Distribution of mammals in monsoon rainforests of the Northern Territory

The mammal fauna of 50 patches of monsoon rainforest in the Northern Territory, Australia, was surveyed. No mammal species is restricted to this habitat, and most of the region's marnmal fauna uses it at least occasionally. Mammal species composition within monsoon rainforests undergoes substantial variation along an extensive environmental gradient reflecting moisture condition and rockiness. For most mammal species, variation in abundance among patches was related more to the position of the patch on this environmental gradient than to patch size or extent of disturbance. Disturbance was positively correlated with the richness and abundance in quadrats of three taxonomic groupingsrodents, 'other' native species, and all native species (other than bats)-and negatively correlated with richness and abundance of macropods. Compared with surrounding (open forest and savanna woodland) vegetation, monsoon rainforests have few grazing herbivores and small granivorous rodents, but more species that eat fleshy fruits and seeds from woody plants. The mammal fauna of monsoon rainforests in the Northern Territory is similar to that of monsoon rainforests of the Kimberley (to the west) but unlike that of wet tropical rainforests in Cape York (to the east). These differences, and the current impoverishment of the mammal fauna of the Northern Territory monsoon rainforest, are attributable to historical processes and the current small area of this highly fragmented monsoon rainforest estate. Three bat species may be important for pollination and dispersal of monsoon rainforest plants.