Dietary Segregation of Macaroni and Rockhopper Penguins at Heard Island

In: Wildlife Research, Band 16, Heft 6, S. 599

Abstract

This paper reports on the first quantitative study of the diet of macaroni and rockhopper penguins
(Eudytes chrysolophus and E. chrysocome) undertaken on sub-Antarctic Heard Island. Stomach contents
were sampled during the late incubation and early chick-rearing phase. Both penguin species generally
fed on euphausiids and fish, albeit in different proportions and frequently on different species and
sizes. In particular, macaroni penguins consumed considerably more fish on a per cent mass basis
(23.2 v. 8.0%), selecting larger sized prey than rockhopper penguins did. It is hypothesised that these
dietary differences provide macaroni penguins with a broader feeding niche leading to a greater
availability of food and are thus an important factor contributing to the numerical dominance of
macaroni penguins on the island.