r e is n o w good evidence that the birds that travel are y e a r l i n g s , which come north for the summer but do not usually breed. Hence these yearling Swifts may find themselves far from home at dusk, often, presumably, in places w h e r e they have not been before. W h e r e , then, do they sleep? W h e r e , for that matter, do the m i g r a n t Swifts sleep on their six-thousand-mile journey from Africa to n o r t h e r n Europe? Occasionally in spring and autumn at our Oxford colony, a 146

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s t r a n g e Swift has tried to enter one of the holes at dusk. P r e sumably, it has seen the local birds and followed them in. Sometimes it has been forcibly ejected, but occasionally the o w n i n g pair have accepted it, and all three have snuggled d o w n t o g e t h e r for the night. Once, also, a strange Swift roosted clinging to the outside wall of the tower, and other birdwatchers have occasionally noticed Swifts at the time of their m i g r a t i o n s roosting on walls or window ledges. One entered a r o o m t h r o u g h an open window and clung all night to a curtain, another squeezed itself under the pillow of an occupied bed in a school dormitory. M o r e remarkable, single Swifts have occasionally been seen to fly up at dusk to an isolated twig on a t r e e and cling there all night, half upside down and swinging in the wind. But records of these kinds are scarce. Rarer, and stranger, is the occasional record from the east coast of England, always in cold wet weather, of Swifts coining t o g e t h e r in clumps of sixty or even a hundred birds for the n i g h t , and h a n g i n g on a cliff, or the wall of a house, like a swarm of bees. T h i s has happened at Dover, Deal, and Harwich; some of the clusters have been two feet across. T h e parallel with a s w a r m of bees is apt. T h e birds cling to each other like bees in their hive in winter, and for the same reason, to conserve heat. D e s p i t e their doing this, some are often found dead below the clump n e x t day, these doubtless being the unlucky birds on the outside, and observers have noticed how at dusk each tries repeatedly to s n u g g l e into the middle of the mass. But I would stress that such occurrences are rare, the last record in E n g l a n d being in Suffolk in 1930. Yet several weather m o v e m e n t s occur every summer. So where do most of the Swifts g o at night? M y wife and I found the answer to this question entirely by accident, when we were looking for somet h i n g else, as so often happens in natural history. On a cool July evening five years ago we were walking along the shore in Suffolk at dusk when a party of Swifts flew over us and out to sea. Stupidly, we paid no special attention, merely supposing that the birds were returning after a weather movement and travelling by night, as many migrants do. But two years later 147

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we were again in the same place at dusk, and, as the light failed, a flock of Swifts that had been feeding over the coastal marshes flew up, circled, and headed out to sea. So we then planned a regular watch there, and have now found that Swifts commonly go out to sea at dusk. These, we presume, are strangers to the district which arrived earlier in the day and have stopped to feed. Once, a big weather movement actually continued until dusk, thousands of Swifts streaming south along the shore against the wind in driving rain. When it grew dark, the movement suddenly stopped, and the birds nearest to me, about a hundred and fifty in all, circled, rose together, and went out to sea through the rain. After this, no more passed, so other flocks presumably went out to sea in the same way at intervals all along the coast, and there must have been many thousands of Swifts out over the water. When on migration, Swifts often feed over inland waters, so last summer I also watched at some big reservoirs, and here too, as it grew dark, I found that parties of up to two hundred Swifts would collect together, circle up into the sky and drift away with the wind. I therefore consider that the mystery of where migrating Swifts spend the night has been solved. They go up into the sky. The possibility that Swifts might roost on the wing has been argued for a long time for another reason. At nesting colonies in fine weather, one sometimes sees a group of the birds at dusk, flying in close circles, screaming intensely, and still rising as they are lost to sight when the light fails. Some observers have claimed that these birds come down to their holes after dark, but a Swiss observer has now proved that they do not do this, and has seen them come down at dawn. Recently, he has even plotted their tracks through the air at night with the help of radar. These findings have brought to light an old record, long disbelieved, of a French pilot in the 1914-18 war who claimed that, when gliding above clouds in bright moonlight, he saw a flock of birds gliding below him, one of which was caught in his machine and proved to be a Swift. 148

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While it now seems clear that Swifts regularly spend the night on the wing, this raises several questions. First, why should they do so? It must, one would suppose, be more tiring than to sleep in a hole. The answer, presumably, is that when on their travels, Swifts often find themselves in places where there are no safe holes for roosting, or at least no holes that they know of. When weakened by shortage of food in bad weather, Swifts are forced to roost in strange places, but this may leave them open to attack by predators and presumably, when they are strong enough to do so, it is safer for them to stay up in the air. Then, what do these Swifts actually do all night? Swifts have long narrow wings, so cannot soar on nearly motionless pinions like eagles. Presumably they can keep up only by flapping their wings every few seconds or at least every few minutes, and presumably they must be awake to do this. Do they take cat-naps in between? Evidently, they do not need sleep in our sense of continuous repose, but do they need it at all? And how, especially on dark rainy nights, do they avoid colliding with other members of the flock? Why, also, when near the coast, should they prefer to be over the sea instead of over the land? Possibly the air is less turbulent over the sea, and there are, of course, no projecting hills or trees, but even so it seems remarkable. But then Swifts, as I hope to have convinced you, are very remarkable birds.

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British Pioneers in Ornithological Research 1859-1939 A few years back, at a time when more new books about birds were appearing than ever before, I was asked by the editor of a well-known journal to name what were, in my view, the five most important bird-books published in Britain in the preceding five years. By 'important' in this connection I took to mean books primarily concerned with new and original findings, especially if these were likely to stimulate others and to open up or develop new lines of approach. After consideration, I gave what I felt was the right answer, namely 'the last five volumes of the Ibis'. Although this was rejected as unsuitable by the editor concerned I still think that it was correct, and that in a period of unprecedented interest in and writings about birds, by both amateur bird-watchers and professional zoologists, more new ideas and stimulating syntheses were being put forward in journals than in books, and in particular, so far as From Ibis 101 (1959), the number celebrating the centenary of the British Ornithologists' Union 153

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Britain was concerned, in the pages of an amateur society's journal, the Ibis. This was not always so. About the year 1930, for instance, I remember a somewhat older member of the British Ornithologists' Union, already a prominent amateur field-ornithologist and now in a highly responsible post, proposing an inquiry into the average number of pages of the Ibis that remained uncut in the homes of members; the figure would certainly have been high. At this date, the Ibis was unread not only by field-observers, but also by professional zoologists, amongst whom ornithology had sunk lower in repute than at any time in its history. The department of zoology at Cambridge, for instance, adhered to a statement attributed to Newton that everything important had been discovered about birds; and even Newton's wonderful library was allowed to moulder there untended in a cramped and dusty attic. It would have been inconceivable then that, only twenty-five years later, not only would the Ibis be eagerly read by both field-ornithologists and professional zoologists, but that research on living birds would be actively encouraged and carried out in the zoology departments of six British universities, Oxford, Cambridge, Bristol, Exeter, Durham and Aberdeen, four of which had established, or had had attached to them, centres of ornithological research. Now the foundations of this resurgence were presumably being laid in the period when the scientific repute of ornithology seemed at its lowest, so it occurred to me to ask, with respect to this earlier period, the question which started this essay, namely what were the five most important books on birds; and for this purpose I reckoned everything published in Britain between 1899 and 1939 (that is, in the second forty years of the British Ornithologists' Union's existence). Attaching the same meaning to 'important' as before, and laying particular stress on pioneering qualities, I made my selection, but before setting it down, I asked various other ornithologists to make theirs on the same terms, and was reassured to find how nearly we agreed. My choices, then, were as follows: (i) Edmund Selous, 154

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Realities of Bird Life (1927), (ii) Eliot Howard, The British Warblers ( 1 9 0 7 - 1 4 ) , (iii) W . Eagle Clarke, Studies in Bird Migration (1912), (iv) Edward Wilson and others, The Grouse in Health and Disease edited by Lord Lovat (1911), and (v) E d g a r Chance, The Cuckoo's Secret (1922). I have added in brackets the date of publication, but this is in two cases misleading, since Selous' 'observational diaries', published in the Zoologist between 1899 and 1916, were much more important than his best book, which was based on observations made twenty-five years earlier; while similarly many of Eagle Clarke's observations appeared ten or more years earlier than his book, chiefly in the Annals of Scottish Natural History and Scottish Naturalist. It should be added, also, that Chance's first book was improved and expanded in his Truth about the Cuckoo (1940). Finally, had I allowed myself two books by the same author, I m i g h t perhaps have preferred Eliot Howard's Introduction to the Study of Bird Behaviour (1929) to either my fourth or fifth choice. T h e five selected authors were not, I think, of equal importance. Selous and H o w a r d would feature in a similar world-list, but E a g l e Clarke's studies, though unique in Britain, had more important precursors abroad, notably Gatke's Die Vogehvarte Helgoland (1891), while Wilson's and Chance's work was of lesser significance. Indeed, if the original question had asked for five ' w o r k s ' , not necessarily books, I would have substituted for my fourth and fifth choices two papers, Julian Huxley's The courtship habits of the Great Crested Grebe (Proc. Zool. Soc. Lond. 1914, 2: 4 9 1 - 5 6 2 ) , and J. P. Burkitt's A study of the Robin by means of marked birds {Brit. Birds 1924-26, 17: 2 9 4 3 0 3 ; 18: 9 7 - 1 0 3 , 2 5 0 - 2 5 7 ; 19: 120-124; 20: 91-101); while h a d I allowed myself two papers by the same author, Julian H u x l e y on 'Clines: an auxiliary taxonomic principle' (Nature 1938, 142-219) might well have found a place. T o r e v e r t to the issue raised in the first paragraph of this essay, whereas since 1945 nearly all the important research on birds has been published in journals and not in books, in the period 1899-1939 both media were equally favoured. Thus, 155

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Howard and Chance published their research exclusively in books, Eagle Clarke and W i l s o n m a d e i m p o r t a n t contributions in both books and papers, while Selous, H u x l e y and Burkitt wrote their scientific work in papers, not books. W i t h r e g r e t it must be added that five of these seven pioneers in ornithology never contributed to the Ibis, while E a g l e Clarke and H u x l e y each placed only a small and u n i m p o r t a n t fraction of their work there. In that period, however, the Ibis was concerned chiefly with collections of skins from abroad, whereas these seven men, quite apart from their main theses, m a d e t w o big innovations, by studying living birds, instead of dead ones, and by studying them in Britain, instead of abroad. T h e reception of these works in the review columns of the Ibis is of interest. Realities of Bird Life w e n t unnoticed, as did all the other books that Selous w r o t e , and they w e r e also unmentioned in British Birds magazine. T h e first p a r t of H o w a r d ' s British Warblers was rather favourably received in the Ibis, though the only comment on behaviour was that 'perhaps a little less might have been said about sexual selection', which to a modern ornithologist is the primary point of value made by Howard in his first section; each later p a r t was also noticed as it was published, and the final summarizing review included full approval of the territory theory and of H o w a r d ' s other findings on behaviour. Later, Territory in Bird Life (1920) was called by F. C. R. Jourdain 'an attractive and thoughtful little work'. Eagle Clarke's book was acclaimed, and the review covered nearly two pages. The Grouse in Health and Disease escaped review. The Cuckoo's Secret was noticed in under half a page, being praised for its methods and particular facts, and much less for its generalizations; but full justice was given to The Truth about the Cuckoo. Huxley on the G r e a t Crested G r e b e received, rather surprisingly, nearly a page of approval, while Burkitt on the Robin passed unnoticed, doubtless because his papers were not sent for review. T h e intervals elapsing between these pioneering efforts and the important developments to which they have respectively given rise have differed greatly. Although Selous was dis156

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regarded by nearly all contemporary ornithologists, he had immediate successors in his field, first Julian Huxley, who owed a big and acknowledged debt to Selous' prior observations on the Great Crested Grebe; while by 1930 the detailed observation of bird behaviour initiated by Selous was rapidly advancing, especially in Holland. The impact of Howard's territory theory was somewhat delayed, partly by the form in which it was published, embedded in a bulky and seemingly conventional bird monograph with expensive plates, and partly by the 1914-18 war, which started when the book was just completed. Hence Howard's second, and in my view less wellconceived, book, Territory in Bird Life (1920), had the greater influence, though this also was delayed. It was the stimulating advocacy of Howard's theories by E. M. Nicholson in Hozv Birds Live (1927) that first gave them a wider currency, while in the early nineteen thirties Mrs M. M. Nice in America carried the factual study of territory further, and critical appraisals of Howard's theories appeared about the same time. Eagle Clarke's work on migration, though widely acclaimed by contemporary British ornithologists, was not seriously followed up in these islands for some forty-five years, being regrettably side-tracked by his incidental discovery that on the Fair Isle and similar places there was a big chance of collecting rarities. This failure is the more surprising since, apart from their scientific interest, both visible diurnal migration and the occasional 'falls' of night migrants are often spectacular, so their study might have been expected to appeal to amateurs. Not until a few years after the Second World War did quantitative observations on visible migration, the regular manning of observatories, and the study of movements in relation to weather, become prominent features of British ornithology, due especially to the prior work on visible migration by members of the Vogeltrekstation Texel in Holland, and to W . B. Alexander's enthusiasm for founding bird observatories in Britain, starting with his preliminary trial at Holy Island with the Oxford Ornithology Society in 1931 and 1932. Chance's work on the Cuckoo, being factual, comes in a 157

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different category from the rest and does not call for discussion in this paragraph, except to say that, as yet, no one has again studied the Cuckoo in this kind of way. Huxley's papers on courtship, of which that on the Great Crested Grebe was only one, provided an important bridge between Selous and the modern workers on behaviour in the nineteen-thirties, while his note on clines had an equally important and even quicker impact on taxonomy and the problem of subspecies. The introduction of individual marking by Burkitt was also followed up very quickly, notably by M. M. Nice on the Song Sparrow in America. It is interesting that, of these seven men, only Huxley was trained as a zoologist, though two others, Eagle Clarke who started as a civil engineer, and Wilson trained in medicine, were professional naturalists for most of their lives. Of the four who were wholly amateur, Chance and Howard were rich men holding responsible positions as directors of private business firms in the Midlands, Burkitt was a civil engineer in Northern Ireland, and Selous apparently supplemented a small private income from the meagre sales of his books. Of these four amateurs, Howard was strongly (some would say too strongly) influenced by Lloyd Morgan, Professor of Psychology at Bristol, who was his only scientific contact until he was sought out, late in his life, by Julian Huxley; Chance had no contact with scientists but trusted to his considerable business acumen; Burkitt was in touch only with a few Irish naturalists; and Selous cut himself off from scientists and fellow ornithologists, in his later years deliberately refraining even from reading their publications. Of the seven, only Huxley became a Fellow of the Royal Society, and this primarily for research on other animals than birds, while Eagle Clarke, an LL.D. of Aberdeen (due to the advocacy of Professor J. Arthur Thomson), was the only other to receive an academic honour, though Wilson might well have done so but for his early death. Eagle Clarke was the only one to be honoured by the Union, being the first recipient of the Godman-Salvin medal. Edmund Selous (1858-1934) was not even a member of the 158

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Union, and was so little known personally that he did not r e ceive an obituary notice in any British ornithological journal, thougli there was an appreciation of his writings in the French journal Alauda (1934, 6: 3 8 8 - 3 9 5 ) , followed by the American Bird Banding (1935: 9 0 - 9 6 ) . It therefore proved extremely difficult to discover anything about his life. His older brother, F. C. Selous, was the famous big-game hunter, whose life by J. G. Millais includes a brief description of the father's home circumstances. In addition, Edmund Selous' only son G. H. Selous, in Appointment to Fez (1956), mentioned that his parents were p o o r and that his father, after his undergraduate days at P e m b r o k e College, Cambridge, was called to the Bar, but soon felt the call of bird-life more strongly. This son was born in 1887; the family lived at Wiesbaden 1888-89, then moved to Mildenhall in Suffolk, where twin sisters were born soon afterwards. T h e family always spoke German, later French, in the h o m e . E d m u n d Selous wrote his first long paper on birds, based on observations on the Breckland round Mildenhall, in 1899, when he was already forty-one years old, a remarkably late start for so original an observer. After that he appears to have devoted himself wholly to watching birds, on a very modest income. His books were published by Constable, whose reader has informed me that 'he was odd, withdrawn, shy and solitary in type and a man of marked idiosyncrasy'. His isolation from other ornithologists, perhaps due initially to the general lack of interest in his kind of field work, was greatly increased by his voluminous unco-ordinated descriptions, rambling style, retiring disposition and awkward temperament. His best work, as already mentioned, was in his 'observational diaries' in the Zoologist, which ceased there when, to his chagrin, the Zoologist was bought up by British Birds magazine. His early books were not so valuable, being a not altogether happy juncture of natural history and nature journalism, in the latter of which he was not nearly so evocative as W . H. Hudson, while his last books were unconvincing speculations on thought-transference and the evolution of habits. Selous' chief asset was his extraordinarily acute observation of action and behaviour, but he was almost 159

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entirely unselective, believing that every observed detail should be published, which makes even his best w o r k almost unreadable except to those who have themselves watched the species concerned. His field-notes and manuscripts, now in the Edward Grey Institute, are in a large, unattractive, s p r a w l i n g hand, and extremely bulky, untidy and unco-ordinated. Y e t t h o u g h neglected by ornithologists in his lifetime, Selous may be regarded as the founder of the modern studies of behaviour, since lie was the first to make intensive observations on individual birds and to theorize on what he saw. Hence he lias probably had a bigger influence on ornithological research than any of the other men discussed here. Excluding some juvenilia in the Zoologist, Eliot H o w a r d (1873-1940) published all his research in five books. H e took immense pains not only in their content but in their style, which especially in his later books is so closely knit that it makes reading hard, though r e w a r d i n g ; and he also concerned himself with their production, the manner and expense of which undoubtedly contributed to their neglect by ornithologists, especially in the case of his first book British Warblers ( 1 9 0 7 - 1 4 ) , and his third An Introduction to the Study of Bird Behaviour (1929). T h e original but straightforward observations and theories on territory and courtship in his first book, repeated and somewhat expanded in Territory in Bird Life (1920), gave place in his third book to equally original but m o r e difficult speculations on the relations between physiology and psychology. Finally, in The Nature of a Bird's World (1935) and A Waterhen's World (1940), Howard tried especially to understand and interpret the bird's 'world' or viewpoint, which led him into exalted metaphysical regions where, as yet at least, he has had no followers. Hence this aspect of his w o r k cannot be properly evaluated, though many have felt that it includes too few observations and too many speculations. His field notes, now in the Edward Grey Institute, could not be in g r e a t e r contrast to those of Selous, being in small neat notebooks, mostly in pencil, in a fine, precise hand, and so abbreviated that it is almost impossible for anyone else to use them. H o w a r d , 160

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though a member of the Union for forty-five years, and serving inconspicuously on the Committee and later as Vice-President, was known to hardly any of the members, his business in Worcester and his retiring nature keeping him from social contacts with ornithologists, and even from corresponding with them; one pictures him as one of those Ecclesiasticus called 'rich men furnished with ability, living peaceably in their habitations'. So little was he known that an important book was actually dedicated to his memory over a dozen years before his death. The marked influence of his friend Lloyd Morgan has already been noted. In addition to his famous book, Eagle Clarke (1858-1938) wrote numerous papers on migration and some on faunistics. He was the first to study visible migration in Britain, the first British ornithologist to watch regularly at lighthouses and on small islands, the 'discoverer', ornithologically speaking, of Fair Isle, and the first to discuss the weather factors responsible for the arrival of night migrants (though he was wrong about the influence of the wind). In addition to his own researches, he co-ordinated the findings of the Migration Committee of the British Association for the Advancement of Science, was a very efficient Keeper of Natural History in the Royal Scottish Museum, and for thirty years edited the Annals of Scottish Natural History and its successor the Scottish Naturalist. He was a member of the Union for over fifty years and President 19181921. Hence in addition to his research, he played a full and valuable part in the affairs of British ornithology, which none of the others did, and his importance as a leader in every branch of Scottish ornithology was particularly outstanding. A full account of his life appeared in the Ibis for 1938 (548-552). The work of Edward Wilson (1872-1912) and others on the Red Grouse and its parasites is not better known partly because there have as yet been no successors in this field in Britain and partly because it was published in a bulky book instead of in a scientific journal. At this date, also, it is not possible to say how much of the most original conclusion in this book, concerning the density-dependent action of a parasite on its host, was due L 161

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to Wilson himself and how much either to R. T. Leiper, later Sir Robert Leiper, F.R.S., who became Britain's outstanding helminthologist in the first half of the twentietli century, or to Sir Arthur Shipley, F.R.S., who directed the team of workers. Nor can one even say whether they were correct to ascribe the basic cause of Grouse fluctuations to interaction with a parasitic organism. The later work on game-bird cycles has shown that, in the American species, disease plays, at most, a very subsidiary role, but the situation in the Red Grouse is not altogether comparable. In any event, Wilson and Leiper were the first to investigate the fluctuations in numbers of a bird species, and they sought for the right kind of explanation, i.e. a density-dependent mortality factor. Wilson did not live to see the book in print, and is now remembered primarily for his achievements in the Far South, his fine descriptive paper on the habits of Antarctic birds and mammals (including the spectacular breeding of the Emperor Penguin), his attractive paintings of polar scenes and birds, and his astonishing physical and spiritual endurance on the journeys to Cape Crozier in midwinter and later to the South Pole with Scott. He was a member of the Union for twelve years and a well-liked member of the associated dining club. His Life has been written by G. Seaver (1933).

