Cephalopod prey of the wandering albatross Diomedea exulans
Cephalopod beaks from the stomach contents of “wandering albatross” (Diomedea exulans L.) chicks from Bird Island, South Georgia, were sampled between May and September in 1983 and 1984. Lower beaks were identified and measured, and allometric data were used to calculated mantle length and biomass of the species consumed. A total of 3421 lower beaks were examined, representing 35 species in the 1983 sample and 45 species in the 1984 sample. Eight of the twenty families contributed over 95% of the biomass. In 1984 there were less Onychoteuthidae and more Ommastrephidae than in 1983 and a decrease in the number of species known to occur south of the Antarctic Polar Front. There was a difference in the size-frequency distribution of the cephalopod diet in the two years; in 1984 there was a higher frequency of intermediate-sized specimens, reflecting the greater importance of ommastrephids, especially Illex sp. The energy content of cephalopods in 1984 may have been greater than in 1983. Serial sampling of cephalopod beaks during the austral winter did not reveal evidence of growth. By the age of 200 d, wandering albatross chicks have consumed a total of approximately 100 kg wet weight of cephalopods each.
Authors: Rodhouse, Paul G., Clarke, M.R., Murray, A.W.A.