What determines the distribution of a threatened species, the brush‐tailed phascogale Phascogale tapoatafa (Marsupialia: Dasyuridae), in a highly modified region?

Abstract

AbstractIdentifying factors that affect species’ distributions in highly modified landscapes, especially threatened species, is a key issue for conservation worldwide. Three types of factors commonly are considered important: the extent and pattern of suitable habitat at a landscape scale; the availability of key resources at a local scale; and interactions with other species. The brush‐tailed phascogale (Phascogale tapoatafa) has undergone range contractions and regional extinctions in Australia and falls within the critical weight range of mammal species with high risk of decline. Yet, in some regions, it persists despite marked habitat loss and disturbance. We investigated the distribution of the brush‐tailed phascogale in a highly modified region in central Victoria where it is a ‘flagship’ for community conservation. At 50 sites, stratified geographically and in relation to topography and surrounding forest cover, we carried out surveys using remotely sensed cameras (in parallel with nest box inspections). We used an occupancy modelling framework and information‐theoretic approach to analyse factors influencing detectability and occupancy. The brush‐tailed phascogale was widespread, recorded at 84% (42/50) of sites. The environmental space occupied by sites with camera records matched that of nest boxes containing established nests of this species. Detection probability was influenced by survey effort and site‐level measures of habitat quality (logs, litter, topographic position) likely reflecting population abundance. Dry forested slopes were favoured compared with gullies. The study area, with its dry forests of rough‐barked eucalypts, is a stronghold for this species. The broad distribution of the brush‐tailed phascogale in this highly modified region can be attributed to retention of ˜36% regional forest cover and a relatively high level of structural and functional connectivity. In such modified landscapes, complementary actions by land managers to sustain remaining large tracts of forest and also a mosaic of wooded vegetation across the rural landscape will help such species to persist.