Behavioural Ecology of Petrogale penicillata In Relation to Conservation.

Abstract

Brush-tailed Rock-wallabies Petrogale penicillata are still widely distributed in the gorges on the east of the New England Tablelands of northern NSW, in small (mean <6 adults) colonies, separated by an appreciable distance (median separation 308 m) from neighbouring colonies. Within colonies, established adults occupy a refuge or set of refuges by day, moving away from the colony to forage mainly at night. A set of 1-3 adult females shares a small number of refuges, with one adult male defending access to them and their refuges. A colony contains one or several such sets. Established females occupy refuges persistently, up to at least 4 years and perhaps until death; males also defend their diurnal ranges persistently, but male ranges do change owner through intrusion or supplanting, as well as when the incumbent dies. Sub-adults of both sexes seem to be the dispersing classes, although a daughter may remain, mature and breed in her mother’s range. Only adults established in refuges appear to breed. The most dominant among the females sharing a set of refuges tends to produce more young than do subordinates. The combination of small and separated colonies, dispersal only by naive sub-adults, a strong restriction of mating opportunities within breeding groups, and unequal contribution to breeding even by females, could make P. penicillata prone to predation by agile predators that can learn the locations of their persistently used sites, and to problems of conserving population numbers and allelic diversity. These latter conservation problems can be simply addressed by artificial dispersal (translocation) of appropriate animals.