Feeding ecology, isotopic niche, and ingestion of fishery-related items of the wandering albatross Diomedea exulans at Kerguelen and Crozet Islands

International audience

英语. Feeding ecology and isotopic niche of the wandering albatross Diomedea exulanswere investigated in the poorly studied population on the Kerguelen Islands and compared to thaton the Crozet Islands. Fish (48% by mass) and cephalopods (46%) were similarly important inchick food at Kerguelen, while cephalopods (87%) dominated the diet at Crozet. Fish preyincluded mainly deep-sea species, with the Patagonian toothfish Dissostichus eleginoides beingthe 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. Histioteuthisatlantica (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%) dominatedat Crozet. Chick feather δ15N values were higher in wandering albatrosses than in otheroceanic seabirds of the 2 communities, indicating that the wandering albatross is an apex consumertogether with the sperm whale and sleeper shark that have similar δ15N values. Satellitetrackedwandering albatrosses foraged in local subantarctic waters and farther north, with someCrozet 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 Crozetindicated the presence of a fairly large number of illegal longliners in the area during the Australwinter 1998. A review of the feeding habits of Diomedea spp. highlights the need for more dietaryinvestigations to achieve effective conservation and management of this endangered group ofcharismatic seabirds.