Long-Term Trends in the Foraging Patterns of Female Antarctic Fur Seals at South Georgia

Abstract

The number of feeding trips to sea made by female Antarctic Fur Seals during lactation may reflect the relative availability of local prey resources. Experimental work utilizing tetracycline-marked teeth confirmed that the feeding trip/suckling cycles of females are reflected as starving/suckling layers in the teeth of their pups. A collection of unmarked Antarctic Fur Seal teeth from Bird Island, South Georgia, was analyzed to estimate: (1) birth year of individuals, and (2) the number of feeding trips made by an individual’s mother during lactation. This analysis showed that between 1962 and 1981 the mean number of feeding trips made by female fur seals varied markedly. From 1962 to 1979 there were several significant increasing and decreasing trends in the mean number of feeding trips, with 1979 being the year with the fewest trips made during the entire 20-year period.