Cephalopods in the diet of wandering albatrosses and sea-surface temperatures at the Sub-Antarctic Front

Cephalopod beaks in the regurgitations of wandering albatross chicks from the breeding colony at Bird Island, South Georgia were collected throughout the austral winters of 1983 and 1984. There were large changes in relative frequency of species between the two years. In 1984 there were fewer Antarctic species in the bird's diet and more species which are known to occur to the north of the Sub-Antarctic Front. Notably, the proportion of an Illex sp. increased from 11% to 33% by number. Illex sp. was absent from a collection of cephalopod beaks from wandering albatross chick regurgitations made in 1976-77. The nearest known stock of this genus is Illex argentinus, which occurs over the Patagonian shelf. The data indicate that in 1984 the wandering albatrosses were exploiting a warmer water cephalopod community. Either their foraging range was extended further to the north and west in that year or there was a south easterly incursion of water from the South Atlantic which carried warmer water cephalopods closer to Bird Island. Sea-surface temperature records (NOAA, Climate Analysis Center) show no evidence of an incursion of warm water in 1984. On the contrary, in 1984 sea surface temperatures were cooler than in 1983. It is proposed that the collapse of the krill population in the vicinity of South Georgia, reported in the literature for the 1983 austral winter, resulted in sufficient disruption of the food web in the region to cause the wandering albatrosses to extend their foraging range in the austral winter of 1984