The most arboreal dasyurid marsupial, the Brush-tailed Phascogale is nocturnal and seldom feeds on the ground. They are agile hunters and can leap as much as 2 m between tree branches or trunks. During the day they shelter in tree hollows. Home range in females can typically be 20-40 ha, while male home ranges may be >100 ha; however, home range can be much smaller in high quality forest (van der Ree et al. 2001). Diet is predominantly invertebrates found on or under bark; nectar is also taken, appearing to be a particularly prized but rare and patchy food source (Scarff et al. 1998).

Rhind (1996) found that, in forests of south-western Australia, Brush-tailed Phascogales used hollows in mature and dead Jarrah Eucalyptus marginata and Marri Corymbia calophylla. Rhind (1996) also found that logging practices of the time removed most habitat trees. Competition for nest hollows from other species that nest or shelter in hollows, including the introduced Honey Bee Apis mellifera, may be limiting (van der Ree et al. 2006).

Rhind (2002) reported that, in south west Australia, habitat quality was correlated with body size and the largest phascogales were found in swamp/gully systems, suggesting food is a normally limiting resource for this species in this environment. Additionally, a significant decrease in growth rate occurred during a drought year, and growth of young seemed restricted during dependency. Maternal mortality appeared high during late lactation as orphaned, unweaned young were encountered in nest boxes. Subsequently, adult males were 25% less in mass than usual; females 15% less. Population decline followed with capture rates one-third of that typically found for the time of year. Recovery was not apparent until two years after drought. In this food-limited environment phascogale populations appear particularly vulnerable to annual fluctuations in rainfall.

The Brush-tailed Phascogale originally occurred in most of south-western Australia, the extreme south east of South Australia, much of Victoria, coastal and near coastal New South Wales, coastal and near coastal Queensland, and the higher rainfall part of north-western Kimberley. It has disappeared from semi-arid south-western Australia, parts of Victoria, and much of New South Wales and Queensland. It is presumed to be extinct in South Australia (with the last reliable record in 1967; Menkhorst et al. 2008), including Kangaroo Island (Inns 2002). The distribution in northern Queensland is poorly known, but an increasing number of recent records has partly resolved its north-eastern range (Covacevich et al. 1994, Winter 2004)

In the south-west of Western Australia, the population fluctuates markedly in response to climatic conditions (Rhind and Bradley 2002). The species may have declined in the south-west in the last ten years; there are fewer records in spite of increased survey effort. Its status in the Kimberley is unclear as there have been very few recent records.

Burbidge et al. (2009) found that the Brush-tailed Phascogale originally occurred in 26 Interim Biogeographic Regionalisation for Australia bioregions, that it was extinct in six of these, had declined or seriously declined in 14 and ‘persisted’ in only five (‘persisted’ meant ‘Persists in >50% of its former range within the bioregion (note that range equates to ‘extent of occurrence’, not ‘area of occupancy’ (IUCN 2001)’.

Recommended actions for this species include: taxonomic work to assess the status of the various regional populations, especially the Kimberley population; developing survey techniques for this species to increase knowledge of its distribution, population status, and to allow for monitoring; identifying key habitats and populations; determining the relative importance of threatening processes throughout its range; and determining the potential impact of 1080 baiting on phascogales in south-east Australia. Development of broad-scale effective control technology for feral cats is a priority.