The diet of shy albatrosses (Thalassarche cauta) at Albatross Island, Tasmania

Abstract

The diet of shy albatrosses Thalassarche cauta at Albatross Island, Tasmania, was examined quantitatively from 1995 to 1998. Two main sample types were examined: (1) whole stomach contents from chicks that had recently died of natural causes; (2) samples of fresh food delivered to chicks by their parents. Fresh food samples were considered most representative of the overall diet composition and, throughout the study, they were predominated by fish (89% by wet mass). Cephalopods, tunicates and crustaceans contributed 10%, < 0.1% and < 0.1% by wet mass, respectively, to the diet. There was little indication of seasonal or inter-annual variation in prey selection, as the composition of the diet was relatively constant through time. Fish from 16 species or families were identified, however, pelagic schooling Jack mackerel Trachurus declivis and redbait Emmelichthys nitidus together accounted for 57% and 80% (by number) of the fish identified in the stomach and fresh food samples, respectively. Cephalopods from 16 species or families were also identified, and here a single species (Gould's squid Nototodarus gouldi), accounted for 66% and 84% (by number) of the cephalopods identified. Both salps Pyrosoma spp. and crustaceans (largely Australian krill Nyctiphanes australis) contributed little by mass, but they occurred frequently and sometimes they accounted for a significant number of the prey items identified. Aspects of the biology and behaviour of the albatrosses and their main prey species combine to indicate that shy albatrosses have a largely predatory foraging nature. Much of their prey can be captured live, at the surface, during the day.