Variation in the timing of the breeding haulout of female southern elephant seals at Marion Island

Using data from an ongoing mark-resight program at Marion Island, we tested whether there is variation in the timing of the breeding haulout of female southern elephant seals, in relation to breeding experience. Females were classed as primiparous or multiparous according to their age and known life histories. The mean breeding season haulout date of primiparae was found to be significantly earlier than that of multiparae in nearly every year of the study. This was caused by differences in the timing of arrival, not by differences in the duration of tenure. In addition, in consecutive seasons, mean moulting and breeding haulout dates of individual females were shown to be significantly correlated. The results of our study fit well with our expectations, assuming that the nutritional condition at the time of the sensitive photoperiod phase affects the timing of implantation, because females in their first pregnancy generally moult sooner than post-parturient females and are likely to recover depleted reserves earlier.