Edgar Chance (1881-1955), like Eliot Howard a business director, was very different from him in character, shrewd, objective, outspoken and efficient, business-like in the conventional sense, no originator of new theories but with a remarkable flair and application in his chosen field of Cuckoo behaviour, where he accomplished an unrivalled feat of field-observation, including the successful management of some most variously qualified helpers. Apart from his two books on the Cuckoo, he published nothing of ornithological importance, though he came to the Cuckoo having first shown for the Red-backed Shrike, by means of a wonderful series of clutches now in the British Museum (Natural History), that each individual hen laid eggs of a characteristic and recognizable pattern. He was blunt in criticizing those who held that the Cuckoo carried its 162

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egg in its beak to the fosterer's nest, and offered M100' n e v e r claimed, to anyone who could establish that this happened. But he did far more than merely to establish how the egg was put in the nest, and worked out the whole remarkable behaviour of nest-finding and egg-deposition by the hen Cuckoo. Chance was a member of the Union for only six years, being forced to resign after his prosecution for taking Crossbills' eggs in East Anglia, the Committee's action in this respect being endorsed at a special meeting. Chance, like Selous, had no obituary in the Ibis and only a brief paragraph in British Birds, but the dislike occasioned by his egg-collecting and blunt manner need not blind us now to the magnitude of his achievement. Sir Julian Huxley (b. 1887), who is happily still with us, wrote many papers on bird courtship in various journals between 1913 and 1925, the most valuable being those on the Great Crested Grebe at Tring (based on some two weeks in the field), and on the Red-throated Diver in Spitsbergen; he also made important contributions to the species problem, with special reference to birds, from 1938 to their culmination in his Evolution: The Modern Synthesis (1942). In both fields, his findings (like those of most other scientists) were stimulated by the work of others, notably by Selous on courtship and by Rensch on speciation, but they included important original 163

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Great Crested Grebe ideas, especially concerning mutual courtship and clines respectively. Perhaps his most significant achievement, however, was to convince fellow zoologists that bird courtship and avian subspecies were worthy of serious scientific study, and it is largely due to Huxley that behaviour and systematics, not merely in birds but in animals generally, have in recent times once more become zoologically respectable. Further, Huxley's felicitous style, especially in his papers on courtship, and his personal enthusiasm, fired others to undertake research in the same fields; and, particularly in the nineteen-thirties, he played an extremely valuable part by his encouragement of younger British workers, amateur and professional, on bird behaviour, ecology and systematics, at a time when both general zoologists and senior ornithologists were, to say the least, discouraging. Huxley has been a member of the Union for over thirty years, but so busy in so many fields that he has rarely attended meetings. In his varied career he has been a professor of zoology in both the United States and Britain; secretary of the Zoological Society of London where, on the one hand, he encouraged professional zoologists to join and on the other hand started Pets' Corner; a research worker productive in various branches of biology outside birds, for instance formulating the concept of heterogonic growth; a supremely successful scientific journalist, writing many semi-popular books, not only on birds, but on 164

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general biology, physiology and evolution, biography, travel and scientific humanism; the recipient of a Hollywood 'Oscar' (for his film on the Gannet); a brilliant raconteur and broadcaster, being one of the original 'Brains Trust'; and sometime Secretary-General of UNESCO. Yet, if a personal prediction be not thought impertinent, I think it likely that, in fifty years' time, he will be especially remembered for his papers on bird courtship and clines. This brilliant public figure could not be in greater contrast to the final pioneer of the seven, also still living, J. P. Burkitt (b. 1870), a civil engineer and between 1900 and 1940 County Surveyor of Fermanagh in Northern Ireland. Burkitt simply placed different patterns of metal bands on the legs of his garden Robins - not coloured rings because he was colour-blind and thus initiated a technical revolution in the field study of the individual bird. By its means he discovered new facts about territorial behaviour and song, including female song; he was one of the first to observe threat display in a bird and to interpret it correctly; and the first to use ringing returns to estimate average age. He did not, he informed me, look at a bird until he was thirty-seven, at which time he had no bird-books and no ornithological friends. Apart from a few papers in the Irish Naturalist, chiefly on song, he did not publish anything else, perhaps because, as he wrote to me in 1944, 'When I was doing the Robin I had pricks of conscience that I was really more interested in the created than the Creator'. He never joined the B.O.U., nor did he have any contact with English ornithologists, except for a correspondence with H. F. Witherby when his papers on the Robin appeared in British Birds. A deeply religious, extremely humble and intellectually able man, he was naively surprised that, for instance, he should receive so many reprints from his great successor, Mrs M. M. Nice, the Professor's wife in Ohio, who colour-banded Song Sparrows; and he has spent his declining years reading his Bible and working in his garden. Summing up the relationship to the British Ornithologists' Union of these seven pioneers, one became President, two 165

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others served their turn as members of the Committee (though Huxley attended only one meeting), two more were members of the Union, though one of these was expelled, and two were never members. Only two published papers in the Ibis and this not their outstanding work, while two were never mentioned in its pages. It will have been noticed that while the period that I have been considering extended from 1899 to 1939, nearly all the works selected appeared before 1914 and the last in 1924 (provided that Selous' papers in the Zoologist are preferred to his book based on them). It may not unreasonably be claimed that, in the first quarter of the twentieth century, Britain led the world in scientific, and especially in field, ornithology, but after that the initiative in research passed decisively abroad. In this later period, i.e. from 1925 to 1939, there were in my view three major advances. First in Alberta, W . Rowan, who was educated in Britain and a member of the Union, showed that an increase in the daily light-ration caused the gonads of male Juncos to mature in the Canadian winter, thus initiating the modern studies of breeding seasons and of avian reproductive physiology. Secondly, B. Rensch in Germany and others demonstrated the adaptive nature of some subspecific differences in birds, and also the possibility that two ends of a chain of subspecies could meet in the same area and behave as good species, which led on to the 'new systematics' (Huxley's term) of E. Mayr in the United States and others. Thirdly K. Lorenz in Austria and soon afterwards N. Tinbergen in Holland, working with tame and wild birds respectively, may fairly be said to have founded the modern study of instinctive behaviour, with special attention to display. In contrast to the seven British pioneers, more than half of whom were amateurs, all these later men were professional zoologists. Some might claim that their discoveries were more important than those of the British workers; certainly they were more scientifically based, and they have since led to important advances in the study not only of birds but also of other animals. Actually there was in this later period another branch of 166

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ornithology in which British amateurs were the chief pioneers, namely bird ecology, beginning with E. M . Nicholson's censuses in 1928 of Herons in England (Brit. Birds 22: 2 7 0 - 3 2 3 , 3 3 4 - 3 7 2 ) and Rooks round Oxford (J. Ecol. 18: 51-66), and carried on especially by members of the newly founded British T r u s t for Ornithology, and also by R. E. Moreau in T a n g a n yika; but I have been too closely associated with this field myself to trust m y historical perspective, so will not discuss it further. In any case, it came into fruit much later than the other branches of ornithology treated in this essay. I would stress that, in this survey of important ornithologists in the period 1899-1939, I have throughout been concerned solely with the pioneers in research. As a leader, a man like H . F . W i t h e r b y had a more important influence on British ornithology than nearly all the men that I have selected for consideration, since he founded what later became the national r i n g i n g scheme, was cliief author of the Practical Handbook of British Birds (1920-24) and its successor the Handbook of British Birds ( 1 9 3 8 - 4 1 ) , and served as President of the Union. M o r e o v e r , as founder and chief editor of British Birds magazine from 1907 to 194-3, he successfully combined amateur enjoym e n t with a steady rise in biological interest and scientific standards. H e was, of course, an amateur, while his friend and successor as editor, B. W . Tucker, who also did so much for the field side of the Handbook and for ornithology at Oxford, was a professional zoologist. But such men come outside my terms of reference. So also do the bird-books, however valuable or imp o r t a n t , that are primarily descriptive compilations, notably the Handbook itself, A. Landsborough Thomson's Problems of Bird Migration (1926) and that outstanding and insufficiently appreciated production by the then Honorary Secretary of the Union, E. C. Stuart Baker's Nidification of Birds of the Indian Empire (1932-35). H a v i n g considered the second forty years of the Union's existence, it naturally occurred to me to select the five most i m p o r t a n t pioneering works on birds published in Britain in the preceding forty years, 1859-99; but, to my surprise, none 167

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seemed of comparable magnitude. In case this impression was due to my belonging too much to m y own g e n e r a t i o n , I asked a leading septuagenarian ornithologist who is both a bird-watcher and a biologist, but his opinion was essentially similar to mine. T h i s was the age of ornithological travels and e x p l o r a t i o n , of classification and anatomy, and while much sound and valuable descriptive work appeared, there seems to have been nothing primarily ornithological of outstanding originality. T h e evidence from one group of birds, the G a l a p a g o s finches, initiated the Origin oj Species (1859), and birds featured p r o m i n e n t l y in Darwin's theory of sexual selection (1871), also in the zoogeographical and other writings of A. R. W a l l a c e , but in these books birds took their place alongside the o t h e r animal g r o u p s . T h e only ornithological paper that m i g h t well have qualified for inclusion had it appeared a year later was t h a t by P. L. Sclater in 1858, 'On the general Geographical D i s t r i b u t i o n of the members of the Class Aves' {J. Proc. Linn. Soc. Lond. (Zool.) 2: 130-145), in which the zoogeographical r e g i o n s of the world were classified on the basis of their bird-life, which regions were later, through the advocacy of A. R. W a l l a c e , adopted for all other animals. Yet 1859-99 was, one had supposed, the g r e a t a g e of British ornithology. T o check this impression, it occurred to me that an objective measure of the repute of o r n i t h o l o g y a m o n g British scientists might be provided by the n u m b e r of Fellows of the Royal Society among the Union's m e m b e r s at any one time. I need hardly point out that this does n o t necessarily provide a reliable assessment of ornithological achievement, but I am concerned here with a much lesser m a t t e r , namely the changes in the climate of scientific opinion t o w a r d s ornithology. Since the Union was founded in 1859 by a g r o u p of y o u n g men, it is not surprising that it then included no Fellows of the Royal Society. By 1869 there were two, by 1879 eight, by 1889 eleven, and by 1899 as many as seventeen. T h e n came the decline, by 1909 to nine, by 1929 to five and by 1939 to one, and he not an ornithologist but an entomologist. T h i s , I think, is convincing, and it becomes m o r e so w h e n the list is analysed, 168

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since of the nine men whose claims to scientific recognition were primarily ornithological, seven had been elected by 1882, the eighth in 1892 and the last in 1911. The first 'Ibis' to be elected to the Royal Society was, deservedly, P. L. Sclater in 1861. The second, surprisingly, was the 'Sacred Ibis', i.e. Canon H. B. Tristram, in 1868, due apparently to Newton's temporarily withdrawing his own name from the lists, an action and an effect which one would have thought impossible were it not vouched for in private letters (A. F. R. Wollaston, 1921, Life of Alfred Neivton: 67-68). Newton himself was elected in 1870, Salvin in 1873 and Godman in 1882. These five were all founder-members of the Union, as was Hudleston who became an F.R.S. for his work in geology, while A. R. Wallace, specially elected to join the founder-members in 1860, was also an F.R.S. Hence of the twenty-one British members of the Union in 1860, no less than seven were to become Fellows of the Royal Society. Needless to say, there has been no later period in the Union's history when one-third of the total membership were future Fellows, and in recent times the proportion has been well below one-hundredth. The nine Fellows of the Royal Society to have been elected primarily, or at least very largely, for their researches in ornithology were, in order of birth, H. B. Tristram (1822-1906), who collected in North Africa and Palestine; P. L. Sclater (1829-1913), who worked especially on zoogeography and classification; A. Newton (1829-1907), who had extremely wide interests; F. C. Godman (1834-1919) and O. Salvin (18S51898), who collected together in Central America and monographed the Petrels; W . L. Buller (1838-1906), who wrote on the birds of New Zealand; A. H. Garrod (1846-1879), and H. F. Gadow (1855-1927), who studied avian anatomy; and the Hon. Walter (later Lord) Rothschild (1868-1937), who assembled the Tring collections and, with Hartert at his elbow, wrote on taxonomy. These men show a nice balance between amateur and professional, since five of them held paid positions, Sclater as Secretary and Garrod as Prosector to the Zoological Society, Newton as Professor and Salvin and Gadow as 169

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successive Strickland Curators in the D e p a r t m e n t of Zoology at Cambridge University; while the other four, T r i s t r a m , Godman, Buller and Rothschild, were amateurs, as was Sclater for part of his life. In addition to these nine, there were seven other Fellows of the Royal Society and members of the Union who, though not primarily ornithologists, published extensively on birds, namely A. R. Wallace ( 1 8 2 3 - 1 9 1 3 ) , who collected in Malaya and discussed avian zoogeography; St G. M i v a r t ( 1 8 2 7 - 1 9 0 0 ) , who studied avian anatomy and m o n o g r a p h e d the Lories; W . T . Blanford (1832-1905), who collected in India, Persia and Abyssinia; two further Indian travellers, H . H . GodwinAusten (1834-1923) and H . J. Elwes ( 1 8 4 6 - 1 9 2 2 ) , of whom the latter became President of the U n i o n ; and t w o further workers on avian anatomy, F . E. Beddard (1858-1925) and P. Chalmers Mitchell (1864-1938). T h i s brings the total to sixteen, of whom eight were primarily travellers or t a x o n o mists writing on the birds of distant lands or on particular groups of birds, and five were primarily anatomists, while three had more general biological interests, Sclater, W a l l a c e and Newton. These proportions of course reflect the scientific trends of the period, when attention was concentrated on zoological exploration and collection, on comparative a n a t o m y and on classification. It is noteworthy that only one of the sixteen paid any serious attention to British birds, N e w t o n completely r e writing the first two volumes of Yarrell's British Birds, which deservedly became the standard w o r k on these islands in the period concerned. In my view only one of these men, P. L. Sclater, produced work on birds as important as that of my seven later pioneers, though A. R. Wallace was justly renowned in a wider field of zoology. T h e remaining Fellows of the Royal Society who were also members of the Union did not undertake any serious research in ornithology: they included A. C. L. G u n t h e r (founder of the Zoological Record and the British Museum Catalogue), V. Ball, H. S. Marks, W . H. Hudleston, J. R. Bradford, H e r b e r t Maxwell, Thomas Lord W a l s i n g h a m , H. W . Riicher, J. 170

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Graham Kerr, R. I. Pocock, H. W. Richmond, K. J. P. Orton (who contributed notes to British Birds) and K. Jordan. Nine of these were members of the Union in the twentieth century, so accounted for most of the Union's representation in the Royal Society in this period. It remains to ask why the scientific repute of ornithology should have declined so markedly after 1900. In the previous fifty years birds had played a prominent part in zoological theory, notably in Darwin's evidence for evolution, natural selection and sexual selection, and in Wallace's views on zoogeography. Yet by the turn of the century birds were ceasing to be zoologically respectable, and they had to wait nearly fifty years for re-admission to the Animal Kingdom as recognized in university teaching departments. Students of zoology learnt only the anatomy of the adult pigeon and the first three days of the embryo chick; all the rest were regarded, in T. H. Huxley's phrase, as 'glorified reptiles'. One reason for the decline of zoologists' interest in birds was the emphasis in formal zoology on classification and anatomy, for by 1900 ornithological classification was regarded as much more nearly completed than that of the other group of animals, while the comparatively uniform anatomy of birds and the scarcity of their fossil remains did not invite the excited attention then accorded by zoologists to reptiles and mammals. Moreover, while the meticulous precision which Newton brought to the subject had earlier converted ornithology from a pastime into a science, it later exerted a deadening influence, at least so far as professional zoologists were concerned. In addition, between 1890 and 1940, hardly any outstanding scientist undertook research on birds, Julian Huxley being an important exception, and ornithology, like the collecting of butterflies, was dismissed as a dilettante pursuit for 'mere amateurs'. This criticism was partly justified, since in that period so much of British ornithology was devoted to the collecting and observation of rarities, and even the new originators, notably Edmund Selous, would not have shone in scientific company. T o bring ornithology back into scientific repute two steps 171

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were needed. First there had to be a complete re-orientation, away from collecting, anatomy and classification, to a study of living birds in their natural surroundings, which was initiated by some highly original ornithologists, mainly a m a t e u r s , between 1900 and 1914. Secondly this n e w type of w o r k needed to be disciplined bj' trained scientists, which occurred especially between 1929 and 1939. T h e British, t h o u g h n o t the Union, played the major p a r t in the first phase, but no part, save for Julian Huxley, in the second phase. At the present day, however, the scientific repute of ornithology seems as high as it was a hundred years ago, and for the first time since 1898 one of the three senior offices of the Union is held by a professional zoologist who is an F.R.S. and, appropriately in view of the Union's beginnings, he is also a m e m b e r of the C a m b r i d g e Zoological Laboratory. I end with seven quotations to illustrate my selections in the first part, though some have been taken from different works from those specified where I thought them m o r e representative of the author concerned. (1) ' W h a t is the particular " m e s s a g e " that I wish, t h r o u g h this work, to convey? It is this, that I believe it possible, t h r o u g h prolonged intensive observation of the habits of birds, to discover the evolutionary sources from and t h r o u g h which these, as we now see them, have arisen and developed.' E. Selous, 1935, The Evolution of Habit in Birds: 2 8 6 - 2 8 7 . (2) 'So long as I perceive two orders of control and refer one to mechanisms in the body and one to acts of mind I lose sight of the bird who loses its identity neither in physical process nor in fragments of mental process nor in change. And in thus losing sight of the bird I lose sight of the continuity. . . . This it is which lurks in the background of e x p e r i m e n t and reveals itself always in natural life; this it is which we seek but cannot find. . . . Behaviour is always something more, something which expresses itself in continuity and persistent change.' H. E. Howard, 1934, The Nature of a Bird's World: 9 4 - 9 5 . (3) 'On consulting a map of Scotland, with a view to selecting a bird-watching station. . . . I was much impressed with the 172

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favourable situation of Fair Isle for that purpose. It seemed, theoretically, to afford quite a number of exceptional advantages. . . . My forecast. . . . has been more than realized. Seven years' investigations have made it the most famous bird observatory in our islands; indeed it has become the British Heligoland.' W . E. Clarke, 1911, Studies in Bird Migration 2: 41-42. (4) 'When one remembers that practically all Grouse are infected with Trichostrongylus pergracilis, and that from every dropping thousands of potential parasites normally emerge, it becomes evident that the greater the number of birds upon a given area, the greater in turn must be the infecting capacity of the moor. But on most moors only a very small proportion of the heather is suitable for food . . . it follows that the parts of the moor from which the food supply is derived are just those likely to be the most heavily contaminated with droppings.' Robert T . Leiper, 1911, The Grouse in Health and Disease: 232. (5) 'Several seasons of really hard work and the closest observation gave me and several of my friends such insight into the ways and habits of the one cuckoo in particular that we were able over and over again, and for three years in succession, accurately to forecast the day and nest in which she would deposit her next egg. . . . I offered to wager a considerable sum of money that no one could produce satisfactory evidence of a cuckoo ever laying other than directly into a nest.' Edgar P. Chance, 1940, The Truth about the Cuckoo: 1-2, 147. (6) 'At the present moment both zoology and photography would profit if naturalists for a little time would drop the camera in favour of the field-glass and the notebook. . . . A good glass, a notebook, some patience, and a spare fortnight in the spring - with these I not only managed to discover many unknown facts about the Crested Grebe, but also had one of the pleasantest of holidays.' J. S. Huxley, Proc. Zool. Soc. Lond. 1914: 492. (7) 'What I aimed at was to try to ring a number of adult Robins, each in apparent occupation of a territory, in such a way that I could know each at sight. . . . Might I encourage others by remarking that I am not a man of leisure. Absolutely 173

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the reverse is the case, but the job meant ruling out other recreations. . . . I am thankful to have had this little bit of research into a corner of God's garden.' J. P. Burkitt, 1924, 1926, Brit. Birds 17:294, SOS; 20:91.

