Collins New Naturalist Library

28

Sea-Birds

James Fisher and R. M. Lockler

Editors:

JAMES FISHER M.A.

JOHN GILMOUR M.A.

JULIAN HUXLEY M.A. D.SC. F.R.S.

L. DUDLEY STAMP C.B.E. D.LIT. D.SC.

PHOTOGRAPHIC EDITOR:

ERIC HOSKING F.R.P.S.

The aim of this series is to interest the general reader in the wild life of Britain by recapturing the inquiring spirit of the old naturalists. The Editors believe that the natural pride of the British public in the native fauna and flora, to which must be added concern for their conservation, is best fostered by maintaining a high standard of accuracy combined with clarity of exposition in presenting the results of modern scientific research. The plants and animals are described in relation to their homes and habitats and are portrayed in the full beauty of their natural colours, by the latest method of colour photography and reproduction.

To

JULIAN HUXLEY

in gratitude for his guidance

and encouragement,and in recollection of the

many happy days we have spent together,

watching sea-birds

Table of Contents

Cover Page

Title Page

Editors

Editors’ Preface

Authors’ Preface

CHAPTER 1 THE NORTH ATLANTIC OCEAN: ITS STRUCTURE AND ITS SEA-BIRDS

CHAPTER 2 EVOLUTION AND THE NORTH ATLANTIC SEA-BIRDS

CHAPTER 3 SEA-BIRD NUMBERS AND MAN

CHAPTER 4 WHAT CONTROLS THE NUMBERS OF SEA-BIRDS?

CHAPTER 5 SEA-BIRD MOVEMENTS

CHAPTER 6 NAVIGATION BY SEA-BIRDS

CHAPTER 7 SOCIAL AND SEXUAL BEHAVIOUR

CHAPTER 8 THE TUBENOSES

CHAPTER 9 THE PELICANS

CHAPTER 10 THE SKUAS

CHAPTER 11 THE GULLS

CHAPTER 12 TERNS AND SKIMMERS

CHAPTER 13 THE AUKS

APPENDIX LIST OF SEA-BIRDS OF THE NORTH ATLANTIC AND THEIR DISTRIBUTION

Bibliography

Index

Plates in Black and White

Colour Plates

Copyright

About the Publisher

EDITORS’ PREFACE

IT IS NATURAL that in a series dealing with the wild life of the British Isles sea-birds would be a subject planned for early publication; and in fact this book was announced as forthcoming five years ago. That it has not been completed earlier is not due to any want of industry on the part of its authors. On the contrary, in their researches for this book they have found their subject so absorbing that they have made the interval an opportunity to continue to publish numerous scientific papers, and two monographs, on sea-birds. James Fisher is the author of The Fulmar (1952); and R. M. Lockley, author of Shearwaters (1942), has just published Puffins (1953). There could, in fact, hardly be any other pair of authors better qualified to describe the sea-birds of the North Atlantic than these with their experience of many years of field work and visits along the coast and islands, from Spitsbergen and Iceland in the cool north, to Madeira and the Salvages in the warm south, of that great demi-ocean. They have made their visits often together, and lived much on the small remote islands where sea-birds breed.

The North Atlantic, busiest ocean in the world, is revealed in the opening chapters not as a monotonous watery plain, but as an intricately varied, densely inhabited foraging ground for sea-birds. This avian community, though remarkably homogeneous in different sections of the broad expanse of the North Atlantic, is fascinating in the variety of the species that compose it, and in the complexity of their movements and migrations. The annual migrations of some species extend the total range of the community from the arctic to the antarctic. These long transatlantic migrations, verified by ringing, take species from east to west between Europe and North America, and from north to south between Greenland and South Africa, Britain and South America.

The authors tell us of the primitive progenitors of the sea-birds, dating from over sixty million years ago, and the evolutionary adventures of their descendants, including the notorious extinction of the strange flightless great auk, the sad decline of many other fine species, also the rediscovery of the cahow after it had been presumed extinct. They have paid special attention to geographical distribution, and have provided a unique collection of maps, giving us, for the first time, the distribution of most species of North Atlantic sea-birds.

Chief among the authors’ interests has been the study of sea-bird numbers. They were largely responsible for organising the surveys of that splendid and typical North Atlantic animal, the gannet, which provided biology with the first reasonably accurate figure for the world population of any single and fairly numerous bird species. They have, from their own notes and those of many amateur and professional bird-watchers, produced interesting statistics of the total population of the fulmar, the Manx shearwater, the puffin and many others. Incidentally, such careful counts, site by site, reveal the continuous change that is going on in sea-bird populations, often directly or indirectly due to man’s influence.

The chapters on life-history are preceded by a general account of social and sexual behaviour, which throws light upon the significance of the prolonged and, to the observer, entertaining, mutual ceremonies of these strictly monogamous birds, their pair-formation, their fidelity to their mates, their nest-sites and their parental duties; at the same time problems of instinct and learning ability are discussed. The life-histories include much original field-work by the authors, who have been responsible for several discoveries concerning the incubation and fledging of a number of sea-birds.

We read of the birds’ ecology, their sharing of the wild frontiers of the land where they nest, their niches in the economy of the ocean. We learn of the contrasts between cliff-dwelling and hole-nesting species, of how the guillemot and razorbill chicks, exposed to many dangers on the open rocks, hasten their feather-growth and depart to the sea in two weeks, while the young puffins, safe in the darkness of their burrows, delay their departue for seven weeks, and are finally deserted by their parents; we learn of the strange lives of the shearwaters and small petrels which wander after the breeding season between the North and South Atlantic Oceans, living in perpetual summer—the Tristan shearwater “wintering” in our northern summer, and the Manx shearwater enjoying its “winter” in the southern summer off the coasts of South America.

But we have said enough to indicate the richness of knowledge brought together in this volume, which we confidently recommend as indispensable to everyone interested in the birds of the sea.

THE EDITORS

AUTHORS’ PREFACE

THE HEROES of our story are rather over a hundred species of birds whose life is a sea-life, whose habits enable them to earn at least part of their living in, or on, salt water, and which have been seen in the Atlantic Ocean north of the Equator.

The North Atlantic is the scene of our book, the great ocean that is now the most travelled by man. Its two sides are provided with an almost equal variety of sea-birds: sixty-eight species, or rather over half are common to both. Of all Atlantic countries Britain, considering its size, has the greatest number of sea-bird species; with no less than eighty, it can boast on its list all but six of those that have been seen on the Atlantic coast of Europe. The British Isles therefore make a good headquarters for a survey of the sea-birds of the North Atlantic. In Britain, and from Britain, the writers of this book have explored the eastern Atlantic sea-bird stations, and enjoyed many fine islands and memorable experiences. One or the other of us has sought the sea-birds south to the frigate-petrel burrows of the Salvages, near the Canary Islands; north to the ivory-gull colonies on the nunataks that rise from the ice-cap of Spitsbergen; or from 30°N. nearly to 80°N., a distance of more than three thousand miles; west we have ranged to Iceland, the Faeroes, Rockall, St. Kilda and the Blaskets of the Kerry coast; east we have travelled to Heligoland, and as far as Laesö in the Kattegat and Gotland in the Baltic, with their off-lying islands of sea-birds. There is no coastal county in England, Wales and Scotland that has not been visited by us both, and not one in Ireland that has not been visited by one of us.

No good British sea-bird cliff or island has been overlooked in our search for what the naturalist searches for; our experience and enjoyment has been long and continuous because both of us are, each in his somewhat different way, obsessed with sea-birds and with islands. We have spent a combined total of nearly seventy years sea-bird watching.

We have seen the little crags and green island swards of the Isles of Scilly and the drowned coast of Cornwall; the granite cliffs and puffins of Lundy; the chalk of south England east from Dorset; the flats and shingles and dunes of Essex and Suffolk and Norfolk, and the sanctuaries of Havergate and Minsmere and Walberswick and Cley and Blakeney and Salthouse, with terns and avocets and many kinds of marsh-birds. One of us has spent many years of his life in the county of Pembroke, living on Skokholm, and on other islands and peninsulas of the Welsh coast; of its sea-birds he has written in many books, and on Skokholm established the first permanent coastal bird observatory in Britain; the other has spent parts of twenty seasons in North Wales, and has worked its coast from St. Tudwal’s Islands to the Little Orme. Both of us know the Yorkshire bird-cliffs most of the way from Flamborough Head to Saltburn; and we have explored the shore of Durham, where bird-cliffs and black industry mix. In Northumberland we know Cullernose Craster, and Dunstan-burgh and Bamburgh Castle, and the cliffs north of Berwick, and other places where sea-birds nest; and we have been to the Holy Island, and to Coquet Isle, and to various of the Farne Islands, where the guillemots and kittiwakes are tame. We have seen the steep cliff-hill of the south part of the Isle of Man, and the sanctuary of the Calf; and have visited the inland gull colonies of North Lancashire and the Lakes.

In Scotland we have, at one time or another, visited every important sea-bird station: in the east St. Abb’s Head, Fast Castle, Tantallon Castle, the Bass Rock, the exciting Isle of May, and many others; in the west the Lowland coast from the Mull of Galloway in Wigtownshire up-Clyde as far as Ailsa Craig, whose magnificent gannetry has been the scene of many weeks of enjoyment and experiment in efforts to improve the counting of nesting sea-birds. Our visits farther north have taken us to Fowlsheugh in Kincardineshire, and round the bird-cliffs of the Aberdeen-Banff border—Pennan Head, Troup Head and others. West along into the Moray Firth we have hunted out the bird-cliffs as far as they go, which is to Covesea in Morayshire.

In the West Highlands we have explored the mainland promontories of Kintyre and Ardnamurchan, and the islands of the Clyde and Inner Hebrides. We have searched the cliffs of west Islay closely from a slow aeroplane. The curious headland of Ceann a ‘Mhara on the lovely sunny Island of Tiree has been investigated, as have the odd-shaped Treshnishs, home of seals, and the capes of Mull. The island of Eigg, where the shearwaters nest in a mountain; the magnificent but somewhat birdless island of Skye, and some of its attendant islets and stacks; both the lonely coast of Ross and its islands—Priest, Tanera, Glas Leac Beg and many others, where Frank Darling first worked out his theory of bird sociality by studying herring-gulls.

In the North Highlands we have watched the birds of the Black Isle Coast, and those of Easter Ross where the coast continues north of the Cromarty Firth to Tarbat Ness. In East Sutherland Dunrobin Castle itself becomes a bird-cliff, because fulmars are now prospecting it—and there we have seen them; in West Sutherland we have travelled nearly the whole wild coast, in instalments spread over several years; we know the crags of Stoer; the Torridonian sandstone precipices of Handa, the best bird island in Sutherland; the lonely cliffs on each side of remote Sandwood Bay—and Eilean Bulgach opposite which only half-a-dozen naturalists have visited; the high promontory of Cape Wrath, and the higher cliff of Clò Mor to the east of it—the highest mainland cliff in Britain—where the guillemots on two-hundred-foot stacks must be observed from six or seven hundred feet above; Fair-Aird Head and the home cliffs and caves of Durness; the huge white crags and stacks of Whiten Head; the complex of islands and cliffs that stretches thence to Caithness, whose headlands too, we know, and their birds—Holborn Head, Dunnet Head, John o’ Groats and Duncansby Head, Noss Head, Berriedale Ness.

In many years, and many boats (as well as from aircraft), we have enjoyed the Outer Hebrides, from North Rona (which many call the loneliest place to have been inhabited in Britain) to Barra Head. We have seen the seals and birds of Rona, and counted the gannets of its lonely neighbour Sula Sgeir; and have hunted out the coast of the Lewis, and much of Harris. One of us has slept some nights on the Shiants, among the rats that may be affecting the population of that vast remote puffinry; and has several times threaded the maze of the Sound of Harris, and eight times has been to St. Kilda, whose unsurpassed cliffs and towering stacks have to be seen to be believed (and are sometimes then not believed). We have traversed the Long Isle—North Uist, Benbecula, South Uist and Barra—and many of its attendant isles, and carried on to sail close under the cliffs of Mingulay and Berneray, which for remoteness, grandeur and personality are rivals—much overlooked rivals—to those mighty precipices of St. Kilda, Conachair, Soay and Boreray.

One hundred and ninety-one miles west of St. Kilda, and about three hundred miles from the mainland of Scotland, lies a tiny rock which has been a magnet for us both—not only because of its bird-problems, but because it is a tiny remote rock! Fisher flew over Rockall in 1947. In 1948 Lockley spent twelve days in a trawler fishing within sight of, and on occasion very close to it. In 1949 Fisher sailed there in H. G. Hasler’s sixteen-ton yawl Petula, and spent some time investigating it at close quarters.

One of us has visited Sule Stack, the lonely gannetry thirty miles west of Orkney; and we have enjoyed nearly every island, from North to South Ronaldsay, from Eynhallow to Hoy, and have seen sea-birds in a great range of surroundings. Neither of us is a stranger to the well-named Fair Isle, a great migration and sea-bird station. We know the Shetland gannetries of Noss and Hermaness, where thousands nest—though forty years ago there was none. We have stood at the top of Foula’s Kame, and gazed twelve hundred and twenty feet to the auk-scattered sea below. We have sailed in and out, and round about, the stacks and rocks and skerries, and voes and geos of straggling Shetland, and seen many a fine cliff, from Sumburgh in the south to Saxa Vord in the north; from Noss on east to Papa Stour on west. We are no strangers to Fitful Head, or Hillswick, or Ronas Voe, or Burra Firth; or to Hascosay, the bonny isle of Whalsay, Fetlar, Bressay or Mousa; or to the Out Skerries, nearest British land to Norway.

Perhaps in Ireland we have not seen all we should; but one of us knows the windy corner of Kerry, the end of the world, where the pure Irish survives on the Blasket, and where the fulmars now glide and play round Inishtearaght, Inish-na-Bro, and Inishvickillaun; and where the gannets mass white on the serrated pinnacles of the Little Skellig, second gannetry of the world. He knows, too, the little gannetry of the Bull, and its neighbour the Cow, and other crags of Cork from Cape Clear Island and Dursey Island east to Great Newtown Head. In Clare the cliffs of Moher bring sea-birds to nest among many beautiful flowers. We have seen the bird-colony of the Great Saltee in Wexford, and that of Lambay not far from Dublin. One of us knows the many fine, high cliffs of Mayo and Sligo, and some headlands of the maze-coast of Donegal; the other has watched fulmars haunting the curious inland cliffs of Binevenagh in Derry, and hunted out the basalt coast of Antrim and the Giant’s Causeway.

Between us, then, we have seen much of the coast of our glorious islands; but we have not seen nearly enough, and we hope to see what we have already seen, all over again. And we would see the west side of the ocean we have grown to love, and compare it with the Britain we know, and other sea-bird countries we have seen—the tuff and lava and basalt of Iceland, the basalt crags of Faeroe, the dissected plateaux of Spitsbergen, the misty cliffs of Bear Island, the drowned coast of Norway with snow-coated Lofotens and dark fjords like corridors, the friendly limestone of Sweden’s Gotland, the skerry-guard of Stockholm and Uppland, the dunes of Denmark and the Dutch islands, the red sandstone cliffs of Heligoland (the only cliffs in western Germany), the chalk and granite of north France, and the islets of Brittany; the benign, sunny slopes and little scarp-precipices of the Channel Islands where one of us lived for a while; the warm, shearwater islands of the Portuguese Berlengas, the Madeiran Desertas, and the Salvages; and the gulleries and terneries of the Camargue, within the Mediterranean.

This book is not a comprehensive survey of a problem based upon a lifetime’s experience nor yet a full bibliographical compilation. We have paused in field-work simply to offer this book as a stimulant, which we hope very much it will be. We intend it as no more. It is a statement of some of the facts concerning the wonderful sea-birds of the North Atlantic, and of some of the interesting problems connected with their lives and their evolution. It is intended to exhibit the ignorance of ornithology as much as its knowledge, and to draw attention to what needs doing as much as to what has been done. It is our wish, we must also add, not only to take the reader with us—if he will come—to the east side of the North Atlantic where the sea-birds are more in our personal experience, but also to the western seaboard, which is zealously worked by the ornithologists of the United States and Canada and described by them with such enthusiasm and thoroughness in numerous books and journals. One of us has corrected the galley proofs of this book in an aircraft bound for North America, on the beginning of a journey among the sea-birds of that continent; as he left Britain, Ailsa Craig flashed white with gannets in an April evening sun, and the first bird he saw in the New World, through Newfoundland clouds next morning, was a gannet.

For help, encouragement and information we have more friends to thank than we can mention. Our search of the literature has been chiefly pursued in books belonging to the Zoological Society of London, the Alexander Library at Oxford, the Royal Geographical Society and the London Library, and we thank G. B. Stratton and W. B. Alexander particularly. Among those who have given us valuable help or information (they have no responsibility for the use we have made of it) are B. M. Arnold, R. Atkinson, J. Buxton, T. Cade, F. Darling, E. A. G. Duffey, A. Ferguson, Finnur Guðmundsson, H. G. Hasler, P. A. D. Hollom, J. S. Huxley, the late P. Jespersen, G. T. Kay, Miss J. Keighley, T. C. Lethbridge, H. F. Lewis, C.–F. Lundevall, S. Marchant, R. C. Murphy, E. M. Nicholson, R. S. Palmer, R. Perry, R. T. Peterson, L. E. Richdale, M. Romer, F. Salomonsen, H. N. Southern, D. Surrey-Dane, N. Tinbergen, L. Tuck, L. S. V. Venables, H. G. Vevers, K. Williamson and V. C. Wynne-Edwards. Mrs. E. Marshall patiently typed several drafts of most of this book. J. F. Trotter prepared the final copies of most of the maps. One of these is on a mapnet invented by the late Professor C. B. Fawcett and is used with his permission and that of the Royal Geographical Society (e.g. Fig. 24). Another mapnet, devised by one of us (J.F.) is used for the first time in this book; it is based on the South Pole with the oceans in three petals, and is useful for showing the range of the many sea-birds that have a primarily southern distribution (e.g. Fig. 22). J. Fisher’s fellow New Naturalist editors have been encouraging; and Eric Hosking in particular has found us many unique photographs. R. Trevelyan, of Messrs. Collins, has been most ingenious and helpful. The American Ornithologists’ Union, who published our frontispiece first in the Auk, have very kindly allowed us the use of it; this fine painting by Roger Peterson of the interesting cahow, long thought to be extinct, embellished the paper by R. C. Murphy and L. S. Mowbray on their recent rediscovery of its breeding-grounds.

