Comparative dietary ecology of two congeneric marsupial folivores

Abstract

Knowledge of species diets is critical to assisting our understanding of their ecology. Using microhistological analysis of faecal samples, we described and compared the diets of sympatrically occurring folivorous congenerics, common and mountain brushtail possums (Trichosurus vulpecula and T. cunninghami, respectively). Throughout the 28-month study period, common brushtails relied heavily on eucalypt foliage, particularly very young leaves, which is consistent with data from captive studies on their dietary physiology. In contrast, eucalypt foliage formed only a small part of the diet of mountain brushtails, which instead relied heavily on silver wattle foliage. The mean number of plant groups per faecal sample was significantly greater for common brushtails than mountain brushtails. No significant differences in diet between male and female mountain brushtails were detected. However, intraspecific differences in diet occurred for common brushtails: the diet of females included significantly less eucalypt foliage and significantly more foliage of the exotic, tree lucerne, than that of males during the Wet Season (April-November), but not during the Dry Season (December-March). Diets varied temporally for both species, with some individuals feeding on seasonally available resources. The diets described for common and mountain brushtails are consistent with those of a dry-adapted and mesic-adapted species, respectively.We discuss how our results contribute to our understanding of the evolutionary history of both study species, and more broadly the family Phalangeridae to which they belong. We also consider the diet of our study species in the context of recent advances in our understanding of interactions between plants that produce secondary metabolites, and mammals specialized to feed on them.

Time to adjust: changes in the diet of a reintroduced marsupial after release

“…In contrast, few tall genera (> 2.5 m height) were available compared to shrubs and annuals, but their frequency of occurrence within scats was high. This suggests that possums spend more time foraging in the canopy than on the ground, a result supported by previous studies of possum foraging and movement, where diet is dominated by canopy species (Foulkes, 2001; Cruz et al, 2012; Gloury & Handasyde, 2016). This could be a result of the avoidance of predators at ground level, the quality of food in the canopy, or a combination of both.…”

“…Although other studies have suggested that possum diet changes seasonally, most studies have not spanned > 12 months (Freeland & Winter, 1975; Fitzgerald, 1984; Statham, 1984; Cruz et al, 2012). In one exception, differences were found between the wet and dry season diet of brushtail possums in the tropics, with some sex effects also observed over the 29 month study period (Gloury & Handasyde, 2016). Although these studies suggest that the post-release dietary acclimatization in our study could have included some seasonal effects, more long-term dietary studies are needed to differentiate between normal fluctuations in possum diet and post-release effects.…”