DEMOGRAPHIC VARIATION AND RANGE CONTRACTION IN THE NORTHERN QUOLL, DASYURUS-HALLACTUS (MARSUPIALIA, DASYURIDAE)

Mark-recapture studies of northern quoll (Dasyurus hallucatus) were co nducted in lowland savanna in Kakadu National Park during two periods: in 1985-87 when total mammal abundance was high, and in 1989-91 when total mammal abundance was low. Population characteristics from these studies are compared with results from a 1977-79 study in sandstone es carpment country 40 km to the south-east and from studies in a range o f habitats on the Mitchell Plateau in the Kimberley. Populations in ro cky country are most dense with animals often surviving two or three y ears. In contrast, populations in savanna are more sparse, with males and females rarely surviving beyond one mating season. While all popul ations seem to undergo an annual period of stress, it is the savanna p opulations that seem most vulnerable. An analysis of the distribution of northern quolls shows a 75% recent range reduction, from being wide spread over much of northern Australia to six smaller rocky regions. P ossible causes of the decline include cattle, cane toads and exotic di sease.