Duration of post-weaning fast and local dispersion in the southern elephant seal, Mirounga leonina, at Marion Island



Post-weaning behaviour of southern elephant seals, M. leonina, was studied at Marion Island. Duration of fast in both sexes increased in direct proportion to weight at weaning, while it decreased with weaning date in males. Both sexes appear to fast until they have reached a lower weight ‘threshold’ of around 70% of weaning weight. Local dispersion after the fast was studied by resighting tagged animals at weekly intervals. Only 460 (7.0%) resights out of 6530 involved a move between sites, representing 378 (16.8%) of the 2246 pups that were tagged. Males moved more frequently between tagging sites and covered greater distances than females. Moves between sites are more frequent and distances travelled are greater in December than November. Differences in dispersion patterns between Marion Island and lies Kerguelen may be caused by differences in coastal configuration. Underyearlings spent 105.0±19.6 days at sea before returning for between 10 and 20 days in the autumn. Weaning weight had no effect on likelihood of hauling out in autumn. Movements between sites during the autumn haulout are infrequent and no fidelity to birth site is evident at this stage.