Ornithologists’ wives do many (if not most) of the chores that husbands normally do. We thank ours for more things than they probably remember.

JAMES FISHER

R. M. LOCKLEY

CHAPTER 1 THE NORTH ATLANTIC OCEAN ITS STRUCTURE AND ITS SEA-BIRDS

THE ATLANTIC OCEAN is a big broad blind alley, kinked like a zig-zag, its jagged north end blocked with ice, its broader south butt cornered by the cold stormy narrow eastern entrance to the Pacific Ocean, and by the warm, windy and wide western gate to the Indian Ocean. It resembles two wedges, their apexes towards the North Pole, one of them truncated midway and at that point connected sideways to the base of the other.

The birds inhabiting the more northerly of these wedges, the North Atlantic, are the birds of this book. Two of these birds have become extinct in historical times: the great auk was never seen alive after 4 June, 1844, and the last Labrador duck was shot in 1875, though some say one was shot in 1878. The number of living species that remain is about one hundred and eighteen, of which eighty-six have been seen on the western seaboard of Europe (which includes Iceland), and ninety-three on the eastern seaboard of the New World (including Greenland).

However, for an understanding of the environment to which the North Atlantic birds are adapted, a description of the whole ocean is necessary, and to this we must proceed.

The extremely simple fundamental shape of the Atlantic invites diagrammatic caricature (Fig. 1). It is the second largest ocean in the world. It is, on an average, over two and a quarter miles deep, and in some places nearly six. It is, on an average, three thousand five hundred miles across (maximum about five thousand); and is nine thousand miles long. Its area has been estimated as thirty-three million square miles, and its volume as seventy-five million cubic miles. It is a vast place, with many miles of coast, upon which much of civilization depends: considering its size, it has few islands. In comparison, the Indian Ocean is not quite as large (about twenty-eight million square miles); but the Pacific (about sixty-four million square miles) has nearly twice the area, and is ten thousand miles across its widest part. The Arctic Ocean (about five and a half million square miles) is small and nearly full of ice at all times of year; in spite of this it is at times very full of life. Finally, it is usual to describe the cold waters round the Antarctic Continent (itself the same size as the Arctic Ocean) as the Antarctic Ocean.

South of the normal steamship route from Britain to New York the Atlantic is almost everywhere over two miles deep, and in large areas more than three. But down mid-ocean, following the tropical kink in the zig-zag, runs a very long submarine ridge, above which is less than two miles of sea; it is only broken by deeps for a short distance on the Equator, and it rises to the surface in places—in the northern hemisphere at the Azores and St. Paul Rocks, and in the south at the lonely isles of Ascension, Tristan da Cunha and Gough. Other oceanic Atlantic islands, such as Bermuda in the north, and South Trinidad and St. Helena in the south, rise abruptly from very deep parts of the ocean. A sketch-chart will be found in Fig. 2c.

It will be seen that there are prominent shallows along the east coast of southern South America, north of the mouths of the Amazon and along the Guianas, in parts of the Caribbean Sea and the Gulf of Mexico (there are also marked deeps in these tropical waters), off the New England States, Nova Scotia and (most particularly) Newfoundland, and round Britain, the Channel and the North Sea, and round Iceland. A submarine ridge, over which the sea is five hundred fathoms or less, cuts the North Atlantic entirely from the Norwegian Sea and the waters of the Polar Basin; Shetland, the Faeroes and Iceland lie on this ridge. Davis Strait is shallow, and the waters of Labrador and Hudson’s Bay very shallow. Where the waters are less than a hundred fathoms deep, what they cover is usually described as the Continental shelf. This has its own particular community of birds.

For practical purposes, and because all charts and maps mark the Arctic Circle and the Tropics, we have classified the North Atlantic and its birds into arctic, temperate and tropical areas based simply on latitude. In our analysis of breeding-distribution, for instance (see here), we regard birds nesting north of the Arctic Circle as arctic, those nesting south of the Tropic of Cancer as tropical, and those nesting between as temperate. However, the temperature of neither air nor water arranges itself, in the Atlantic, according to latitude.* For instance, if we examine the July air isotherms over the world north of the Tropic of Cancer we see that that for 45° F. runs well south of the Arctic Circle in the areas Greenland-Baffin Island and Bering Strait, and well north of it off Scandinavia, avoiding Lapland altogether.

FIG. 1

Diagram of the Atlantic Ocean

If we examine a map of the world (showing particularly the lands between the Tropics), we see that the summer isotherm for 80°F. (July in the northern hemisphere, January in the southern) runs well north of the Tropic of Cancer in Mexico and the southern States, and in Africa and Asia, and south of the Tropic of Capricorn in Africa and Australia; yet large parts of the tropical Pacific and Atlantic Oceans never reach an average summer air temperature of 80°F.

In the North Atlantic there is not only relatively little direct correspondence between isotherms and latitude, but there is a good deal of difference in position between the same isotherms under the surface, on the water surface and in the air.

The primary cause of the ocean currents, and of the prevailing winds which are associated with them, is the rotation of the earth. The plot of the Atlantic currents and Atlantic winds is almost, though not quite, coincident. To a very large extent the distribution of Atlantic water temperatures, and to a large extent that of air temperatures, is a consequence of these currents and prevailing winds. However, in parts of the Atlantic evaporation and the melting of ice produces temperature and salinity gradients which themselves produce consequent currents. Hence the web of sequence and consequence, of cause and effect, becomes complex. We must examine the great equatorial current first, for almost every one of the more important sea masses in the Atlantic owes its existence to it. It is quite justifiable to write in terms of sea masses, for, as we shall see, the Atlantic waters are by no means homogeneous and can be divided, sometimes with strikingly sharp boundaries, into volumes possessing very diverse properties.

We need scarcely remind the reader that if he faces a globe, poised in the ordinary way with North at the top, and spins it as the earth naturally rotates, the points on its surface will travel, as they face him, from left to right. The points travelling with the greatest velocity will be those on the equator, and the two points represented by the Poles will travel with no velocity relative to the earth’s axis.

In general terms it is true that, as the earth rotates, its atmosphere rotates with it. However, there is a certain effect due to inertia or drag; and this effect, obviously, is greatest at the equator, where the surface velocity is greatest. The effect operates on all objects but can put only liquids and gases into a dynamic state. Upon these Corioli’s force—the deflecting force of the earth’s rotation—acts in a simple manner. It sets them in motion in a direction which, at the equator, is opposite that of the rotation of the earth. Thus if we examine a map of the prevailing winds and ocean currents of the world, we find pronounced positive east-to-west movements in all equatorial regions. The liquids and gases thus displaced circulate into the temperature regions and perform return movements in the higher latitudes where the Corioli’s force is less. Consequently, in the northern hemisphere water and wind currents tend to turn right-handed, whereas in the southern hemisphere they turn left-handed. (Exceptions to this rule are mostly found in minor seas, where the impact of the currents upon coasts may cause contra-rotation.) The main clockwise movement of the northern hemisphere wind and currents is very obvious.

The Atlantic equatorial current can be traced from the African coast south of the equator westwards as far as the sea reaches. Approaching the coast of Brazil it attains a remarkable speed. It sets past the isolated oceanic island of Ascension so that even in calm weather it leaves a wake of turbulence which must make that island unusually visible from far off by its numerous bird inhabitants.

Just north of the equator the lonely St. Paul rocks, which represent the pinnacles of a submerged, steep-sided mountain over thirteen thousand feet high, face the full strength of the great equatorial current, especially in August, when the associated south-east trades are blowing their hardest. During the cruise of the Challenger in 1860 H. N. Moseley saw the great ocean current “rushing past the rocks like a mill race.” A ship’s boat was quite unable to pull against the stream.

The equatorial current divides when it impinges on the corner of Brazil at Cape São Roque. The northern element—the Guiana coast current flows past the mouth of the Amazon with sufficient rapidity to displace the outgoing silt 100 miles or more in a northerly direction; and it continues steadily past the mouth of the Orinoco and Trinidad to flow with scarce-abated force into the Caribbean, mainly through the channel between Trinidad and Grenada in the Windward Islands.

Through the Caribbean the current flows from east to west, turning northerly and entering the Gulf of Mexico through the fairly narrow channel between Yucatan and Cuba. It is no doubt aided here by the climate, for this part of the world is very hot, and not excessively wet, and there is much evaporation of the waters of the Caribbean and the Gulf of Mexico, which has to be replaced. The current finally comes up against the coast of Louisiana and Texas and proceeds to mill right-handed, escaping finally through the narrow gap between Florida and Cuba, into the Bahama Seas.

Here the Gulf Stream is formed, not only by the waters escaping from the Gulf of Mexico but by more northerly elements of the equatorial current which impinge upon the outer shores of the West Indies and are deflected northwards. This north equatorial current flows across the ocean from the Cape Verde Islands and the joint product swings quickly east again, narrowing in width but probably gaining in velocity, to sweep past the tail of the Great Bank of Newfoundland and thence to carry on as what is now called the West Wind Drift (because of its associated air currents). The most direct continuation of this drift flows northwards and eastwards past the west coast of Ireland (giving off a branch towards Iceland), between Rockall and the Hebrides, through the channel between Shetland and Faeroe, north-eastward up the coast of Norway, whence elements strike east into the Barents Sea and north to reach Spitsbergen. It is because of this warm drift that, of all lands reaching latitude 80°, Spitsbergen has been the most accessible. If it was not for the Gulf Stream, many Oxford expeditions could never have explored there in the Long Vacation and got back in time for the Michaelmas Term.

So far we have described the simplest and best-known currents of the North Atlantic. The fate of the waters in their return circulation is more complex. Much of the return circulation is below the surface, for cool water is denser than warm water. In the lower latitudes of the North Atlantic, between the westward-flowing north equatorial current, and the eastward-flowing Gulf Stream and drift, there is an area of clock-wise milling. The centre of this area is the part of least water-movement, and bears some resemblance to an oceanic desert. This is the Sargasso Sea, usually windless, too, with masses of the floating Sargasso weed, which has berry-like air vessels, and is used by sea-birds as a resting-platform; but on the whole this stagnating area is as devoid of animal life as it is of movement.

There is a corresponding and not dissimilar area in the South Atlantic, which also has calms. It has never been named, though it could well be called the Southern Sargasso. These Sargasso areas contain fewer plants and animals than any other part of the ocean. In both there is a rather fluctuating and not very well marked line or lines of convergence between the warm equatorial waters and the comparatively cool temperate waters.

We must now return to the temperate waters, which, as we have seen, form a drift right across the Atlantic and into the Polar Basin. starting on the west below latitude 30°N. and reaching latitude 70°N, or more on the east side. The counter-movements and mills consequent on this great temperate drift are mostly in an anti-clockwise direction. Thus the waters of the North Sea tend to rotate anti-clockwise, running south down the British coast, east and north round the Heligoland Bight, and north-west from southern Norway. In the Norwegian Sea two major and several minor anti-clockwise mills can be detected, and the waters of the Barents Sea also tend to revolve anti-clockwise.

But the greatest counter-movement in the North Atlantic is composed of the Greenland and Labrador currents, carrying cold, heavy water south past Labrador, past Newfoundland and far down the United States’ eastern seaboard. This great counter current sets south along the east coast of Greenland down the Denmark Strait between Greenland and Iceland, round Cape Farewell, the southern tip of Greenland carrying with it many bergs tumbled from the sliding glaciers of the inhospitable east Greenland coast, runs north some hundreds of miles up the west coast of Greenland, then west and once more south, collecting the ice of Davis Strait and Baffin Island, and pursues its final course down the Labrador shore. As it turns the corner of Newfoundland and passes over the great shallow Banks, it deposits its last icebergs and suddenly impinges on the northern boundary of the Gulf Stream or West Wind Drift. Here a long, well-marked line of convergence extends for many hundreds of miles. The cold water sinks rapidly under the warm, and much turbulence is the result. Many organisms are brought to the surface. There is a steep temperature-gradient and frequent climatic upheavals, including fogs. It is largely because of the cold Labrador current that New York, though a full ten degrees farther south, enjoys a climate similar to that of London though with greater extremes of temperature.

The Atlantic thus is a mosaic, not a homogeneous area. Each patch in the mosaic is characterised by some peculiarity of climate. In practically all areas the water, the prime constituent, is in a state of continual movement. The fortunes and distribution of our sea-birds depend on this environment, so continually in turmoil. We must beat the bounds, then, of the North Atlantic and discover how our birds and their lives are interlocked with this climate and scenery.

A suitable place from which to begin our tour of the North Atlantic is the St. Paul Rocks. Only three species of sea bird nest on them—the brown booby Sula leucogaster, and the noddy terns, Anoiis stolidus and A. minutus. The islands have been visited by many naturalists, including Charles Darwin, who spent some hours of the afternoon of 15 February 1832 obtaining bird specimens with his geological hammer!

From here we move to the coast of South America between the Equator and the Caribbean: this is a mud-coast and not, as are many tropical coasts, a coral coast. Indeed, there is no sign of the coastal coral barrier-reef off Brazil until some distance south of the Equator. If we start at the Equator, on the islands in the mouth of the Amazon, we find a typical river bird-community. The water is fresh for some considerable distance outside into the ocean and the birds consist of skimmers (Rynchops nigra) and various river-loving terns such as the gull-billed tern Gelochelidon nilotica, the yellow-billed river-tern Sterna superciliaris, and the large-billed river-tern Phaëtusa simplex. Off-shore the true sea-birds come in, and Murphy records species such as Leach’s petrel, Wilson’s petrel, the Tristan great shearwater, the great skua, boobies and tropic-birds. North of the Amazon mouth the Brazilian Guiana coast is forested down to the muddy shore. Many small rivers, often choked with the debris of tropical forests, flow into it.

In French Guiana, however, rocky promontories and islets appear, and they are inhabited by some sea-birds; regrettably little is known about the species involved, but they probably include boobies and tropic-birds. Along the coast of Dutch and British Guiana we are once more in a muddy coast with no headlands or islands. North-west of the mouth of British Guiana’s main river, the Essiquibo, there are some shell-beaches, but most of the coast is of mangrove-swamp jungle, in which the only animal resembling a sea-bird is the Mexican or bigua cormorant Phalacrocorax olivaceus. Over the Venezuelan border we are at once in the delta of the great river Orinoco. It is a land of dense mangrove forest and a very large number of low wooded islands. Off-shore the immense tonnage of mud and silt is seized by the equatorial current and driven northwards towards Trinidad, which it thus provides with a very wide continental shelf. As Murphy (1936, see here) writes, “The delta of the Orinoco is not the home of birds that can be called marine … Only our adaptable old friend the Bigua cormorant seems … at home.”

Generally speaking, from the mouth of the Amazon to the mouth of the Orinoco the coast scarcely harbours a breeding sea-bird. However, the British islands of Trinidad and Tobago, off the northeast corner of Venezuela are provided with rocky promontories and many islets on which sea-birds nest. The brown pelican Pelecanus occidentalis, the red-footed booby Sula sula, the man-o’-war or frigate-bird Fregata magnificens, nest on low trees or on mangroves. On the bare Soldado rock the sooty tern Sterna fuscata, and the two species of noddy, nest. One tubenose, Audubon’s shearwater Puffinus I’herminieri, nests on Tobago, which is its southernmost breeding place on this coast. The gull-billed tern nests in fresh water marshes.

West of Trinidad we are in the Caribbean Sea and following the coast, which for 250 miles more has a wide continental shelf, with small islands dotted in it. Opposite the western part of Venezuela, however, the water is much deeper close in-shore, and the off-coast islands of Curaçao and other Dutch possessions rise from a deep sea. Both the islands of the shallow shelf, such as Los Hermanos and the Testigos, and these Dutch islands, have many sea-birds, including three kinds of boobies, man-o’-war birds, tropic-birds, noddies and sooty terns. At least eight species of terns are found at Aruba, the westernmost of the Dutch islands. But there are few species which can be described as oceanic, though the boobies are marine; many of the sea-birds probably nest on the islands rather than on the mainland because of the additional safety and the existence of outcrops of rock such as are not found along the interminable mangrove coast.

Of all coasts that we have so far considered, those of northern Venezuela are the driest, and the Caribbean is the hottest part of the North Atlantic region. The western Caribbean, however, has intense summer rain; in spite of this, evaporation is great and the equatorial current is boosted along, flowing into the Gulf of Mexico with some rapidity.

In the Antilles, which form the eastern and northern boundaries of the Caribbean Sea, we find islands clad still in fairly thick jungle vegetation, with coastal mangroves, but also many sandy islets and bars and real coral reefs. Though the Guiana coast was too muddy to support coral reefs, these are found fringing the islands north of Venezuela, such as Curaçao. There are also many reefs along the western shore of the Caribbean, particularly at the corner of Nicaragua and Honduras, at the end of the shallow Mosquito Bank. Throughout the West Indies the distribution of sea-birds is linked primarily with available food, but that of the breeding adults probably also with available nesting-sites. Islets where there are exposures of rock or sand are much favoured, but some species as we have seen, including the red-footed booby, the brown pelican, the bigua cormorant, the darter Anhinga anhinga, and some terns, nest in trees. One very rare petrel Pterodroma hasitata (see here) nests above the tree-line on some of the West Indian islands, among the rocks of steep mountains.

A typical sea-bird islet in the West Indies is Desecheo, described by Alexander Wetmore. This lies in the hot dry zone west of Porto Rico. It is a rocky islet with cliffs and a gravel beach, and a thin top-soil covered with a dense thicket of cacti and the curious West Indian birch. Here brown boobies nested on the ground among the thickets and floundered through the prickly pear and cactus. Sooty terns nested on ledges, on shelves on the limestone cliffs, and B. S. Bowdish found a few bridled terns Sterna anaetheta, nesting on flat ledges. This species also breeds on the little islets or cays of the Barrier Reef south of Jamaica, among the broken coral rock and the mangroves.

North of the Antilles the low-lying British islands of the Bahamas occupy a large area of the west Atlantic. The blue Atlantic beats directly against steep east-facing limestone cliffs, while to the west there are shelving beaches. Many of these islands are covered with cacti, and the sea-grape Coccolobis, which forms low, thick vegetation in which brown boobies nest, scraping slight hollows in the ground and lining them with grass. In some Bahamas the man-o’-war bird builds its nest quite on top of the prickly pears, though more normally on the mangroves in the swamps, together with brown pelicans and the double-crested cormorant of Florida Phalacrocorax auritus floridanus. Upon the more exposed sandspits in the Bahamas several kinds of tern breed, including the gull-billed tern, the little tern Sterna albifrons, the roseate tern S. dougallii, Cabot’s tern Thalasseus sandvicensis, and the sooty tern.

