Age, sex and status of wandering albatrosses Diomedea exulans L. in Falkland Islands waters

Abstract

Records (by a scientific observer on a longline fishing vessel around the Falkland Islands) of 86 different individually colour-banded wandering albatrosses from South Georgia, provide new insights into the use of the waters of the Patagonian shelf slope by birds from breeding grounds some 600 km to the south-east across the Antarctic Polar Front. Birds recorded were aged from 3–39 years, almost the full range (except 1 and 2 year olds) of South Georgia colour-banded birds, about 5% of whose colour-banded population was observed during the study. Immature birds (up to age 7 years) formed only 9% of the total; this may reflect relative absence from the area but might also relate to their subordinate status to adults at fishing vessels. Most birds seen were current breeders at South Georgia, including both sexes in the month prior to arrival on the breeding grounds (October), females during the pre-laying exodus (December) and both sexes during incubation (January) and throughout the main chick-rearing period (May, June, October). Only birds which had already failed were seen in the brooding period (March–April), when foraging trips are too short to reach the Falklands. Females outnumbered males in all these categories, supporting suggestions of different distributions of the sexes at sea during breeding. Birds of both sexes that had bred at South Georgia in the previous year were seen mainly between January and April. Birds that had not bred for at least three years were mainly males and mainly seen in January. These data indicate the importance of the waters near the Patagonian Shelf, especially around the Falklands, for wandering albatrosses from South Georgia, particularly breeding birds but also birds in their year(s) between breeding attempts. This is of particular relevance, given the globally threatened status of the species and the possibility of hydrocarbon exploitation in waters around the Falklands.