Abstract: The Guadalupe fur seal (Arctocephalus townsendi) and the California sea lion (Zalophus californianus) have co-inhabited the Islas San Benito since 1997. This archipelago is the only place where there is a sympatric occurrence of colonies of both species; this particular situation makes it an excellent model to explore overlap or spatial segregation in their terrestrial habitat. We used data collected at Islas San Benito in the summer of 2008 to test the hypothesis that local habitat use differs between the two species. We found evidence that there is terrestrial habitat segregation between species (Bray-Curtis distance = 0.64, p = 0.02), and our results show that the two species differed in their habitat use: Guadalupe fur seals used irregular beaches surrounded by cliffs, while California sea lions used open and flat beaches. The Guadalupe fur seal has been classified as vulnerable by the International Union for Conservation of Nature (IUCN), and the results obtained are important to understand the physical factors that affect its terrestrial habitat selection. The Guadalupe fur seal population at Islas San Benito continues to expand, and the statistical method employed in our study, applied through several counts, can be a useful tool to track changes in its distribution and patterns of habitat use.

Key Words: habitat segregation, cohabitation, Guadalupe fur seal, Arctocephalus townsendi, California sea lion, Zalophus californianus

Document Type: Research article

DOI: 10.1578/AM.39.1.2013.54

Page Numbers: 54-60