Are smaller subspecies of common brushtail possums more omnivorous than larger ones?

Abstract

Body size is often associated with a dietary divergence within taxonomically related groups so that large animals are often folivorous, while smaller species shift progressively towards omnivory or carnivory.This trend may be influenced by allometric constrains which result in relatively high energetic requirements, but low gut capacities in small animals, compared to their large counterparts. The common brushtail possum (Trichosurus vulpecula, Phalangeridae) has six subspecies ranging widely in weight (1-4 kg). They are not strictly folivorous, but supplement their diet with more nutritious, non-foliar foods. We predicted that T. vulpecula subspecies diverged in diet in association with body size, with smaller subspecies consuming higher proportions of non-foliar foods. We assessed this with a review and a meta-analysis of previous Australian studies. We also investigated the previously unquantified diet of T. v. hypoleucus at three sites in the northern jarrah forest of Western Australia. Results from the meta-analysis and the review supported our prediction. However, the large variability in the data highlighted their limitations and those of the techniques commonly used to quantify the diet of T. vulpecula. Nonetheless, small subspecies of T. vulpecula appear to consume higher proportions of non-foliar foods. These results should encourage further research into the body size/diet relationship within T. vulpecula and other possum species. Results from the dietary study of T. v. hypoleucus emphasized their omnivorous diet, which was dominated by foliage and flowers and smaller proportions of invertebrates, seeds and fruits. The common brushtail possum is seldom an exclusive arboreal folivore, but rather ranges from folivory to omnivory.

Effects of territorial status and life history on Sandhill Crane (Antigone canadensis) population dynamics in south-central Wisconsin, USA

“…Two-year-olds and territorial birds had the highest apparent survival rates, 0.977 and 0.942, respectively. Survival of territorial birds was significantly greater than survival of non-territorial birds (no overlap of 95% confidence intervals, Table 3; Cumming 2009;Cruz et al 2012).…”

Craniomandibular Variation in Phalangeriform Marsupials: Functional Comparisons with Primates

“…Species selected for each genus were based on the best represented sample in the available osteological collections. Subspecies of Trichosurus vulpecula differ in the degree of commitment to folivory (Smith and Ganzhorn, ; Cruz et al, ). The diet of T.v.…”

Comparative dietary ecology of two congeneric marsupial folivores

“…Local diet data are particularly important for species with variable ecology, such as the common brushtail possum (Kerle 1984). Frequently considered a eucalypt folivore, common brushtails span a continuum from folivory to omnivory (Foulkes 2001;Cruz et al 2012), and at some sites eucalypt foliage is absent from their diet (Kerle 1984). In contrast to marsupials that specialize on Eucalyptus, our understanding of folivorous species that feed primarily on other plant taxa is limited, and much of the diet of these remains poorly known.…”