Bg. Walker et Wd. Bowen, BEHAVIORAL-DIFFERENCES AMONG ADULT MALE HARBOR SEALS DURING THE BREEDING-SEASON MAY PROVIDE EVIDENCE OF REPRODUCTIVE STRATEGIES, Canadian journal of zoology, 71(8), 1993, pp. 1585-1591
We studied the behaviour of 43 male harbour seals (Phoca vitulina) dur
ing the 1991 breeding season on Sable Island, Canada. Males were class
ified as subadults (n = 21) or adults (n = 22) based on their initial
body mass. Throughout the 40-d study, twice-daily beach surveys were c
arried out to locate marked males. Two spatial (average distance moved
between haul outs, and the proportion of possible sightings in which
a male was hauled out) and three social (fighting and composition and
number of different groups in which the male was observed) variables w
ere used to describe the behaviour of males during the premating perio
d, when there were no, or few, receptive females, and the mating perio
d, when receptive females were increasingly numerous. Of 39 males with
complete behavioural data, principal components and cluster analyses
identified a subset of 7 adults that differed from the other males. Th
ese seven adults exhibited evidence of intermale fighting (i.e., wound
ing on the neck and hind flippers), showed greater fidelity to a singl
e haul-out site, associated with fewer groups, and were more often sig
hted alone or in all-male groups. We suggest that these adults may rep
resent the most successful males.