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CHAPTER 3 SEA-BIRD NUMBERS AND MAN
ОглавлениеEVERY 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: