Diet and Feeding Ecology of the Royal Albatross Diomedea epomophora - King of the Shelf Break and Inner Slope

Abstract

Diet samples, mainly regurgitations by Royal Albatross Diomedea epomophora nestlings, were obtained at Chatham Islands (34), Taiaroa Head (151) and Campbell Island (79), New Zealand, between 1973 and 1997. Cephalopods and fish were the main items of food, with only small amounts of crustaceans and tunicates. Being completely digested faster, fish are likely to be under-represented in the samples, but most identified were fisheries targets or by-catch. Prevalent cephalopods eaten were Histioteuthidae, Onychoteuthidae, Cranchiidae and, at Taia-roa Head, Octopodidae. Although Histioteuthis atlantica was generally the most commonly taken species, Moroteuthopsis ingens adults contributed most biomass and this indicates that most feeding was possibly on post-spawning cephalopods. While partly similar to the diet of the Wandering Albatross D. exulans species-group, the relative absence of oceanic species in the diet of Royal Albatross indicates that it feeds closer to land, or over shallower waters, than the former, and that it avoids Antarctic waters. The preference of Royal Albatross forM. ingens could explain their migration between two apparent centres of distribution of M. ingens: the continental shelf break and inner slope of southern New Zealand and of southern Chile—Argentina. These feeding areas also keep Royal Albatross away for much of the time from most seas where tuna long-lining occurs, rendering them less vulnerable than Wandering Albatross to such by-catch mortality. Scavenging at fishing vessels may now provide an increased food supply, and partly account for the increase in some populations.