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12 Bi?~d Artists Bird-watching is nowadays a sport for the masses, and there are mass-produced bird-books to cater for the ever-growing demand. But in the eighteenth century, ornithology was an elegant pastime for a few rich patrons, and the volumes on birds were heavy folios, finely printed on thick paper, with stately frontispieces and rich binding, but usually spoiled by their illustrations, which were crude in both drawing and colouring:. These works, from what Sacheverell Sitwell has called the 'primitive period', have curiosity and charm, and some of them fetch high prices, yet they but dimly foreshadow the riches that were soon to come. These riches were produced particularly by two men, Audubon the French-American and Gould the Englishman. Audubon broke away from the formal presentation of obviously stuffed specimens and, in his huge 'double-elephant folio' aquatints, he showed the birds life-size in vivid attitudes against a naturalistic background. He conveys the excitement of the Review of Fine Bird Books, 1700-1900 (Collins & Van Nostrand) in New Statesman, 1953

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wilderness, particularly of the swamps and waterbirds of the southern states, but it is w r o n g to call his pictures natural. Surely no flamingo ever assumed the fantastic attitude in which he showed it; but his distortion here, and in many other pictures, is effective and striking. Again, his four species of auks sail on ice-floes past icy mountains in an Arctic that never existed, but the arrangement, though false to nature, is highly decorative, as it is in many of his pictures of songbirds in association with flowers. T h e hand-coloured engravings by John Gould are, in comparison, more formal, but what they lose in vitality they gain m accuracy, delicacy, and richness of colour. T h e y reveal the wonderful beauty of feather patterns, and Gould was particularly successful with the metallic brilliance of humming-birds, trogons and other tropical forms. But while he often d r e w from skins the birds that he had not seen alive, he did travel to Australia to study in nature the birds of that continent, and The Bird of Australia is one of his greatest works. It m u s t also be remembered that, while Gould himself was a skilled craftsman, many of the books that bear his name were illustrated by others, including H. C. Richter, Edward Lear and Joseph Wolf. Indeed, some would regard the last-named as the g r e a t e s t bird illustrator, particularly in his birds of prey, which combine accuracy with power. One must, I think, qualify this statement by 'of the western world', because the bird paintings from India and China surpass anything that the W e s t has yet produced, and only these, perhaps, come in the category of g r e a t art. T h e patrons of the eighteenth and nineteenth centuries were few, and the great bird-books had limited editions. Copies that were once pored over with delight in wealthy homes are now either unopened in reference libraries or cut up for trays and lamp-shades by the dealers. So this sumptuous production is timely; though where one is to p u t a l a r g e folio volume in the modern house is a problem I have n o t yet solved. T h e r e are thirty-eight full-size reproductions, sixteen of t h e m in colour, and beautiful colour. Particularly lovely are the Roseate Cockatoos from Gould's Birds of Australia, but many others are 176

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almost as erood. Audubon, with four coloured and four uncoloured plates, has twice as large a representation as Gould, who comes second. This, surely, is to exaggerate Audubon's merit, perhaps with an eye to American sales. Most of the other illustrators are represented by one or two reproductions. In addition to the plates, there is a pleasantly rambling and evocative essay by Sacheverell Sitwell, discussing both the birds and the men who illustrated them, and including some striking word-paintings of Gould's humming-birds (which the publishers wisely decided not to reproduce in colour). There is also a comprehensive bibliography by Handasyde Buchanan and James Fisher, with a Baedeker system of starring, their awards for merit being judiciously distributed. The book is handsomely produced in every way, but with all the skill that has gone into it, one lays it down with a faint feeling of distaste. Something esoteric and commercialized seems to have intruded itself, which is absent from the original works. Perhaps, after all, they should have been left undisturbed on their shelves. They have served their turn, like the birds that were slaughtered to bring them into being. The modern bird-watcher looks forward; and living birds are so beautiful, their scientific study so absorbing, that we have outgrown this reminder of a rich man's age.

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The Edward Grey Institute} Oxford I welcome the invitation of the Editor of Bird Notes to say something about the Edward Grey Institute of Field Ornithology. It may help to answer the question, so often asked us, of what is the difference between the Edward Grey Institute and the British Trust for Ornithology. It may even help to reduce the number of letters which arrive addressed to 'Mr Edward Grey'! The history of the Institute starts in 1927, when Mr E. M. Nicholson and other members of the flourishing Oxford Ornithological Society founded 'The Oxford Bird Census'. This organization undertook various pieces of team-research, especially censuses, work which led up to the famous British Birds Census of Heronries in 1928 organized by E. M. Nicholson. The success of this work led E. M. Nicholson and B. W. Tucker to consider whether it would not be possible to develop at Oxford a permanent centre for field ornithology, but the project seemed in danger of petering out after some of the keenest members of the Bird Census, including M r Nicholson, went From Bird Notes 23 (1949)

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down from the University. With the immediate aim of a permanent centre, W . B. Alexander was in 1930 appointed Director of the Bird Census. The title 'Oxford University Research in Economic Ornithology' was authorized in the following year. These first researches necessarily had an economic bias, as the funds for them were provided by the Empire Marketing Board and the Ministry of Agriculture. Meanwhile, the success of The Practical Handbook and its many gaps on the field side, together with the expansion of the ringing scheme and in field ornithology generally during the 'twenties, had impressed H. F. Witherby and his collaborators with the need for more systematized field work on birds. Witherby and his associates therefore encouraged the initiative taken at Oxford, and informal discussions were held in which the main national interests in field ornithology and the idea of a centre at Oxford were eventually brought together in partnership. A first formal meeting of prominent ornithologists was held at the British Museum (Natural History) in February 1932, and in the following May this group chose the name 'British Trust for Ornithology' for the new national organization which was to support the Oxford scheme. In parallel discussions at Oxford, the University proved favourably disposed and a University Committee for Ornithology was set up in October, 1932. The University, however, though willing to give University status to an institute for field ornithology, was not (at that date) willing to provide funds, which would have to come from an outside source. An appeal for the British Trust for Ornithology under the signatures of Britain's leading ornithologists, with E. M. Nicholson as Secretary and B. W. Tucker as Treasurer, was launched in The Times on 1st July 1933. The appeal stated that 'the Trust will apply any funds in the first place to establishing and supporting an Institute of Ornithology at Oxford, taking over the existing scheme'. One of the signatories of this appeal was Viscount Grey of Fallodon, famous statesman and ornithologist, and Chancellor of Oxford University. Within a few months Lord Grey died. The University considered that the 179

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proposed institute might fittingly be named after its late Chancellor, and a similar view was taken by the committee of the national Viscount G r e y M e m o r i a l Fund, which later contributed the sum of ,£3,000. Owing, however, to various delays, the Edward G r e y Institute of Field Ornithology did not receive its formal University statute until June 1938. In the period 1933-38, the institute at Oxford received free quarters from the University, while the funds came from the British T r u s t for Ornithology. O w i n g largely to the slump, these funds were not as extensive as had been hoped, so that the Institute staff consisted only of the director, W . B. Alexander, together with, near the end of the period, a part-time secretary. T h e main field research was a succession of co-operative inquiries, chiefly on population problems. Some of these inquiries were organized by W . B. Alexander, others by amateur members of the British T r u s t for Ornithology, while the basic observations were made by the main body of T r u s t members. This work, which was effectively exploiting a n e w technique, was directed by a joint sub-committee of the University and the B.T.O. Also during this period, W . B. A l e x a n d e r b r o u g h t together the nucleus of the fine library which now bears his name. Funds were, however, so short at this t i m e that the cost of every book purchased resulted in a corresponding deduction from the Director's salary. (The Alexander Library is now the most complete ornithology library in E u r o p e for w o r k s p u b lished during the twentieth century, and has been increased by numerous private gifts, and by exchanges t h r o u g h the B.T.O. and British Ornithologists' Union. It is available for all serious workers in ornithology, amateur and professional from Britain and overseas. T h e many books and journals received in duplicate have been formed into the B . T . O . Lending Library.) W i t h the founding of the Edward G r e y Institute in 1938, the University contributed a small annual grant, but the T r u s t continued to provide most of the income. Before m a t t e r s could develop further, the war intervened. In the latter p a r t of the war, the British T r u s t for Ornithology undertook research at the Institute on economic ornithology, receiving g r a n t s for this 180

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purpose from the Agricultural Research Council. The Institute itself carried on, but necessarily at a very reduced level of activity. In October 1945, Mr Alexander retired as Director. At the end of the war, as part of its general policy, the University was anxious to merge its smaller institutes into larger departments, and in the case of the Edward Grey Institute, was prepared to increase substantially its grant, if the Institute could be linked up with other zoological work in the University. When I became director in October 1945, a further series of valuable and friendly discussions therefore took place, in which the chief part was played by B. W. Tucker, Professor A. C. Hardy (the new Linacre Professor of Zoology) and Dr Landsborough Thomson (Chairman of the British Trust for Ornithology). As a result, it was finally decided to make the Institute, together with the Bureau of Animal Population (Director, C. S. Elton), the nucleus of a new Department of Zoological Field Studies, with Professor Hardy as its head. This arrangement came into force in July 1947. As a result, the Institute gained considerably in the University, with an assured status and income, while retaining its individuality and also its strong link with the amateur, a link which is safeguarded by an Advisory Council on which amateur ornithologists (particularly the B.T.O.) are represented. It will now be clear why the Edward Grey Institute and the British Trust for Ornithology have so often been confused, since they have been closely linked. To recapitulate, the Institute was founded by the B.T.O. but is part of Oxford University, it consists of a small body of zoologists undertaking research on field ornithology, and it houses a fine library available to all ornithologists. The British Trust for Ornithology is a trust (not a society) of amateur ornithologists created in the first place to provide funds for a national centre of field ornithology at Oxford, but including in its charter many other important aims, some of which will be developed now that the Institute has an assured status. (This account was written in 1949. It may be added that of the two men to whom the B.T.O. and E.G.I, owed most, 181

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E. M. Nicholson for the initial idea, the drive and the organization of the B.T.O., and B. W . Tucker for maintaining relations with Oxford University, E. M. Nicholson has since applied the same talents as Director General of the Nature Conservancy, while B. W . Tucker died in his prime and his obituary follows next.)

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14 B. TV. Tucker

(1901-1950)

With the death of Bernard William Tucker on 19th December 1950 after a long illness, British ornithology loses its central figure. This position Tucker had come to fill, in characteristically unobtrusive fashion, partly through the width of his interests, which ranged from the identification of rare waders to the physiology of feather-growth, and particularly through his varied services to ornithology. He was Reader in Ornithology at Oxford University, Editor of British Birds, a former VicePresident of the British Ornithologists' Union, and ViceChairman of the British Trust for Ornithology. Born on 22nd January 1901, at Northaw in Hertfordshire, Tucker spent most of his boyhood at Chewton Mendip in Somerset; and his first publication was on the birds round Chewton Mendip in the report of the Wells Natural History and Archaeological Society in 1918. He was educated at Harrow School, where he won the Lord Claud Hamilton Biology Prize in 1918 and the William Roundell Leaving Scholarship in 1919. He went up to Oxford in 1919 with a From Ibis 93 (1951)

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demyship (senior scholarship) at Magdalen College, and obtained 1st class honours in Zoology in 1923. He then obtained the Oxford scholarship to the Stazione Zoologica at Naples, where he worked on parasitism in Crustacea for a year, paying later brief visits to Naples in 1925, 1927 and 1928. At Naples, also, he met his future wife, Gladys Allen, whom he married in July 1925. In the same year he was appointed a Demonstrator in the Zoological Laboratory at Cambridge, Professor Stanley Gardiner's intention being that he should fill Gadow's place as lecturer in vertebrate anatomy. When Gadow unexpectedly postponed his retirement, Tucker in 1926 returned to Oxford under Professor Goodrich, and he became a University Demonstrator and Lecturer in Zoology and Comparative Anatomy in the following year. This post he held for the rest of his life, becoming Browne Research Fellow of the Queen's College 1944-47 and Reader in Ornithology in 1946. Tucker once told me that he differed from most ornithologists in that he did not develop an overriding interest in birds until unusually late, about his eighteenth year. At school, botany had been a major interest, and as an undergraduate he was noted for the variety of reptiles and amphibia which he kept in vivaria in his rooms. At Oxford, he came strongly under the influence of the Rev. F. C. R. Jourdain, then rector of Appleton near Abingdon, and Tucker told me that Jourdain's influence was what in fact turned him into an ornithologist. For a short time Tucker even collected eggs. Jourdain's influence on Tucker is apparent in their common interest in local natural history, in the care and precision of their field notes, and in the variety of duties in which Tucker co-operated with or followed Jourdain. In the zoology department at Oxford, Tucker lectured mainly on the vertebrates, including of course the birds, and he was one of the first in Britain to supplement the orthodox lectures on anatomy with others on habits, including migration. He was noted for his skill both in dissection and in anatomical diagrams, some of the latter being published in De Beer's Vertebrate Zoology, which became a standard textbook for students. His students tell me that Tucker's lectures were sound and methodi184

B. W. TUCKER

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cal, unexciting but extremely accurate, even when he was lecturing outside his main field, and that he always presented his material in such a way and at such a speed that the secondrate students, who after all compose the majority, could appreciate what he was saying. In his tutorials, likewise, he was noted for his care and accuracy, and for taking just as much trouble with second-rate as with brilliant students. Outside his teaching, Tucker helped any undergraduates interested in birds, and often accompanied them in the field. Mention should also be made of his services on many University committees. Tucker has had an extremely important influence on British ornithology in three different ways, through his work with local ornithological societies, through his work on field characters, particularly as published in the Handbook of British Birds, and through his work for the Edward Grey Institute at Oxford. The Oxford Ornithological Society was founded in 1921 and Tucker was its first Honorary Secretary. The tradition of an undergraduate secretary has since been maintained by this society, of which Tucker was Vice-President 1926-34 and President from 1934 until his death. Jourdain and Tucker together edited the first annual reports on the birds of Oxford, Berks and Bucks, and Tucker continued to edit this annual report for twenty years. These matters are of more than local importance because the Oxford society was the first of many ornithological societies founded subsequently, the existence of which we now rather take for granted. Most of these societies were stimulated by the Oxford example, and took the Oxford annual reports as a model. The standard of meticulous accuracy set by Jourdain and Tucker at Oxford, particularly in regard to the sight records of rare birds, had an influence throughout Britain. It may be added that Tucker was also an original member of the Cambridge Ornithological (later, Bird) Club, and played an important part in the ornithological section of the Somerset Archaeological and Natural History Society, serving on the editorial committee and as Vice-President from 1931 onwards, and as President in 1950. When H. F. Witherby decided to produce a revised edition 185

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of the Practical Handbook, with greater emphasis on field studies, Tucker was an obvious choice as assistant editor, and he was responsible for the sections on field characters, general habits, voice, display and habitat in the Handbook of British Birds (1938-41). These five volumes are generally recognized as the best regional ornithology that has ever been published, and they owe much of their value and originality to Tucker's contributions. The book was published at a time of rapid increase in the number of British bird-watchers, and Tucker's notes on field characters have had a very great influence in raising the standards of identification throughout the country. Indeed, they are indispensable to the field ornithologist. These notes were a combination of personal observation and an intensive search of the literature. In the nineteen-twenties and thirties, Tucker made a series of summer trips to many parts of Europe, including Spitsbergen, Lapland, Gotland, Heligoland, Holland, Switzerland, the Pyrenees, the Camargue and southern Spain, and one of his main objects was to record full details of the appearance and voice of species previously unknown to him. On these trips he was nearly always accompanied by his wife, often by other ornithologists, and in some cases he organized a party of undergraduates. Tucker became assistant editor of British Birds when Jourdain died in 1940, and editor-in-chief at the death of H. F. Witherby three years later. In his seven years as editor, Tucker maintained Witherby's high standard of accuracy combined with popularity. He possessed unique qualifications, as he was equally competent to deal with a technical biological paper and the latest rarity at a sewage farm. He took immense pains in correspondence to ensure the accuracy of the rare-bird records submitted to him. Had he lived longer, he would doubtless have played a much larger part in developing the journal, but he was severely handicapped, at first by war and post-war restrictions, and later by his illness. In 1927, mainly on Tucker's initiative, the Oxford Ornithological Society started a new venture, and founded the Oxford Bird Census. This was the first step in the founding of 186

B. W. T U C K E R

(1901-1950)

the British Trust for Ornithology and the Edward Grey Institute of Field Ornithology. Tucker took a prominent part in the creation of both the national society and the Oxford institute. He was the first Hon. Treasurer of the B.T.O., serving for two years, later served repeatedly as an ordinary member of Council, finally as Vice-Chairman, and the Council had intended that he should be the next Chairman. Perhaps his most important contribution to the B.T.O. was as a member of the Advisory Scientific Committee (later, Research Committee), on which he served from the start until'his death, during part of this time acting as chairman. On this committee, his high standard of integrity and his sound and critical judgement were invaluable. In B.T.O. affairs, however, Tucker's greatest service was at Oxford, for he, more than anyone else, was responsible for getting University support for the Institute. It may be recalled that, through over-emphasis by Professor Newton, and because of their relatively uniform morphology, birds had been effectively banished from the Animal Kingdom by orthodox zoologists for some thirty years. It was a bold step for a British university to recognize field ornithology, which zoologists tended to regard as the domain of the dilettante amateur. Indeed, that this recognition no longer seems absurd is largely due to the Oxford example, and hence to Tucker. The struggle was a long one. It took twenty years from the creation of the Oxford Bird Census to the full recognition and adequate endowment of the Institute by the University. Throughout this period Tucker bore the main burden, serving on the responsible committees, coping with the repeated difficulties due to the clash of personalities and shortage of money, and helping the Institute forward at every stage. He was particularly active in two periods, during the discussions which led to the original formation of the Institute, and during the period 1944-46 when the Institute was in the gravest danger of complete collapse. At one period in 1945, Tucker interviewed individually every member of the University Committee concerned and also several others who he hoped might help; and but for his 187

