Structure et dynamique de la population de chats harets de l’archipel des Kerguelen

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Abstract
The offspring of the cats freed in 1951 on the Kerguelen Archipelago have reproduced and represent a danger to the native bird population. Since 1973, eradication campaigns have been set up to destroy the cats. In 1977, i.e., 5 yr later, a representative sample of 281 cats was collected (Oct. 1976-Jan. 1977) and the individual ages of these animals was determined. The older animals found were 7-8 yr old. Hunting halved the maximum life span and lowered the population age. It may also have caused a disequilibrium in the sex ratio. The high number of males is responsible for the early fecundation of the primiparous cats and then for their high perinatal mortality. Hunting reduced geographical extension of the cat population located on 1/3 of Grande Terre. Multiparous well-synchronized cats reproduce twice a year, giving birth to 4 kittens each time (Sept.-Oct. and Jan.-Feb.). Primiparous cats have only a yearly litter (Oct.-March). Stomach analyses indicated that 1.2 million birds were probably killed every year by cats. There apparently is no intra- and interspecific competition, and no disease or parasites. The cat seems well-adapted to its new environment and any hunting recess will be followed in this population by a demographic explosion with colonization of new areas and the disappearance of certain bird populations.