Dynamics of male dominance of southern elephant seals (Mirounga leonina) during the breeding season at King George Island

ABSTRACT: Southern elephant male seals (Mirounga leonina Linnaeus, 1758) were studied at King George Island (62°14´S, 58°40´W) from September to December 1999. The first males came ashore at the beginning of September. Twenty−five adults were im− mobilized, hot iron branded, and measured. Thirteen out of the 25 marked males spent an average of 66 (±8) days on land. Early arrival was positively correlated with the time spent ashore (r = 0.88, P < 0.05). Nine harems were formed in the study area. At the maxi− mum haul−out of females (28 October) mean harem size was 32±42 females (range 3–107). During the course of harem development, 10 changes in male harem dominance were observed. These changes were more frequent during the early (1–20 October, n = 6) than during the mid (21 October – 10 November, n = 2) and late (11–29 November, n = 2) periods of harem development. Overall, there were 14 dominant males; five of these in two different harems and nine in one harem. Of the 25 marked males, 44 % were resighted in the following breeding or moulting season, and 16 % seemed to improve their potential breeding success. Key words: male competition, southern elephant seal, Mirounga leonina, pinnipeds