Aspects of the Demography of the Western Grey-Kangaroo, Macropus-Fuliginosus-Melanops, in Semiarid Northwest Victoria

Abstract

The study was carried out at Hattah-Kulkyne National Park in semiarid north-west Victoria, during 3 years immediately following a severe drought. A sample of animals which died as a result of the drought (n= 196) and a shot sample (n=546) were examined to determine patterns of breeding, mortality and age structure. Births were concentrated in spring and summer, with a peak in November. Only 46% of mature females bred during the drought, whereas 100% bred two seasons later. The sex ratio of pouch young was not significantly different from parity, but showed a slight male-bias, however, the sex ratio of the adult population was markedly female-biased (1:3). Projected population growth was not realised in the years following the drought because of high mortality. There was evidence of male-biased mortality which was apparently accentuated during the drought. This biased mortality appeared similar in all adult age classes, and may have been a consequence of the disparate energy costs imposed by sex differences in body size and in mobility.