Density distributions and habitat associations of red kangaroos, Macropus rufus, and western grey kangaroos, M. fuliginosus

Abstract

Density distributions of red and western grey kangaroos in the South Australian pastoral zone were determined for the period 1978-86. The habitat associations of these kangaroos were analysed using the densities on half-degree blocks, and information on landform and soil type, land use and degradation, vegetation, and climate. Red kangaroos were found throughout the pastoral zone, the highest densities being in the north-east. Western grey kangaroos were restricted to the southern parts of the pastoral zone. Higher densities of red kangaroos were associated with pastoral land use, with brown calcareous and red duplex soils, and with areas dominated by low bluebush shrublands. They were not particularly closely associated with areas dominated by mulga. Habitat associations of red kangaroos were different in drought years compared to non-drought years. Changes in density distribution during drought appears to have been due to the patchiness of rainfall. The relative effect of the drought was greatest in the northern part of the pastoral zone. Outside this effect, recent rainfall was found to be of only secondary importance to the overall density distribution of red kangaroos. Climatic factors appeared to be the major determinants of the density distribution of western grey kangaroos. Low evaporation and relatively high rainfall characterised areas with high densities of western grey kangaroos. As was the case with red kangaroos, habitat heterogeneity appeared to be an important requirement of western grey kangaroos. Also, habitat associations were different in drought and non-drought years. Despite this, as was the case with red kangaroos, recent rainfall was only of secondary importance to the overall distribution of western grey kangaroos.