Feeding ecology, isotopic niche, and ingestion of fishery-related items of the wandering albatross Diomedea exulans at Kerguelen and Crozet Islands
Résumé
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 δ15N 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 δ15N values. Satellitetracked
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.