The conservation status of rodents in the monsoonal tropics of the Northern Territory

The rodent fauna of the monsoonal tropics of the Northern Territory compris es 23 native species and two introduced species. Three species (Zyzomys mai ni, Z. palatalis and Pseudomys calabyi) are endemic to the area, and four s pecies (Pseudomys hermannsburgensis, P. desertor, P. johnsoni and Notomys a lexis) enter the area only on its southern (arid) fringe. The rodent fauna is closely related to that of the Kimberley, Western Australia. Distribution maps for all species are given. One species (Z. palatalis) has an extremely restricted range and is regarded as critically endangered. Th e lack of information on the distribution and abundance of rodents in gener al in this area is evident in the national classification of five of its sp ecies (Xeromys myoides, Mesembriomys macrurus, Notomys aquilo, Pseudomys de sertor and Pseudomys johnsoni) as Insufficiently Known. The two introduced rodents (Mus domesticus and Rattus rattus) are virtually restricted to urba n and highly modified areas, although R. rattus also occurs on one uninhabi ted island. In contrast to that of much of the rest of Australia, this rodent fauna has apparently retained its full complement of species since European colonisa tion. This enduring legacy is attributable largely to the relatively limite d modification of its environments. However, three species (Mesembriomys ma crurus, Rattus tunneyi and Conilurus penicillatus) appear to be declining. The pattern of decline in these species, and in the mammal fauna generally, is obscured by the very limited historical data. However, declines appear most pronounced in the cattle country of the Victoria River District and Gu lf regions. Priorities for the management of this rodent fauna include survey of poorly known areas, survey for poorly known species, monitoring of rodent communi ties, and landscape-wide management of the three pervasive processes with p robably greatest impacts fire, grazing and feral predators.