Diet of the brown skua Catharacta skua lönnbergi on the Kerguelen archipelago: comparisons between techniques and between islands

Abstract

The diet of the brown skua Catharacta skua lonnbergi was studied on the Kerguelen archipelago, during the chick-rearing period, over four breeding seasons (1987/1988, 1990/1991, 1992/1993 and 1993/1994). Prey remains and regurgitated pellets left by the breeding pairs were analysed and compared between two nearby and similar islands that mainly differ according to the presence or absence of the rabbit, since its eradication from one of them in 1992. Proportions of prey in diets varied between sampling methods (remains/ pellets), localities, years, breeding territories, breeding pairs and non-breeding individuals. The brown skua preyed upon few species of burrowing petrels and mainly on the blue petrel. Rabbits were exploited secondarily although they apparently reduced the predation pressure on the blue petrel. The eradication of rabbits from one of the islands, during a restoration programme, has not basically changed the trophic interactions between brown skuas and petrels.