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energy and tact at this time, the E d w a r d G r e y Institute miglit well no longer exist. F o r this arduous w o r k he sought no credit, indeed he never spoke of it except to those directly concerned, so that its importance is not generally known. Apart from his major contributions to the Handbook, Tucker's original publications on birds are few and unimportant. He wrote two papers in the Ibis, one jointly with Professor Van Oordt, on the birds of Naples, and about a dozen papers in British Birds, mostly very short, or compilations of the work of others. H e also wrote a paper on the crown feathers of M a r s h and W i l l o w T i t s in Proc. Zool. Soc. Land, in 1935, the birds in the List of British Vertebrates published by the British M u s e u m in 1935, an essay on the origin of birds in Essays presented to Professor Goodrich in 1938, and four papers on zoological subjects other than birds. Tucker's paper on the rookeries of Somerset, which appeared in the local r e p o r t for 1935, was probably the best of the series of rook censuses published around this time, and his careful contributions to the national censuses of heronries and Great Crested Grebes were also written up fully in the appropriate local journal. Finally, he w r o t e the sections of Bent's Life Histories of North American Birds ( 1 9 4 6 1950) which deal with European species on the American list, and his accounts of Rook, Hooded Crow, W h i t e W a g t a i l , Meadow and Red-throated Pipits, Redwing, Fieldfare and Blackbird are unquestionably the best accounts of these species available. T h e y show what Tucker might have done had he found time to write his own book on European birds. Finally, mention must be made of his reviews, which appeared in British Birds and elsewhere. T h e s e were characterized by a remarkable ability to summarize sympathetically and clearly the gist of a work, even when quite a n e w idea was involved, also by complete fairness in criticism, with encouragement to the learner and a faithful dealing with the inaccurate or pretentious. Tucker acted with quiet efficiency as local secretary of the 8th International Ornithological Congress at Oxford in 1934. He was made a Corresponding Fellow of the American Ornithologists' Union in 1941. 188

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Tucker's great influence on British ornithologists was not only as an authority but also as a friend, hence readers will expect some attempt to be made at the difficult task of depicting his personality. Tucker was lightly built and never looked strong, but this was in part deceptive, as he was a walker of great endurance. As late as 1946, when he took a party of undergraduates to the Cairngorms, one of the party ruefully remarked to me that Tucker easily outwalked them all, and half of the party had sometimes to be left behind exhausted. About the same time he on one occasion bicycled fifty miles each way to see a Pectoral Sandpiper. His lecturing and conversational style was sincere but tended to be pedantic and involved, with occasional surprising but effective interpolations of schoolboy slang. In contrast, his written style, like his handwriting, was extremely clear and precise. His use of words gave rise to a number of anecdotes, the most famous being on the occasion when a Buzzard flew low over the destroyer as the members of the 8th International Congress started for Skokholm. Through the excited cries of 'Adler' and 'Aigle', a quiet Oxford voice penetrated decisively: 'No. Buteo buteo buteo.' On the other hand, after stalking to a Scottish loch-side where it was hoped there might be wild geese, Tucker, who got the first view, excitedly announced to his companions 'Lots of stuff'. Tucker's enthusiasm for rare birds never left him, but his appreciation of a new scientific development was equally enthusiastic, and in both fields he maintained high critical standards. His personal attitude to birds is best summed up in his address on 'Amateur Ornithology' to the Devon Bird Watching and Preservation Society, published in Devon Birds, vol. 3, 1950. Tucker was completely unassuming, and it is in character that no formal photograph of him is available. His shyness and modesty were such that strangers sometimes thought him stand-offish, an impression which was immediately dispelled by his kindness when they got to know him. He talked with restraint on subjects outside birds, and his shyness limited the number of his intimates, but he was in helpful contact and 189

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correspondence with a very large n u m b e r of ornithologists. In later years his correspondence g r e w so large that it somewhat overwhelmed him, particularly as he never g o t used to the idea of using a secretary, even when editing British Birds. As he did not allow his editing to intrude on University time, he worked at it mainly for two or three hours each evening after supper. In this work, in his heavy teaching and lecturing p r o g r a m m e , and in his committee work, T u c k e r never spared himself, so that by the end of the s u m m e r t e r m at Oxford he was usually exhausted, but he recuperated on his s u m m e r field trips. His generosity with his time was outstanding, and is one reason why he w r o t e so little of his own. H e always p u t others first, and many of the papers that he did write were in response to a direct request by someone else. On committees, where some of his best w o r k was done, he showed good judgement of both people and affairs, and consistent integrity. He never considered his personal interests, indeed he never appeared to have any to consider, and he never troubled about his own reputation. If one had r e m a r k e d on this to him, I think he would merely have been bewildered at the idea that any different attitude should be possible. H e became a Reader in Ornithology, for instance, not because he sought honour, but to provide a needed link between the E d w a r d G r e y Institute and the main Zoology D e p a r t m e n t at Oxford. On committees, also, his tenacity over a point of principle surprised those who had known only his diffidence in conversation. He would never accept compromise on an issue where he believed one side was right and the other w r o n g , but at the same time he did his best, usually successfully, to effect personal reconciliation between the contending individuals. Bernard Tucker was both a believing and a practising Christian.

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P A R T FOUR

Darwinian Evolution

V

Darwin's

Finches of the Galapagos

On the Galapagos Islands, in the Pacific, Charles Darwin in 18S5 saw a group of small, drab, finch-like birds which were to change the course of human history, for they provided a powerful stimulus to his speculations on the origin of species - speculations that led to the theory of evolution by natural selection. In the study of evolution the animals of remote islands have played a role out of all proportion to their small numbers. Life on such an island approaches the conditions of an experiment, in which we can see the results of thousands of years of evolutionary development without outside intervention. The Galapagos finches are an admirable case study. These volcanic islands lie on the Equator in the Pacific Ocean some 600 miles west of South America and 3,000 miles east of Polynesia. It is now generally agreed that they were pushed up out of the sea by volcanoes more than one million years ago and have never been connected with the mainland. Whatever land animals they harbour must have come over the sea, and very few species have established themselves there: just two From the Scie?itific American, 1953 N

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kinds of mammals, five reptiles, six songbirds and five other land birds. Some of these animals are indistinguishable from the same species on the mainland; some are slightly difFerent; a few, such as the giant land-tortoises and the mockingbirds, are very different. The latter presumably reached the Galapagos a longtime ago. In addition, there are variations from island to island among the local species themselves, indicating that the colonists diverged into variant forms after their arrival. Darwin's finches go further than this: not only do they vary from island to island, but up to ten different species of them can be found on a single island. The birds themselves are less dramatic than their story. They are dull in colour, unmusical in song and, with one exception, undistinguished in habits. This dullness is in no way mitigated by their dreary surroundings. Darwin in his diary succinctly described the islands: 'The country was compared to what we might imagine the cultivated parts of the Infernal regions to be.' This diary, it is interesting to note, makes no mention of the finches, and the birds received only a brief mention in the first edition of his book on the voyage of the Beagle. Specimens which Darwin brought home, however, were recognized by the English systematist and bird artist, John Gould, as an entirely new group of birds. By the time the book reached its second edition, the ferment had begun to work, and Darwin added that 'one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends'. Thus obscurely, as an afterthought in a travel book, man received a first intimation that he might once have been an ape. There are 13 species of Darwin's finches in the Galapagos, plus one on Cocos Island to the north-west. A self-contained group with no obvious relations elsewhere, these finches are usually placed in a subfamily of birds named the Geospizinae. How did this remarkable group evolve? I am convinced, from my observations in the islands in 1938-39 and from subsequent studies of museum specimens, that the group evolved in much 194

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the same way as other birds. Consequently, the relatively simple story of their evolution can throw valuable light on the way in which birds, and other animals, have evolved in general. Darwin's finches form a little world of their own, but a world which differs from the one we know only in being younger, so that here, as Darwin wrote, we are brought nearer than usual 'to the great fact - that mystery of mysteries - the first appearance of new beings on this earth.' The 14 species of Darwin's finches fall into four main genera. First, there are the ground-finches, embracing six species, nearly all of which feed on seeds on the ground and live in the arid coastal regions. Secondly, there are the tree-finches, likewise including six species, nearly all of which feed on insects in trees and live in the moist forests. Thirdly, there is the warbler-like finch (only one species) which feeds on small insects in bushes in both arid and humid regions. Finally, there is the isolated Cocos Island species which lives on insects in a tropical forest. Among the ground-finches, four species live together on most of the islands: three of them eat seeds and differ from each other mainly in the size of their beaks, adapted to different types of seeds; the fourth species feeds largely on prickly pear and has a much longer and more pointed beak. The two remaining species of ground-finches, one large and one small, live chiefly on the outlying islands, where some supplement their seed diet with cactus, their beaks being appropriately modified.

The ground-finch Geospiza magnirostris

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Of the tree-finches, one species is vegetarian, with a parrotlike beak seemingly fitted to its diet of buds and fruits. The next three species are closely alike, differing primarily in body size and in the size of their beaks, presumably scaled to the size of the insects they take. A fifth species eats insects in mangrove swamps. The sixth species of tree-finch is one of the most remarkable birds in the world. Like a woodpecker, it climbs tree trunks in search of insects, which it excavates from the bark with its chisel-shaped beak. While its beak approaches a woodpecker's in shape, it has not evolved the long tongue with which a woodpecker probes insects from crannies. Instead, this treefinch solves the problem in another way: it carries about a cactus spine or small twig which it pokes into cracks, dropping the stick to seize any insect that emerges. This astonishing practice is one of the few recorded cases of the use of tools by any animal other than man or the apes. The warbler-like finch is in its own way as remarkable as the Galapagos attempt at a woodpecker. It has no such wonderful habit, but in its appearance and character it has evolved much closer to a warbler than the other finch has to a woodpecker. Thus its beak is thin and pointed like that of a warbler, its feeding methods and actions are similar, and it even has the warbler-like habit of flicking its wings partly open as it hunts for food. For nearly a century it was classified as a warbler, but its internal anatomy, the colour of its eggs, the shape of its nest and other characteristics clearly place it among the finches. The close resemblance among Darwin's finches in plumage, calls, nests, eggs and display suggests that they have not yet had time to diverge far from one another. The only big difference is in their beaks, adapted to their different diets. It is reasonably certain that all the Galapagos finches evolved from one original colonizing form. What is unusual about them is the existence of several distinct species on the same island. In this we may have an indirect clue to how separate species establish themselves. Let us consider first how new forms of an animal may originate from a common ancestor. When a member of the original 196

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species m o v e s into a new environment, it is likely to evolve new features adapted to the new local conditions. Such geographical variations a m o n g animals are commonly found; in the G a l a p a g o s , for instance, the land birds other than finches vary from island to island, with only one form on each island. These forms are n o t distinct species but subspecies, or geographical races. T h e i r differences, however, are hereditary and not trivial o r accidental. T h e r e are several examples of such geographical variation a m o n g Darwin's finches. Three common species of the ground-finch, for instance, are found on most of the islands; they are large, medium and small, evidently feeding on l a r g e , m e d i u m and small seeds respectively. Now on two s o u t h e r n islands the large species is missing, and here the m e d i u m species has a r a t h e r larger beak than elsewhere, presumably an adaptation to the large seeds available to it in the absence of the l a r g e species. Again, on another islet the small ground-finch is absent, and the medium species fills the gap by being r a t h e r smaller than elsewhere. On still other islets the m e d i u m species is missing and the small species is rather larger than elsewhere. It seems clear that the beak differences among the subspecies of D a r w i n ' s finches are adaptive. Further, some of these differences are as g r e a t as those distinguishing true species. W h a t is likely to happen if a subspecies evolved in isolation on one island later spreads to an island occupied by another race of the same species? If the two populations have not been isolated for l o n g and differ in only minor ways, they may interbreed freely and so m e r g e with each other. But evidence from the study of insects suggests that if two populations have been isolated for a long time, so many hereditary differences will have accumulated that their genes will not combine well. Any hybrid offspring will not survive as well as the parent types. Hence natural selection will tend to intensify the gap between the t w o forms, and they will continue to evolve into two distinct species. D a r w i n ' s finches provide circumstantial evidence for the origin of a n e w species by means of geographical isolation. 197

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Consider three different forms of the large insectivorous treefinch. On the most southerly Galapagos island is a small dark form with a comparatively small beak. On another island to the north-west is a rather larger and less barred form. On the central islands is a yet larger and paler type with a larger, more parrot-like beak. Evidently these three forms had a common ancestor and evolved their differences in geographical isolation. The differences among them do not seem great enough to set them apart as separate species, and they would be classed as subspecies but for one curious circumstance: on the southernmost island the two extremes - the small dark form and the largest pale form - live side by side without merging. Clearly these must be truly separate species. It seems likely that the large pale form spread from the central islands to the southern island in comparatively recent times, after both it and the small dark form had evolved into distinct species. If differentiated forms are to persist alongside each other as separate species, two conditions must be met. First, they must avoid interbreeding. In birds this is usually taken care of by differences in appearance (generally in the colour pattern) and in the song. It is no accident that bird-watchers find male birds so easy to recognize: correct identification is even more important for the female bird! Darwin's finches recognize each other chiefly by the beak. I have often seen a bird start to chase another from behind and quickly lose interest when a front view shows that the beak is that of a species other than its own. The second requirement for the existence of two species together is that they must not compete for the same food. If they tend to eat similar food, the one that is better adapted to obtain that food will usually eliminate the other. In those cases where two closely related species live side by side, investigation shows that they have in fact evolved differences in diet. Thus the beak differences among the various Galapagos finches are not just an insular curiosity but are adapted to differences in diet and are an essential factor in their persistence together. It used to be supposed that related species of birds overlapped considerably in their feeding habits. A walk through a wood in 198

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summer may suggest that many of the birds have similar habits. But having established the principle of food differentiation in Darwin's finches, I studied many other examples of closely related species and found that most, if not all, differ from one another in the places where they feed, in their feeding methods or in the size of the food items they can take. The appearance of overlap was due simply to inadequate knowledge. Now the key to differentiation is geographical isolation. Probably one form can establish itself alongside another only after the two have already evolved some differences in separate places. Evolutionists used to believe that new species evolved by becoming adapted to different habitats in the same area. But there is no positive evidence for that once popular theory, and it is now thought that geographical isolation is the only method by which new species originate, at least among birds. One ot Darwin's species of finches provides an interesting illustration of this. The species on Cocos Island is so different from the rest that it must have been isolated there for a long time. Yet despite this long isolation, along with a great variety of foods and habitats and a scarcity of other bird competitors, the Cocos finch has remained a single species. This is because Cocos is an isolated island, and so does not provide the proper opportunities for differentiation. In the Galapagos, differentiation was possible because the original species could scatter and establish separate homes on the various islands of the archipelago. It is significant that the only other group of birds which has evolved in a similar way, the sicklebills of Hawaii, are likewise found in an archipelago. W h y is it that this type of evolution has been found only in the Galapagos and Hawaii? There are other archipelagoes in the world, and geographical isolation is also possible on the continents. The ancestor of Darwin's finches, for instance, must formerly have lived on the American mainland, but it has not there given rise to a group of species similar to those in the Galapagos. The answer is, probably, that on the mainland the available niches in the environment were already occupied by efficient species of other birds. Consider the woodpecker-like 199

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finch on the Galapagos, for example. It would be almost impossible for this type to evolve in a land which already possessed true woodpeckers, as the latter would compete with it and eliminate it. In a similar way the warbler-like finch would, at least in its intermediate stages, have been less efficient than a true warbler. Darwin's finches may well have been the first land birds to arrive on the Galapagos. T h e islands would have provided an unusual number of diverse, and vacant, environmental niches in which the birds could settle and differentiate. T h e same may have been true of Hawaii. In my opinion, h o w e v e r , the type of evolution that has occurred in these t w o g r o u p s of islands is not unique. Similar developments could have taken place very long ago on the continents; thus our own finches, warblers and woodpeckers may have evolved from a common ancestor on the mainland. W h a t is unique about the Galapagos and Hawaii is that the birds' evolution there occurred so recently that we can still see the evidence for it. Much more is still to be learned from the finches. Unfortunately the wonderful opportunities they offer may not long remain available. Already one of the finches D a r w i n found in the Galapagos is extinct, and so are several o t h e r animals peculiar to the islands. W i t h man have come hunters, rats, dogs and other predators. On some islands men and g o a t s are destroying the native vegetation. This last is the m o s t serious threat of all to Darwin's finches. Unless we take care, our descendants will lose a treasure which is irreplaceable. Postscript: Since this was written, R. I. Bowman has shown that it is the hardness, not the size, of the seeds to which the size of the beaks of the different ground-finches are adapted.

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16 The Darwin Centenary,

1858-1958

Charles Darwin was a very great man indeed, perhaps the greatest of all the Victorians. For though his theory of evolution concerned animal life, it decisively affected many other branches of learning. The centenary celebrated this year (1958) is that of Darwin's technical paper (with Alfred Russell Wallace) on natural selection. So far as the general public was concerned, the storm did not break until the following year, 1859, when Darwin published his great book, the Origin of Species. The wide range and powerful impact of Darwin's ideas, not only at the time but now, a hundred years later, is well shown in a new volume of essays, edited by Dr S. A. Barnett of Glasgow University. These essays discuss not only the theory of animal evolution as such, but the meaning and origin of the separate species, or kinds, of animals, the ways in which characters are inherited (which Darwin knew little about), the fossils in the rocks, embryos, the anatomy of fossil men and man-like forms, female choice and the meaning of bird display, the emotions of dogs and apes, the ways in which coral reefs Reviewing A Century of Darwin, ed. S. A. Barnett, in the Glasgow Herald, 1958 201

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are formed, and also the less happy influence of D a r w i n i s m on the social sciences and on moral values. Of the fifteen experts, some have reviewed D a r w i n ' s achievement, others have brought his findings up to date and a few have looked provocatively to the future. All have written with authority, but, unlike Darwin, most of them have written for fellow biologists and not for the general public, so that the layman will in m o s t cases understand only part, though often a stimulating part, of what is said. Compare this with the Origin of Species, of which the first edition sold out immediately because it was bought by the general reading public. But the writers of the p r e s e n t volume are all professionals, whereas D a r w i n was an amateur. Indeed, one wonders how he would have fitted into the m o d e r n world, since, as one of the essayists states, he would almost certainly have failed his 11-plus examination; and he did so badly at Cambridge that he would scarcely have had his student g r a n t renewed, if he had ever g o t one. F e w g r e a t men have made so unimpressive a start. Darwin's great idea came to him in t w o stages. First, as naturalist on the voyage of H . M . S . Beagle round the world, he came in 1835 to the Galapagos Islands, off South America, where he found a little world on its own, with peculiar tortoises and land birds. So Darwin could almost imagine one species turning into another, and this, as he w r o t e later, seemed 'like confessing a murder'. Secondly, soon after his r e t u r n to E n g land, in 1838, he read the essay on human populations by Malthus. This suggested to him the means by which evolution is brought about, that if many more animals are produced than can survive, on the whole it will be the better adapted that leave offspring, what Darwin termed 'natural selection'. As is well known, Darwin then brooded on his ideas for another twenty years before publishing. And he m i g h t not have published even then, if another naturalist, A. R. W a l l a c e , lying sick in the Malay Archipelago, had not read M a l t h u s ' essay and drawn similar conclusions from it. Wallace sent his paper to Darwin, and then both were presented t o g e t h e r to the Linnean Society of London on 1st July, 1858. 202

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The impact of the Origin of Species was tremendous, because at once a whole series of disconnected facts of natural history fitted into a coherent pattern. Tliere was the tendency for many types of animals to be built on a similar anatomical plan, though others were very different. There was the tendency for embryo animals to look more like each other than the adults (the gill slits of the human embryo provide one of many instances) . There was the presence of similar animals in distant places which are now (but were not formerly) separated by the sea, and the presence of peculiar animals in long isolated lands like Australia. There were fossil bones, some similar to, and others very different from, those of living animals. There were the changes man had been able to induce in his domestic animals, while in a later book, Darwin also discussed 'sexual selection', showing how the bright colours of male birds and other animals might have arisen through female choice. Had this been all, Darwin would certainly have been recognized today as a great, and probably the greatest, naturalist who ever lived. But his centenary would not have attracted such interest among the general public. This interest arises because, looming behind Darwin's first book, was the tremendous possibility that man himself might have evolved from apes. This possibility Darwin faced up to in his Desce?it of Man, published in 1871, which gave the anatomical evidence and showed that seeming rudiments of human behaviour were present in other animals. Since then, the discoveries of fossil 'missing links' in Java, Pekin and South Africa, none of them known m Darwin's day, have fully justified his conclusions on the physical side. The moral side is another matter. That ardent agnostic and Darwinist, T . H. Huxley, another of the great Victorians, argued that man's moral standards could not possibly be a product of natural evolution. Some later biologists, notably his grandson Sir Julian Huxley and Professor C. H. Waddington, have thought otherwise, but their views are effectively rebutted in the present book by a philosopher, D. D. Raphael. So the Victorian fear that man's moral nature was to be brought 203

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under the dominion of natural selection has not, yet at least, been realized. The only disappointing omission from the present book is that it does not touch the greatest of all the questions raised by Darwinism, its bearing on religion. This, after all, was the chief reason for the excitement a century ago. Do we now agree with T. H. Huxley that the theory of evolution is neither against nor for religious belief, and has no more to do with it than, say, geometry? That depends on whether religion rather than natural selection is allowed to rule man's spiritual life. Leaving the arguments on one side, T. H. Huxley's 'neutralist' view would seem justified by the fact that, while many modern biologists are agnostics, many others, of equal eminence, are Christians. But Charles Darwin himself left such non-scientific controversies to T. H. Huxley, and lived on quietly at Down in Kent, if not cultivating his garden, at least studying the earthworms on his lawn. W e salute today the achievement of a genius, one of the greatest naturalists and scientists that the world has known.