The coast of the Gulf of Mexico is low-lying, with coral reefs and an extensive continental shelf, especially off Yucatan. Breeding sea-birds are scarce, except terns and the ubiquitous bigua cormorant, which is as much a fresh-water as a salt-water bird. The Sandwichtern, which is known as Cabot’s tern in North America, breeds in several parts of the Gulf coast of Mexico, which is more suited for terns than for any other sea-birds. On the grassy islands among the lagoons and marshes of the Texas coast, the gull-billed tern and Forster’s tern Sterna forsteri, are found. The beautiful Caspian tern Hydroprogne caspia, also nests in a few places on sandy islands, and there is an interesting outpost breeding-station of the white pelican Pelecanus erythrorhynchos, on the Laguna de la Madre, south of Corpus Christi, near the Border. The rest of the population of this fine bird is found in western North America.

Along the Louisiana coast, where there are many protected reservations, there are very big colonies of the laughing gull Larus atricilla, especially in the marshy islands of the Mississippi delta, which are overgrown with grass and low mangroves. One of the reservations is in the Breton Islands, 114 miles off the main Louisiana coast. Here are great colonies of terns on low flat sandy spits, including Caspian, Cabot’s and royal Thalasseus maximus (Bent 1921). Forster’s and common terns Sterna hirundo, also nest in the Breton Islands, as do numbers of the extraordinary black skimmer, an aberrant tern whose lower mandible is prolonged and with which it scoops food from the surface of the sea. The peninsula of Florida has to its west an immense continental shelf, along the lower end of which is a famous chain of Keys. Beyond Key West, at the terminus of the Key railway, many miles to sea, lie the dry Tortugas, flat islands of coral, their surface, largely of coral sand, clothed in parts with dense cactus as well as with bay cedar, with many bare and grassy spaces between. On the cedars and the cactus immense numbers of noddy terns nest: often over the nests of the sooty terns on the ground below.

The Florida coast has one of the best stations in the U.S.A. for the roseate tern. The darter, which most North Americans allude to as the water-turkey (it is a fresh water lover), and the double-crested cormorant of Florida, commonly nest in trees in many swampy places along the coast. Brown pelicans nest by lagoons and in mangrove-keys on both sides of the peninsula.

Naturalists accustomed to British coast conditions can have little notion of the interminability of the low-lying eastern coast of North America. Indeed, on the entire stretch of mainland coast from Southern Mexico to Maine, about four thousand miles, there is not a single cliff, nor indeed a mountain coming down to the sea. All through Florida, Georgia, the Carolinas, Virginia and Maryland to the New England States, runs a complex of lowland and shallow shores, broken in places by inlets such as those of Chesapeake and Delaware Bays and Long Island Sound. This is a tern coast. In the northern parts the effect of the Labrador current is felt and there is a fairly steep decline in temperature, which is why such tropical forms as the brown pelican and Florida double-crested cormorant drop out of the community in South Carolina. One tropical species which is distributed all along this coast, however, is the laughing gull; and the gull-billed tern reaches north to Virginia. Rather oddly, two terns, the common tern and Forster’s tern, appear to avoid the mainland coast from Florida to South Carolina, though they breed to the west and north of it.

The distribution of tern populations on this Atlantic coast has had a chequered history, and is dealt with in some detail in the chapter on Sea-Bird Populations (Chapter 3, see here).

In the New England States and Maine we encounter the first truly northern elements in the Atlantic sea-bird fauna, and a community of sea-birds which is intensively watched and studied, as is the very similar community on the eastern side of the Atlantic, ten degrees farther north. We now meet not only some of the terns but some of the gulls that breed in the British Isles. In Maine and New Brunswick, where little cliffs begin and the wooded coast closely resembles the skerry-guard of Stockholm, and other parts of the Baltic archipelago, we find the southernmost auks—black guillemots Cepphus grylle, puffins Fratercula arctica, and perhaps still a pair or two of razorbills Alca torda. We even find tubenoses breeding in Maine, birds which we had last encountered in the Caribbean Antilles. (Apart from Audubon’s shearwater and the rare diablotin (see here), which nest in various of the Antilles, no breeding petrel is found in the western North Atlantic south of Maine, save on Bermuda.)

The rocks and coral reefs of Bermuda, which is 580 miles from Cape Hatteras, the nearest point on the United States mainland, support an interesting little community of sea-birds, which consists of the northernmost outposts of the breeding population of an otherwise completely tropical species, the white-tailed tropic bird Phaëthon lepturus, besides the common tern, the roseate tern, possibly the Manx shearwater Puffinus puffinus, Audubon’s shearwater, and the cahow Pterodroma cahow, thought to be extinct for many years.

It is in the Bay of Fundy, then, on the borders of the U.S. and Canada (Maine and New Brunswick) that the northern birds really begin. Here in burrows in the island rocks nest the southern elements of the rather small Atlantic population of Leach’s petrel Oceanodroma leucorhoa. Here, too, are the representatives of the northern race of double-crested cormorant, which are separated by a gap of some hundreds of miles from the geographical race of the same species belonging to Florida and the Carolinas.

Other birds which come on the scene between Cape Cod and the Bay of Fundy are the great black-backed and herring-gulls, Larus marinus and L. argentatus, which are now quickly spreading south down the coast, and the arctic tern Sterna paradisaea, which still nests as far south as Cape Cod. If we move north to the Gulf of St. Lawrence, we can also bring in an outpost population of the European cormorant Phalacrocorax carbo, the ring-billed gull Larus delawarensis, which is very closely related to our common gull, the common guillemot Uria aalge, and, rather surprisingly, an arctic species, Brünnich’s guillemot Uria lomvia, whose breeding distribution extends from the Magdalen Islands via Newfoundland and Labrador to the High Arctic There is a curious relict population of the Caspian tern also here. In many ways the Gulf of St. Lawrence has arctic properties and there is, as we have seen, a very steep gradient in water temperature at its mouth, at the convergence of the west wind drift and the Labrador current. Here we find the southern outposts of the largest temperate North Atlantic sea-bird, the gannet Sula bassana—though the majority of its breeding-population is found on the other side of the ocean; and we meet our first kittiwakes Rissa tridactyla.

In structure the coasts of the Atlantic right round from Maine via Nova Scotia, the Gulf of St. Lawrence, Newfoundland, Labrador, Greenland and Iceland to Britain, have a good deal of similarity. They have a fairly even supply of estuaries, inlets, beaches, sands, cliffs, skerries, stacks and islands, and it is probable that the distribution of no sea-bird is seriously limited by lack of suitable nesting sites.

There are two inland species of North American dark-headed gull, Franklin’s gull Larus pipixcan, and Bonaparte’s gull L. philadelphia, neither of which breeds near the coast.

From the Gulf of St. Lawrence, via Newfoundland, Labrador, Greenland and the Canadian Arctic Archipelago, we find a gradual disappearance of the temperate, sub-arctic and some low arctic species as we progress towards the shores where the sea is still near-freezing in July—the true High Arctic. In Newfoundland we reach the limit for breeding gannets, ring-billed gulls and common terns, and perhaps also Caspian terns. The Leach’s petrels breed as far as Newfoundland Labrador, but no farther, and it is doubtful whether the double-crested cormorant now breeds as far. South-west Greenland is less ‘arctic’ than opposite parts of the Canadian Arctic Archipelago at the same latitude; and it is not surprising that some species extend beyond Labrador to West Greenland, though not to Baffin Island and the other Canadian islands. Such species are the razorbill and common guillemot, the latter having only one small colony in West Greenland. The European cormorant extends to West Greenland and previously had a small outpost in Baffin Island, from which it has now disappeared, and it is also extinct in Newfoundland Labrador, after much human persecution. The puffin does not breed in the Canadian Arctic but goes far north in Greenland where it is of a distinctive, large arctic race.

Species which extend in breeding-range all the way from Newfoundland to Arctic Greenland and Canada are the herring-gull, great black-back, kittiwake, arctic tern and black guillemot. All these except the blackback reach the High Arctic, if we regard the Iceland gull Larus argentatus glaucoides, as a herring-gull, as we think we should.

The glaucous gull Larus hyperboreus, does not now breed in Newfoundland, but nests commonly from Newfoundland Labrador all the way to the High Arctic, as does the arctic skua Stercorarius parasiticus; two other skuas, the pomarine S. pomarinus, and the long-tailed skua S. longicaudus, do not breed in Labrador, but farther north in both Canadian and Greenland Arctic. On the west side of the Atlantic-Arctic the fulmar Fulmarus glacialis, breeds no farther south than Greenland and Baffin Island, although it nests south to about latitude 50° north on the east side of the Atlantic.

This leaves the three High Arctic sea-birds of the West Atlantic for consideration—the little auk Plautus alle, Sabine’s gull Xema sabini, and the ivory-gull Pagophila eburnea. All three breed in the more northerly parts of the Canadian Arctic Archipelago and Greenland, though the first may not have more than one colony west of Baffin’s Bay. Sabine’s gull is a rare bird that often nests in arctic tern colonies. The ivory-gull is the most northerly bird in the world in the sense that it breeds nowhere south of the Arctic Circle, but as far north as the land goes. The extraordinary, rare, Ross’s or rosy gull Rhodostethia rosea, which normally nests in the aldergroves of some north-flowing rivers of eastern Siberia, has once bred in Greenland.

The breeding sea-birds of the lands and islands north of the Arctic Circle belonging to the Atlantic or the Atlantic section of the Arctic Ocean.

With the exception of a few gulls, sea-birds entirely desert the arctic regions bordering Baffin’s Bay and Davis Strait in October and do not return until April. From no other part of the northern hemisphere is there so great a withdrawal of sea-birds to avoid a period of inhospitable climate.

The eastern arctic islands—Jan Mayen, Bear Island and Spitsbergen, Franz Josef Land and Novaya Zemlya, which lie across the Polar Basin where it abuts on the North Atlantic, have a very similar breeding sea-bird community to that of Greenland, though none has so many members. We can best make this comparison in the form of a table, adding columns for the Canadian Arctic, Arctic Russia-in-Europe and Arctic Norway. (see here)

We now come to the seabird community of Iceland, Faeroe, the British Isles, Scandinavia, the Baltic, and the North Sea and English Channel. This community is very homogeneous, considering the range of latitude over which it is spread, though there are some members which do not reach the south end of this range and a few which do not reach the north. Among the species which are found over almost the entire twenty degrees of latitude are the Manx shearwater, the storm-petrel Hydrobates pelagicus, the gannet, the shag Phalacrocorax aristotelis, the cormorant, the herring-gull, the lesser blackback Larus fuscus, the great blackback, the black-headed gull L. ridibundus, the kittiwake, the common and arctic terns, the razorbill, the guillemot, and the puffin. Species which occupy the more northerly parts of this temperate European stretch include the great skua Catharacta skua, and Leach’s petrel (Iceland, the Faeroes and Britain only), the fulmar, the arctic skua, and the black guillemot. The glaucous gull, little auk and Brünnich’s guillemot breed (in this part of the Atlantic) only in Iceland.

There is a central group of sea-birds which breeds neither as far north as Iceland nor as far south as Atlantic France; this is headed by the common gull Larus canus, and includes also the little gull L. minutus; its other members are terns, the whiskered tern Chlidonias hybrida (only casual, in Holland), the black tern C. nigra, the white-winged black tern C. leucoptera (casual only), the gull-billed tern and the Caspian tern. The populations of all these terns are low, and only two of them (black and gull-billed) have recently bred in Britain, and that casually; their headquarters lie between Holland and the South Baltic. The Baltic Sea, though it has as many breeding terns and gulls as any other part of this stretch of the east Atlantic, lacks tubenoses and has no gannets, shags, kittiwakes or puffins. The long-tailed skua has a somewhat specialised breeding distribution in Lapland, mostly inland. The remaining birds of this temperate stretch of the east Atlantic breed from Britain, the North Sea or the Baltic south beyond its limits; they are the roseate, little and Sandwich terns. Britain is the European headquarters of the roseate tern.

About half the members of this east and north Atlantic temperate sea-bird community are truly oceanic; that is, they may be found in mid-ocean, up to the greatest possible distance from land, wherever there are suitable feeding waters. Storm-petrels, Leach’s petrels and fulmars are the oceanic tubenoses of this community, and we now find that the Manx shearwater also has a right to be considered oceanic. Among the auks the dovekie and Brünnich’s guillemot from the north join the puffins, razorbills and guillemots in ocean wanderings. Here, too, are found all the four skuas of the northern hemisphere and one, but only one, gull—the highly specialised kittiwake. In the waters a hundred fathoms deep or less, that is, on the so-called continental shelf, we find all the birds previously mentioned, together with the gannet, the black guillemot, and gulls of the genus Larus—the great blackback, the lesser blackback and the herring-gull. Once we are within sight of shore quite a number of species are added to our list, and the tubenoses, except for the Manx shearwater and fulmar, drop out. Here are the terns, the black-headed and common gulls, and also the cormorant and shag, the one haunting mostly seas in sight of sandy shores, and other seas in sight of rocks.

By far the most impressive of the sea-bird haunts are the breeding cliffs, where the different species are zoned vertically as well as horizontally. Whether the rocks be volcanic or intrusive or extrusive or sedimentary, we are sure to find Larus gulls breeding on the more level ground a little way back from the tops of the cliffs—fulmars on the steeply sloping turf and among the broken rocks at the cliff edge, puffins with their burrows honeycombing the soil wherever this is exposed at the edge of a cliff or a cliff buttress, Manx shearwaters or Leach’s petrels in long burrows, storm-petrels in short burrows and rock-crevices, razorbills in cracks and crannies and on sheltered ledges, guillemots on the more open ledges where they can stand; perhaps gannets on broad flat ledges or on the flattish tops of inaccessible stacks, cormorants with their nests in orderly rows along broad continuous ledges, shags in shadowy pockets and small caves and hollowed-out ledges dotted about the cliff, kittiwakes on tiny steps or finger-holds improved and enlarged by the mud-construction of their nests, tysties or black guillemots in talus and boulders at the foot of the cliff. These wild, steep frontiers between sea and land are exciting and beautiful. They probably house larger numbers of vertebrate animals, apart from fish, in a small space, than any other comparable part of the temperate world.

Not many sea-birds of the east Atlantic do not breed on cliffs; but the skuas nest on moors, and the terns and black-headed gulls nest on sand and shingle. Many of the Larus gulls, and recently the fulmar, are catholic in their taste in nesting sites, and may be found on moors and even sand dunes. Quite a large number of sea-birds can be inland nesters, even including tubenoses. Fulmars now nest up to six miles inland in Britain, and many of the Larus gulls at much greater distances. The black-headed gull, in particular, is often a completely inland species, since some individuals nest in England as far as they can from the sea, e.g. in Northamptonshire, and may never visit it except in casual search for food.

As we go south along the Atlantic seaboard of the Old World we leave behind in the Channel Islands and Brittany the last elements of certain temperate cliff-breeding sea-bird species—the gannet, lesser blackback, great blackback, arctic tern (only a casual breeder so far south), razorbill and puffin. South of the Bay of Biscay we encounter a large sub-tropical and tropical community of about forty species (a few of which belong to sea-bird families but which have become river-birds or inland birds), which is distributed in four main geographical regions—the Lusitanian coast (the Atlantic coast of Spain and Portugal), the Mediterranean, the Atlantic coast of Africa north of the equator, and the Atlantic Islands. These last comprise the Azores, Madeira (to which pertain the Desertas and Salvages), the Canaries and—near the equator—the Cape Verde Islands. Many species breed, of course, in more than one of these regions, though only the herring-gull (rather doubtfully the little tern and cormorant) breeds in them all.

Of the species in the table, the crested pelican Pelecanus roseus, the pigmy cormorant Haliëtor pygmeus, the Mediterranean black-headed gull Larus melanocephalus, and the lesser crested tern Thalasseus bengalensis breed on no North Atlantic shore, and the rare slender-billed and Audouin’s gulls, Larus genëi and L. audouinii, are primarily Mediterranean species. It will be noted that three tubenoses have established themselves in the Mediterranean, but that no less than eight species breed in the Atlantic Islands, which have a greater variety of species of this order than any other part of the North Atlantic.

The distribution of breeding sea-birds on these coasts is best illustrated in tabular form :

Of the four main groups of these Atlantic islands, Madeira and the Cape Verdes have probably the largest sea-bird communities, with ten or a dozen species each. One tubenose, the North Atlantic great shearwater, Puffinus diomedea, nests on all of them as well as on the Berlengas of Portugal. Bulwer’s petrel, Bulweria bulwerii, and the little dusky shearwater, Puffinus assimilis, also nest on all four island groups. The Madeiran fork-tailed petrel, Oceanodroma castro, nests on all but the Canaries. The Manx shearwater nests on the Azores and Madeira, but not yet farther south. The little storm-petrel reaches south to the Canaries (although in small numbers and probably to these Atlantic islands only). The rather rare soft-plumaged petrel, Pterodroma mollis, is believed to nest on Madeira; it does so on the Cape Verdes. The beautiful frigate-petrel, Pelagodroma marina, breeds on the Salvages (which belong to Madeira but are nearer the Canaries), the Canaries and the Cape Verdes.

The red-billed tropic-bird, Phaëthon aethereus, the brown booby and the frigate-bird (man-o’-war bird) do not appear farther north than the Cape Verdes. Here the cormorant, which had dropped out in Morocco, reappears as a new race, primarily South African. The bird communities of these islands are only moderately well-known. Most of the sea-birds nest on rocks whose comparative inaccessibility has been both a temptation and a deterrent to the visiting ornithologist. As for the coast of West Africa and the islands lying close to it, no organised investigation of the sea-bird communities of this difficult region has yet been made. We know that one group of species breeds on the Atlantic African coast to Morocco, but no farther south—the shag, herring-gull, the whiskered tern, probably the gull-billed tern, possibly the slender-billed gull. Farther south both white and pink-backed pelicans, Pelecanus onocrotalus and P. rufescens, and the grey-headed gull, Larus cirrhocephalus, reach the tropical sea-coast in some places, and the brown booby nests on at least one island off the coast of French Guinea. The Caspian tern, whose world distribution is, to say the least, peculiar, may have breeding stations on this coast, and the little tern, which we had left behind in Morocco, reappears as a separate race on the coast and rivers of the Gulf of Guinea.

