Gradient analysis of the distribution of mammals in Stage III of Kakadu National Park, with a review of the distribution patterns of mammals across north-western Australia

Abstract

A total of 56 native mammal species (about one quarter of the species of land mammals known from Australia) was recorded from the Stage III area of Kakadu National Park, Northern Territory. A single environmental gradient (of substrate and disturbance) described well the distributions of species other than bats from this area. For most species, there was little shift in gradient position between three trapping periods (spaced over three years). The mammal fauna comprised a rocky upland assemblage, a lowland monsoon rainforest-swamp assemblage, and an open forest-woodland assemblage. Mammal diversity and abundance was greatest in the rocky uplands. The distribution of most bat species was not clearly associated with this gradient. The Stage III mammal fauna is compared with that described from elsewhere in north-western Australia. Across this region, the fauna shows little variation with longitude, but undergoes substantial latitudinal change in conjunction with a steep rainfall gradient. The habitat reSationships of the Stage III mammal fauna are broadly repeated across north-western Australia. The fauna of sandstone ranges is attenuated with decreasing size and increasing isolation of these ranges. The mammal fauna of monsoon rainforests is depauperate, reflecting the small size and patchiness of this habitat. The mammal fauna of open forest/woodland is characterised by extensive distributions of its constituent species and a relative lack of arboreal folivores and small macropods.