The biology of the fulmar (Fulmarus glacialis (L.)) in North-East Scotland, with special reference to the pre-laying period

• Main Author: Macdonald, M. A.
• Published: University of Aberdeen 1975
• Subjects: 578.012
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.592976

A population of Fulmars (Fulmarus glacialis (L.)) on the Sands of Forvie National Nature Reserve, Aberdeenshire, were studied between October 1972, and August 1975. Supplementary observations were made on Eynhallow in Orkney. The voice and displays of the Fulmar are described, illustrated and compared with those of other Fulmarine petrels. Stomach contents of 24 Fulmars indicated that the diet contained a large, but unknown, proportion of animals of benthic or deep-water origin which were probably taken at trawls. Rocoveries of ringed breeders showed movements of several hundred kilometres from their colonies. The pre-laying period began in the last 10 days of October. Numbers at the colony varied widely from day to day and showed no consistent pattern over the winter. Female breeders were rarely seen on land except in the company of their mates. Lone males and pairs were frequently present defending small territories which were usually centred on the nest-site. Movements of breeders within the colony were limited, and associations outside the pair were rare. Between 30% and 50% of birds at Forvie in winter did not breed there. Most were probably pre-breeders. Fidelity to the mate and the nest-site was high. The results from Eynhallow were broadly similar to those from Forvie. Testis growth began in January and oocyte growth in April. Copulation occurred during April. From mid-April all females and most males left the colony for (on average) 3 and 1½ weeks, respectively. Laying commenced in mid-May. Three sub-populations with different laying-dates were identified. Pairs tended to lay at the same relative time each year. About 34% of nests were successful. Early eggs produced more chicks than late ones. Eighteen cases of non-breeding by experienced breeders were recorded. Fulmars and Herring Gulls contested for nest-sites, but the former always retained ownership.