The African darter, Anhinga rufa, reed-cormorant, Haliëtor africanus, and the African skimmer, Rynchops flavirostris, haunt the rivers and in places reach the coast; but they are not sea-birds: and on islands in the Gulf of Guinea the noddy and the white-tailed tropic-bird, Phaëthon lepturus, breed. It is suspected that the frigate-bird may nest on this coast, but its breeding-place has not been found. Neither has that of the bridled tern, Sterna anaetheta, or the sooty tern, S. fuscata, although both species are seen in considerable numbers. There is at least one other riddle: a population of the royal tern, Thalasseus maximus, haunts almost the whole coast of West Africa from Morocco to some hundreds of miles south of the Equator. Systematists have separated it from the West Atlantic population as a subspecies (albidorsalis), on valid differences, and it does not appear to leave this coast, yet no ornithologist has yet seen its nest or even its eggs.

Only in the tropical parts of the Atlantic are there still these distributional queries. In the temperate and arctic zones the breeding places of the birds are well-known and described. And with this little mystery we conclude our tour of the Atlantic, for we are back on the equator and can strike west to the St. Paul Rocks, where we began.

FIG. 2a The breeding sea-birds of the North Atlantic, arranged by five geographical regions. No species breeds in more than four. Number of species; see opposite page for actual species

The sea-birds of the North Atlantic can be listed in the form of a table (Appendix, see here), and plotted according to which parts of the ocean they breed in, in the form of a diagram (Fig. 2). For the purpose of completeness, the secondary sea-birds have been included, those belonging to families whose fundamental evolution has probably been non-marine (like anatids and waders) or which are only sea-birds in winter (divers and grebes). Only the more important of these are on the diagram, and they are not otherwise treated in this book. It is interesting that more than half of them are northern ducks which winter at sea, though usually within sight of shore.

It must also be pointed out that several species belonging to the families of primary sea-birds have secondarily taken to life inland, on rivers, or on estuaries, and may reach the sea only incidentally or not at all. Certain West African species, in particular, are river-birds (the pelicans Pelecanus onocrotalus and P. rufescens, the reed-cormorant Haliëtor africanus, the darter Anhinga rufa, the skimmer Rynchops flavirostris). The terns of the genus Chlidonias are primarily lake and marsh species throughout their range. In North America the gulls Larus pipixcan and L. philadelphia are purely inland species in the breeding season, and the tern Sterna forsteri and the pelican Pelecanus erythrorhynchos almost so. In South America the terns Phaëtusa simplex and Sterna superciliaris are purely river-species.

FIG. 2b Actual species. Arrows point to replacement species or to nearest ecological counterparts

One hundred and eleven species of primary and thirty-two of secondary sea-birds have been identified by competent observers at sea or on some shore in the North Atlantic since 1800: a total of one hundred and forty-one. Of these one primary sea-bird, Alca impennis the great auk, and one secondary sea-bird, Camptorhynchus labradorius the Labrador duck, are now extinct. Of the survivors, eighty-two primary and thirty secondary sea-birds actually nest, or have nested, on or near a North Atlantic or Mediterranean shore or a shore of that part of the Arctic (north of the Circle) that communicates directly with the North Atlantic (this brings in six arctic species: ivory-gull, Ross’s gull, little auk, white-billed northern diver, brent-goose and Steller’s eider). Two further species (Larus pipixcan and L. philadelphia, see table) are purely inland breeders.

Most remarkably, the number breeding on the Old World and New World sides is almost exactly the same. We can derive the following summary of breeding-species from the Appendix; the totals include the two North American purely inland species, and the two extinct species. Doubtful (“?” in the Appendix) and casual cases are deliberately included—most of them are from tropical West Africa north of the equator where the breeding of the species in question seems likely but, owing to the scanty exploration of the coast, is not formally proved.

We can see that if we add the six purely arctic breeders to those species which are common to both east and west sides of the North Atlantic, we have fifty-five, out of a total of 116, or about half. Of the remaining sixty-one species, 24 breed only on the west side of the North Atlantic, four on the west side and in the Arctic; and six purely on the east side, and seven on the east side and in the Arctic. Those on the east side include four ‘sea-birds’ which breed in the Mediterranean area but not in the North Atlantic (the crested pelican, pigmy cormorant, Mediterranean black-headed gull and the lesser crested tern).

The general conclusion is of considerable ecological interest, showing how exactly the sea-bird communities of both sides reflect one another. Although only about two-thirds of the members of the community on one side of the Atlantic are found in that of the other, the species comprising the remaining third ‘balance each other’ and occupy very much the same ‘niches’ or places in nature. Opposite species which pair off by occupying similar niches are grouped together in the list in the Appendix, see here.

A NOTE ON NON-BREEDERS AND CASUAL WANDERERS

Apart from these 116 breeders, the limbo of twenty-six primary sea-birds and one secondary sea-bird (the spectacled eider Somateriafischeri, which has been recorded twice in Norway, though it breeds on the other side of the Polar Basin) consists of casual wanderers, with three remarkable exceptions. These are all tubenoses (two shearwaters and a storm-petrel) which breed in the southern hemisphere but which cross the equator in large numbers to ‘winter.’ The most familiar of these in Britain is the Tristan great shearwater Puffinus gravis, which is rather similar, and certainly closely related to the heavier North Atlantic or Cory’s shearwater, P. diomedea. Incidentally we suggest confusion between the two would be reduced if P. diomedea were consistently called ‘North Atlantic shearwater’ and P. gravis ‘Tristan great shearwater’—not just ‘great shearwater.’

The Tristan great shearwater nests only on Nightingale and Inaccessible Islands, in the Tristan da Cunha group; possibly a few may survive on Tristan itself. The population remains vast, though ‘farmed’ by the Tristan islanders, and an annual penetration of the North Atlantic by off-season birds has put the species on the list of regular and expected visitors to both West Atlantic and East Atlantic waters, as well as some arctic waters of Greenland. The northward movement reaches the North Atlantic in May, mostly on the west side at first, but odd birds appear in Irish and west British waters in June and have even been seen then in the Skagerak; one of us saw a few already at Rockall in mid-May (1949), and they were abundant there and in moult by late June (1948).

The Tristan great shearwater seldom comes close to land, and it is never common in British waters within sight of shore; but some distance to sea off west England, Ireland and the Hebrides it is always present in July and August; and some elements usually penetrate northabout into the North Sea, descending to the latitude of Yorkshire. The Tristan great shearwater is much more common than the Northern Atlantic shearwater in our seas; indeed, the Mediterranean race of the latter P. d. diomedea, and Cory’s race P. d. borealis, have each only once been taken ashore in Britain, although birds which may have been of Cory’s subspecies have several times been seen at the entrance of the Channel. The only Scottish record is of one, seen at sea close to Aberdeen on 10 September 1947, by R. N. Winnall. Normally as Wynne-Edwards and Rankin and Duffey have shown, Puffinus diomedea does not get much farther north in the Atlantic than 50°N., and that at about 30°W. It is much more common on the North American coast than on that of Britain, although this coast is much farther from its base; ‘they seem to arrive on our coasts early in August,’ writes Bent, ‘and spend the next three months with us, mainly between Cape Cod and Long Island Sound.’ The Tristan great shearwater also probably reaches its greatest abundance on the North American coast, particularly in the area of the Newfoundland Banks, where it is known as the ‘hagdon’; from here it extends every season along the coast of Labrador to Greenland;—it has been recorded near Iceland.

The other southern hemisphere shearwater that regularly visits North Atlantic waters is Puffinus griseus, the sooty shearwater. It is much rarer than the Tristan great shearwater, though it has been seen in British waters regularly enough to be classed as an autumn visitor. It breeds in New Zealand and its islands, in southern South America and its islands, and the Falkland Islands (in places many miles inland), and ranges the Pacific as well as the Atlantic; its Atlantic population is low compared with that of the other southern shearwater. Unlike the Tristan great shearwater, it probably makes its way into the North Sea by the Channel; and it is regular in small numbers in the Western approaches. At Rockall on 17 May 1949 J.F. saw none, but from 18 to 27 June 1948 R.M.L. found them always present there, singly and up to eight together, that is in the proportion of about one to a hundred hagdons. On the Newfoundland Banks, where it is in the same proportion, the fishermen called it the haglet. It reaches Greenland and Icelandic waters, and has been seen once as far north as Bear Island.

The storm-petrel from the south is Wilson’s petrel Oceanites oceanicus, which nests in vast numbers in the antarctic continent and on the southern islands of South Shetland, South Orkney, South Georgia, Falkland, Tierra del Fuego and Kerguelen. It disperses into, and across, the Equator in the Atlantic, Indian and Pacific Oceans. Wilson’s petrel has been the subject of an exhaustive monograph by Brian Roberts (1940), who mapped the dispersal in the Atlantic month by month (Fig. 29). Records north of the Equator are only irregular and sporadic between November and March, but in April the species is spread widely over the western half of the North Atlantic as far as Cape Cod. In May the petrels spread eastwards reaching from Cape Cod across the Atlantic towards Portugal and the Bay of Biscay, off which there is quite a concentration in June. By July there is a band of Wilson’s petrels across the whole North Atlantic with its northern border at about 40°N., but not reaching Britain. In August the eastern Atlantic petrels disappear, though on the west a concentration remains with its nucleus near Long Island Sound; and this persists in reduced population in September, by which time most Wilson’s petrels are making their way home. In September they reappear again off Portugal, and the homeward stream in October runs south along the north-west coast of Africa, continues its line across the Atlantic to the corner of Brazil, and carries on mainly down the east coast of South America; in November and December the concentration is at its greatest in the triangle Rio de Janeiro-South Georgia-Cape Horn.

There are only about ten records for this abundant and successful species, in Britain. It does not normally reach our islands, though elements cannot be within much more than a few hundred miles of Cornwall in June and July. Most of the British records are between October and December—suggesting young non-breeding birds, inexperienced in the ways of wind and wave.

Among the two dozen casual sea-bird visitors to the North Atlantic undoubtedly the most exciting are the kings of the tubenoses—the albatrosses, whose occurences in the North-Atlantic-Arctic are really monuments not so much to the fact that from time to time the best-adapted birds make mistakes and get right out of their range, as to the extraordinary powers of endurance and flight of the world’s greatest oceanic birds. Five albatrosses have strayed into the North Atlantic, four of the genus Diomedea, which includes the largest kinds, and one Phoebetria. All breed in the southern regions of the southern hemisphere.

The most frequent in occurrence has been the black-browed albatross D. melanophris, of which we can trace nine records. The first of these is astonishing; on 15 June 1878, north-west of Spitsbergen and north of latitude 80°N., the whaler-skipper David Gray shot one that is now in the Peterhead Museum; it was farther north than the species ever gets south, even though it nests to latitude 55°S. Another northerly record is from West Greenland, and others have been shot south-west of the Faeroes and in the Oslo Fjord, Norway; one is even alleged to have reached Oesel in the Baltic. In 1860 (Andersen 1894) a female black-browed albatross turned up among the gannets of Mýkinesholmur in Faeroe, and came to the cliff every season with them until 11 May 1894, when it was shot by P. F. Petersen. For many years the only British record was of one which was caught exhausted in a field near Linton, Cambridgeshire, on 9 July 1897; but on 14 May 1949 an immature albatross which was probably of this species was seen at the Fair Isle, between Orkney and Shetland. It was first noticed soaring off the south face of the Sheep Craig, the famous landmark on the east side of the island, and obligingly glided over George Waterston, G. Hughes-Onslow and W. P. Vicary, who got a fine view of it (Williamson 1950, 1950b). Further, in September 1952 one was picked up alive in Derbyshire (Edmunds, 1952; Serventy, Clancey and Elliott, 1953).

No other albatross has been certainly seen in Britain: a record of the yellow-nosed albatross from the Lincolnshire-Nottinghamshire boundary on 25 November 1836 is not admitted to the British list. This species, D. chlororhynchos, has been certainly obtained, however, in south Iceland, at the mouth of the St. Lawrence river, in the Bay of Fundy (New Brunswick), and in Oxford County, Maine. A record of D. chrysostoma from Bayonne in France* may possibly refer to this species, for D. chlororhynchos and D. chrysostoma are extremely similar, and almost impossible to distinguish in the field. D. chrysostoma, the grey-headed albatross, has, however, certainly been recorded once in the North Atlantic—from South Norway in 1837 (or 1834). The light-mantled sooty albatross Phoebetria palpebrata, a relatively small species which breeds on sub-antarctic islands, has been recorded from Dunkirk, France*. The greatest of all the albatrosses, the wandering albatross Diomedea exulans, has been taken, in France (Dieppe), Belgium (Antwerp) and on the Atlantic coast of Morocco; this magnificent animal has a wingspread up to 11¹&frasl;₂ feet and may weigh seventeen pounds or more; we can imagine the excitement of those humans who encountered these South Atlantic wanderers on their North Atlantic wanderings!

Sometimes these wanderings may end in queer places; for instance, F. J. Stubbs (1913) found an albatross that he judged to be D. exulans hanging among the turkeys of Christmas 1909 in a game-dealer’s shop in Leadenhall Market. When he saw it ‘the bird appeared quite fresh, and bright red blood was dripping from its beak.’ There was no indication whence it had been obtained.

Unidentified albatrosses have been seen at sea west of Spitsbergen on 2 May 1885, by the Captain David Gray who shot the 1878 black-browed albatross; off the mouth of Loch Linnhe, West Highlands of Scotland, in the autumn of 1884 by W. Rothschild; and twenty miles north-west of Orkney on 18 July 1894, by J. A. Harvie-Brown (1895).

Apart from the three regular non-breeding summer visitors and the albatrosses, at least six other tubenoses have wandered into the North Atlantic from the South, or from the Pacific. The Cape pigeon Daption capensis, has been recorded from France*, Holland and Maine, but the three British records have been rejected from the official list on the grounds that sailors have been known to liberate captured specimens in the Channel. Quite probably they are valid. Peale’s or the scaled petrel Pterodroma inexpectata, has once been taken in New York State. Pterodroma neglecta, the Kermadec petrel, has been once found dead in Britain (on 1 April 1908 near Tarporley in Cheshire). One Trinidad petrel Pterodroma arminjoniana, was driven to New York by the hurricane of August 1933, and possibly this close Atlantic relative of the Kermadec petrel may cross the equator fairly often, as it breeds on South Trinidad Island (only), which is fourteen hundred miles south of the equator, surely no very great distance for a petrel. One collared petrel Pterodroma leucoptera, a Pacific species, was shot between Borth and Aberystwyth in Cardiganshire, Wales, at the end of November or the beginning of December 1889. The last wandering tubenose is the black-bellied storm-petrel Fregetta tropica, a sub-antarctic species which was first collected off the coast of Sierra Leone and has also been taken in Florida. It seems likely that this last species may cross the equator fairly regularly, at least as far as the Tropic of Cancer.

One Pelecaniform wanderer has crossed the equator into the North Atlantic from South Africa—the Cape gannet Sula capensis, which may reach north to the Canaries.

From the western United States the California gull Larus californicus (which may be a race of the herring-gull, see here) winters fairly regularly to Texas, and thus (in our definition) to the North Atlantic region. Another gull which enters the North Atlantic, from more distant breeding-grounds, is the great black-headed gull, Larus ichthyaëtus of the Black Sea and farther east, which has reached Madeira and Belgium and has been seen in Britain about eight times.

Four exotic terns have wandered into the North Atlantic. The South American Trudeau’s tern Sterna trudeaui, has once reached New Jersey. On the east side Sterna balaenarum, the Damara tern of South Africa, has migrated across the equator as far as Lagos in Nigeria. Thalasseus bergii, the swift tern, breeds on the west coast of South Africa north to Walvis Bay, whence occasional individuals may sometimes pass north across the equator. The elegant tern Thalasseus elegans, of the Gulf of California, has accidentally reached Texas. And finally Gygis alba, the tropical, white, almost ‘transparent’ fairy tern breeds north in the Atlantic to Fernando Noronha, and therefore probably occasionally operates across the two hundred miles that would bring it to the North Atlantic, though there is so far no formal record of this. It has a wide distribution in all tropical seas, but is very much attached to, and does not often fly far from, its breeding-grounds; nevertheless R. C. Murphy (1936) ponders: ‘Since there are seasons when powerful southeast trade winds blow from Fernando Noronha across the equator almost as far as the mouth of the River Orinoco, speculation offers me no clue as to why Gygis has not succeeded in jumping the next gap and establishing itself in the West Indies.’

The remaining wanderers are from the North Pacific—auks from that cradle of the sub-order of auks. Aethia pusilla, the least auklet, has not actually reached the Atlantic, but one was found ‘halfway’ from the Pacific to the Atlantic, in the Mackenzie delta in May 1927. The ancient murrelet Synthliboramphus antiquus has been found three times in the Great Lakes area, but no farther east. Aethia psittacula, the paroquet auklet,* has actually reached the Atlantic by turning up in, of all places, Sweden: in December 1860 one was captured in Lake Vattern! If the least auklet has not reached the Atlantic, its congener Aethia cristatella, the crested auklet, has, for even if we reject (as most do) the alleged Massachusetts record, we must accept that of 15 August 1912 when one was shot north-east of Iceland. Finally Lunda cirrhata, the tufted puffin, was obtained by the great naturalist Audubon in Maine: other records from the Bay of Fundy and Greenland are erroneous.

FIG. 2c Bathymetrical sketch-chart of the Atlantic Ocean

CHAPTER 2 EVOLUTION AND THE NORTH ATLANTIC SEA-BIRDS

GEOLOGISTS DIFFER in their opinions of the origin of the Atlantic Ocean. The followers of the geomorphologist Alfred Wegener believe that it is a real crack in the earth’s crust whose lips have drifted away from each other, and this opinion is lent verisimilitude by the neat way in which the east coast of the Americas can be applied to, and will fit with extraordinary exactitude, the west coast of Europe and Africa. It must be stated that, while the present opinion of most geographers is that the resemblance of the Atlantic to a drifted crack is purely coincidental, this is not shared by all students of animal distribution and evolution, some of whom, find the Wegener theory the most economical hypothesis to account for the present situation.

Whatever the truth is, there is no doubt that the boundaries of the Atlantic, and their interconnections, have varied considerably; thus halfway through the Cretaceous Period, about ninety million years ago (during this long period nearly all the principal orders of birds evolved), there were bridges between Europe, Greenland and Eastern North America cutting the Arctic Ocean from the North Atlantic completely; and from then until the late Pliocene—perhaps only two million years ago—there was no continuous Central American land bridge, but a series of islands.

