Haulout site usage by southern elephant seals, Mirounga leonina, at Marion Island

Abstract

Data obtained from annual tagging and regular tag resighting of southern elephant seals at Marion Island has allowed the investigation of the patterns of terrestrial haulout site usage by this species. Southern elephant seals were found to prefer some sites while discriminating against other sites for the various haulout events, with different age and sex classes using different sites. The degree of preference showed signs of having intensified during the stage of population stabilisation, highlighting the influence of population density on site selection. Certain age classes seemed not to tolerate each other at the beaches, especially the adults and juveniles during their breeding and moulting haulouts respectively when an overlap in these events occur. Elephant seals prefer open beaches with smooth surfaces during the breeding season. Sites with access to moult wallows were preferred during the moulting season by adult seals. There is some indication that juvenile seals also preferred such sites during the moult haulout although this was not supported statistically. Wintering young animals did not show strong site selection. Overall, sites with low anthropogenic influence were preferred, especially during the breeding season. Some popular sites were simply used for all haulouts and by all age and sex groups, and apparently have all the requirements of a good site for terrestrial haulout by southern elephant seals.