Diet selection by the brush-tailed rock-wallaby (Petrogale penicillata) in East Gippsland, Victoria

Abstract

Resource selection by animals is assumed to have fitness benefits so quantifying resource selection can help determine suitable conditions for species persistence and be used to inform management plans. We studied diet selection by the ‘Critically Endangered’ Victorian brush-tailed rock-wallaby (Petrogale penicillata) by comparing proportions of plant functional groups consumed with their availability in the three remaining rock-wallaby colonies in East Gippsland, Victoria. We estimated availability using an adaptation of the point transect method, identifying 63 plant functional groups and their abundance within the foraging range. Using microhistological analysis of faecal pellets we determined diet composition at the resolution of plant functional groups: ferns, forbs, monocots, shrubs and trees. At all sites the plant functional groups constituting most of the diet were forbs, monocots and shrubs. However, diet composition and selection was different among the sites, particularly with regards to the consumption and selection of monocots, which appeared to be favoured at two sites, and of shrubs, which were favoured at the third site. Overall, the diet composition suggested that brush-tailed rock-wallabies consume a diverse range of food types. The results can be used to improve current management by increasing the availability of preferred food types, perhaps through targeted fire regimes, and to guide the selection of reintroduction sites.