Our present knowledge of the tree of bird evolution owes much to Alexander Wetmore and his school, who have so notably added to our knowledge of fossil birds during the last twenty years, especially in North America. Birds do not appear very frequently in the sedimentary rocks—their fossil population does not generally reflect their true population in the same way as that of mammals is reflected. However, if land-birds are rare in the beds, water-birds are relatively common, and the periods and epochs in which all our sea-bird orders, and many of our sea-bird families and genera, originated are quite well known. A recent paper by Hildegarde Howard (1950), of the school of Wetmore, enables us to show a diagrammatic family tree of birds (Fig. 3), with special reference to sea-birds, and to collate its branching with the approximate time scale of the epochs, so cleverly established by geomorphologists in recent years from studies of sedimentation-rate and the radioactivity of rocks. It will be seen that the primary radiation of birds and the great advances into very different habitats consequent upon the first success of the new animal invention—feathered flight—took place in the Cretaceous period, the first birdlike feathered animals having been found as fossils in Jurassic deposits of the previous period, over a hundred and twenty million years old. In the Cretaceous period—the period of reptiles—ostriches were already foreshadowed, as were grebes and divers, and the pelican-like birds, and the ducks.

In the Cenozoic period—the period of mammals—the radiation of birds into all nature’s possible niches continued rapidly, especially in the first two of its epochs—Eocene and Oligocene—from sixty to thirty million years ago. In these epochs grebes can be distinguished from divers, and a bird of the same apparent genus (Podiceps, or, as the North Americans have it, Colymbus) as modern grebes has been found. Gannet-boobies of the modern genus Sula have been found in the Oligocene, as have cormorants of the modern genus Phalacrocorax. The only penguin fossils known are later—of Miocene age—but it seems probable that they share a common stem with the tubenoses, which would mean that their ancestors branched off in the Eocene. The tubenoses diversified in the Oligocene—from this epoch we have a shearwater of the modern genus Puffinus; and from the Miocene Fulmarus and albatrosses. The ducks started their main evolution in the Cretaceous, and by the Oligocene we find modern genera such as Anas (mallard-like) and Aythya (pochard-like); in the Pliocene we have Bucephala (Charitonetta)—one of the tribe of sea-ducks.

For the Lari-Limicolae, the order which includes waders, gulls and auks, the fossil record is rather indefinite, mainly owing to the difficulty of distinguishing the present families by bones alone. However, we know that the auk family was early—an Eocene offshoot; that the waders and gulls diverged in the Oligocene; and that the gulls, terns and skuas probably diverged in the Miocene—which means that an important part of the adaptive radiation of this order was comparatively late. One of the early auks, the Pliocene Mancalla of California, out-penguined the great auk, Alca (Pinguinus) impennis, for it had progressed far beyond it in the development of a swimming wing.

FIG. 3

Diagrammatic family tree of sea-birds, mainly after Hildegarde Howard (1950)

According to Howard (1950) a few living species of birds have been recorded from the Upper Pliocene, but large numbers of modern forms occurred in the Pleistocene. Of course in the Pleistocene the oceans approximated very closely to what they are today, with the Central American land-bridge closed, the Norwegian Sea wide open between Arctic and Atlantic Oceans, the Mediterranean a blind diverticulum of the North Atlantic. We need this picture as a background to a consideration of the North Atlantic’s present sea-bird fauna, for we shall find that it has few sea-bird species of its own, and only two genera; for the primary sea-bird species which now breed in the Atlantic (and Mediterranean) and in the neighbouring parts of the Arctic, and nowhere else in the world, are no more than twelve: the Manx shearwater Puffinus puffinus*; the very rare diablotin and cahow of the West Indies and Bermuda (Pterodroma hasitata and P. cahow); the storm-petrel Hydrobates pelagicus; the North Atlantic gannet Sula bassana; the shag Phalacrocorax aristotelis; the lesser black-back Larus fuscus; the great blackback L. marinus; the Mediterranean gulls L. melanocephalus and L. audouinii; the Sandwich tern Thalasseus sandvicensis; the razorbill Alca torda, the puffin Fratercula arctica; besides the extinct Alca impennis, the great auk. The two present genera peculiar to the North-Atlantic-Arctic are Hydrobates and Alca.

The sea-birds which qualify by birth and residence to be members of the North Atlantic fauna (excluding purely Arctic and Mediterranean species) include thirteen tubenoses, seventeen cormorant-pelicans, fourteen gulls, nineteen terns, two skimmers, four skuas and five auks (besides various secondary sea-birds, notably about eighteen ducks, three divers and two phalaropes). If we are to understand how these have got into the North Atlantic we should analyse the present distribution of the sea-bird orders and groups as between the different oceans.

The most primitive group of sea-birds, yet the most specialized, is that of the penguins. The Sphenisci have fifteen species in all, of which eight breed in the South Pacific, seven in the Antarctic Ocean, five in the South Atlantic and two in the Indian Ocean. One (and one only) reaches the Equator, and thus the North Pacific, at the Galapagos Islands. No live wild penguin has ever been seen in the North Atlantic.* It seems certain that the evolution of this order of birds has taken place in Antarctica and in the neighbouring sectors of the South Pacific.

The great order of Tubinares the albatrosses, petrels and shearwaters, probably originated in what is now the South Pacific. Nobody knows exactly how many species belong to this order, as there is a good deal of disorder in the published systematics of this very difficult group; but the number is certainly eighty-six, and may be over ninety. Of these fifty-four breed in the South Pacific, twenty-seven in the Antarctic, twenty-five in the North Pacific, twenty-four in the South Atlantic, seventeen in the Indian Ocean, thirteen in the North Atlantic, three in the Mediterranean, and only one, the fulmar, in the Arctic Ocean.

The Steganopodes are an order which is particularly well represented in the South Pacific and Indian Oceans. The pelicans, gannets, cormorants, darter, tropic– and frigate-birds number fifty-four species in all. Thirty-one breed in the South Pacific. Twenty-eight breed in the Indian Ocean. The North Pacific has twenty-three, the South Atlantic twenty, the North Atlantic sixteen, the Mediterranean six, the Antarctic three, and the Arctic two. The present distribution suggests that the order radiated from what is now the East Indian region—from south-east Asia or Australasia.

In the order Laro-Limicolae the family Chionididae, two curious pigeon-like sheathbills, Chionis, are found in Antarctica; and one also breeds in the South Atlantic and South Pacific.

In the family Laridae the gulls (subfamily Larinae) number forty-two. In the North Pacific sixteen of these breed, in the North Atlantic fourteen, in the Arctic eleven, in the South Pacific nine, in the Indian Ocean six, in the South Atlantic five, in the Mediterranean five, in the Antarctic two. Besides these two breed inland only in North America, one inland only in South America, and three inland only in the Palearctic Region. This appears to be the only group of sea-birds whose evolutionary radiation may have taken place from the north; the Arctic and neighbouring parts of the North Pacific and Atlantic appears to be the origin of the gulls. The terns (subfamily Sterninae) number thirty-nine, of which twenty-three breed in the North and twenty-two in the South Pacific, nineteen in the Indian Ocean, nineteen in the North Atlantic, fifteen in the South Atlantic, ten in the Mediterranean, two in the Antarctic, two in the Arctic and one inland only in South America. The radiation of terns appears to be pretty general over the world’s seas, and they may have originated in the tropics, perhaps in the Indian Region. The skuas (subfamily Stercorariinae) have only four species, one of which (Catharacta skua, the great skua) has its breeding-headquarters in the Antarctic; it also breeds in the South Pacific, South and North Atlantic. The other skuas have an arctic breeding-distribution which extends into the North Pacific and North Atlantic. The three skimmers Rynchops belong to a separate family, Rynchopidae; North Atlantic, South Atlantic and South Pacific each have two; the Indian Ocean has one. Some workers regard them as all of one species.

The family Alcidae (the auks) take the place in the north of the penguins of the south. Undoubtedly their origin has been in or not far from the Bering Sea. Of the twenty-two species, sixteen belong to the northern part of the North Pacific, twelve to the Arctic Ocean north of the Circle, and six to the northern part of the North Atlantic.

This concludes the list of sea-birds belonging to groups of super-family or higher status whose evolution has been marine. There are several further (secondarily marine) groups which contain sea-birds, or part-time sea-birds; thus all four members of the order Gaviae the divers, breed in the Arctic, and North Atlantic and Pacific regions, and winter at sea on the coasts of the oceans. Many of the twenty species of grebes, order Podicipedes, are marine outside the breeding-season, and six of them visit the coasts of the North Atlantic at that time. Among the geese and ducks many (see Appendix, see here) are partly marine, and some (e.g. eiders and scoters) are largely marine in the breeding—as well as in the off-season: two eiders and three scoters breed in the North Atlantic-Arctic. Among the waders (Charadriidae) the subfamily Phalaropinae contains only three members, all of which breed in the Arctic, North Atlantic and North Pacific, and two of which winter in the open sea.

If we ignore these secondary sea-birds, and consider the 267 species of the primary marine groups, we find that the hierarchy is this: South Pacific 128 (51 per cent.); North Pacific 107 (40 per cent.); North Atlantic 74 (28 per cent.); South Atlantic 73 (27 per cent.); Indian Ocean 73 (27 per cent.); Antarctic 44 (16½ per cent.); Arctic 31 (11½ per cent.); Mediterranean 24 (9 per cent.); and purely inland only 7 (2½ per cent.).

It can be seen that the North Atlantic, with its seventy-four species, is much lower than either half of the Pacific than would appear warranted by its area. There is not the faintest hint, from the radiation of any of the sea-bird groups, that either North or South Atlantic has been the arena of any great evolutionary changes. The Atlantic has been colonised from without; by penguins from the Antarctic; by petrels from the South Pacific; by pelecaniform birds and terns probably from the Indian Ocean; by gulls and auks from the Arctic. The North Atlantic and the immediately neighbouring parts of the Arctic have but two present sea-bird genera and only thirteen species of their own. We need not be surprised at this indication that the Atlantic’s bird fauna is derived from that of other oceans if we accept Wegener’s theory of the origin of the Atlantic; but whether the Wegener theory is true or not it is quite clear that the North Atlantic has not been the home in which any important group of sea-birds has evolved. This is not to say that there has been no sea-bird evolution in the North Atlantic; but it has not usually gone beyond the differentiation of species. Of this it has, indeed, much to show. Some of the classic examples which E. Mayr (1942) has discussed are North Atlantic species. Mayr’s thesis is that one species can only become two after it has been differentiated geographically. He opposes the notion which has found favour in some quarters that speciation may occur by ecological differentiation or by the differentiation of behaviour.

So far the available evidence appears to uphold Mayr’s view—at all events, for birds. During the present century much systematic work in the description and measurement of birds has been conducted in American and European museums, and much practical and theoretical work on evolution has also been done. But it needed the persuasions of Mayr and Julian Huxley (1942), amongst a few others, to collate the work of the systematists and the evolutionary zoologists. Sea-birds lend themselves to evolutionary study because they are so largely confined to coasts for breeding purposes. This makes their distribution often linear rather than of the ordinarily spatial two-dimensional type; and this linear distribution makes it easy to apply Huxley’s concept that the characteristics of animals tend to grade from one part of their range to another in an orderly way. Some of these gradations had been recognised long before Huxley thought of the word “cline” because they are adaptations to the environment. For instance Bergmann’s Rule states that from the warmer parts of an animal’s distribution-area to the colder parts there tends to be an increase in its size. Thus the puffins, black guillemots and eider-ducks of the Arctic are considerably bigger than those of Britain. The main adaptive reason for this is that larger animals have less surface in proportion to their weight, and consequently heat is not lost from them (if warm-blooded) so rapidly as it is from small animals. Another rule, Allen’s Rule, states that warm-blooded animals of cold climates tend to have their heat-radiating surfaces decreased by a reduction in size of their extremities and limbs such as ears, tails, necks, legs and noses. There is also a general tendency (Gloger’s Rule) for animals to become darker as humidity increases.

If we examine those sea-birds which are widely distributed, we find clines in various characteristics, notably in size, i.e. total size, and also size of limbs and extremities, beak-length, wing-length, etc., and in colour. There are also clines in shape; for instance the fulmars of the north-east Atlantic have very thick bills, those of Baffin Island rather more slender bills, those of the North Pacific more slender bills still, and those of the Antarctic very slender bills indeed. No sea-bird is arranged quite evenly in its geographical distribution. Just as the distribution in space is never even, so are the gradations in character never even. From one part of the geographical distribution of a species to the other, change often occurs more as a series of steps rather than as continuous ramp.

Most working ornithologists today will agree that there are more subspecific names about than a true understanding of bird evolution requires. It is the species which has reality and significance. In this book we have tried to be sparing in the use of subspecies, and have rejected some that appear in many current text-books. Nevertheless, a study of the geographical races of the species of the North Atlantic sea-birds will lead us to examine here some of the more fascinating examples of geographic differentiation. The classic example among the sea birds is the chain of the Larus argentatus and fuscus group, the herring-gulls and lesser blackbacks, which may include some birds which are regarded as separate species, e.g. the California gull L. californicus, and the so-called ‘Iceland’ gull, or better the Greenland herring-gull, L. glaucoides or leucopterus. The relationships of this superspecies (Fig. 4a) were first worked out by B. Stegmann (1934): we have included the results of subsequent systematic work in this map (Fig. 4b) and in the discussion which follows.

It will be seen that the subspecies is composed of three chains of subspecies which unite in Central Siberia, where the resident breeding subspecies is Birula’s herring-gull Larus argentatus birulai. The two northerly chains link round the Polar Basin, the two end links of one overlapping with the two end links of the other. Where they overlap, the two races of one chain-end are ‘herring-gulls,’ of the other ‘lesser blackbacks.’ These behave as different species. It can be found convenient to make the ‘species’ separation in the chain, between the two races birulai and heuglini, thus calling the latter Larus fuscus heuglini (it is the first really dark-mantled gull in the chain). This is more practical than splitting the chain into argentatus and fuscus in the Bering Strait area, though this is probably the place of origin of the ancestral gull that gave rise to the whole chain; for if all the palearctic group were fuscus some confusion would surround the light-mantled Mediterranean forms.

Special comments can be made on various members of the chain. In the zone of overlap in Western Europe the herring-gulls are distinguished from the lesser blackbacks not only by form but by many habits. The lesser blackbacks breed often inland on moors, and when coastal tend to colonise flattish ground set back from the cliff-tops beloved of the herring-gulls. While the herring-gulls are dispersive in winter, the lesser blackbacks are almost entirely migratory, wintering south of all but their most southerly breeding-places, though some of the dark L. f. fuscus of Scandinavia winter in Britain, and recently a minority of the British race L. f. graellsii has ‘revived’ an old habit of wintering in England, especially in Cheshire and Lancashire. Both species are also extending their breeding-range north; L. a. argentatus has colonised east and north-east Iceland since 1909, and a herring-gull of this or the Scandinavian race omissus was breeding on Bear Island in 1932, though not 1948. The graellsii lesser blackback has established itself in south Iceland since about 1925, and a group intermediate between graellsii and fuscus in Denmark since 1922.

The North American situation is of great interest. As the herring-gulls range north-east they become generally paler in colour. The much-discussed Kumlien’s herring-gull L. a. kumlieni was for a long time held to be a hybrid between the ‘Iceland’ gull of Greenland and L. a. thayeri, Thayer’s gull of the Canadian Arctic and Thule corner of north-west Greenland. But there seems no doubt that it is a valid race (Taverner, 1933) with its own discrete breeding-distribution in southern Baffin Island, though on the western marches of its distribution there are apparently some forms intermediate between it and thayeri (Hørring, 1937) and colonies off south-west Baffin Island have been described as mixed (Soper, 1928).

FIG. 4

Breeding distribution and relationships of all subspecies of Larus fuscus, L. argentatus and related forms. a Diagram of forms, with leg and mantle-colour

The palest of all the herring-gulls is the ‘Iceland’ gull. Unquestionably this extremely pale bird, with pale flesh legs, is a herring-gull, and conspecific with the other herring-gulls of North America. Reports of its breeding in the Canadian arctic archipelago are due to confusion with thayeri; there is no evidence whatever of its overlapping with this or any other subspecies of L. argentatus anywhere; and its similarity in size, structure and plumage is obvious. It is just a very pale kind of herring-gull; and at the same time happens, through convergence, to be extraordinarily similar to, though smaller than, the glaucous gull.* It is entirely confined to Greenland, breeding north to Melville Bay on the west (this inhospitable coast separates it from thayeri) and to Kangerdlugssuaq (at the south end of the Blosseville coast) on the east. Evidence of its breeding farther north in east Greenland, and elsewhere (e.g. Franz Josef Land, Novaya Zemlya) is quite unsatisfactory, and probably due to confusion with the glaucous gull; on Jan Mayen it was stated by F. Fischer to be as abundant as the glaucous gull in 1882–83, and to be nesting on low ledges, but it has not been proved to breed there since.

FIG. 4bBroken line: in Eurasia, L. fuscus; in North America southern limit of possible area of overlap between L. californicus and L. argentatus smithsonianus. Fig. 4a gives the key to the numbered forms.

In a complex situation, such as this, a confusion of scientific names is to be expected. In other cases it is often found that the vernacular name is less equivocal, and certainly more stable, than the scientific name! Such is not the present case, however; for the name ‘Iceland gull’ makes confusion worse confounded. It has never bred in Iceland. Hørring and Salomonsen (1941) have already used the English name Greenland Gull to describe it, and regard it as a race of Larus argentatus. We commend to our readers, and to the compilers of the Lists of the American and British Ornithologists’ Union : the Greenland Herring-Gull, Larus argentatus glaucoides (= L. a. leucopterus).

FIG. 5

Breeding distribution of Larus canus, the common gull, and the closely related L. delawarensis, the ring-billed gull

Among the North Atlantic sea-birds are others whose species have differentiated geographically and whose range-end populations have become different enough to occupy the same geographical area—but separate ecological niches, and thus preserve their identity. For instance, it is probable that the ring-billed gull Larus delawarensis, of North America, and the common gull of the Old World, L. canus, have not long since shared a common ancestor, though a subspecies of the common gull, which has probably spread across the Bering Straits from the Old World, now occupies Alaska and parts of the Canadian North-West, where it overlaps with the western element of the ring-billed gull (Fig. 5). Here the two act as different species. The glaucous gull and the great blackback, which overlap in eastern North America, Iceland and parts of the European Arctic (Fig. 6) may be not long ago descended from a common ancestor. They very rarely hybridise. How the three species of terns—the arctic, common and Forster’s—which are very closely related, arrived at their present distribution (Fig. 7) is difficult to imagine at this stage of their evolution, but they all may be descended from a common tern of north-east Asia or an arctic tern of the North Pacific—from which part of the world the species has probably spread, differentiated and overlapped.

