Population Size and Breeding Season of the Antarctic Fur Seal Arctocephalus Gazella at Heard ISLAND—1987/88 (original) (raw)

1990, Marine Mammal Science

Fur seals at Macquarie Island were harvested indiscriminately from the time of its discovery in July 1810 until the supply of animals was exhausted. The identity of the original fur seal is unknown and no specimens exist. The New Zealand fur seal Arctocephalusforsteri has been recorded at the island since 1948 when Australian National Antarctic Research Expeditions (AN ARE) began there. Numbers have increased slowly to about 1200 animals, most of them on North Head peninsula. The species is present throughout the year but does not breed on the island. Breeding colonies of the su bantarctic and antarctic fur seals, A. tropicalis and A. gaze/la, were first recognised in Goat Bay and Secluded Beach on North Head peninsula in 1981-82. These species can generally be distinguished from each other and A.forsteri on the basis of external characters and vocalisations. A. tropicalis has not previously been reported as breeding in Australian waters; A. gaze/la breeds also at Heard Island. In the 1985-86 and 1986-87 summers, the two groups of fur seals (non-breeders and breeders) were equally prevalent on North Head peninsula until late December, when numbers of the non-breeders increased markedly and numbers of the breeders decreased slightly. In these two summers 30 and 37 pups were recorded. In 1986-87, the median pupping date was lO December. Pups were born in six territories, four of which were held for most of December by A. tropicalis bulls and contained 86% of the pups. A. gaze/la bulls were smaller than A. tropicalis bulls. Almost all of the cows were identified as A. gaze/la, only a few A. tropicalis cows being recognised.

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