Diet of Royal and Rockhopper Penguins at Macquarie Island

Abstract

The diet of Royal Eudyptes schlegeli and Rockhopper E. chrysocome Penguins, studied during the 1981/82 breeding season on Macquarie Island, is described. Quantitative analysis was performed on 29 stomach samples from Royal Penguins at Bauer Bay (west coast) and 21 samples from Sandy Bay (east coast). Samples were also obtained from 19 Rockhopper Penguins at Garden Cove (east coast). Principal dietary components were Euphausiids: Euphausia vallentini and Thysanoessa gregarra; Amphipods: Primno macropa and Parathemisto gaudichaudi; fish and squid, which were in general unidentifiable. Results of dietary analysis are presented as percent frequency of occurrence, and as percent frequency composition by weight. Considerable differences in dietary composition between the two coasts were observed with fewer euphausiids (45% cf 95%) and more amphipods (86% cf 38%) being taken on the west coast than on the east. Length of time that the parent was away from the chick and the fact that, with only minor exceptions, all dietary species were pelagic indicate that these penguins may feed at a considerable distance from the island.