Various suggestions could be made as to the origins of the two guillemots, the common and Brünnich’s guillemot (Fig. 8). Possibly the original guillemot was a common guillemot (Uria aalge) type which got divided into two subspecies in the Atlantic and Pacific by the Ice Age, but not before it had had time to give rise to an arctic race adapted to the harder life. After the Ice Age, with the ameliorating conditions, perhaps both the Atlantic and the Pacific guillemots began pushing north again, this time to meet and overlap with their arctic descendant, which, meantime, had differentiated sufficiently to offer no direct competition. It is interesting to note that the most arctic of the common guillemot races, Uria aalge hyperborea of Iceland, Novaya Zemlya, and Lapland, has a very thick bill and a considerable resemblance to Brünnich’s guillemot, with which it, however, does not interbreed, nor apparently compete. Perhaps it is recapitulating some of the early stages in the origin of Brünnich’s guillemot. To some extent Brünnich’s guillemot, with its razorbill-like beak, appears to replace the razorbill in the arctic, where it may occupy the same ecological (feeding and breeding) niche in relation to the common guillemot as the razorbill does in relation to that bird in the south part of the common guillemot’s range.

The student of variation will find much material for his researches among the North Atlantic sea-birds. Several species of North Atlantic birds, notably the common guillemot, the three smaller skuas and the fulmar, are polymorphic or dimorphic. They exist in several so-called phases. Some common guillemots have a white ring embracing their eye from which a white line runs back towards the back of their heads. These are called ‘bridled’ guillemots, and were for long actually thought to be of a different species. The phases of the skuas range from very light phases with yellow over their ears and the back of their necks, white throats and bellies, to those which are almost uniformly brown. The breeding fulmar population of Britain, the Faeroes, Iceland, Jan Mayen and West Greenland are all light-coloured with white bellies, necks and breasts, but in Baffin Island, Spitsbergen and Franz Josef Land the fulmars are nearly all very dark coloured. Between the light forms of Britain, etc., and the dark forms of Spitsbergen, there are a number of puzzling intermediates, most in evidence on Bear Island (and often to be seen at sea in the Rockall area), and the situation among the fulmars is therefore one not of dimorphism but of polymorphism, as it is among the skuas.

FIG. 6

Breeding distribution of a group of closely-related gulls: Larus occidentalis, the western gull: L. glaucescens, the glaucous-winged gull; L. schistisagus, the slaty-backed gull; L. hyperboreus, the glaucous gull; and L. marinus, the great black-back. Areas of overlap shaded. Black areas in Canadian Arctic represent outpost breeding-places of L. marinus

Southern, who has carefully studied the problem of the differential distribution of the bridled guillemot, thinks that its ‘bridle’ is probably controlled by a single Mendelian factor, which appears to control also a slight difference in the skull structure and the shape of the tail-feathers. He organised counts of the percentage of bridled guillemots throughout Britain in the years round 1939 and again in those round 1949; and he has also collected as much evidence as he could from the rest of the guillemot’s range. Two main conclusions are apparent: first, the percentage of bridled birds increases from SSE to NNW (with a reversal in Iceland); and secondly the percentage is not always constant at any one place—there are signs of trends towards increase or decrease, and of shifts, or drifts, of the balance. Possibly the possession of a bridle gives a guillemot an advantage over other guillemots in some environments, and a disadvantage in others, though we do not know why: the alternative is that possession of the bridle is the result of an advantageous mutation that is spreading through the population; which is unlikely to be the case on the evidence, though Southern has been careful to show that the possibility still exists. There is no indication that bridled guillemots prefer to mate with each other rather than with unbridled guillemots; mating in a mixed colony appears to be completely, or almost completely, at random.

FIG. 7

Breeding distribution of three closely-related terns: Sterna hirundo, the common tern; S. paradisaea, the arctic tern; S. forsteri, Forster’s tern. Areas of overlap shaded. S. h. turkestanica is a doubtful subspecies

Southern shows that the percentage of bridled birds marches fairly closely with humidity and cloudiness; but, as he points out, many other factors may be involved. The changes between c.1939 and c.1949 may be linked with the climatic amelioration, but “might very well be due to random fluctuation.” The actual percentages as recorded in the paper of Southern and Reeve (1941) and Southern (1951), and in a few notes published by other observers, are shown on the maps (Figs. 9a, 9b). The results of Southern’s enquiry of 1949 have shown that out of the very many colonies studied in Britain at only five has a significant* change been recorded in ten years, four of which show decreases of the percentage of bridled birds and one an increase. One of the decreases is at St. Kilda, where the expedition of 1939 found 16.5 per cent. of the guillemots bridled and that of 1948 only 10.3 per cent. (one of us took part in both counts). Other decreases in Britain have been significant, as at the Isle of May, 5.3 to 3.2 in ten years; and at Unst in Shetland—23.8 to 16.9 per cent. in the same period. There has also been a significant decrease—of about one-third—in Iceland; thus at Grimsey in the north, from 8.7 in 1939 to 6.9 per cent. in 1949; at Hafnaberg, in south-west Iceland, from 29 per cent. in 1939 to 18.1 per cent. in 1949; in the Westmann Islands a parallel decline from 75 per cent. in 1935 (Lockley, 1936) to 50 per cent. in 1949.

FIG. 8

Breeding distribution of two closely-related guillemots or murres: Uria aalge, the common guillemot; and U. lomvia, the arctic guillemot (Brünnich’s guillemot* in the Atlantic, Pallas’s murre in the Pacific). Areas of overlap shaded.

Increases noted in the 1939–1949 enquiries were several, but only one, at Foula in Shetland, was significant and by checked observers (from 24 per cent. in 1938 to 29.4 per cent. in 1948–49). Increases on the margin of significance were recorded from St. Bee’s Head in Cumberland, Marwick Head in Orkney, and the Fair Isle. Apart from these small increases in the last decade, there was a significant increase of the percentage on Noss in Shetland from 15.5 in 1890 to 26.5 in 1938, which seems great enough to embrace a possible slight observer-error.

Unfortunately, too few of the early bridled guillemot counts are reliable, though some from Berneray and Mingulay (‘Barra Head’) in the Outer Hebrides may be so. This had 20.2 per cent. in 1871; 12 in 1939; 9.8 in 1949; 12.6 in 1950. The decrease between 1871 and 1939 is significant, though the other apparent changes are not so. Elsewhere we have followed Southern in discarding such vague records as ‘about one in every nine or ten.’

Nothing is yet known about the percentage of bridled guillemots along the coast of Norway, except that it has remained slightly over 50 per cent., at Bear Island from 1932 to 1948. At the Karlov Islands off the Murmansk coast the percentage was 42 in 1938. It seems likely, from the rather scanty figures from Novaya Zemlya, which Southern slightly misdates and misplaces, that the percentage may be about the same on islets in Pukhovy and Bezymiannaya Bays off that island (36.4 and 50).

These changes are curious and it is clear that much remains to be solved about this interesting problem in distribution and evolution. Nor is much known about the distribution of the bridled form in the New World, save the following: H. F. Lewis found 128 bridled out of a sample of 724 (17.7 per cent.) in the colonies along Quebec Labrador in 1929. One of us found 51 bridled out of a sample of 295 (17.3 per cent.) at Cape St. Mary, on the south-west corner of the Avalon Peninsula of Newfoundland, in 1953. In June, 1940 at Funk Island and other parts of the east coast of Newfoundland within forty miles of it W. Templeman (1945) collected twelve common guillemots (? at random) of which six (50 per cent.) were bridled. When Hørring and Salomonsen (1941) compiled a list of all the common guillemots that had been then collected on the west coast of Greenland they recorded six out of thirty-two (18.7 per cent.) as bridled, but knew of no breeding-colony. Soon afterwards Salomonsen (1944) became aware of the colony in the Sukkertoppen district; but no count has apparently yet been made there.

FIG 9a The principal breeding-colonies of the common guillemot in Britain. The percentages of bridled forms in the breeding-populations, as determined chiefly by H. N. Southern and his colleagues, are shown. Minus and plus signs in brackets indicate changes in the decade c. 1939–c. 1949 which are significant, or on the borderline of significance. Crossed circles mark sites of former colonies.

FIG. 9b The distribution of bridled guillemots in the East Atlantic breeding-populations: O: no bridled birds observed. A: under 1 per cent bridled. B: under 2 per cent bridled. C: under 5 per cent bridled. D: under 10 per cent bridled. E: under 20 per cent bridled. F: under 50 per cent bridled. G: over 50 per cent bridled.

All the four skuas appear to vary in plumage; the bonxie (great skua) particularly in the amount of rufous colour, especially among some of its southern forms; the three smaller skuas have a ‘normal’ pale phase of plumage with light breast and underparts, and yellowish or buff on the sides of their necks; and a ‘dark’ phase which is almost uniformly, or uniformly, dusky; and intermediates. The dark phase of the long-tailed skua is so rare that it has hardly ever been seen. Among the population of pomarine skuas, wherever they may breed, from five to twenty per cent. are dark; the distribution of dark birds is even, in the sense that there is no detectable gradient. Southern’s detailed analysis (1944) shows that no geographical area contains significantly more dark pomarine skuas than any other. Among the arctic skuas (Southern, 1943), however, the situation is quite different. In the southern parts of this bird’s breeding-range about three-quarters of the birds are dark; in the middle parts about half, in the Low Arctic less than half, and in the High Arctic a quarter or less. In north-east Greenland, indeed, the dark form is unknown. There are a few, rare, birds intermediate in colour between the pale and dark forms. This looks like a quivering balance between two ‘stable’ types. The proportion of the colour-forms in the British colonies is (Southern points out) subject to rather special considerations, since the colonies are generally small and scattered, and thus liable to random fluctuations—in fact between the limits of 50 and 86 per cent. dark. The mean probably lies at about 75 per cent.

Southern has attempted to correlate the distribution of the dark arctic skuas (Fig. 10) with temperature, relative humidity and various ecological factors. His material carries darkness with humidity over a considerable part of the bird’s total range; but the correlation breaks down in Norwegian Lapland—also, good meteorological figures are not available for all the arctic regions.

FIG. 10

Distribution of colour-phases of the arctic skua, Stercorarius parasiticus, from H. N. Southern (1943), showing isolines for percentage of the pale phase in the breeding population.

We found the same difficulty in correlating the distribution of the colour phases of the fulmar, Fulmarus glacialis, with climate and other environmental factors. In the Atlantic (though not the Pacific) part of the fulmar’s range the situation is in many ways the opposite of that among the arctic skuas; where the surface of the sea is above freezing (i.e. in the Low Arctic and rest of the range) the fulmars are nearly all light. The gradient runs from 0 per cent. dark in Britain to a hundred per cent. (probably) in the High Arctic of Spitsbergen and Franz Josef Land; in West Greenland (Low Arctic) the fulmars are very nearly all light. Finn Salomonsen suggested to Fisher (1952) a correlation between this distribution (Fig. 11) and surface water-temperature. Dark fulmars are only found in the areas where the water is nearly freezing, or freezing, in July, in which month the adults collect food for the chick fulmar. It is interesting to note that approximately the fifty-fifty situation in the distribution of colour-phases of the fulmar (as also of the bridling in the guillemot) is found at Bear Island, whose position is between Low and High Arctic. However, the Pacific fulmar appears to reverse the situation found in the Atlantic; the dark fulmars are found in the warmer parts of the Pacific fulmar’s range, and the light fulmars progressively towards the colder parts, though nowhere does this race of the fulmar breed in truly High Arctic waters.

FIG. 11

Breeding distribution of the fulmar, showing the approximate preponderance of dark birds in the populations, indicated by the dark parts of the circles (from Fisher, 1952)

The existence of these polymorphic forms of some birds constitutes a problem of the greatest interest, which travellers and amateur naturalists might well help to solve by collecting simple counts of the relative proportions of easily recognisable forms.

CHAPTER 3 SEA-BIRD NUMBERS AND MAN

EVERY BIRD has a history, which is a tale of adventure and fluctuating fortunes, of success, or of failure; for every bird, like every other animal, suffers change. In any study of the life of birds, and the place of birds in nature, an understanding of their numbers is fundamental.

Since most sea-birds are social animals, and nest in colonies in wild and beautiful places, their numbers can often be studied very closely, and with a great deal of enjoyment. So enthusiastic is the average amateur bird-watcher about visiting sea-bird stations, and ‘collecting’ islands, that it is safe to say that every important seabird colony on both coasts of the United States (not Alaska), and on those of the Faeroes, Britain, France, Belgium, Holland, Denmark, Germany, Finland, and Sweden is known to somebody who can distinguish its birds from each other; and most of those in Norway, Spain, Portugal, Iceland and St. Lawrence-Canada are known. The sea-bird stations of Greenland, thanks to a tradition of accurate observers from Giesecke to Bertelsen and Salomonsen, are better known than those of the Canadian Arctic, Newfoundland, the U.S.S.R., China, and perhaps even Japan. Those of the Antarctic and Subantarctic, and South America, are perhaps better known than those of the tropical Pacific. Probably a very adequate list of the sea-bird stations of the United States (excluding Alaska) or of north-west Europe could be compiled by some bibliophilic ornithologist with access to all the local as well as national bird and natural history journals of those countries. Such lists would be useful documents; they would have to be carefully dated, because of what history tells us of the fortunes of animals, and of change. Fisher has recently compiled a dated list of all the fulmar colonies of the world, and we have both, at different times, compiled lists of the world’s gannetries. It is surprising how certain it is possible to be of being complete, within reasonable limits. Thus after the publication of his Report on the 1938 survey of black-headed gull colonies P.A.D. Hollom (1940) had no colony known (or not known) to be occupied in 1938 to add or subtract from his list of 342 such colonies. When Fisher and Vevers (1943–44) organised a census of the North Atlantic gannet in 1939, only two small colonies of the twenty-three which then existed were overlooked in that year. When Fisher and Waterston (1941) reported on the fulmar colonies known to them in Britain in 1939 they believed that there were 208 separate stations at which the fulmars were breeding. Ten years later, after carrying on research and correspondence with the same intensity to discover the situation in 1944 and 1949 (during which ‘back information’ was also collected), Fisher discovered that he had overlooked only nineteen, all small (and some in very remote parts), and unimportant as far as the fulmar’s population, or the actual extent of its range, were concerned.

A census of the sea-birds of the North Atlantic is no longer a wild dream. A start has been made with certain obvious species, with limited distribution or small populations. The organisational problems are not insuperable; we have an ever-increasing body of highly competent bird-watchers available for, and keen on, the counting of nests: for a sea-bird census depends on the assessment of the number of occupied nests. Such a census has already been performed for several species on the coasts of Germany (Schulz, 1947), and, judging from the descriptions of the distribution of sea-birds in Sweden (Lundevall, unpublished), Denmark (Jespersen, 1946, and Løppenthin, 1946), the Netherlands (van Ijzendoorn, 1950) and Belgium (Verheyen, 1951), it need not be long before a census of the southern North Sea and Baltic could be complete. In Britain good surveys, if not censuses, exist for the sea-bird colonies of most counties in England, and there are records published in the present century concerning almost every bird-cliff in mainland Britain (though not every species on the cliff) and many in the Hebrides, Northern Isles and Ireland. Complete censuses, or careful estimates, have been made of many species of sea-birds in various countries with a North Atlantic-Arctic seaboard; of which a selection is:

SOME CENSUSES

of apparently occupied nests (i.e. an approximation to the apparent total breeding pairs) of North Atlantic sea-birds in some parts of their range (in a few cases, world census). Censuses of single colonies are not included unless these are of great importance.

Fulmar, c. 100,000 in Britain, including St. Kilda, in 1949 (and five-yearly estimates since eighteen-seventies; Fisher, 1952): c.350 in Norway in 1947 (P. Valeur, 1947): c. 200,000 in West Greenland (F. Salomonsen, 1950): c.200,000 on Bear I. in 1932 (Bertram and Lack, 1933): c.100,000 + at Cape Searle, Baffin I. in 1950 (V. C Wynne-Edwards, 1952).

North Atlantic (Cory’s) shearwater, c.20,000 on the Salvages, pertaining to Madeira, in 1939 (R. M. Lockley, 1952).

Great (Tristan great) shearwater, world population between 2 and 2½ million, all on Tristan da Cunha in 1949–50 (M. K. Rowan, 1952).

Cahow, world population all on Bermuda where 13 or 14 nests found and 1951 population “perhaps of the order of 100 adult birds, there may be fewer, but there are not likely to be more.” (Murphy and Mowbray, 1951).

Leach’s petrel, c.2,000 in Britain; this estimate contains a guess of 1,000 nests on St. Kilda in 1931 which is unreliable since not all the St. Kildan islands on which the species nests were visited (Atkinson and Ainslie, 1940): c.13,000 in Newfoundland in 1942–45 (Peters and Burleigh, 1951).

American white pelican, world population c.15,000 in 1932 (B. H. Thompson, 1932).

North Atlantic gannet, world population c.83,000 in 1939, of which c.70,000 in Iceland-Faeroes-Britain; in 1949 c.82,000 in Iceland-Faeroes-Britain (Fisher and Vevers, 1943–44, 1951). See here.

Double-crested cormorant, Population entire n.e. subspecies P. a. auritus, c.20,000 in ’twenties (H. F. Lewis, 1929); re-established on eastern seaboard U.S. c.1925 (E. H. Forbush, 1925, H. L. Mendall, 1936); c.900 in 1931 (Norton and Allen, 1931), over 10,000 in 1944 (A. O. Gross, 1944).

European cormorant, in Holland c.1,200 in 1926, c.2,600 in 1934, c.4,000 in 1937, 4,622 (peak) in 1940, 4,359 in 1941 (van Ijzendoorn, 1950); in Belgium 30 in 1950 (R. Verheyen, 1951); in North America 1,086 in 1940 (H. F. Lewis, 1941).

Great skua, just over 100 in the Faeroes in 1942, c.200 in 1946 (K. Williamson, 1945b, 1948, L. Ferdinand, 1947); c.1,000 in Great Britain (all Shetland and Orkney) around 1946 (R. Perry, 1948, Royal Society for the Protection of Birds watchers and other sources).

Ring-billed gull, c.1,750 in Gulf of St. Lawrence in 1940 (H. F. Lewis, 1941b.).