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17 Mr Laxuson of Charles The centenary of the publication of the Origin of Species in 1959 has led to a spate of British books, symposia, papers in scientific journals and articles in the Press, to commemorate the great naturalist who changed not merely the study of biology but man's attitude to the universe. Yet none of these recent writers has thought fit to discuss Mr Lawson of Charles, though Darwin himself fully acknowledged his debt to him in his travel book familiarly known as the Voyage of the Beagle (but published under the title: Journal of Researches in the Geology and Natural History of the Countries visited during the Voyage of H.M.S. Beagle round the World'). Recent authorities are agreed that one of the important principles leading to Darwin's realization of evolution, and the point which of all others made the most vivid impression on him during his voyage, was that, in various animals, the forms on different Galapagos Islands differed recognizably and consistently from each other. But, and this is the point of the present article, this was not Darwin's original discovery. From the American Scientist, 1962 205

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Let us turn to D a r w i n ' s account in Chapter 17 of the Journal of Researches (2nd edition). 'I have not yet noticed by far the most remarkable feature in the natural history of this archipelago; it is, that the different islands to a considerable extent are inhabited by a different set of beings. M y attention was first called to this fact by the Vice-Governor, M r Lawson, declaring that the tortoises differed from the different islands, and that he could with certainty tell from which island any one was brought. I did not for some time pay sufficient attention to this statement, and I had already partially mingled the collections from two of the islands. I never dreamed that islands, about fifty or sixty miles apart, . . . would have been differently tenanted.' Darwin then went on to describe insular differences in respectively the tortoises, the marine iguanas, the mocking-birds, the finches and the flora. It was of the finches that he also w r o t e : 'Seeing this gradation and diversity of structure in one small, intimately related group of birds, one m i g h t really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends'. T h i s was the only published hint of Darwin's theory of evolution before 1859, and he included it in the 2nd edition of the Journal of Researches of 1845, but not in the 1st edition of 1839. T h e order in which Darwin visited the various Galapagos islands was first Chatham, next Charles, then Albemarle and Narborough, and finally James. W h i l e he mingled some of his bird specimens, this mingling was not so extensive as some later writers have implied, and examination of D a r w i n ' s bird specimens in the British M u s e u m (Natural History) suggests that it concerned only the two islands which he visited first, namely Chatham and Charles. This is borne out by D a r w i n ' s statement, just quoted, that he mingled the collections from 'two of the islands', and more specifically a page later, where in discussing the finches, he mentioned 'the numerous specimens shot either on Chatham or Charles Island (for the t w o sets were mingled together)'. Moreover it was on Charles t h a t D a r w i n met M r Lawson. A penal colony was established on Charles a few years before 206

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Darwin's visit. 'The inhabitants are between two and three hundred in number; they are nearly all people of colour, who have been banished for political crimes from the Republic of the Equator.' In describing the tortoises, Darwin wrote that 'Mr Lawson, an Englishman, and vice-governor of the colony, told us that he had seen several so large that it required six or eight men to lift them from the ground.' That is all that seems to be on record concerning Mr Lawson. It may be wondered how an Englishman came to be deputy governor of the new Ecuadorean colony. As Darwin found later, and cited in the Journal of Researches, differences between the tortoises on different Galapagos islands had been discovered earlier by Captain Porter {Journal of a Cruise made to the Pacific, 2nd edition, 1822). Porter was captain of the U.S. frigate Essex during the war with Britain of 1812, and captured twelve British whaling ships in Galapagos waters. His account of the insular variations in the tortoises was unheeded by biologists. "Whether Darwin would have recognized the fact for himself may be doubted, as his visit was short and the differences between the tortoises are not striking. He might well have come to notice the same phenomenon in the Galapagos mocking-bird, in which the various island forms differ not only in size but in colour, and also in the proportionate size and shape of the beak. But he would not, of course, have done so if he had continued to mingle the specimens collected on different islands, and he stopped mingling them because of what M r Lawson told him. It may be wondered whether the Origin of Species would have been written if M r Lawson had not existed. It may also be wondered whether M r Lawson ever became aware of the tram which his simple but accurate observation had fired, and which burst on the world twenty-four years after he met Darwin. Of course, M r Lawson's part in no way diminishes Darwin's achievement, for it was not so much the fact of geographical variation, as its interpretation, that required genius. Nevertheless, credit should be given as Darwin gave it, to Mr Lawson, who must have been a naturalist of perspicacity and accuracy. 207

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Herein lies the moral, for perhaps one of us will unknowingly provide, perhaps has already provided without knowing it, a key fact for the Darwin of the next generation.

Marine Iguanas

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18

T. H. Huxley and the Nature of Man Before I started studying the great controversy of the last century on evolution, I took the view, which appears to be widespread today, that the one great figure was Charles Darwin, and that Thomas Henry Huxley's importance lay, not in any views of his own, but in his championship of Darwin's. As Huxley pointed out, 'exposition was not Darwin's forte. But there is a marvellous dumb sagacity about him - like that of a sort of miraculous dog.' Huxley provided the exposition, and since one of his aims in life was 'to smite all humbugs, however big', he did so forcibly. His comment on first reading the Origin of Species, 'How extremely stupid not to have thought of that', might also suggest that he was not himself an original thinker, until, perhaps, we pause to note that Huxley told this story against himself. In fact, Huxley's thinking on evolution Adapted from the Huxley Memorial Lecture at Birmingham University, 1962. Quotations from T. H. Huxley are, unless otherwise stated, from The Life and Letters of Thomas Henry Huxley (ed. L. Huxley 1903), Evolution and Ethics (Huxley's Romanes Lecture of 1893) or Huxley's chapter on the reception of the Origin of Species in Life and letters of Charles Darwin (ed. F. Darwin 1887). Some of them have been shortened. o 209

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was far from negligible or derivative, and he was primarily responsible for working out the implications and consequences for human thought of Darwin's theor}', such wider topics being avoided by Darwin himself. Huxley, indeed, seems far more deserving of the title 'philosopher of evolution' than the overrated Herbert Spencer, on whom his contemporaries conferred it. To discuss how the concept of evolution by natural selection affects man's interpretation of his own nature is to penetrate the ill-defined borderland, thick with pitfalls, between the domains of science, religion and philosophy, and even though I am not trying to put forward any new interpretations myself, I cannot hope to avoid errors. Nevertheless, it is probably the professional's duty at times to risk leaving his narrow path in search of wider views, provided always that he keeps Huxley's words in mind: 'Sit down before fact as a little child, be prepared to give up every preconceived notion, follow humbly wherever and to whatever abysses nature leads, or you shall learn nothing.' Animal evolution is today accepted as a fact, including the origin of man from ape-like ancestors. It is also widely, if not quite universally, accepted among biologists that the means of evolution is the natural selection of inherited changes. While offspring resemble their parents closely, small inherited changes are liable to occur. These are random with respect to the biological needs of the animal, but because far more animals die than leave offspring, while those that leave offspring do so to different extents, harmful inherited changes tend to be eliminated and favourable ones to spread through the population, gradually changing the character of the species. Many critics felt in the past, and a few still do so today, that natural selection is inadequate to account for the elaborate and intricate organs and adaptations of animals, particularly for those which seem to require many synchronous changes before they can be effective. The biological case rests partly on the experimental proof of natural selection in the wild state for small mutations, such as for dark-coloured moths near industrial 210

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towns. Further, there seems no good reason why natural selection should not have produced much larger changes in the past, though one could not expect to have observed larger changes, for instance the production of a new species, in the time available for observation. In addition, the alleged necessity for complex changes to have evolved synchronously has been largely met by the concept of 'mosaic evolution', whereby, as is now known, one part of an elaborate organ may be fully evolved a nd functional before another part has started to evolve. Moreover no satisfactory scientific alternative to natural selection has been produced, and the objectors, who include both Christians and humanists, have proposed only the vague alternative of a 'Life Force' or 'Creative Evolution'. But the Life Force cannot be measured, or even observed, and it is invoked primarily for those aspects of evolution for which natural selection seems at present to be inadequate, which is always a dangerous procedure in science. Further, it implies that the inherited changes, the mutations, are responsible for the direction of evolution, whereas biologists are agreed that mutations occur at random with respect to the biological needs of the animal, and that the directions of evolution are determined by the subsequent selection. Finally, the Life Force is at least in part a metaphysical concept, and in so far as this is true, it has no place in science. Indeed one suspects that the advocates of Creative Evolution are objecting, not so much to the particular theory of natural selection, as to any wholly natural means of evolution. Apart from any biological objections to natural selection, Victorian theologians feared that it dispensed with the need to Paley's then popular argument that animals are so wondertu y designed that they must have had a Designer. But as Huxley pointed out, Paley's argument had already been refuted y H u m e ; and Christians should be the last persons to object to the refutation of a fallacious argument in favour of theism. 1 n e real fear was that Darwin's theory meant that evolution had occurred 'by chance', but this Huxley termed 'the most singular of these, perhaps immortal, fallacies' concerning evolution. 211

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What Darwin's theory really did, of course was to bring animal evolution into the realm of natural law, and law is the reverse of chance. Huxley, indeed, went much further and, influenced presumably by Laplace, concluded that 'the existing world lay potentially in the cosmic vapour, and a sufficient intelligence could, from a knowledge of the properties of the molecules of that vapour, have predicted, say, the state of the British fauna in 1869, with as much certainty as one can say what will happen to the vapour of the breath on a cold winter's day'. But Huxley was probably wrong to regard the freezing point of vapour as a scientific fact of the same order as the particular historical sequence of fossil organisms, and it seems doubtful whether such extreme determinism can be justified on scientific, materialistic or, for that matter, on religious grounds. At least, however, Huxley was far nearer the truth than were those who supposed that Darwin's theory meant evolution 'by chance'. Surveying the sequence of evolution leading up to man, Teilhard de Chardin (in The Phenomenon of Man, 1959) concluded that it is part of a grand plan which leads finally to the omega point, which he equated with the divine. Surveying the same sequence, Julian Huxley (in Evolution after Darwin, ed. Sol Tax 1962) sees merely 'the blind opportunistic working of natural selection'. This divergence of views based on the same data is due not, I suggest, to one of these two writers being wrong, but to both using an illegitimate way of arguing, deducing metaphysical conclusions from scientific facts. As T. H. Huxley said: 'The doctrine of evolution is neither theistic nor anti-theistic. It has no more to do with theism than the first book of Euclid has'. Nor, similarly, has it any valid application to politics, though in the late nineteenth century it provided very different thinkers with their respective bases for laisser faire economics, communism, and German racial theories. Natural selection was formerly criticized not only because it implied evolution by chance, but because it inevitably operates through the death of millions of animals every year. As T. H. Huxley wrote: 'The animal world is on about the same level as a gladiator's show', and again, 'it is not clear what compen212

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sation the Eohippus gets for his sorrows in the fact that some millions of years afterwards one of his descendants wins the Derby'. It was this point, in particular, which led Bernard Shaw and other humanists to reject natural selection. Various Christians, likewise, though forced on biblical authority to concede that lions seek their prey from God, have supposed that disease organisms are the responsibility of the Devil, though the principle involved is the same. But humanists should not reject a scientifically established fact because it conflicts with human values: 'Follow humbly wherever nature leads, or you will learn nothing'; while for Christians the proper attitude is, surely, that of Dr Pusey ('Un-science, not science, adverse to faith,' 1879): 'What are we that we should object to any mode of creation as unbefitting our Creator.' At the present day, the theory of evolution by natural selection is generally accepted for other animals, and usually for man also, though the problems raised in this connection by man's peculiarities tend to be overlooked and are, in fact, far from solved. Is man in any sense unique? Certainly not in body, as was stressed by T. H. Huxley in his Evidence of Man's Place in Nature (1863), and since confirmed by the discovery of many fossil links with ape-like forms. Moreover the earliest fossil forms that are nearer to modern man than to any known ape, namely the South African ape-men or australopithecines, had a brain-case very similar in size to that of apes. Hence the most distinctive anatomical feature of modern man, the extremely large fore-brain, was not present at this first human, or partly human, stage. Nor can it any longer be claimed that man's intelligence is of a different order from that of other mammals, as studies since Darwin's day have shown that far more of man's behaviour is innate (or instinctive) and far more of the behaviour of other animals is learned, and due to intelligence, than was formerly supposed. There are also parallels in man's social behaviour with what is found in other mammals, notably in the dog, and though it used to be claimed that dogs acquired their social sense through association with man, modern work on animal 213

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behaviour makes it reasonably certain that the dog merely transfers to man its innate responses previously evolved in relation to life in a pack. If, then, man is unique, the reason must lie elsewhere, not in anything overt, but in that part of his experience subsumed under such terms as free-will, moral conduct, the apprehension of truth and beauty, and self-awareness. If we accept the principle stressed by T. H. Huxley of the 'continuity of evolution', which finds a ready response in the minds of all scientists, we would expect that these more subjective attributes of man were likewise evolved by natural means and in that case, we should expect to find rudiments of them in other animals. So far as self-awareness is concerned, all those engaged on research in animal behaviour whom I have asked agree that animals have feelings. This also was T. H. Huxley's view. It seems, nevertheless, to be a hunch rather than a scientific observation. Admittedly the nerves of other animals respond to stimulation, such as pain, but one is claiming considerably more in asserting that animals feel pain, and I can see no reliable scientific grounds for either accepting or rejecting it. One is aware of oneself by introspection, and one assumes self-awareness in other men through talking with them, but these methods of inquiry are not available for other animals. On the other hand, because we cannot prove scientifically that animals feel pain, no one would advocate that we may therefore ill-treat them. There is the further difficulty that, if animals have no true self-awareness, how did this faculty come into man? Teilhard de Chardin claimed that it must have come in a sudden jump, and though in most respects I disagree with his views, I think that he is saying something important here. Although one may develop increasing self-awareness, the difference between its presence and absence seems absolute. Also, the gradual appearance of self-awareness as we wake from sleep, or recover from unconsciousness, or as the human embryo grows into an adult man, provides no valid parallel with the evolutionary change that presumably occurred in man's sub-human ancestors, which involved a succession of adult beings. 214

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Free-will presents greater difficulties. One sees, for instance, a dog hesitate before acting, but the students of behaviour postulate merely that it is being subjected to conflicting internal drives (or some similar term), and the possibility of free choice by the dog is excluded from their account. Indeed one cannot devise any experiment to test whether or not another animal possesses free-will. For that matter, one cannot devise such an experiment for man, and we are aware of free-will in ourselves only through introspection and through discussing the conclusions of their introspection with others. Hence free-will appears to be outside the terms of reference of science. Yet most of us hold that it is one of man's most important attributes, and while one might develop an increased degree of freedom, the difference between its presence and absence seems absolute. Turning now to moral conduct, most modern biologists would, I think, accept the view that the social behaviour of such animals as dogs, let alone of ants, has been evolved by natural selection, and certainly by natural means. In social ants, bees and wasps, the workers are sterile and their behaviour is inherited through the royal caste, so that natural selection can operate on the hereditary variations of the queens. In mammals, much if not all social behaviour seems to be derived from the relations between parents and their offspring, where straightforward natural selection is again involved, and such behaviour may tend to be transferred to larger groups if the individuals living in them thereby have a higher chance of survival than those living solitarily. A dog may even behave as if 'guilty', though, as in human blushing, this behaviour is evoked not by the performance of an antisocial act, but by its detection by others. In view of such considerations, it is reasonable to infer that the social behaviour of man likewise originated through evolution by natural selection. But there seems to be a critical difference between social behaviour and moral conduct. Even if we loosely speak of a dog as 'guilty', we scarcely hold it responsible for its actions in the same sense as an ordinary (as distinct 215

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from a psychopathic) man. Indeed, the existence of the term psychopath implies that we recognize that, rarely, a man can lose his moral responsibility. Seeing, however, the need for T . H. Huxley's principle of continuity, various evolutionists from Herbert Spencer onward have sought to derive man's moral conduct from his evolutionary history. T h e chief modern advocates of evolutionary ethics have been Julian Huxley {Evolution and Ethics 1947, Evolution in Action 1953) and C. H. W a d d i n g t o n {Science and Ethics 1942, The Ethical Animal 1960). T . H. Huxley was strongly opposed to such views. So are the professional philosophers, a recent authoritative review {Ethics since 1900 by M . W a m o c k , 1960) omitting all discussion of evolutionary ethics, presumably because it is not worth serious consideration. T h e key point in Julian Huxley's views is that 'the ultimate guarantees for the correctness of our labels of rightness and wrongness are to be sought among the facts of evolutionary direction'. But in view of the diversity of evolution, one may reasonably claim that Julian Huxley has selected particular directions for his purpose, and further he crives no reason as to why, if there is an evolutionary direction, we ought to prefer it to any other. T . H. Huxley took an opposite view, holding that 'the practice of that which is ethically best involves a course of conduct opposed to that which leads to success in the struggle for existence'. In the prolegomena to his Romanes lecture, he drew an instructive parallel between ethical behaviour in man and the beautiful flowers which could prosper in his Eastbourne garden solely because he had excluded the competitive wild plants outside. ' T h e ethical progress of society depends, not on imitating the cosmic process, still less in running away from it, but in combating- it.' In his earlier essay, C. H. W a d d i n g t o n wrote that ' W e must accept the direction of evolution as good simply because it is good according to any realist definition of that concept'. But this equates the good with that which has survived, a view which caused T . H. Huxley to quote Pope's ' W h a t e v e r is, is right' and to comment that, if the moral sentiments of man were 216

