The Breeding Distribution, History and Population of The Fulmar (Fulmarus glacialis) in the British Isles

Abstract

Extensive correspondence and review of literature trace the spread of the fulmar along the coasts and islands in the British Isles. The fulmar is a Palearctic marine species with breeding outposts only in such parts of the Nearctic as have considerable Palearctic affinities. The southward breeding distribution in both the Atlantic and Pacific is bounded by the 60[degree]F. July isotherm. Fulmars are known to have been present on St. Kilda since 1697, but they did not begin to spread elsewhere until 1878, when their dispersal around the British Isles developed in 5 main directions. The breeding population of St. Kilda has remained stationary at about 21,000 pairs. Elsewhere, the population in 1939 was as follows: England and Wales, 240 breeding pairs; Lowlands of Scotland, 225; Highlands of Scotland, 4600; Outer Hebrides, Orkney, and Shetland, excluding St. Kilda, 34,500; and Ireland, 1100. The human inhabitants of St. Kilda have taken for food each year a thousand fulmars for every 8 persons. The advent of modern storage of food on St. Kilda and consequent lesa necessity for killing of fresh meat coincided with the start of the fulmar''s spread. Actually, the number of birds killed each year remained the same, so the cause for the spread remains unknown. Probably only one bird out of 3 breeds each year and statistical considerations suggest that the normal life span is over 12 yrs. The habitat preference for breeding is clearly for islands and oceanic headlands, but the species will also nest some distance inland. First preference for breeding sites is cliffs over 200 ft. above sea-leyel, but as the population increases breeding occurs on lower cliffs, although seldom below 50 ft. in height. The typical nest site is on a steep slope rather than a true cliff. Here the species competes with the rabbit, cormorant, shag, gannet, herring gull, kittiwake, Arctic tern, razorbill, and possibly puffin. There are no predators on the Atlantic fulmar except man. Analysis of breeding conditions tends to support Darling''s principle that social life has an influence on success of reproduction. Fewer eggs or young are produced per breeding pair in small colonies than in larger ones. At large colonies birds arrive a month earlier than at small colonies, and two months or more earlier than at non-breeding colonies. Birds at non-breeding colonies depart earlier. Egg-laying is generally earlier in large colonies than in small ones and is completed in a shorter period. In a colony the social stimulus of numbers is required to enable the fulmars to go through their full breeding cycle. Usually 4-5 years elapse between the first record of a new colony and its coming into breeding. Members of these new small colonies are probably young birds, and this factor must be considered in any analysis of the social effect of colonies on breeding. For food, the fulmar depends on plankton, especially Coelenterata, and any oily matter it can get. It is not known if the dispersal of the species that began in 1878 was due to change in food supply. The prediction is made that the dispersal in Britain will continue.