Common gull, c.500,000 in Denmark in 1939 (P. Géroudet, 1946); 20,221 in Germany in 1939 (Schulz, 1947); c.250 in Holland in 1949 (van Ijzendoorn, 1950); a few occasionally on the Belgian border (Verheyen, 1951); c.30 in England in 1941.

Herring-gull, c.27,500 in Holland in 1938 (van Ijzendoorn, 1950); 28,569 on North Sea coast of Germany in 1939 (Schulz, 1947); under 9,000 in Maine in c.1900, c.16,500 in 1921, c.25,000 in 1931 (Norton in Palmer, 1949).

Lesser blackback, 1 in Germany 1927–28, c.6 in 1938–47 (Schulz, 1947); colonised Holland since 1926, not more than 50 (van Ijzendoorn).

Great blackback, c.1,100 in England and Wales in 1930 (Harrisson and Hurrell, 1933); c.20 in Denmark in 1941 (F. Salomonsen, 1943); 16 on Bear Island in 1948 (Duffey and Sergeant, 1950); 3 in United States in 1928, at least 1,250 in 1944 (A. O. Gross, 1945).

Laughing gull, c.25 in Maine in 1860–70, 1, 2, 3 or 4 from c.1884 to c.1918, c.150 in 1931, 1936, c.250 in 1937–38, c.300 in 1940, c.50 in 1941, none since. (Palmer, 1949); in Western U.S. 2 in 1928 (Miller and van Rossem, 1929).

Black-headed gull, 35,000 in England and Wales in 1938 (P. A. D. Hollom, 1940, S. Marchant, 1952).

Little gull, 15 in Holland in 1942, 18 in 1943, 13 in 1944, 1 or 2 in 1945, c.8 in 1949 (van Ijzendoorn).

Kittiwake, 6,000 to 8,000 in England in late 1940’s (J. Fisher, from literature and notes); 11 in Denmark in 1941, 15 in 1942, 124 in 1946 (Salomonsen, 1941, Løppenthin, 1948); 1–3 in Germany in 1938–39 (R. Drost, 1939); 24,400 in Newfoundland in 1941–45 (Peters and Burleigh); probably c.10,000 in Gulf of St. Lawrence in 1940 (H. F. Lewis, 1941b and others).

Black tern, 8 in Britain in 1941, 5 in 1942 (R. Cooke, 1946); none in other recent years.

Whiskered tern, 8 in Holland in 1938, 9 in 1945 (invasions; van Ijzendoorn).

White-winged black tern, 1 in Belgium in 1937 (R. Verheyen, 1951).

Gull-billed tern, 1 in Holland in 1931, 1 in 1944, 2 in 1945, 3 in 1949 (van Ijzendoorn).

Caspian tern, 300 in Germany in 1819, 25 in 1874, none since 1918; 7 in California in 1922, 296 in 1930, 378 in 1943 (A. H. Miller, 1943); c.200 in Gulf of St. Lawrence in 1884 (M. A. Frazar, 1887), 30–55 between 1925 and 1940 (H. F. Lewis, 1941b.), 45 in 1945 (O. H. Hewitt, 1950).

Common tern, c.4,450 in Maine in 1931–36 (Palmer, 1949); c.15,000 in Cape Cod region of Massachusetts in 1930–44 (O. L. Austin, 1946) ; 15,000–16,000 in Germany in 1939 (Schulz); c.19,000 in ‘de Beer’ sanctuary, Hook of Holland, in 1939 (van Ijzendoorn); doubtful whether in any year in the present century more than 7000 in England and Wales, and likely that over half of these have been in Norfolk (J. Fisher from literature and notes).

Arctic tern, c.5,970 in Maine in 1931–36 (Palmer); c.4,700 in Germany in 1939 (Schulz); probably under 200 in Holland (van Ijzendoorn); doubtful whether in any year more than 3,000 in England and Wales, and likely that over half of these have been in the Farne Islands (J.F.).

Roseate tern, c.276 in Maine in 1931–36 (Palmer); 1 or 2 in Germany in most years since 1904 (Schulz); 2 in the south of France in 1951 (R. M. Lockley); over 1,000 in the British Isles in recent years, about a third of which are in Anglesey and about half of which are in Ireland (J.F.)

Sooty tern, in Pacific c.166,950 on Laysan Island (Dill & Bryan, 1912); in Indian Ocean over 25,000 in 1937 on Goelette, c.65,000 on Bird Island (Seychelles), c.5 million in 1931 and at least ¼ million in 1937 on Desnoeufs (D. Vesey-Fitzgerald, 1941); in U.S.A. (breeds Dry Tortugas only) c.7000 in 1903, 9,000 in 1907, 10,000 in 1908, 9,000 in 1917, 15,000 in 1935, 20,000 in 1936, 50,000 in 1937, 32,029 in 1938, 35,000 in 1939, c.50,000 in 1940, over 50,000 in 1941, 32,500 in 1942, 54,500 in 1945, 48,600 in 1946, 32,135 in 1947 (P. Bartsch, 1919; A. Sprunt, 1948).

Sandwich tern, c.40,000 in Holland in 1940 (van Ijzendoorn, 1950); this perhaps four-fifths of whole population of north-west Europe; other occupied countries, all with very fluctuating numbers, Sweden (200–300 nests in early ’forties), Germany (3,957 in 1940), Denmark (unknown number), the British Isles (fluctuating between two and five thousand nests, and about 3,500 in early ’forties, J. F. from literature and notes), and Danzig, Brittany and Portugal (a few each).

Noddy, in U.S.A. 200 in 1903, 2,000 in 1907, 700 in 1908, 2,000 in 1917; 1,500 in 1935, 2,000 in 1936, 1,000 in 1937, 206 in 1938, 125 in 1939, 90 in 1940, 500 in 1941, 225 in 1942, 375 in 1945, 275 in 1946, 125 in 1947 (as sooty tern).

Little auk, in Iceland, now breeds Grimsey only, where c.50 in 1820, 150–200 in 1903, c.20 birds in 1934, at least 19 birds in 1949 (see here.)

Razorbill, 12 in Germany in 1939 (Schulz), all on Heligoland; 318 in Denmark in 1939 (Salomonsen, 1943), all on Græsholm, where 60 pairs in 1944 (K. Paludan, 1947). Peters and Burleigh (1951) suggest that there may not be more than 450 in Newfoundland.

Common guillemot, c.25,000 pairs in Sweden in early nineteen-forties (F. Salomonsen, 1944), nearly all on Störa Karlsö, where only 10 in 1880, c.1,250 in 1918; in Denmark established Græsholm in 1928, c.60 in 1936, 100 in 1938, 122 in 1939, 127 in 1940, 208 in 1941, 158 in 1942 (Salomonsen, 1943, 1943b); c.200 in c.1946 (P. Jespersen, 1946); in Germany c.2,000 all on Heligoland (Schulz and ourselves). Peters and Burleigh (1951) suggest that there may not have been many more than 25,650 in 1941–45 in the whole of Newfoundland, but it seems clear that the total west Atlantic common guillemot population is at least 40,000, of which there are about 7,700 in Quebec Labrador (R. A. Johnson, 1940), c.10,000 on Anticosti Island (H. F. Lewis, 1941c.), and perhaps 500 on Bonaventure Island in Quebec and 700 on the Bird Rocks in the Magdalen Islands (A. C. Bent, 1919).

Brünnich’s guillemot, c.2 million in Greenland (Salomonsen, 1951).

Black guillemot, c.250 in Maine in 1948 (Palmer); 3 in England in 1940 (Cumberland; Blezard and others, 1943).

Atlantic puffin, world population 1952, not less than 7,612,500, of which 2,500,000 each Iceland, Faeroes; 2,000,000 Brit. Is. (J.F. thinks this an under-estimate); 62,500 France, Channel Is. (R.M.L., 1953).

Though this list includes some very small numbers of sea-birds breeding in some countries and lands desultorily, or at the very edge of their range, there have been some big censuses; and of five North Atlantic sea-birds, Tristan great shearwater, cahow, American white pelican, gannet and puffin, we have estimates of the world population.

We must again remind readers that the figures do not refer to birds (unless this is particularly pointed out); but to occupied nests or breeding ‘pairs.’

Not many of the censuses made so far are of the species with very large populations. Indeed, if we were to judge solely from completed censuses, we might come to the conclusion that the populations of sea-birds were not high. In fact, they are often extremely high. “The Fulmar Petrel lays but one egg,” wrote Darwin in The Origin of Species, “yet it is believed to be the most numerous bird in the world.” We now know (Fisher, 1952) that, while there may be over two million, there are under ten million fulmars in the world, and that, far from being the most numerous bird, the fulmar is less numerous than many sea-birds, and even some land-birds. One of us has already suggested (Fisher, 1940) that “the most abundant bird in the world is certainly a sea-bird, and probably Wilson’s petrel,” and nothing discovered in the last ten years has encouraged him to change that view. Nevertheless, many species of sea-birds are astonishingly abundant, and quite a number of North Atlantic species, if not vastly numerous in the Atlantic proper, certainly darken the sky round their arctic breeding-haunts just as Wilson’s petrels darken some antarctic skies. The miles of cliffs round Bear Island (especially at its south end) harbour millions (an unknown number of millions) of Brünnich’s and common guillemots. Some of the buttresses rise fourteen hundred feet sheer from the sea, and, as Bertram and Lack say, “have been described with justice as the finest bird-cliffs in the Northern Hemisphere.” However, those of St. Kilda are (in one place) also fourteen hundred feet high, and are more varied, with a better-known history. Those who have seen both may think St. Kilda finer, though Bear Island has more birds and is more magnificently sinister. It certainly has a higher sea-bird population than any comparable place in the North Atlantic-Arctic; though it seems to have competitors in the Pribilov, Aleutian and Kurile Islands and other parts of the North Pacific. But there are many great bird-stations besides Bear Island and St. Kilda, where the observer may behold a community of a million birds or more. On the basalt cliffs of the Faeroes, particularly north-west Streymoy, he may find this number. Perhaps nowhere in Iceland is there a cliff-site with a million birds, but there are many rocks with many thousands, from the Westmann Isles in the south to Grímsey in the north; from Latrabjarg in the west to Skruður and Papey in the east. Jan Mayen has at least a million sea-birds; and there may well be millions at more than several places in Spitsbergen; perhaps on the hills of Horn Sound, Cloven Cliff off the north-west, Magdalena Bay and Brandy Bay in North-east Land; almost certainly on the Vogel Hoek of Prince Charles Foreland, the great auk hill of Advent Bay, and the dolerite Alkrange of Hinlopen Strait. A pioneer ecologist and student of animal numbers (Elton in Longstaff, 1924) wrote of the Alkrange:—

“It is impossible to describe the multitudes of the Guillemots on the bird cliffs. The place was teeming with them: literally hundreds of thousands. The cliffs are made of columnar dolerite which weathers into pinnacles and which rise several hundred feet sheer out of the sea. On the numerous narrow ledges the birds were so crowded that there was room for no more. The rows of black and white birds rising in tiers up to near the top, and the ghostly noise of the combined twitter made by them, made it seem as if one was in a vast opera house, packed with crowds of people in white shirt-fronts and black tails, all whispering comments on each other and rustling their programmes.”

It seems clear that either the little auk or Brünnich’s guillemot is the most abundant bird of the north. It is hard to decide which; the little auk colonies are perhaps fewer, and certainly less obvious as dense loomeries, because the birds nest in crevices and not on flat open ledges. But the dark cloud of circling, twittering dovekies betrays their density, and we believe with Salomonsen that their actual numbers are greater. Nevertheless, some Brünnich’s guillemot loomeries are vast, and those at Bear Island, Jan Mayen and Spitsbergen are not the only ones that are stupendous. The largest loomery in the U.S.S.R. is probably that at Bezymiannaya Bay in Novaya Zemlya, where S. K. Krasovskii (1937) has estimated that about 1,600,000 Brünnich’s guillemots (birds, not pairs) nest. But Salomonsen (1944) has estimated that in 1936 over two million Brünnich’s guillemots (birds) bred at the rock Agparssuit (Cape Shackleton), north of Upernavik in West Greenland. This was about half the population of this species in Greenland. There are many other huge bird rocks in Davis Strait and Baffin’s Bay; in West Greenland several on Disko Island, in Umanaq Fjord (notably Sagdleq, which may have a million Brünnich’s) and in the Upernavik district (notably Qaerssorsuaq, or Sanderson’s Hope, where the guillemot cliff is at least three miles long and over three thousand feet high and has two hundred thousand Brünnich’s), and several in the Thule district in the far north-west, notably Saunders and Hakluyt Islands, and Cape York, which contains what is probably the largest little aukery in the world;* nobody has been able to guess how many millions nest there.

Other huge bird-colonies in the western Arctic are to be found in Ellesmere Island, North Devon Island, Bylot Island and Baffin Island. Indeed, throughout the Arctic, where the naked rock escapes from the clutch of ice, and precipices rear to the sky from shores, the kittiwakes and dovekies, the puffins and guillemots, the fulmars, the glaucous gulls and pale herring-gulls, make their nests, and operate from them to the feeding grounds, to the leads in the ice, the convergences of tide and current, the upwelling zones at glacier faces and by the side of big icebergs. And below the cliff-ledges is the tell-tale of the bird city, rich plants, sudden patches of green in the arctic drab, green swards indeed, bright yellow-green grass; the round leaves of scurvy-grass, lush, six times as high as in the barren places, which means six inches high. On the slopes of scree and talus and broken rocks below is a special mat of little flowering plants, benefiting from the bird-dung leached and washed down from above; perhaps not the purple opposite-leaved saxifrage, which shuns this community (it is too rich for it), but alpine foxtail, the arctic poppy, the arctic buttercups, and the polar creeping willow; and tufted, drooping, alpine brook saxifrages; and the alternate-leaved golden saxifrage; and alpine mouse-ear chickweed, various arctic whitlow-grasses, poas and a woodrush, and Wahlbergella; and sometimes carpets of Jacob’s ladder. There are many mosses, too, with bright colours; and all over these arctic cliffs—not only below the bird ledges—grow lichens. One of them is the beautiful orange Caloplaca elegans; it grows all over the bird rocks of Spitsbergen, shines yellow orange among the dark rock and green grass-ledges of the fulmar-haunted bastions of Disko in West Greenland, and colours from top to bottom the mighty buttresses of Cape Searle in eastern Baffin Island, the site of what may be the world’s largest fulmar colony. Grey fulmars sit on green ledges above orange rocks.

In Britain, St. Kilda is the greatest sea-bird station. Upon its thousand-foot precipices nests one of the densest communities of vertebrate animals in the North Atlantic—probably the densest south of the Arctic Circle. The gannets of Boreray and its stacks have about seventeen thousand nests—one-sixth of the world population of this species. A quarter of Britain’s fulmars (up to forty thousand pairs) nest on St. Kilda. Undoubtedly more than a million puffins’ eggs are laid on St. Kilda in a normal year; the question is, how many million? There are seven separate puffin-slopes on St. Kilda each of which is larger than the largest puffin colony anywhere else in the British Isles, even the largest puffinry in the mossy talus-slopes of the Shiant Isles, where blocks of columnar basalt lie below the cliffs like the forgotten bricks of a child. The puffin is certainly one of the most numerous birds in the North Atlantic. In his monograph on the puffin (1953) Lockley estimates a minimum world population of 15,000,000 adults.

From the study of the ecology of animals we are learning that their numbers are controlled primarily by the amount of food they can get, and only secondarily by their parasites and predators; and parasites are probably more important than predators. But there are exceptions to this; and the chief one is when the predator is man (another is when new predators are introduced through his agency). Except in a few places such as most of Greenland, Jan Mayen, Spitsbergen, Franz Josef Land and a few other arctic islands, man is, or has been, the most important predator of sea-birds. He has been one, of a kind, ever since he has been Man—even before; for there is ample evidence that during the second of the two advances of the ice in the second of the two glaciations of the Great Ice Age, some of the latest members of the species Homo neanderthalensis ate great auks. This was about twenty thousand years ago; the Neanderthals left their auk bones in the cave of St. Brélade in Jersey and in the Devil’s Tower at Gibraltar. Their successors, the first of Homo sapiens, Men of the Aurignacian age (the early part of the Upper Old Stone Age, c.16,000 to c.11,000 B.C.), were of two main races, the tall short-faced Crô-Magnons, and the shorter Grimaldians, perhaps closely related to African bushmen (W. J. Sollas, 1924). Great auk bones have been found in Grimaldian deposits in the Grotta Romanelli in the heel of Italy* and in another cave whose habitation goes back to the end of the Old Stone Age, El Pendo in north Spain, a wall-etching (Fig. 12) of Magdalenian age (c.8,000 B.C.) may represent a great auk (H. Breuil and others, 1911; G. Clark, 1948). It is probable that between the end of the last glaciation of the Ice Age (about 15,000 B.C. in southern Europe, about 10,000 B.C. in northern) and the present day, i.e. during the Upper Old Stone, Middle Stone, New Stone, and Iron Ages the great auk had quite a wide distribution; judging by the number of bones, and the presence of the bones of young, in some prehistoric kitchen-middens in Britain and western Scandinavia, its breeding-range was possibly wider than it was found to be in historical times (Gulf of St. Lawrence, Newfoundland, Iceland, Faeroes and Britain). We cannot, however, quite agree with Clark (1948), who has collected the information about these deposits, that it was certainly wider, for it seems to us likely (see here) that the young great auk left its breeding skerry very early, perhaps, like the razorbill, without either primary or secondary wing-feathers, not much more than a fortnight after hatching; and probably swam with its parents many hundreds of miles before ‘fledging.’ Clark’s list shows great auk bones in middens of the Middle Stone Age in France, Denmark, West Sweden and Norway, of the New Stone Age in France, Denmark and Norway, of the Iron Age in west Sweden and Norway. Several brochs (small forts) in Orkney and Caithness inhabited by the Picts also contained great auk bones; this practically brings the great auk to historical times.

FIG. 12

Upper Palaeolithic (probably Magdalenian) rock-engraving at El Pendo, near Santander, North Spain, showing what are probably great auks of which modern sketch on left. (After H. Breuil, 1911; G. Clark, 1948)

We suspect that the prehistoric exploitation of the great auk was largely confined to interception of the birds on passage and in their winter quarters;* the final collapse and extinction of the species took place only when Man in modern ships reached and attacked its main breeding-haunts.

