New evidence of unexpectedly high animal density and diet diversity will benefit the conservation of the critically endangered western ringtail possum

A comprehensive and contemporary understanding of habitat and resource requirements has been critical to the conservation of multiple taxa and ecosystems globally. Until recently, much of the ecological knowledge that contributes to conservation priorities and strategies for the critically endangered western ringtail possum (Pseudocheirus occidentalis) was largely derived from decades-old observations in peppermint (Agonis flexuosa) and marri-jarrah (Corymbia calophylla and Eucalyptus marginanta ) woodlands in the northern parts of the species range. These observations do not account for more recent evidence of their flexible use of habitat resources in other regions of its range. This may represent a significant conservation opportunity for the species through the identification of additional habitats that warrant protection. In a region where knowledge of their ecology is scarce, we used scat analysis and quantitative spotlighting to determine the diet and density of western ringtail possums in three vegetation types; peppermint, sheoak (Allocasuarina fraseriana) and marri-eucalypt (C. calophylla, E. marginanta and E. staerii) woodlands. Given the species’ reported dependence on peppermint woodlands and dominant canopy species for food sources, we hypothesised that western ringtail possums would be most abundant in this habitat type and that their diet would comprise the foliage of few (≤ 2 species) canopy species. We found western ringtail possums consumed a higher diversity of plant species than expected (8-14); exhibited dietary preference for non-dominant canopy species; and were present in all sampled vegetation types at substantially higher densities than previously recorded for the region (as high as 17 possums ha-1). Our results confirm (1) the western ringtail possum is flexible in its use of habitat resources, and (2) the significant conservation value of sheoak and marri-eucalypt woodlands in the southern-most portion of its distribution.