Origins, age composition and change in numbers of moulting southern elephant seals (Mirounga leonina L.) in the Windmill Islands, Vincennes Bay, east Antarctica, 1988–2001

Abstract

We discovered that the number of male southern elephant seals (Mirounga leonina) moulting at wallow sites in the Windmill Islands, Vincennes Bay, Antarctica has decreased by 88% since the last data were presented in 1989. This figure equates to an annual decrease of 6.5%, a figure quite different to the known population trends at the islands from where the seals originate. The seals inhabited four fewer wallows in 2001 than in 1990. Brand and tag resights confirm that seals moulting at Browning Peninsula and Peterson Island originate from Macquarie Island and Heard Island. Male seals aged 1–7+ years of age were present but most (68%) were aged over 7. Males aged 4 years old began to haul out in mid-February while prior to that time only male seals older than 5 years were seen. Timing of moult for particular age classes was similar to that observed at other breeding islands. Trends in the numbers of adolescent and mature male seals hauled out at the sub-antarctic breeding locations require investigation.