These, as far as can be discovered, were the certain breeding-colonies of the great auk:

In Britain, St. Kilda and Papa Westray

In Iceland, Geirfuglasker and Eldey, S.W. of Cape Reykjanes and Geirfuglasker in the Westmann Islands

In the Magdalen Islands (Gulf of St. Lawrence), Bird Rocks

In Newfoundland, Funk Island (east)

Other stations at which it possibly nested, but about which the evidence is not entirely satisfactory, are:

In Britain, the Calf of Man

In the Faeroes, Fugloy and Streymoy

In Iceland, Hvalbakur and Tvísker

In Maine, the Georges Islands in Knox County

In Nova Scotia, an island near Yarmouth (? in Tusket Is.)

In the Gulf of St. Lawrence, Cape Breton

In Newfoundland, ‘Penguin Island’ off Cape La Hune (south) and ‘Penguin Island’ near Cape Freels (east)

In Greenland, Leif’s and Erik den Røde’s Islands, near Angmagssalik.

There is no doubt that the main population, when history overtook the great auk, was around the island of Newfoundland, and particularly upon Funk Island, where, according to Peters and Burleigh (1951), it was probably first seen in 1170 by some early Norse explorers of the New World from Greenland.

When Jacques Cartier visited Funk Island on his first voyage to Newfoundland in May 1534 his crews filled two boats with the birds in less than half an hour, and every ship salted down five or six barrelfuls. Two years later the voyager Robert Hore came to one of the Penguin Islands or Funk Island, and found it full of auks and their eggs. They spread their sails from ship to shore and drove a great number of the birds on board upon the sails; and they took many eggs. By 1578 it was the normal thing for French and British crews in the Gulf of St. Lawrence or on the Newfoundland Banks to stock their ships with auk-meat, stopping at the Bird Rocks, or Penguin Islands or Funk Island, and driving the great auks aboard on planks. Today there is nothing but old ships’ logs and travellers’ diaries to record where the western auks once lived in thousands, save on Funk Island, where a great many bones have been found.

It seems clear, from the account of Peters and Burleigh, that the great auk became extinct in Newfoundland in about 1800. George Cartwright (1792), who lived in Newfoundland Labrador for most of the period 1770–1786, and who often sailed across the Straits of Belle Isle to northern Newfoundland, only logged personal meetings with great auks in his diary twice, on 4 August 1771 and 10 June 1774. On a visit to Fogo Island harbour on 5 July 1785 he wrote:

“A boat came in from Funk Island laden with birds, chiefly penguins. Funk Island is a small flat island-rock, about twenty leagues east of the island of Fogo, in the latitude of 50° north. Innumerable flocks of sea-fowl breed upon it every summer, which are of great service to the poor inhabitants of Fogo; who make voyages there to load with birds and eggs. When the water is smooth, they make their shallop fast to the shore, lay their gang-boards from the gunwale of the boat to the rocks, and then drive as many penguins on board as she will hold; for, the wings of those birds being remarkably short, they cannot fly. But it has been customary of late years, for several crews of men to live all the summer on that island, for the sole purpose of killing birds for the sake of their feathers, the destruction which they have made is incredible. If a stop is not soon put to that practice, the whole breed will be diminished to almost nothing, particularly the penguins: for this is now the only island they have left to breed upon; all others lying so near to the shores of Newfoundland, they are continually robbed. The birds which the people bring from thence, they salt and eat, in lieu of salted pork. It is a very extraordinary thing (yet a certain fact) that the Red, or Wild Indians, of Newfoundland should every year visit that island; for, it is not to be seen from the Fogo hills, they have no knowledge of the compass, nor ever had any intercourse with any other nation, to be informed of its situation. How they came by their information, will most likely remain a secret among themselves.”

FIG. 13

Known (•) and putative (Θ) breeding-places of the great auk.

Nobody knows when the Norse-Gaels of St. Kilda came first to Hirta, their main island, and established Britain’s most interesting colony of wildfowlers. Certainly by 1549 there was a stable human community on St. Kilda, whose life was based to a large extent on “wyld foullis” (D. Monro, 1774). In about 1682 the Lord Register, Sir George M’Kenzie of Tarbat, gave an account (1818) of St. Kilda to Sir Robert Sibbald. He probably did not visit St. Kilda himself, but he says: “There be many sorts of … fowls; some of them of strange shapes, among which there is one they call the Gare fowl, which is bigger than any goose, and hath eggs as big almost as those of the Ostrich. Among the other commodities they export out of the island, this is none of the meanest. They take the fat of these fowls that frequent the island, and stuff the stomach of this fowl with it, which they preserve by hanging it near the chimney, where it is dryed with the smoke, and they sell it to their neighbours on the continent, as a remedy they use for aches and pains.”

When Martin Martin (1698), tutor to the son of the islands’ laird, the MacLeod of MacLeod, arrived at St. Kilda in June 1697 he wrote a classic and accurate account of its natural history, which included this:

“The Sea-Fowl are, first, Gairfowl, being the stateliest, as well as the largest Sort, and above the Size of a Solan Goose, of a black Colour, red about the Eyes, a large white Spot under each, a long broad Bill; it stands stately, its whole Body erected, its Wings short, flies not at all; lays its Egg upon the bare Rock, which, if taken away, she lays no more for that year; she is whole footed, and has the hatching Spot upon her Breast, i.e. a bare spot from which the Feathers have fallen off with the Heat in hatching; its Egg is twice as big as that of a Solan Goose, and is variously spotted, Black, Green, and Dark; it comes without Regard to any wind, appears the first of May, and goes away about the middle of June.”

We quote this in full, as it is really a most remarkable and convincing description. As we explain elsewhere (see here) the interval between the first of May and the middle of June is about seven weeks, the combined incubation and fledging period of the great auk’s closest surviving relative, the razorbill. The description also otherwise fits the bird perfectly. Martin arrived at St. Kilda on 1 June 1697 by the calendar of his day, which would be 12 June by our present calendar. If great auks had actually been breeding on one of the islands (Soay would have been the most likely) in that year it is almost certain that he would have been shown them by the inhabitants, and made some comment thereon in his careful notes: as it is his passage that we have quoted reads very much as if the information in it had been taken from natives who themselves had seen the bird nesting and remembered it clearly, but not from Martin’s own observations. From this we conclude that the great auk nested at St. Kilda not in 1697, but within the memory of some alive in that year, i.e. most probably in the second half of the seventeenth century; we can also conclude from the account that its eggs were sometimes taken. The M’Kenzie information for c.i 682 also suggests breeding in this period.

The great auk appears to have been seen at St. Kilda occasionally after Martin’s visit. The notes of A. Buchan, who was minister on St. Kilda from 1705 to 1730, respecting the bird derive from Martin; but Kenneth MacAulay (1764) who was on the island for a year in 1758–59, alludes to irregular July visits (not every year) by the great auk; he did not see one himself. “It keeps at a distance from [the St. Kildans],” he writes, “they know not where, for a course of years. From what land or ocean it makes its uncertain voyages to their isle, is perhaps a mystery in nature.” After MacAulay’s visit the only certain records of great auks at St. Kilda are two: one was taken at Hirta in the early summer of 1821 and kept alive until August. In this month it was being taken to Glasgow by ship; near the entrance to the Firth of Clyde it was put overboard, with a line tied to its leg for its daily swim, and escaped. Another was found on Stac an Armin, the highest rock-stack in the British Isles (though no doubt the auk got ashore at the shelving corner), in about 1840, and was beaten to death by the St. Kildans L. M’Kinnon and D. MacQueen as they thought it was a witch. Obviously it had been a generation or more since any St. Kildan had seen a garefowl.

The existence of the great auk in the Isle of Man is indicated by a picture of an adult in breeding plumage standing on a ledge on the Calf of Man, drawn by Daniel King, probably in 1652. Williamson (1939), who draws attention to this earliest British depiction of the bird, comments that there is no parallel indication in contemporary Manx literature that the great auk inhabited the Calf. It is quite possible that it may have bred, though this of course is not proved; there are suitable low rock-shelves on the Manx coast on which it could have hauled ashore.

In Orkney one pair certainly bred in 1812. It is not at all certain that the great auk had previously been a regular breeder at Papa Westray (the place of the 1812 nest), or anywhere else in Orkney. The site in 1812 was in a recess low down on the Fowls Craig on this island. The female was killed with a stone while sitting on her egg. In 1813 the male was also killed; it was shot by the native Willy Foulis for William Bullock, the collector, having lived on the ledge after the death of its mate. The natives called them the King and Queen of the Auks (Buckley and Harvie-Brown, 1891).

So much for the great auk in Britain; the last of all, except for St. Kilda’s 1840 ‘witch,’ was an odd bird which was found at the entrance to Waterford Harbour in Ireland in 1834, was kept alive for four months on potatoes, milk, and trout, and which is now in the museum of Trinity College, Dublin.

The early historians of the Faeroe Islands, Ole Worm (1655), who died in 1654, and Lucas Debes (1673), both knew the great auk and handled live specimens caught in the islands. J. K. Svabo (1783) who was in the islands in 1781 and 1782, records the capture of a female on the island of Fugloy which was found on dissection to contain a well-formed egg; and Jørgen Landt (1800, 1810), who wrote his MS. not earlier than 1797, mentions great auks as “climbing up the low rocks.” C. J. Graba (1830), who was in the Faeroes in 1828, met old natives who had formerly seen the great auk at Vestmanna on Streymoy, and one who told him that he had killed one on an egg at this place. J. Wolley (1850) in 1849, interviewed an old man who “had seen one fifty years ago, sitting among the Hedlafuglur,* that is young Guillemots and other birds upon the low rocks, and old men told him it was very rare. This was about the time when Landt wrote.” Wolley was told that formerly, when many were seen, it was considered a sign of a good bird year; which suggests that the auks may have been desultory visitors for a long time. Finally H. W. Feilden (1872) interviewed an old fowler in 1872, who claimed to have killed a great auk on the island of Stóra Dímun on 1 July 1808; the last record for the Faeroes. K. Williamson (1948) points out that none of these records constitutes proof of breeding, though we agree with him that, though scarce, it probably did breed in the Faeroes until the eighteenth century.

The great auks of southern Iceland are well documented, and their history has often been related. They certainly bred on two, and perhaps bred on four Geirfuglaskers, or gare-fowl skerries off the coast; from east to west these can be identified as Hvalbakur, the most easterly point of Iceland, about 26 statute miles east of the island of Papey, near Djúpivogur; Tvísker off Breiðamerkursandur under the great southern ice-cap of Vatnajökull; Geirfuglasker, the southernmost islet of the Westmann Islands, and the most southerly point of Iceland; and (until it sank beneath the waves in a volcanic disturbance in 1830) Geirfuglasker, nineteen or twenty miles south-west of Cape Reykjanes, the most south-westerly point of Iceland save a rock Geirfugladrangur less than a mile further to sea, which still stands but was probably never inhabited by great auks. After the volcanic disturbance the garefowls went for as long as they were spared to the island of Eldey, almost exactly between Geirfuglasker and Cape Reykjanes.

It would seem from the accounts of Ólafsson (1772) and Olavius (1780) that Hvalbakur, the distant whale-back skerry of east Iceland, may have been inhabited by great auks when those historians were in Iceland (between 1752 and 1777); but when N. Mohr (1786) visited nearby Djúpivogur in 1781 he evidently found no news of occupation in that year. If it was true, as Ólafsson thought, that Tvísker (a skerry which at present slopes up to a height of about 46 ft.), was a breeding-place, its occupation must be put before 1764, the last year he was in Iceland; there is no subsequent history here. In the eighteenth century the Westmann islet of Geirfuglasker (which rises to 190 ft., but, as we have seen, has a low platform on one side and low skerries around), had a big colony but, as Friedrich Faber (1822), records, the last known breeding-pair and egg were seen there in about 1800.

The end of the great auk in Iceland, and in the world, took place south-west of Cape Reykjanes. It seems probable that the great auks nested only on Geirfuglasker and afterwards Eldey, and never on the satellite stacks belonging to these rocks—Geirfugladrangur and Eldey-ardrangur. It was known that great auks occupied Geirfuglasker, and were at least occasionally raided by Man, in the first half of the seventeenth century. Though the accounts of the eighteenth century (e.g. J. Anderson, 1746; N. Horrebow, 1752) sometimes slightly conflict it seems clear that Geirfuglasker was occupied in 1729 and that in some years of the first half of that century (if not, perhaps, in that particular year) its great auk population was a “great multitude.” Nevertheless, it could have been exaggerated. Horrebow stated that at his time the Geirfuglasker fowlers “filled their boats with the eggs of the Garefowl.” (All through the early, uncritical literature of fowling we find boatloads of eggs—they have even been allegedly taken from Rockall, where seldom have more than a couple of dozen guillemots been seen in attitudes of incubation.) But a manuscript of c.1760 (S. Grieve, 1885, p.19) states that the “garefowl is there not nearly so much as men suppose … the space he occupies cannot be reckoned at more than a sixteenth part of the skerry … and this only at the two landing-places; further upwards he does not betake himself, on account of his flightlessness.” Mohr, who visited Iceland in 1780–81, also thought Horrebow’s account exaggerated, though he did not go out to the skerry himself.

In the nineteenth century the doom of the auks was sealed by the raid of the Salamine, a private pirate-ship which had plundered Tór-shavn in the Faeroes on its way north. The crew of this ship was ashore on Geirfuglasker on (it is said) 8 August (? a late date) 1808, and killed many birds and their young. There may have been another raid from the Faeroes in 1809 (H. C. Müller, 1862); there was certainly a big one in 1813, when, during the war between Britain and Denmark, the armed schooner Faeroe landed a party which killed all garefowls that came within their reach, and arrived later in Reykjavik with twenty-four on board, besides numbers that had been salted down; fifty or sixty were taken back to the Faeroes. On 1 July 1821 Friedrich Faber and H. C. Raben visited Geirfuglasker, and Raben actually climbed Geirfugladrangur. They saw no garefowls at all: it is possible that the auks might have already gone to sea (especially if their eggs had already been taken that season). In 1828 at least one adult was taken, for a skin for the Copenhagen Museum. This is the last visit to Geirfuglasker that we hear of; in early March 1830 a series of earthquakes took place in which the skerry sank beneath the sea. The great auks moved at once to Eldey, ten miles nearer the coast, and attempted to breed there in the same season.

Eldey is a remarkable block of volcanic tuff with sheer sides and a flattish top that is distinguished by being the site of the second largest gannetry in the world (see here). It is about 250 feet high, at its highest point. On the east side of its north end, below the cliff, is a broadish ledge which slopes and slants into the sea (Pl. IIa), and, as one of us (Fisher) who visited it in 1949 saw for himself, was a suitable landing place and, under the sheer cliff, also a suitable nesting-place for the garefowls. Eldey is made of a particularly resistant type of volcanic tuff; normally such a formation weathers and erodes easily, but Eldey has not significantly changed in a century,* and the Icelanders, who are sensitive to tradition and history, and whose fowlers work with their fathers and sons, are positive that the garefowl ledge is still as it was. It was certainly easy, in 1949, to imagine the great razorbills bobbing buoyantly in the fuss of spray and breakers round the landing-places, clawing a foothold and waddling and struggling clumsily ashore. But they only did this at Eldey for fifteen years. In the first year, the year of the earthquake 1830, two boats took twenty or twenty-one skins for dealers; in 1831 twenty-four were taken; in 1834 at least nine skins and several eggs; in 1840 at least one egg; in 1841 three skins and one egg (the egg was probably laid by a female which laid an egg taken in 1840, judging by their remarkable similarity). On a day between the second and fifth (most probably the fourth) day of June 1844 a boat of fourteen men, under the leadership of Vilhjálmur Hákonarsson, sailed the fourteen miles from Kirkjuvogur to Eldey; the sea was rough, and only three men could get ashore, Sigurður Íslefsson, Jón Brandsson and Ketil Ketilsson. They found two garefowls and an egg. Ketilsson smashed the egg, because it was already cracked, and the others each caught and killed an auk. On their way home the men sold the skins to a certain Christian Hansen, who sold them to the bird-stuffer at Reykjavik, Möller. Since that day no great auk has been certainly seen alive by anybody, anywhere.

There is only one other place at which the great auk has been suspected to have bred; it is certainly the most remote and romantic of the lot—romantic because it is the first place in the New World to have been seen by an European. In 877 a Norwegian, Gunnbjörn Ulfsson, on his way to Iceland to settle, was driven west past Iceland by storms, to some skerries, beyond which was land. The land was the the east coast of Greenland, and the skerries, once thought to be what are known as Graah’s Islands, at about the same latitude as the Snæfell Peninsula of Iceland, and now thought (G. Holm, 1918) to be Leif’s and Erik den Røde’s Islands north-east of Angmagssalik. It was from Snæfellsnes that Erik the Red set sail in 982 to found the first European colony in the New World—and he navigated west to Gunnbjörn’s skerries on his way. In the old sailing directions they are regarded as “midway between ‘Greenland’ (the Norse colonies in S.W. Greenland) and Iceland”; which is correct. Many fishermen and voyagers to Greenland after Gunnbjörn and Erik sailed to, or by, Gunnbjörn’s skerries, and in the twelfth or thirteenth century at least one such voyager, according to the M.S. sagas of Iceland (Anon., 1838, W. Preyer, 1862), discovered a great multitude of great auks on them. Between 1586 and 1596 the fisherman Látra Clemens from Adalsvík in Iceland is said to have taken a ‘boatload’ of garefowls here. There is no later record of great auks at this place,* and it may have become too ice-bound with the deterioration of climate at about that time.

Such is the grim history of the great auk. As Salomonsen (1945) points out, the downfall of the great garefowl probably began when the Indians of the east coast of North America exterminated it on the mainland and neighbouring islands; by the time the hungry sixteenth-century transatlantic sailors found it in the Gulf of St. Lawrence and Newfoundland it was probably already driven to skerries out of reach of the Indians’ canoes. Maybe in prehistoric times the great auk also had a wider breeding-distribution in north-west Europe, or at least a very much denser distribution in Iceland-Faeroe-Britain. At the last, in its final miserable nineteenth-century years of slaughter, it was demanded for collectors (though while it was alive they did not pay much for it, contemporary accounts show). For years its passing was not known, and it was still sought high and low, by Steenstrup, Wolley, Newton, Grieve, Lucas; the devoted interest of these ornithologists only served to show that ornithology came not quite in time to save the auk, and that ignorance and greed are sometimes more powerful than knowledge and truth.

The end of the great auk was the only extinction in historical times of a primary North Atlantic seabird; but a secondary sea-bird, the Labrador duck, followed it in 1875 or 1878. Man the ignorant killer was again the agent of its death, armed this time with a shotgun. The evidence against him, in this particular case, is circumstantial; for nobody knows much about the population of Camptorhynchus labradorius

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