University of Tasmania

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Studies of the rabbit population on Macquarie Island.

posted on 2023-05-27, 16:00 authored by Skira, Irynej Joseph
Studies were made of the ecology of rabbits on Macquarie Island, the predation on rabbits by skuas and the distribution and extent of spread of the European rabbit flea. The numbe:r of rabbits on Macquarie Island estimated from visual counts was in the order of 50 OOO. Most rabbits were present on 35% of the island, of which 7% had >15 rabbits per 2 ha. 'I'he coat colours were agouti (83%) and black (17%). The rabbits moulted twice a year. Females were heavier than males during the summer when breeding occurred, while males were heavier during winter. The mean weight of liver, kidneys and spleen in female rabbits was greatest in the summer and adrenal glands were heaviest in the winter. In male rabbits the kidneys and spleen were heaviest in the smamer, the liver and adrenal glands heaviest in winter. The breeding season extended from late August 1974 to mid-March 1975 Skua territories were widely distributed on the island but no pairs that nested in the bleak upland regions searched,reared chicks. Eighty pairs formed territories in the areas of > 15 rabbits per 2 ha compared with 30 pairs in areas with 6-15 rabbits per 2 ha. Predation on rabbits increased only during the first month of the skua chicks growth thereafter remaining constant with 98% of rabbits taken under 0. 74 kg. Only 28% of all the rabbits sampled carried European rabbit fleas. Infestation levels fell when rabbits were not breeding and did not increase until two months after rabbits began to breed again. Dispersal of fleas from areas where they were released was very slow. In the one hundred years that the rabbit has been on Macquarie Island it has adapted to the environment until it is now found in many localities where suitable habitat is present, and its numbers vary locally in abundance from sparse to numerous. and both sexes showed an annual cycle in development and regression of the gonads. Sixty-four per cent of natality occurred by mid-December; female rabbits in their first year of breeding bearing the greatest number of kittens. The sex ratio of male to female was 1:0.84. Adult rabbits predominated in the population in the 1973-74 summer while in the 1974-75 summer the population was composed equally of adults and rabbits 12 months old or less. Mortality occurred mainly amongst rabbits less than 4 months old and was considered to be mainly due to effects of wet burrows and predation by feral cats and skuas.


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Copyright 1979 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s). Thesis (M.Sc.)--University of Tasmania, 1979. Bibliography: l. 162-171

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