Biogeography and conservation of reptiles, mammals and birds across north-western Australia: an inventory and base for planning an ecological reserve system

Abstract

The distributions of mammals (94 spp. =38% of the Australian total), land birds (252 spp. =52%), and terrestrial reptiles (269 spp. = 39%) in north-western Australia are analysed. Of these species, 133 (mostly reptiles) are restricted to this region. Reptiles (and especially endemic species) characteristically have small ranges in this area. For all three groups, diversity is highest in coastal, high rainfall areas (especially of Arnhem Land and the northern Kimberley). Such areas are relatively well represented in the existing nature reserve system. Assemblages of species are mapped, on the basis of classification of the 123 lo latitude by lo longitude cells in the region. For both mammal and bird species, four defined assemblages were distributed in high rainfall coastal areas, inland low rainfall areas and two transitional zones, all extending over a broad east-west span. Reptile assemblages show a similar initial (wet-dry) division, but then split into east and west subdivisions. For all three animal groups, transitional and inland assemblages are poorly reserved (<0.25% of land area). A total of 58 reserves occur in the region. Most are small (median 24km*2) and concentrated around population centres. Biological information is lacking for most reserves. Largely because of the dispersion of existing reserves, almost one quarter of the species considered (and about the same proportion of endemic species) are not known to occur in any conservation reserve in the region. Priorities are assigned for the placement of future reserves. The most significant additions should be in the north Kimberley, south-west Kimberley, northern fringe of the Tanami Desert, Gulf of Carpentaria hinterland and eastern Arnhem Land. The conservation of this fauna is not dependent solely on the provision of a park network, but demands also informed management of reserves and adequate environmental protection of land outside reserves.