Aspects of the Ecology of South Polar Skuas Catharacta maccormicki at Hop Island, Rauer Group, East Antarctica

Abstract

Aspects of the ecology of South Polar SkuasCatharacta maccormicki were investigated at Hop Island, Rauer Group, East Antarctica between December 1990 and February 1991. Data were obtained from pairs across the island generally for comparison with skuas (fringe-dwellers) nesting away from Adélie Penguin Pygoscelis adeliae colonies. While most defended territories included colonies of Adélie Penguins, Antarctic Petrels Thalassoica antarctica or Southern Fulmars Fulmarus glacialoides, others held no surface-nesting seabirds; however, all skuas took penguin material. Activities of two fringe-dwelling pairs, whose territories included fulmars, and fulmars and petrels, were intensively monitored; behaviours were associated mostly with brooding, vigilance or foraging. Foraging trips were longer and less frequent where only fulmars bred, but hunting success was similar to that of the pair hunting in petrel and fulmar colonies. The small number of fringe-dwelling pairs produced proportionally fewer chicks than others; the need to forage away from nesting areas, and to obtain penguin material, even when feeding territories include Antarctic Petrels and or Southern Fulmars, indicates the lower quality of their territories (which may vary). Breeding and other activities are considered in relation to breeding chronology of other local seabirds: the breeding success of fringe-dwellers may be modified by that of neighbouring seabird colonies.