Breeding distribution of the Great Skua at Macquarie Island in relation to numbers of rabbits

Abstract

During the 1974-75 summer at Macquarie Island the breeding success and distribution of Great Skuas Stercorarius skua in relation to numbers of rabbits were studied on the plateau and the coastal terrace. On the plateau there was a strong correlation between the occurrence of rabbits and of nesting Skuas. On the coastal terrace, however, no such relation was found. The Skuas bred with similar success in both areas.

Remains of food in Skuas' territories indicated that Skuas, nesting on the plateau, preyed heavily on rabbits from 200 to 1,200 grams in weight, with eighty-two per cent of rabbits eaten weighing less than 450 and ninety-eight per cent weighing less than 740 grams. Skuas, nesting on the terrace, in contrast, took few rabbits and depended largely on killing and scavenging on penguins and elephant seals. Present relations between predators and prey on the island are briefly discussed.