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evolved 'the immoral sentiments have no less been evolved, there is as much natural sanction for the one as the other'. 'The thief and the murderer follow nature just as much as the philanthropist.' Waddington modified and expanded his views in his later book, and concluded in particular that the human infant has been evolved as an 'authority-accepter' and that this has greatly assisted human social evolution. On this view, natural selection has resulted in the evolution, not of ethics as such, but of the capacity to acquire ethics. While, however, this stimulating idea may help to elucidate how ethical values have been acquired, it does not explain why they are of value. As T. H. Huxley pointed out: 'Cosmic evolution may teach us how the good and evil tendencies of man may have come about; but, in itself, it is incompetent to furnish any better reason why what we call good is preferable to what we call evil than we had before.' In connection with this last difficulty, Waddington drew a parallel with eating and continued that 'if any individual • . . prefers to grow in an abnormal and unhealthy manner, the nutritionist can do no more than tell him that if he does so he will be out of step with nature'. This suggests that goodness is to be equated with social conformity, but this may be to press Waddington's parallel further than he intended. On his view, ethical standards are to be assessed by what he termed 'biological wisdom'. 'The criteria, of biological wisdom in the case of ethics, or healthy growth in the case of eating, which can be derived in this way, are immanent in nature . . . not superposed from outside.' Admittedly one might define healthy growth objectively, but on Waddington's admission, there is no compelling reason for our preferring it, while in regard to ethics, Waddington can only state that 'we can therefore justifiably conclude that an examination of the direction of evolution can provide us with a criterion from which we can judge whether any particular ethical system is fulfilling this function efficiently or not'. However, even if, with Julian Huxley, we could recognize the direction of evolution, then, in T. H. Huxley's phrase, 'ethics would then become applied natural history'. But it is 217

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much more than that, since otherwise we need not feel that we ought to follow the direction of evolution, once found. One contributor to Waddington's first book suggested that evil was to be equated with neurosis and psychosis, while another considered that it was behaviour appropriate to man's pre-social existence which was inapplicable to his present social way of life. But while both of these views contain partial truths that might help to explain the origins of antisocial behaviour, neither shows why one type of action ought to be preferred to another. Nor do any of the advocates of evolutionary ethics explain the hardest problem of all, of why man, knowing what is good, so often chooses the evil. As T. H. Huxley, the great agnostic, commented: 'It is the secret of the superiority of the best theological teachers to the majority of their opponents that they recognize these realities of things, however strange the forms in which they clothe their conceptions. The doctrines . . . of original sin, of the innate depravity of man, of the primacy of Satan in this world, of a malevolent Demiurgus subordinate to a benevolent Almighty, who has only lately revealed himself, faulty as they are, appear to me to be vastly nearer the truth than the "liberal" popular illusions that babies are all born good, and that the example of a corrupt society is responsible for their failure to remain so; that it is given to everybody to reach the ethical idea if he will only try; that all partial evil is universal good, and other optimistic figments.' It is not surprising that Huxley called his Romanes lecture 'a very orthodox production on the text "Satan the Prince of this World" '. Because T. H. Huxley showed that ethical values cannot be justified by the theory of evolution, and because, at the same time, he himself was an agnostic who held clear views on right and wrong, he and those who thought like him were criticized by A. J. Balfour (The Foundations of Belief, 1895): 'their spiritual life is parasitic: it is sheltered by convictions which belong, not to them, but to the society of which they form a part. . . . And when those convictions decay . . . the alien life which they have maintained cannot be expected to outlast them'. Gwen 218

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Raverat {Period Piece, 1952) made a similar comment about Charles Darwin's sons: 'They accepted the Christian ethics, and would have liked to be ordinary Christians themselves, if they could have believed in the dogmas. In fact they might well be called Christian Parasites'. Some years prior to his Romanes lecture (in Science and Morals) T . H. Huxley wrote 'the safety of morality lies neither in . . . philosophical speculation or . . . theological creed, but in a . . . belief that the fixed order of nature sends social disorganization upon the track of immorality as surely as physical disease after physical trespass.' It would be unfair to Huxley's memory to believe that so naive and untenable an idea was the best reply that he could have made to Balfour's point, but unfortunately he died before his considered answer to Balfour was completed, so we do not know what he would have said. Nor has any later writer provided a satisfactory basis for morals in terms of T . H. Huxley's premises. A parallel difficulty is presented by our apprehension of truth. This is a hard point on which to think clearly, but if our theories and beliefs are solely the product of our evolutionary history, there seems no valid reason for supposing them to be true. It seems essential that we should, in some sense, be free to assent or dissent if our mental conclusions, including our scientific theories, are to be trusted. It may therefore be wondered whether, despite the attractiveness of T. H. Huxley's idea of the continuity of evolution, there could, after all, be a real gap between other animals and man. Nearly all agnostics and many modern Christians reject such an idea. Some agnostics, as already mentioned, have sought to bridge the gap by building upward from other animals, but this leads, among other things, to the idea of evolutionary ethics, which, if meaningful, seems to exclude genuinely moral values, and certainly has not yet accounted for the ethical experience. Other agnostics and many Christians, including Teilhard de Chardin, have sought to build from man downward, usually invoking a Life Force or similar entity, while since rudiments of the specifically human attributes must ex hypothese 219

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be found in the stages below man, they have sometimes postulated that life, and even a soul, is present in inanimate molecules, which seems to be nonsense and is certainly unobservable. Hence the problem of man's origin is not yet solved. This is partly because the attributes of man under discussion, his selfawareness, free-will, moral responsibility and so on, are not detectable in his overt behaviour, but only by introspection, so are unobservable by scientific means. Hence even if we could be transported back a million years to study scientifically the behaviour of the australopithecine or other subhuman ancestors, we could not, presumably, discover whether they possessed these attributes. It is therefore possible that the apparent g a p between man and other animals is unreal and due to the limitations of human inquiry; but these attributes seem so vital to man that it may be doubted whether this could be the whole explanation. T h e y belong to man's private and subjective world and are linked in some way with personality. As Sherrington {The Physical Basis of Mind, 1950) wrote: 'Aristotle, t w o thousand years ago, was asking " h o w is the mind attached to the body?" W e are asking that question still.' If there are two rival scientific theories, we can normally afford to wait until the problem has been settled by further knowledge. But the seeming opposition between natural evolution and man's subjective world has somehow to be evaluated now, as we all have a basis for our moral decisions. Clearly, we must accept the findings of science in their p r o p e r sphere, but the question is whether moral conduct and related problems come within the sphere of scientific investigation or whether, of their nature, they are outside it. Scientists should not, presumably, be judges in their own cause, but when in the past the limits of their study have been imposed by theologians or philosophers, they have often ignored them and thereby opened up new fields of knowledge. Both the scientific method of inquiry and moral values are so important that perhaps we should accept both, even if they are seemingly irreconcileable. William Bragg {The World of Sound, 1932) wrote: 'Sometimes people ask if religion and science are not opposed to one another. T h e y 220

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are: in the sense that thumb and fingers are opposed to one another. It is an opposition by means of which anything can be grasped.' But that assertion would, I suspect, have been anathematized in his inimitable manner by that grand agnostic, Thomas Henry Huxley.

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PART FIVE

Entertainments

19

An Ornithological Examination Paper Note: The following 'ornithological' paper was set in January 1949 to provide a light-hearted evening at a conference of zoology students at the Edward Grey Institute, Oxford. The prize went to an Oxford undergraduate with a score of about 50 per cent, a Cambridge man came a close second, while a member of the Institute staff (who were not eligible) got about half as much again - this as a guide to what the ordinary reader should be able to achieve. The answers are given in the Appendix on p. 253. I.

CALL-NOTES

W h a t kind of bird said: 1. 'Never more'. 2. 'Pieces of eight'. 3. 'Willow'. 4. 'Everybody has won and all must have prizes'. 5. 'I'll dig his grave'. F r o m The New Naturalist P

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6. 'His hound is to the hunting gone, His hawk to fetch the wildfowl home, His lady's ta'en another mate, So we may make our dinner sweet'. 7. 'Tell me thou bonny bird When shall I marry me?' 'When six braw gentlemen Kirkward shall carry thee'. 8. 'What a beautiful pussy you are.' 9. 'I can't get out.' 10. 'Where are you? Where have you been? How come you here?' II.

DIVINITY

(The students were not asked to add which book of the Bible is concerned, but the experienced reader should be able to add this. Quotations are from the Authorized Version.) 1. What is the first species of bird to be mentioned in the Bible? 2. What were wished for to enable a man to fly away and be at rest? 3. 'Doth the fly by thy wisdom, and stretch her wings toward the south?" 4. What 'came up at even and covered the camp'? 5. What bird 'in the heaven knoweth her appointed times'? 6. 'I watch and am as a alone upon the house-top'. 7. 'Gavest thou wings and feathers unto the , which leaveth her eggs in the earth and warmeth them in the dust, and forgetteth that the foot may crush them, or that the wild beast may break them. She is hardened against her young ones, as though they were not hers; her labour is in vain without fear; because God hath deprived her of wisdom, neither hath he imparted to her understanding. What time she lifteth up herself on high, she scometh the horse and his rider.' 8. 'For lo the winter is past, and the rain is over and gone, the 226

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flowers appear on the earth, the time of the singing of birds is come, and the voice of the is heard in our land. The fig tree putteth forth her green figs, and the vines with the tender grapes give a good smell.' 9. 'There be three things which are too wonderful for me; yea four which I know not. The way of a in the air, the way of a serpent upon the rock, the way of a ship in the midst of the sea, and the way of a man with a maid.' 10. W h a t hath found 'a nest for herself where she may lay her young, even Thine altars O Lord of Hosts.' III. HISTORY, FIRST

PAPER

The following famous persons, all British, have ornithological names. 1. Architect. 2. Divine who has written bird-books. 3. Divine who wrote satires. 4. Nineteenth-century novelist. 5. Physiologist. 6. Capturer of Gibraltar. 7. Circumnavigator. 8. Magician. 9. Musical composer. 10. Nurse. IV. M U S I C (This section has had to be modified, as the illustrations were played on a gramophone and their titles were not given which makes the test much harder). Who composed: 1. On hearing the first Cuckoo in Spring. 2. A symphony which included the whistles and calls of the bird-fowler. 3. Hark, hark the Lark. 4. The Golden Cockerel. 5. The bird-catcher's song beginning 'Der Vogelfanger bin ich ja, stets lustig, heissa, hop-sa-sa.' 227

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6. The Fire-Bird. 7. A symphony which included the calls of nightingale, quail and cuckoo. 8. The Thieving Magpie. 9. Swan-Lake. 10. Tit Willow. V. E N G L I S H

LITERATURE

What bird is referred to, and who wrote the passage concerned? 1. 'Thou wast not born for death, immortal Bird! No hungry generations tread thee down.' 2. 'Thorough the fog it came; As if it had been a Christian soul, W e hail'd it in God's name. It ate the food it ne'er had eat, And round and round it flew.' 3. 'He sings each song twice over Lest you should think he never could recapture The first fine careless rapture.' 4. 'Blithe spirit'. 5. What bird ate a missionary on the plains of Timbuktoo, coat and bands and hymn-book too? 6. 'How can thine heart be full of the spring? A thousand summers are over and dead. What hast thou found in the spring to follow? What hast thou found in thine heart to sing? What wilt thou do when the summer is shed?" 7. 'Sometimes he would gasp When he saw a wasp. A fly or a gnat He would fly at that. And prettily he would pant When he saw an ant. Lord how he would pry After the butterfly. Lord how he would hop 228

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After the grasshop. And when I said Phip phip Then he would leap and skip.' 8. 'It can never get at me here - she thought - it's far too large to squeeze itself in among the trees. But I wish it wouldn't flap its wings so - it makes quite a hurricane in the wood — here's somebody's shawl being blown away.' 9. 'Shall I call thee bird, Or but a wandering voice?'* 10. 'The eats between his meals, And that's the reason why He ver}', very rarely feels As well as you or I. His eye is dull, his head is bald, His neck is £rrowinor thinner. O what a lesson for us all T o only eat at dinner.' VI.

LATIN

W h a t is the meaning of the following Latin names: 1. Caprimulgus for the Nightjar. 2. Carduelis for the Goldfinch. 3. morinellus for the Dotterel. 4. Regulus for the Goldcrest. 5. Somateria for the Eider Duck. 6. Haematopus for the Oystercatcher. 7. ridibundus for the Blackheaded Gull. 8. coelebs for the Chaffinch. 9. Phasianus for the Pheasant. 10. apoda for the Bird of Paradise. VII. MODERN

LANGUAGES

T o what British birds are the following most closely allied (the group name is sufficient): * State the alternative preferred, with reasons for your choice. 229

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1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

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Booby Noddy Laughing Jackass Chickadee Mutton-bird Whip-poor-will Brain-fever-bird Whisky-jack Wideawake Old Squaw VIII.

SCIENCE

1. What bird species never sets foot on land during the whole of its life? 2. What bird species regularly rides on another bird species? S. What birds have asymmetrical ears? 4. What bird species is confined to Britain? 5. Which was the last European bird, resident in Britain, to be recognized and named as a distinct species? 6. Name two passerine species which breed both in Britain and North America. 7. Name two species recorded to have bred in Britain in only one year ever, both in the twentieth century. 8. Name two native resident species which, within Britain, breed only in Scotland and are exceedingly rarely, if ever, seen in the rest of Britain. 9. Name two native resident species which, within Britain, breed only in England and are exceedingly rarely, if ever, seen in the rest of Britain (including Wales). 10. Name two birds which are completely fabulous. IX. HISTORY, S E C O N D

PAPER

1. What poet was killed by a bird? 2. What kind of bird saved a city from destruction? 3. What emperor wrote a bird-book? 230

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4. W h a t king contributed a paper on ornithology to a scientific journal? 5. W h a t British statesman was photographed with a wild bird perched on his head? 6. W h a t English King had a bird-book dedicated to him? 7. W h a t bird is linked with the Prince of Wales? 8. W h a t bird, stuffed, is in Westminster Abbey? 9. W h a t bird was burnt by order of the Vice-Chancellor of Oxford University? 10. W h o discovered that the cuckoo ejects the nestlings of its host? He also has a statue in Gloucester Cathedral, played the flute, was a minor poet, and a famous doctor. X. E N G L I S H

BIRD-NAMES

Part i. Philology 1. Name two British species other than the Cuckoo whose official English name is onomatopoeic (i.e. represents the call or song). N.B. Unofficial names, such as Peewit for the Lapwing, are not allowed. 2. Name two British species named after towns in southern England. 3. Name two regular but scarce British species whose official names are those of distinguished British ornithologists. 4. Name two British species whose present-day official English name is compounded of the Elizabethan name with a Christian or nickname added (Robin-Redbreast would have done if these names had normally been used together, instead of as alternatives). 5. A miniature apostle. Part ii. Alternative meanings Note: Several of the birds in this section are not native to Britain, but all of them are well known. 1. Ecclesiastic. 2. W o r n formerly by Englishmen and now sometimes by choir-boys. 2S1

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S. Sometimes worn by a judge. 4. The name of a country where the species concerned is not, and never has been, found wild. 5. Kind of wine. 6. Kind of horse. 7. This can be made with string. 8. Useful in the garden. 9. Boy's plaything. 10. Connected with the British Navy in the last war, but not in the days of Nelson. XI.

QUOTATIONS

Who wrote the following passages? Nearly all of them are written by distinguished naturalists. 1. 'Faunists, as you observe, are too apt to acquiesce in bare descriptions, and a few synonyms: the reason is plain; because all that may be done at home in a man's study, but the investigation of the life and conversations of animals is a concern of much more trouble and difficulty, and is not to be attained but by the active and inquisitive, and by those that reside much in the country.' 2. 'There is more joy in finding a problem than in trying to solve one, for to solve a problem is vain delusion. There is a mystery of flight, a mystery of song, a mystery of a nest; and yet, not three mysteries but one: a bird is the mystery, for it steals our values of beauty and mingles them strangely. And no less strangely it seems to mingle the blindness of an insect with the intelligence of an ape; and because nothing is really blind and no one is likely to know what intelligence really is, mysteries will be mysteries still. I would not change it.' 3. 'After five years' work, I allowed myself to speculate on the subject and drew up some short notes.' 4. That a King-fisher hanged by the bill sheweth in what quarter the wind is by an occult and secret propriety, converting the breast to that point of the Horizon from whence 232

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the wind doth blow, is a received opinion, and very strange: introducing natural Weather-cocks, and extending Magnetical positions as far as Animal Natures. A conceit supported chiefly by present practice, yet not made out by Reason or Experience. As for experiment, we cannot make it out by any we have attempted; for if a single Kingfisher be hanged up with untwisted silk in an open room, and where the air is free, it observes not a constant respect unto the mouth of the wind, but variously converting, doth seldom breast it right. If two be suspended in the same room, they will not regularly conform their breasts, but oft-times respect the opposite points of Heaven. 5. T h e visibly vicious vulture who wrote some verses to a veal cutlet in a volume bound in vellum. 6. T h e writer speaks of Rooks. 'I can see or hear nothing to suggest a signal given in any manner either by a leader or sentinels (nor are these to be seen), and that the whole of them do not rise, each time, because a few or some do, seems proved by the fact that such few or some are, between flight and flight, in constant motion, rising, hovering and flying a little further over the heads of the majority, amongst whom they re-alight and who are not thereby affected.' 7. 'Not always, however, does the wren's song give this impression of force. On a bleak day in autumn, when chill wind is blowing, a wren's song will unexpectedly be heard and at a distance will sound thin. Wordsworth describes this aspect of wren song: 'To the wind she sometimes gives A slender, unexpected strain.' 8. 'All of this family are dear to me, and I perhaps admire the others more — the fieldfare, for instance, the chattering winter "blue-bird"; and the missel-thrush, the loudvoiced storm-cock that sings in wet and blowy weather in February; and, above all, the blackbird, the big, ebonyblack thrush with a golden bill and fluting voice; but I love 233

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the redwing more. There is a wildness, a freshness, in the feeling he gives me which may be partly due to the fact that he is not a cage-bird, that, on this account, there are no degrading images and associations connected with this species.' 9. 'But the nightingale, another of my airy creatures, breathes such sweet loud music out of her little instrumental throat, that it might make mankind to think miracles are not ceased. He that at midnight, when the very labourer sleeps securely, should hear, as I have very often, the clear airs, the sweet descants, the natural rising and falling, the doubling and redoubling of her voice, might well be lifted above earth, and say, "Lord, what music hast Thou provided for the saints in heaven, when Thou affordest bad men such music on earth?" ' 10. C: What is the opinion of Pythagoras concerning wildfowl? M: That the soul of our grandam might haply inhabit a bird. C: What thinkest thou of his opinion? M: I think nobly of the soul and no way approve of his opinion. C: Fare thee well. Remain thou still in darkness; thou shalt hold the opinion of Pythagoras ere I will allow of thy wits; and fear to kill a wood-cock lest thou dispossess the soul of thy grandam. Fare thee well.

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20 Old Brecks or New Forests? A Protest to the Editor of Bird Notes from Thomas Titmouse, Esq. and the Hon. Reg. Regulus (Thetford Chase, Norfolk) O teacher, our teacher, sir, sir, sir! Your Society is 'for the protection of birds' - all birds, we had supposed, not merely some birds. We pipe our protest at the distorted picture of East Anglia by one of your members, who writes of the new Breckland forests (vol. 24, p. 49): 'these huge geometrical tracts of conifers bring little but Jays and foxes in their train, and drive such native birds as the Stone Curlew before them.' This view is widely shared. How often have we overheard your bird-watchers, hurrying past us to the next sandy breck, declare our coniferous habitations 'birdless' - thus showing, incidentally, that they had not overheard us! Is Isaiah forgotten? 'The desert shall rejoice, the glory of Lebanon shall be given unto it,' and again, 'instead of the thorn From Bird Notes 24 (1951) 235

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shall come up the fir tree.' W e pass over the benefits to your own species of the conversion of barren brecks to fruitful forests. The benefits to us birds are equally great. In summer, these conifer plantations support at least three, and in winter at least thirty, times as many birds to the acre as the brecks and heaths. If you object that quality, not quantity, is the aim of your Society, we would point out that the heaths support only 18 regular breeding species, while the conifers, so far from bringing in 'little but Jays', support 24 regular species - and the Jays form only one-hundredth of the total population. Further, most of us conifer birds are there throughout the year, not merely in summer like our heathland cousins. If y o u r a i m i s t o p r o t e c t the beautiful, we claim that in colour, form, agility and grace we are more than a match for the S t o n e Curlews, whose chief asset is an uncouth rarity.

