Home range, burrow-use and activity patterns in common wombats (Vombatus ursinus)

Abstract

Wombats are large, marsupial herbivores able to exploit low-productivity habitats largely because of their low energy requirements. In addition to using deep, thermally favourable burrows, wombats might use a strategy of conservative above-ground ranging behaviour to achieve their low energy expenditure. This study examined home range, burrow use and diurnal activity patterns of common wombats (Vombatus ursinus) in eucalypt forest, woodland and pasture using trapping and radio-tracking. Wombats ranged through all three vegetation types with forest and pasture clearly being important habitats. Home ranges (95% harmonic mean) were typically almost circular, and averaged 17.7 ha with core areas (50% harmonic mean) averaging 2.9 ha. Home-range size is small compared with that expected for most mammals of comparable body mass. Ranging behaviour for wombats was similar between sexes and ranges extensively overlapped between and within sexes, indicating that ranges are not actively defended. Wombats did not markedly change the size or location of home ranges, ranging behaviour or feeding areas between summer and winter. The density of active burrows (0.25 ha–1) far exceeded the estimated density of wombats (0.13 ha–1). Wombats typically spent 1–4 days sleeping in the same burrow and then moved to another. On average, each active burrow was used by 2.2 different individuals. The activity pattern of wombats is characterised by a strong diel cycle, with most activity occurring nocturnally. Activity peaks at the beginning and end of each night are consistent with a ‘travel out, graze, travel back’ movement pattern. Despite widely distributed food resources, small home ranges and obligate burrow use constrain wombats to meeting their year-round food and water requirements from a small area near their burrows.