Abstract:
While studies of dispersal note significant fidelity to natal site and to the site of first
reproduction, few consider fidelity to other sites, and none have done so systematically.
This study examined fidelity to all terrestrial sites within the study area during the
course of its life, by a migratory marine predator, the southern elephant seal, Mirounga
leonina. It also attempted to assess the role played by the winter haulout in terms of site
fidelity. Finally it examined the influence of possible deterioration in spatial memory
over time on site fidelity. The data used in this study were generated by a long-term
mark-recapture programme conducted at subantarctic Marion Island.
Although immature elephant seals of both sexes return to the vicinity of their natal sites,
they appear to avoid popular breeding beaches, returning closest to the site previously
used. At the first reproductive haulout, however, females return closer to their natal site
than any other site, while males, although hauling out in the vicinity of their natal site,
haul out closest to sites used in the year prior to the first breeding haulout.
Subsequently, adults of both sexes breed closest to the breeding haulout of the previous
year and moult closest to the moult haulout of the previous year. While males show
greater site fidelity during the breeding season, there is no difference in site fidelity during the moult. Primiparous females show greater levels of site fidelity if recorded in
the study site as an immature animal during either the winter or the moult haulouts.
Also in female elephant seals, lower site fidelity is associated with an increase in the
duration of period of absence from a site, and a lower number of visits to a site.
Various factors related to site familiarity, social factors and anthropogenic disturbance
may be responsible for the lack of strict site fidelity that is evident. Dispersal patterns
may differ between the sexes due to differences in their life history. While purpose of
the winter haulout by immature seals may be to increase familiarity with haulout sites,
and thus site fidelity, the moult haulout also plays a role.
