THE EFFECTS OF SEASON, SEX AND HABITAT ON THE DIET OF THE MOUNTAIN PYGMY-POSSUM (BURRAMYS-PARVUS)

The mountain pygmy-possum (Burramys parvus) is a rare marsupial (approximately 2300 individuals) with a restricted distribution (10 km2) confined to isolated patches of heath in the Australian Alps that are vulnerable to clearing and modification for ski-run development. In Mt Kosciusko National Park the diet of Burramys averaged 71% arthropods, 27% seeds and berries, and 2% other material. The diversity of arthropod prey was low and dominated by a single species, Agrotis infusa (the Bogong moth). The diversity of seed and berry intake was high (8 species) and dominated by the seed and fruit of Podocarpus lawrencei (8%) and fruit of Leucopogon montanus. The relative proportion of arthropod to seed and berry in the diet changed significantly with sex, age, reproductive state, body weight, season, elevation and habitat (Podocarpus lawrencei cover, boulder cover and moth abundance). Females had a higher intake of arthropod than males in all seasons and locations. This result is consistent with their higher protein requirement for reproduction and the need to ensure that young grow rapidly enough to gain sufficient weight to survive their first winter in hibernation. Patterns of spatial and seasonal variation in food availability explain the unique patterns of sexual segregation and daily and/or seasonal migration exhibited by Burramys. Nightly or seasonal movement is necessary to optimise exploitation of Bogong moths on high-elevation peaks in summer and seeds and berries in lower-elevation heaths during late summer and early autumn. These results signify the importance of protecting migration corridors along boulder screes, between low- and high-elevation habitats, from destruction or modification during ski-run development.