Continuing decline of the common brushtail possum in central Australia

Abstract

Australia’s recent mammal declines have been most severe in the arid regions, with at least 14 species extinctions occurring therein. The common brushtail possum (Trichosurus vulpecula) is a semi-arboreal marsupial that historically occurred widely across arid Australia but has disappeared from much of this region. We surveyed the last known sites for the species in central Australia. In 2012, we detected possum scats from 3 of 19 sites in Tjoritja National Park in the Northern Territory. Presence sites were separated by <4 km and characterised by extreme ruggedness. Further scat surveys in 2016–17, and 10 499 camera-trap nights of targeted survey in 2020–21, resulted in no possum detections. Moreover, no possums were detected during >60 000 camera-trap nights at nearby monitoring sites targeting other species in 2016–22. The contraction of common brushtail possums to rugged refuges by 2012 is consistent with a decline driven by mammalian predators. The possible extirpation also coincided with or followed record years of high temperatures. The culturally significant common brushtail possum is a priority candidate species for reintroduction to parts of central Australia. Reintroduction attempts must manage mammalian predators and consider the suitability of source populations and translocation sites in the face of a rapidly warming climate.