Habitat requirements of the endangered red-tailed phascogale, Phascogale calura

Abstract

Context The red-tailed phascogale once occurred widely across semiarid and arid Australia, but is now confined to the southern wheatbelt of Western Australia. Its apparently extensive former range suggests a broad habitat tolerance, yet it is now reported primarily from remnant vegetation within farmland containing wandoo Eucalyptus wandoo and rock sheoak Allocasuarina huegeliana associations. Aims To establish the habitat requirements of phascogales with a view to understanding their current and likely future distribution and status. Methods We established presence or absence of phascogales at a number of sites within their current range, primarily by trapping, and then compared habitat attributes between the two classes of sites to establish those of apparent significance to species persistence. Key results Phascogales are widespread in suitable upland (wandoo–rock sheoak) and lowland habitat (riverine fringing vegetation of swamp sheoak Casuarina obesa, York gum E. loxophleba and wandoo). They occupy areas of remnant vegetation of varying sizes from very small to very large, many on private agricultural land. Large connected areas, such as riverine corridors and clusters of upland remnants appear important to their long-term persistence. Sites isolated by increasing distance from another occupied site tended to be unoccupied. Habitats occupied by phascogales typically had a greater canopy density and greater abundance of hollows than unoccupied sites. The presence of plants of the genus Gastrolobium, often cited as a key factor in the persistence of phascogales, did not appear to influence the presence or absence of phascogales. Conclusions Red-tailed phascogales currently occupy a broader range of habitats than identified in the literature and the role of some key aspects of habitat in protecting them from further decline may have been overstated. The presence of suitable hollows for nesting and shelter and a dense mid-storey canopy, perhaps to protect from predation by owls, are key features of suitable phascogale habitat. Implications Suitable habitat for phascogales appears widespread in the surveyed portion of the remaining range of the species, but is under threat over the longer term. Increasing salinity in lowland areas (which transforms woodland to samphire with a consequent long-term loss of nesting hollows), lack of fire in upland areas to maintain dense stands of rock sheoak and the increasing loss of corridors of vegetation along roadsides due to the widening of roads by local councils are all contributing to loss of habitat and habitat connectivity.