Stone curlew This leaves you, sir with one final e x c u s 6 ) ^ you protect me DrecRs and hate the forests because the brecks are the natural habitat of the rep-ion Sir v«, -vu u •> 1C 1UU oir & - > you are wrong. The brecks are areas cleared of natural vegetation by your species in order to grow crops, and then after some years abandoned. Your friends the Stone Curlews haunt these unnatural wastes, but when a respectable vegetation clothes them once more, the Stone Curlews depart. Indeed, if your ancestors had not introduced rabbits, the breckland would revert to forest. Yes, the new conifers are much closer to the natural vegetation of the 236

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region than are the brecks - they are rather more orderly, it is true, but yours, sir, is the last species which should accuse mere trees of regimentation! Lest you should think us as biased in one direction as your correspondent in the other, we hasten to add that we highly approve your purchase of one or two brecks. And provided that you will run a tank or bulldozer over the ground every few years, you will damage the natural vegetation sufficiently to keep your Stone Curlews happy. Live and let live, sir. We will tolerate a few Stone Curlews, even though they disturb us nightly with their low-frequency caterwaulings. But we do hope that your bird-watchers will stop calling our forests 'birdless', and that they will reconsider why a few ungainly Stone Curlews are always to be preferred to many beautiful titmice.

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21 A Vision of Home,

1960

A contribution rejected by the Ibis, whose demise it foretells by C A S S A N D R A L A R K At the recent International Ornithological Conference at Helsinki, Britain was represented by five ornithologists and a hundred bird-watchers. (An ornithologist: one who attends lectures illustrated by graphs; a bird-watcher; one who slips away from such lectures in order to add new species to his lifelist; The New Ornithological Dictionary.) So, next time, it became the International BW. Conference, and was held with the Olympic Games at Rome. And thus it was that we found ourselves, an hour before dawn, in a floodlit stadium outside the city, to see the start of the first Bird-watching Olympic, run according to Harvard Rules, each national team of three trying to see as many species as possible between dawn and dusk. As the Austrian team entered in their green-collared jackets, the band struck up with Schubert's 'Hark, hark the Lark (Alauda arvensis)'. They followed with a vaguely familiar classiFrom Bird Notes 28 (1959) 238

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cal theme with bird-calls interlarded; 'Pastoral Symphony', said my companion, 'it must be the Germans'. And there they were, headed by Doctor Dee with a portable Heligoland trap, at which the band merrily switched to 'Der Vogelfanger bin ich, ja', from The Magic Flute - but nets were disallowed, only field-glasses and one handbook per team being the rule. The French had similarly to discard their guns. Sibelian chords 'Swan of Tuonela' murmured my companion, as three superbly fit Finns entered. The Thin-billed Nutcracker Suite heralded the Russians. Then the high tone was lowered by a catchy jingle: 'Ah, yes, of course, Tit Willow (Atricapillus parus kleinschmidti)' and in came R. S. R. Scott, J. Fitt and P. Fish; but the applause we gave them was hushed when protest was raised that they were not amateurs. The judges allowed two of them through, but had to disqualify one. 'It's not,' they said, 'a question of royalties, but he once' - and here a groan echoed round the stadium - 'he once used a histogram'. The Reverend Peter Pugnax, who was standing near, was hastily co-opted as a substitute, the judges failing to detect that his clerical collar concealed a past that was black with graphs and significance-tests. Next came the Scots, led in by the only lady competitor, Evelyn, Queen of the May, whose keen eye and steady tread belied her years, which stretch back to the Dark Ages when people studied ornithology for enjoyment, and she was accompanied by the ex-Laird of Fair Isle (now nationalized) and Professor Hoodwinksbane. The Irish team was headed by a Jesuit priest, and then, 'Here we are like birds in the wilderness' chanted a row of bobbysoxers; but their cheer-leader was drowned by the flapping of a thousand field-guides as Tory himself led in the Americans. He was followed by a huge man no one had seen before, in fact a professional strong man, 'to carry our handbook', explained Tory, and we saw that he held eight heavy volumes. 'But only one handbook is allowed,' said the judges. However, inspection showed that the rules had not been broken, though we were puzzled to know how they could use The Birds of Tropical West Africa. As the first Skylark uttered, the teams set off, most at a 2S9

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smart walk, the Finns at a steady lope. 'Where are you going?' a reporter asked the Scots. ' W e ' r e bound for the high tops,' said George. 'And you, M r Pugnax?' 'Anywhere save towards Rome,' he shuddered. The Dutch mounted bicycles, the Italians Vespas, and inspection of the rules showed nothing to prohibit them. Then came a noise from the sky, the band played 'O, for the wings, for the wings of a Dove' and a helicopter descended for the Americans. The Irish, feeling quite outclassed, decided instead to head for the Eternal City, first discarding their footwear, as is customary. There is no space here to relate the deeds of that clay, which would fill many books. As we returned to the stadium before first owl-hoot (Otus scops), the Germans were clocking up 178 species, the highest score so far, and there were only the English, the Irish and the Americans to come in. Then the English entered. Their three, like several other teams, had gone separate ways, and when the first two between them were found to have included 176 species, excitement rose high. But alas, the Reverend Peter Pugnax had seen only one species, the Italian Sparrow. The seeming reporter who had asked him where he was going was really a foreign agent, who went ahead and placed a stuffed mount of an Italian Sparrow in his way. The resulting displays from nearby breeding pairs proved new to science, so Mr Pugnax had spent all day recording them (and later he was to publish a long paper with twenty tables, which helped to earn him a D.Sc). But 'Hardly bird-watching, what? His irresponsibility has cost England their medal', growled Dr Macdonald, secretary of the B.T.BW., to which Mr Pugnax outrageously replied that he hoped that the century of the common man was not to become the century of the uncommon bird. The Americans now returned in their helicopter, with a score of 405, achieved because, after transferring to a stratocruiser, they had spent the day in W e s t Africa. Their overwhelming victory was greeted with somewhat chagrined applause from the other nations who had not thought of using air transport, in the course of which the Irish walked in. The band, 240

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which had been quietly playing the Catalogue Song from Don Giovanni (spiritual, if not actual, ancestor of all life-listers), now broke into song with 'Son gia mille e tre', and, sure enough, the scoreboard read 1,003 species. 'It was simple, really,' the Irish explained later. 'Thinking we stood no chance, we heard mass in St Peter's, then had a morning in the Vatican. After lunch, the Major remembered that he wished to check a point of racial variation in Chaffinches, so we went to the Museum, and it was only after we had been there an hour that it occurred to us that there was nothing in the rules to say that the birds seen had to be alive. W e could easily have clocked up 2,000 if we had left ourselves more time.' In future years, we understand, the Committee will tighten up the rules. Meanwhile we English must take ourselves to task. For we, after all, invented bird-watching, though the present rules stem from Harvard, and to fail to get even third place is a national disgrace. Steps are already being taken. The magazine British Birds is changing to New British Birds, and Harwell scientists are co-operating to produce atomic gales to drift more American species to England. 'Our aim,' said the Prime Minister, Sir Nicholas Maxton, in a rousing speech, 'must be one new species a month for the British List. But,' he continued, 'the battle was largely lost on the playing fields of Eton,' and he was therefore launching an Appeal for a National Sewage Farms Association. Further, the G. White (formerly E. Grey) Institute, under its new director, P. Brown, has turned from research to the training of BW. coaches, and the Public Schools are to replace games by compulsory bird-watching. At the Lees School Speech Day, for instance, the Chairman of the Governors, D r Phildguyd Holfort, announced, to loud cheers, that next term any boy would be beaten who failed to see 70 species a day, while any swot would be expelled who stopped to Observe Habits. At that, there came a wailing cry from the heavens as the last Ibis flapped mournfully from our shores towards the sunset, to join the Dodo and the Solitaire. But its passing was unheeded, its cry 'quo ibis?' unheard, as the Hopes of the Future broke into their school song: R

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Bird-men, raise the exultant strain. Ornithology is slain, Photography, ringing, have had their day, And mere bird-loving has passed away. None of these triflings will be missed, For the one true goal is a long life-list. Rise with the dawn, for the rare birds fly. Floreant ornithoscopi. Notes to Chapter 21 T h e following notes have been added for those non-ornithological readers who may not know all the persons referred to. T h e y are cited in order. Ibis, journal and symbol of the British Ornithologists Union. 'Harvard rules' because the sport of birdlisting owes most to the late Ludlow Griscom, formerly ornithologist at the Museum of Comparative Zoology, Harvard. 'Doctor D e e ' , D r Drost for long director of the Vogelwarte Helgoland. T h e three English representatives, really James Fisher, Richard Fitter and Peter Scott, who have done more than any others in Britain to introduce a wider public to an appreciation of nature and to the urgent need for conservation. 'Peter Pugnax', the Reverend P. H. T . Hartley, formerly a professional zoologist, now a country parson and chairman of the council of the Royal Society for the Protection of Birds, noted for his outspokenness on behalf of what is right. 'Oueen of the M a y ' , the late Evelyn Baxter, who, with the late Leonora Rintoul, presided over Scottish ornithology with such grace for so long, and who made her name by studies of migration on the Isle of M a y . T h e 'ex-laird of Fair Isle' is G e o r g e W a t e r s t o n , who founded the famous bird observatory there, and 'Professor Hoodwinksbane' is Professor M a u r y Meiklejohn, who failed to see a Hoodwink there, to the delight of all subsequent ornithologists. T h e Jesuit priest is Father Kennedy, joint author of The Birds of Ireland (1954) with 'the Major', R. F . Ruttledge, mentioned later. ' T o r y ' is Roger T o r y Peterson, who in his 242

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field guides has set an altogether new standard of bird identification. ' D r Macdonald', quite unconnected with the head of the Bird Room at the British Museum (Natural History), was the appropriate rival to Dr Bruce Campbell, at that time secretary of the B.T.O. (British Trust for Ornithology). 'Sir Nicholas Maxton', M a x Nicholson, Director General of the Nature Conservancy, to whom we all owe so much for the promotion of nature reserves in Britain. P. Brown, the secretary of the Royal Society for the Protection of Birds. 'Lees' School, because of J. Ferguson Lees, editor of British Birds magazine. 'Phildguyd Holfort', a conflation of Philip Hollom and Guy Mountfort, joint authors of A Field Guide to the Birds of Britain and Europe. I need scarcely add that for all these persons I have the greatest respect, and that this entertainment was in no instance directed against them, but solely against the modern habit, which all of them deplore, of restricting ornithology to the addition of new species to one's 'life-list'.

22 An Undiscovered Species of Swift At the end of this academic year, Professor Sir Alister Hardy, F.R.S. retires as head of the Department of Zoological Field Studies at Oxford. This is the department, set up by him, which includes the Edward Grey Institute of Field Ornithology, and I owe him an immense debt for his wise and warm-hearted counsel and guidance throughout the last sixteen years. The following unorthodox tribute was paid to him at the annual student conference of the Institute, and I trust that its airiness will not conceal my deep-felt gratitude. T h a t any species of bird should r e m a i n undiscovered by 1963 is an ornithological event. It is true that in recent y e a r s a few n e w forms have turned up, but they have been little b r o w n birds in j u n g l y corners of N e w Guinea, the C o n g o or A m a z o n basins, or the bird cases in the British M u s e u m ( N a t u r a l H i s t o r y ) . T h e species to be described here is native t o Britain, of s t r i k i n g appearance, and unique both in habits and in the w a y in which its existence became suspected. F o r while the o t h e r n e w species of recent years w e r e shot intrepidly from L a n d R o v e r s , o r m o r e From Bird Notes 30 (1963) 244

AN

UNDISCOVERED

SPECIES

OF

SWIFT

refinedly, were separated from their congeners by statistical tests, the existence of the new swift, like that of the planet Neptune, was deduced from scientific principles, and I here name it in honour of the zoologist on whose work the deduction is based, Professor Sir Alister Hardy, F.R.S. 'Natura abhorret vacuum' (Rabelais 1534; Gargantmch. V). W h e r e v e r a palatable natural food exists, an animal has been evolved which preys upon it. Professor Hardy first studied the planktonic organisms which drift on subantarctic seas, and when he assumed a professorial chair, he by an easy transition of the mind suspended nets from tall radio masts to catch the insects drifting in the air above us. Such aeroplankton he found numerous, and while most drift passively, he personally ascended in a barrage balloon to test whether, since moths fly towards any light, they rise steadily, if vainly, each night towards the moon. T h e abundant aeroplankton must surely support a predator, and it is my privilege to announce that this is Hardy's Swift [Apus dams) which takes over from the Common Swift {A. apus) above lOOO metres. The high altitudes which it frequents constitute the chief reason why it has not yet been seen by the numerous bird-watchers who throng our fast-vanishing sewao-e farms to add yet another species to their life-lists. But though it never comes within visual range, Hardy's Swift is regularly detected by radar. This has until now been obscured by the unwarranted Air Force terminology by which the echoes i n question have been classified as 'angels'. However, 'angeli non resonant' (Aquinas 1275; De Caelo), and the blips in question obviously come from Hardy's Swifts. It is a beautiful bird, about the size of a Common Swift, but white instead of black, and from below nearly translucent, which is another reason why it has for so long escaped attention. It j s always in flight, sailing on its long wings. When feeding, j t keeps its wide mouth open, so that the aeroplankton drifts i n and is filtered from the air by the dense fringe of bristles coated with saliva. All swifts possess oral bristles and thick saliva, but these adaptations have been intensified in Hardy's Swift, t h U s providing yet another example (in the evolutionary field w ith 245

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which we particularly associate Professor Hardy) of convergent evolution, in this case with the Broad-billed Prion (Pachyptila vittata), which similarly filters marine plankton from the sea. The bones of Hardy's Swift are even lighter than those of the Common Swift, owing to their great air-spaces. One air-space is sealed off by a sensitive membrane, from which nerves run to the cerebellum, and it is by thus registering the changes in atmospheric pressure that Hardy's Swift is able to maintain its high altitude. Like the Common Swift, it spends the night on the wing, and it is not known how either of them dispenses with the need for sleep. The breeding season of Hardy's Swift is adapted so that the young hatch when aeroplankton is most abundant. This means that it lays its single egg in late April or May. Like other swifts it mates on the wing, the male mounting the female and both gliding silently downward for about ten seconds. Four days later, when the egg is ready to be laid, the female attracts her mate by a musical twang, the only time that she breaks silence. He then flies up behind her, turns right over and sails upside down below her, at which moment she lays the egg. He grips the egg in his legs, then bends his mouth over it and sticks it to the bare brood-patch on his abdomen with saliva, in the same way that the Palm Swift {Cypsiurus parvus) sticks the eggs to its nest on a vertical palm leaf. The egg is sky-blue, thus matching the heavens, and in size and shape is extremely like that of a Starling (Stumus vulgaris). Its transfer from male to female is the main cause of nesting losses, for the male occasionally misses it altogether or fails to secure it to the brood-patch. The egg then falls to the ground, and not infrequently appears on grass lawns, quite undamaged, at this time of year. It can readily be distinguished from the eggs of earthbound species because, of course, it is single, and it is not surrounded by a nest or covered by a parent bird. Indeed a number of eggs found under these circumstances are in the cabinets of oologists, but the latter are a sensitive race, particularly since the passing of the new bird protection act, so do not communicate their findings to the British Ornitholo246

AN U N D I S C O V E R E D S P E C I E S OF SWIFT

gists' Union. Hence until now, the occasional sky-blue eggs on lawns have remained a mystery. Incubation is entirely by the male which, when the egg needs turning, glides briefly upside down. This is presumably why the wings have so shallow a camber, since otherwise this method of flight would be highly unstable. At hatching, the male presses the emerging chick against his body by means of his legs, and so soon as the chick's own legs are free, it grips the male's body feathers with its claws, which, as in other swifts, are very strong. T h e outstanding puzzle about Hardy's Swift is how it dies. It reproduces annually, and as the population is evidently stable (for the sky is never obscured), the death-rate should balance the birth-rate. How, then, do the birds die? Unusually, the views of the Director General of the Nature Conservancy (How Birds Live 1927, How Birds Died 1964) are inapplicable, since through a temporary oversight by the manufacturers, toxic chemicals have not yet penetrated the heavens. Moreover, Hardy's Swift has never been found on the ground, which equally rules out death by starvation or disease. Only one density-dependent factor remains, and the clue is given, I suggest, by the bird's translucent colouring, sky-blue eggs and habitual silence, which, obviously, are cryptic adaptations. Crypsis can be evolved only through predation, so if we look carefully, we may eventually see dashing from the cover of one storm-cloud to the next, the sinister figure of, surely, Hardy's Hawk (Accipiter fortis), but this further discovery I leave to a younger generation of naturalists. Finally, because, since Sir Charles Snow, every scientist has to exhibit his culture, there are the poets. Shakespeare's 'Swift, swift, ye dragons of the night' {Cymbeline, Act 2, sc. 2) is not accepted by recent critics as applying to the new species. Keats' 'Thou wast not born for death, immortal bird' is, as demonstrated above, untrue, but then he elsewhere admitted to confusing truth with beauty. W e are on much surer ground, however, in referring Shelley's ode beginning 'Hail to thee, blithe spirit' to Hardy's Swift, particularly in view of the second line. 247

23 Robins for Christmas This is the season of the year when we send each other pictures of robins inscribed "Wishing you a Merry Christmas'. There can hardly be a house in the land without several such cards on the mantelpiece, the top of the piano or wherever else we have found to display them, whereas you will often search in vain for any card showing the Holy Baby, Whom, some will suppose, is what Christmas is really about. How do the robins come to be there in such numbers? Their position is unique, for no other kind of bird serves the purpose, not even the wren, which in folklore is sometimes the robin's wife. The obvious suggestion is that, in times past, the robin had a special place in Christian lore. But this is not so. A Breton legend linked the bird with blood falling from the Cross, but this story is more commonly told of other small birds with red in their plumage, and anyway has nothing to do with the birth of Christ. A small bird is often shown in late medieval paintings of the Madonna and Child, but this is a goldfinch, not a robin, and though the wren has been called 'Our Lady's hen', the robin From The New Scientist 8 (1960) 248

Plate :;. Christmas Card Designs of the Eighteen-Sixties

]. Robin postman.

2. Robin postman.

•

,'i. Robin and crossing sweeper.

