The frequency and costs of harassment in southern elephant seals

Notwithstanding the important role of male harassment of females for theori es of the evolution of mating systems, accurate estimates of its frequency and costs are available for only a few species. In this paper, we quantify the frequency of harassment in southern elephant seals, compare occurrences of harassment inside and outside harems, and estimate the costs of harassm ent in two populations at Sea Lion Island (Falkland Islands) and Punta Delg ada (Valdes Peninsula). Southern elephant seal males are much larger than f emales, have enlarged canines, and are much more agile on land; hence, fema les have a small probability of escape from approaching males and may suffe r intense molestation. Most males had limited access to females due to the despotic mating system, and their libido was high. Females were approached by males at high frequency mostly when out of oestrus. The harassment level was negatively related to the ratio of breeding females to breeding males, and females breeding at the peak of the season suffered a lower level of h arassment. Females of large harems were harassed less, and their likelihood of interact with secondary males was lower. The activity of harem females was less disrupted, and females in large harems had a higher proportion of: resting time. Isolated females suffered more herding episodes, and were ap proached more frequently by secondary males. The main short-term cost of ha rassment was disruption of the females' activity schedule; harassment level and total active time were positively related. Suckling bouts were rarely interrupted by male harassment. Mother and pup separations caused by males interaction were rare, short-lasting, and rarely permanent. There was littl e effect of harassment on weanling weight, physical damage of females was r are, and there was only a slight non-significant negative relationship betw een harassment level during one season and the likelihood of surviving to t he next.