Abstract: Feeding ecology and isotopic niche of the wandering albatross Diomedea exulans were investigated in the poorly studied population on the Kerguelen Islands and compared to that on the Crozet Islands. Fish (48% by mass) and cephalopods (46%) were similarly important in chick food at Kerguelen, while cephalopods (87%) dominated the diet at Crozet. Fish prey included mainly deep-sea species, with the Patagonian toothfish Dissostichus eleginoides being the main item. Cephalopod beaks were identified, most of which were from adult oceanic squids. Albatrosses preyed upon the same taxa at both localities, but in different proportions. Histioteuthis atlantica (30% by number), Galiteuthis glacialis (13%), and Kondakovia longimana (10%) were the main squid prey at Kerguelen, while K. longimana (35%) and H. eltaninae (23%) dominated at Crozet. Chick feather ?15N values were higher in wandering albatrosses than in other oceanic seabirds of the 2 communities, indicating that the wandering albatross is an apex consumer together with the sperm whale and sleeper shark that have similar ?15N values. Satellite-tracked wandering albatrosses foraged in local subantarctic waters and farther north, with some Crozet birds overlapping with those from the Kerguelen population in western Kerguelen waters. Anthropogenic items (e.g. plastic fragments, hooks) were found in half the food samples. All fishery-related items were from the local toothfish fishery. The high number of hooks from Crozet indicated the presence of a fairly large number of illegal longliners in the area during the Austral winter 1998. A review of the feeding habits of Diomedea spp. highlights the need for more dietary investigations to achieve effective conservation and management of this endangered group of charismatic seabirds.

Abstract: The cephalopod diet of the light-mantled sooty albatross Phoebetria palpebrata was determined for the first time at the subantarctic Kerguelen Islands by sorting ?7000 accumulated beaks from 66 regurgitated boluses. Twenty-two taxa were identified, including four dominant squid species that are all endemic to the Southern Ocean: Galiteuthis glacialis (49.8% of the lower beaks) Psychroteuthis glacialis (18.5%), Martialia hyadesi (16.2%) and Moroteuthopsis longimana (6.9%). Beak ?13C values indicated that all adult P. glacialis, almost all juvenile M. longimana, and most adult G. glacialis were caught in Antarctic waters, while albatrosses preyed upon juvenile M. hyadesi in subantarctic waters. Comparative analysis of lower beaks accumulated in food samples of Kerguelen albatrosses showed that the four main sympatric albatross species segregate primarily by species-specific foraging grounds. Light-mantled sooty albatross feed on the Antarctic P. glacialis, wandering albatross Diomedea exulans on subantarctic and subtropical histioteuthids (41.4%), and grey-headed albatross Thalassarche chrysostoma and black-browed albatross T. melanophris on subantarctic ommastrephids (69.3% and 65.7%, respectively), with black-browed albatross also preying upon neritic endemic octopuses (17.6%). Cephalopod prey of Kerguelen albatrosses highlight the abundance and importance of some squids in the functioning of the pelagic ecosystem of the southern Indian Ocean, such as ommastrephids, M. longimana, P. glacialis, Histioteuthis atlantica, H. eltaninae, and G. glacialis. Based on the diet of the light-mantled sooty albatross, P. glacialis appears common in high-Antarctic waters of the southern Indian Ocean, whereas the poorly known Psychroteuthis sp. B (Imber) is evidently present in Antarctic waters south of the Kerguelen Islands.