^.v "

>

ROBINS

FOR

CHRISTMAS

apparently has no associations with the Virgin. Nor, so far as I am aware, does the robin feature in any other Christian lore. Christmas was, of course, preceded by a pagan festival, but the robin also seems to have been uncommon in pagan folk lore, at least so far as can be judged from the surviving tales collected in the nineteenth century. Like other red birds, robins were sometimes associated with the bringing of fire, but this seems far too tenuous a link to explain the bird's popularity at the winter solstice. T h e search for an explanation can be narrowed considerably by keeping three points in mind. Firstly, the robin is regular on Christmas cards only in Britain and not in any other country. Secondly, there appears to be no mention of the robin in English Christmas festivities until the coming of the Christmas card, a little before 1860. Thirdly, the robin is regular on the first Christmas stationery to be produced commercially - indeed it was much commoner then than now. Hence, whatever the explanation, the tradition is evidently British, and it originated not in the half-forgotten past of folklore but in the reign of Queen Victoria. Around the year 1860 Christmas stationery included folded letter-paper, small embossed cards like calling-cards and envelopes to match. The design at the head of the letter-paper, in the centre of the card, or on the back of the envelope, was usually small and formal, in two simple colours, in position and design like a nobleman's crest, and equally pleasing. Nearly always, there was a robin on the Christmas stationery and a bunch of flowers for the New Year, but New Year greetingcards seem to have vanished. The essential clue explaining robin's presence is to be found on some of this early stationery, in which the bird is shown carrying a letter in its beak, or le commonly, lifting the knocker on a front door. Both tnes< designs are illustrated here from stationery of about the yea 1860. There were sometimes larger pictures of robins, on both letter-paper and cards, and these provide further information. One card, in particular, bears a robin in stiff cardboard, an dangling from the bird's beak are two threads, each with a tiny 249

ROBINS

FOR

CHRISTMAS

apparently has no associations with the Virgin. Nor, so far as I am aware, does the robin feature in any other Christian lore. Christinas was, of course, preceded by a pagan festival, but the robin also seems to have been uncommon in pagan folk lore, at least so far as can be judged from the surviving tales collected in the nineteenth century. Like other red birds, robins were sometimes associated with the bringing of fire, but this seems far too tenuous a link to explain the bird's popularity at the winter solstice. T h e search for an explanation can be narrowed considerably by keeping three points in mind. Firstly, the robin is regular on Christmas cards only in Britain and not in any other country. Secondly, there appears to be no mention of the robin in English Christmas festivities until the coming of the Christmas card, a little before 1860. Thirdly, the robin is regular on the first Christmas stationery to be produced commercially - indeed it was much commoner then than now. Hence, whatever the explanation, the tradition is evidently British, and it originated not in the half-forgotten past of folklore but in the reign of Queen Victoria. Around the year 1860 Christmas stationery included folded letter-paper, small embossed cards like calling-cards and envelopes to match. T h e design at the head of the letter-paper, in the centre of the card, or on the back of the envelope, was usually small and formal, in two simple colours, in position and design like a nobleman's crest, and equally pleasing. Nearly always, there was a robin on the Christmas stationery and a bunch of flowers for the New Year, but New Year greetingcards seem to have vanished. The essential clue explaining the robin's presence is to be found on some of this early stationery, in which the bird is shown carrying a letter in its beak, or less commonly, lifting the knocker on a front door. Both these designs are illustrated here from stationery of about the year 1860. T h e r e were sometimes larger pictures of robins, on both letter-paper and cards, and these provide further information. One card, in particular, bears a robin in stiff cardboard, and dangling from the bird's beak are two threads, each with a tiny 249

ROBINS

FOR

CHRISTMAS

apparently lias no associations with the Virgin. Nor, so far as I am aware, does the robin feature in any other Christian lore. Christmas was, of course, preceded by a pagan festival, but the robin also seems to have been uncommon in pagan folk lore, at least so far as can be judged from the surviving tales collected in the nineteenth century. Like other red birds, robins were sometimes associated with the bringing of fire, but this seems far too tenuous a link to explain the bird's popularity at the winter solstice. T h e search for an explanation can be narrowed considerably by keeping three points in mind. Firstly, the robin is regular on Christmas cards only in Britain and not in any other country. Secondly, there appears to be no mention of the robin in English Christmas festivities until the coming of the Christmas card, a little before 1860. Thirdly, the robin is regular on the first Christmas stationery to be produced commercially - indeed it was much commoner then than now. Hence, whatever the explanation, the tradition is evidently British, and it originated not in the half-forgotten past of folklore but in the reign of Queen Victoria. Around the year 1860 Christmas stationery included folded letter-paper, small embossed cards like calling-cards and envelopes to match. The design at the head of the letter-paper, in the centre of the card, or on the back of the envelope, was usually small and formal, in two simple colours, in position and design like a nobleman's crest, and equally pleasing. Nearly always, there was a robin on the Christmas stationery and a bunch of flowers for the New Year, but New Year greetingcards seem to have vanished. The essential clue explaining the robin's presence is to be found on some of this early stationery, in which the bird is shown carrying a letter in its beak, or less commonly, lifting the knocker on a front door. Both these designs are illustrated here from stationery of about the year 1860. T h e r e were sometimes larger pictures of robins, on both letter-paper and cards, and these provide further information. One card, in particular, bears a robin in stiff cardboard, and dangling from the bird's beak are two threads, each with a tiny 249

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folded letter at the end, one of which says 'A Merry Christmas' and the other 'A happy New Year'. Above the robin, and this is the critical point, is written: 'A little gentleman much sought after at Christmas time, the postman'. The robin is called 'postman' on several other cards surviving from this early period, and the same design and title occur on a few Valentines. The robin has no other connection, so far as known, with St Valentine's Day or with Valentine celebrations, and the common factor is evidently the 'postman'. When one reads that the cook at Framley Parsonage called the official 'Robin postman' (and Trollope worked in the post office, so should have known what postmen were called), and when one finds that in 1860 the postman's uniform was bright red (the royal colour), it becomes reasonably certain that the postman was nicknamed 'Robin' at this date, and that this is why the robin was put on Christmas cards. That the tradition was later forgotten is readily explained, because in 1861 the postman's uniform was changed to dark blue with red facings, and today the royal red survives only on pillar-boxes. If the postman's uniform had been changed a few years earlier, robins would presumably not have featured on Christmas cards. Although the link with the postman disappeared so soon, the robins have stayed, and in the next thirty years they featured on every variety of card. There were straightforward pictures of robins in snow, robins being fed by little girls, robins outside a church. There were Gothick cards in pseudo-illuminated lettering. There were facetious pictures of robins skating on the ice, or driving a sleigh or pulling crackers. There were occasional inappropriate cards, such as a robin entering a baited brick-drop trap, a German chromolithograph evidently copied from a bird-book of the period by someone who did not appreciate why pictures of robins were in such demand by English stationers. There were highly elaborate cards. In one, for instance, a child is putting out crumbs in the snow, and when the card is held up to the light, robins are seen flying to the meal, the birds having been painted on the back of a semitransparent part of the card. In another example, robins are 250

KOBINS

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dressed up as soldiers, and when a small lever is pulled at the base of the card, the birds strut and present arms. In yet another, the whole card can be opened up into a three-dimensional nesting-box with a robin at the entrance. Since then, Christmas cards have become simpler, but I was sent one modern one in which the robin carries a letter, presumably an accidental throw-back to a century ago. While the original link with the 'Robin postman' seems undoubted, this in itself would scarcely have enabled robins to persist on Christmas cards to the present day. In midwinter, however, these birds come for bread round our doors, and so remind us of the seasonable charity. Indeed, near the end of the nineteenth century, the word 'robin' was actually used for a little boy or girl beggar, and 'robin dinners' were organized for London's poor children. One Christmas card of this period shows a beggar girl and some robins resting in the cold outside the front doors of a large house; the doors can be opened, and reveal inside a rich children's party. There are two reasons why robins come round our doors in winter. It was already reported two centuries ago that they approach travellers in the forest, and I accidentally discovered the reason for this one winter's day when watching a pheasant scratching in the frozen leaf-litter. A robin was also watching, and when the pheasant moved on, the robin flew down and fed on small insects and other material which the pheasant had made available to it. Robins have also been seen following closely above the place where a mole was tunnelling near the surface. Presumably they also follow other animals which might break up the ground, and from this it is only a short step to their watching the man with a spade. One wonders whether the peculiar Elizabethan story of robins covering dead bodies with leaves was due either to the birds watching grave-diggers or to their coming up to lost travellers in the forest. Probably, all European robins follow digging animals, but a second reason for the bird's presence with us at Christmas is especially English. On the Continent, most robins migrate south for the winter, and where they do not do so, they may be 251

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killed and eaten. But though a few English robins migrate south, many stay with us, and it is evidently safer for them to do so around houses than in woods. Thus in the hard winters of the nineteen-forties, robins almost vanished from English woods, but they survived, though in reduced numbers, around houses and farmsteads. This is partly because robins seem able to find their natural foods in winter more easily in gardens than woods, and partly because Englishmen put out food for small birds in winter, and no bird is so regular at the bird-table as the robin. Indeed the British robin, which differs very slightly in plumage from the Continental race, is much more readily distinguished by its tameness in the presence of man. Since a proportion of English robins migrate while others stay, the chances of survival over the winter must be almost equal, on balance, for the migrants and the residents. Otherwise natural selection would have eliminated the one or the other habit completely. Presumably, therefore, our creation of 'English gardens' and our putting out food for birds in winter have tipped the balance for the robin farther towards residence and away from migration, and at the present day it is perhaps chiefly in dense woods and in occasional hard winters that the migrants have the advantage of their fellows. Hence if more robins stay for the winter than did so several hundred years ago, it is evidently through our own efforts. Through replacing forests by fields, we have changed the conditions for many other British birds, but there is none that enters into so intimate a relationship with man in winter as the robin, and this is presumably why, long after the original symbol was forgotten, we still allow robins to carry our seasonal messages of good will.

252

Appendix A N S W E R S TO AN ORNITHOLOGICAL EXAMINATION PAPER

I. l. 2. 3. 4. 5. 6. 7. 8. 9. 10. II. l. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Raven (Edgar Allen Poe) Parrot (Long John Silver's, in Treasure Island) T o m Tit (in The Mikado) Dodo (in Alice in Wonderland) Owl (in 'Who killed Cock Robin?') T w a Corbies (Crows) (in the ballad of that name) Robin (in Walter Scott's Proud Maisie) Owl (in Edward Lear's Owl and Pussycat) Starling (in Sterne's Sentimental Journey) Parrot (Robinson Crusoe's) Raven {Genesis) W i n g s of a Dove {Psalms) Hawk {Job) Quails {Exodtis) Stork {Jeremiah). Note: Turtle, crane and swallow are wrong; they knew the time of their coming Sparrow {Psalms) Ostrich {Job) Turtle {The Song of Solomon) Eagle {Proverbs) Swallow {Psahns)

III. 1. W r e n 2. Raven S. Swift 253

APPENDIX

4. 5. 6. 7. 8. 9. 10.

Peacock Starling Rooke Drake Merlin Byrd Nightingale

IV. 1. Delius 2. Leopold Mozart (Toy Symphony), commonly attributed to Haydn S. Schubert 4. Rimsky-Korsakov 5. Mozart (Magic Flute) 6. Stravinsky 7. Beethoven (6th) 8. Rossini 9. Tchaikowsky 10. Sullivan V.. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Nightingale (Keats) Albatross (Coleridge) Song-thrush (Browning) Skylark (Shelley) Cassowary (Bishop Wilberforce) Swallow (Swinburne) Sparrow (Skelton) Crow (Lewis Carroll). Cuckoo (Wordsworth) Vulture (Belloc)

VI. 1. 2. 3. 4. 5.

Goat-milker (from an ancient superstition) Thistle-bird (the bird's favourite food) Little fool (Dotterel also means this) Little king (from the gold crown) Body-wool (the specific name mollissima means very soft) 254

APPENDIX

6. Red foot 7. Laughing 8. Bachelor (the name was given by Linnaeus in Sweden, where in winter only the males remain behind) 9. Of the Phasis, the river of Colchis (traditionally the home of the Pheasant) 10. Leg-less (the first Birds of Paradise sent to Europe had had their legs removed by the New Guinea natives, as they thought them ugly. This gave rise to extraordinary beliefs, for instance that the birds never came down to earth, the female laying her eggs on the back of the male) VII. l. 2. S. 4. 5. 6. 7. 8. 9. 10.

Gannet (tropical) Tern (tropical) Kingfisher (Australian) Tit (North American) Shearwater (Australian) Nightjar (U.S.A.) Cuckoo (Indian) Jay (Canadian) Tern (tropical) Duck (U.S.A.)

VIII. 1. Emperor Penguin (it breeds on the Antarctic seaice) 2. Bee-eater (on the Bustard, in Africa) 3. Owls 4. Red Grouse 5. Willow-tit, distinguished from Marsh-tit in 1897 6. Willow-tit (chickadee), Tree-Creeper, Magpie, Raven, Snow Bunting 7. Icterine Warbler (1907), Black-winged Stilt (1945), Moustached Warbler (1946) 8. Ptarmigan, Crested Tit (Capercaillie is not strictly correct, as it became extinct in Scotland, and the present stock was introduced from Scandinavia; 255

APPENDIX

Golden Eagle might be permitted but occurs as an uncommon winter visitor in England) 9. Dartford Warbler, Bearded Tit 10. Roc, Phoenix IX. 1. Aeschylus (a large bird dropped a tortoise on his bald head; the bird was almost certainly a Lammergeier, which breaks up its food by dropping the bones on to rocks) 2. Geese (Rome, in an invasion of the Gauls) 3. Frederick II of Sicily - Stupor Mundi (on falconry) 4. Ferdinand of Bulgaria (in Journal fur Ornithologie) 5. Viscount Grey of Fallodon, with his tame Robin 6. Edward VI (the first British bird-book, written by William Turner in 1544), George V (The Grouse in Health and Disease, 1911) 7. Ostrich - the three feathers in the crest 8. Parrot (it belonged to Frances Stuart, Duchess of Richmond and Lennox, and died in 1702. It is the oldest known mounted bird in Britain) 9. Dodo (the only stuffed specimen in existence, it was burnt in the eighteenth century as it was getting moth-eaten) 10. William Jenner, inventor of vaccination X. 1. 2. 3. 4. 5. 1. 2. 3. 4. 5. 6. 7.

Curlew, Chiffchaff, Chough, (Hoopoe) Dartford Warbler, Sandwich Tern Bewick's Swan, Montagu's Harrier Magpie, Jackdaw Petrel Cardinal (U.S.A.), Bishop (Africa) Ruff Blackcap Turkey Canary Hobby (Cob, a male swan, might be allowed) Knot 256

APPENDIX

8. Roller ('Moa' disallowed, but an ingenious try) 9. Kite ('Common or Velvet Scooter' disallowed, but a pleasing attempt) 10. Wren XI. 1. '2. S. k 5. 6. 7. 8. 9. 10.

Gilbert White in The Natural History of Selborne II. Eliot Howard in The Nature of a Bird's World Charles Darwin in the Origin of Species Sir Thomas Browne in Pseudodo.via Epidemiol Edward Lear (who started as a professional birdpainter) in one of his alphabets Edmund Selous in Thought Transference, or What?* Edward Grey in The Charm of Birds* W . H. Hudson in Adventures Among Birds Izaak Walton in The Compleat Angler William Shakespeare in Twelfth Night

* The passages Nos. 6 and 7 are quoted by kind permission of Messrs. Constable (6) and Sir Cecil Graves and Messrs. Hodder and StOUghton (7).

S

257

)

Index A e s c h y l u s 256 A l b a t r o s s 254 A l e x a n d e r , W . B. 157, 179, 180, 181 Allen, G . 184 A n g e l s 5 1 , 245 Ant 215 A p e 2 0 1 , 21.'J A p o d a 229 A q u i n a s 245 A r i s t o t l e 220 A u d u b o n 175, 177 A u k 176 A u s t r a l o p i t h e c i n e 2 1 3 , 220 A x e l l , H . E. 56, 60, 61

Bowman, R. I. 200 Bradford, J. R. 170 Bragg, W . 220 Brain-fever-bird 230 British Museum (Natural History) 179, 206, 244 British Ornithologists Union 153, 154, 159, 161, 163, 165, 167, 168, 180, 183, 242, 246 British Trust for Ornithology IS, 16, 17, 167, 178, 179, 180, 181, 182, 183, 187, 243 Brown, P. 243 Browne, Sir Thomas 29, 257 Browning, R. 254 Buchanan, H. 177 Buller, W . L. 169, 170 Bunting, Snow 255 Burkitt, J. P. 155, 156, 158, 165, 174 Bustard 255 Butterfly 35-38, 43, 45, 48, 142 Buzzard 189

Baird, J. 121 B a k e r , E. C. S. 167 Balfour, A. J. 218, 219 Ball, V. 170 B a r n e t t , S. A. 201 Bat 4 2 B a t h W h i t e Butterfly 35 B a x t e r , E. 242 Cambridge Bird Club 185 B e d d a r d , E. 170 Campbell, B. 243 Bee 215 Canary 256 B e e - e a t e r 255 Capercaillie41, 255 B e e t h o v e n 254 Caprimdgus 229 Belloc 2 5 4 Cardinal 256 B e n t 188 Carduelis 229 Bird of P a r a d i s e 229, 255 Carroll, Lewis 254 B i s h o p 256 Blackbird 65, 66, 73, 112, 113, Cassowary 254 Chaffinch 32, 33, 34, 45, 59, 60, 188, 2 3 3 65, 73, 82, 95, 97, 98, 109, Blackcap 256 110, 111, 119, 122, 229, 241 Blanford, W . T . 170 Chance, E. P. 155, 156, 157, 158, Booby 230 162, 163, 173 B o u r n e , W . R. P. 118, 120, 124, Chickadee 230 127 259

INDEX

Chiffchaff 256 Chough 256 Clarke, W . Eagle 24, 155, 156, 157, 158, 161, 173 Clouded Yellow Butterfly 35, 38, 43, 45 Cockatoo 176 Cockerel, Golden 227 Cocos finch 195, 199 coelebs 9.10 Coleridge, S. T . 254 Coral 201 Crab 43 Crane 253 Crossbill 163 Crow 253, 254 Crow, Hooded 101, 108, 163, 188 Cuckoo 155, 157, 158, 163, 173, 227, 228, 231, 254, 255 Curlew 68, 124, 256 Cuttlefish 43 Cypsiurus parvus 246

Darwin, C. 18, 23, 168, 171, 193, 194, 195, 2 0 1 - 2 0 9 , 210, 211, 2 1 2 , 2 1 3 , 215, 257 D a r w i n , F . 209 Darwin's Finches 18, 168, 1 9 3 200, 206 De Beer, G. 184 de Chardin, T . 212, 214, 219 Delius 254 Diver, Red-throated 163 Dodo 241, 253, 256 D o g 201, 213, 214, 215 Dotterel 229, 254 Dove 240, 253 Dove, Stock 34 Dove, T u r t l e 253 Dragonfly, 36, 37, 43, 46, 47 Drake, F . 254 Drost, R. 242 D r u r y , W . H. l i s , 121 Duck, 42, 255 Duck, Eider 229 Dunlin 68

Eagle 253 Eagle, Golden 256 Eastwood, E. 72 Edward VI 256 Edward G r e y Institute of Field Ornithology 16, 56, 100, 160, 178-182, 185, 187, 188, 190, 225, 244 Eel 42 Eider Duck 229 Elton, C. S. 181 Elwes, H. G. 170 Eohippus 213 Episyrphus balteatus 37 Falcon, Peregrine 35 Ferdinand, King 256 Fieldfare 49, 66, 118, 188, 233 Finches, D a r w i n ' s 18, 168, 1 9 3 200, 206 Firebird 228 Fisher, J. 177, 242 Fitter, R. 242 Flamingo 176 Flycatcher, Pied 15, 30, 113, 115, 116 Flycatcher, Spotted 14, 15 Fowler, W . W a r d e 38 Frederick II, 256 F r o m m e , H. G. 104, 106

Gadow, H. F . 169, 184, 169 Gannet 165, 255 Gardiner, J. S. 184 Garrod, A. H. 169 Gatke, H. 155 Geese 256 G e o r g e V 256 Geospiza magnirostris 195 Godman, F . C. 158, 169, 170 Godwin-Austen, H. H. 170 Goldcrest 229, 235 Goldfinch 33, 45, 57, 59, 63,