Time budgets and activity patterns of sub-Antarctic fur seals at Gough Island

Abstract

The diurnal activity patterns of sub-Antarctic fur seals, Arctocephalus tropicalis, were observed at a non- breeding colony site at Gough Island (40°20′S, 9°54′W) during summer. Time budgets of adult males were also studied at idle and breeding colony sites, Levels of activity were highest during the early morning and late afternoon. High ambient temperatures depressed the interaction rate on the dry hauling ground, but activity increased as a result of the movement of heat-stressed seals to and from the sea where favourable conditions for heat loss exist. The fur seals were largely inactive, in particular adult males which spent 93,2% of the time inactive in breeding colonies and 97,9% of Ihe time inactive at idle colony beaches. The daily change in numbers ashore, the relative contribution of the different age and sex classes, their location and distribution on site, and the prevailing weather conditions influence the pattern of interaction and allocation of time to the various activities in A. tropicalis. The predominance of inactivity is considered to be a behavioural thermoregulatory response to limit endogenous heat production as is energy conservation. Both views translate into improved tenure for territorial males, in particular those without access to water for cooling during the breeding season.