The effect of habitat type and seasonal conditions on fauna in two areas of the Tanami Desert

Australian deserts are characterised by highly patterned plant productivity and an extremely unpredictable climate. The Tanami Desert in central Australia is dominated by vast sandplains interspersed with more productive habitats such as palaeodrainage lines. During 1996 and 1997 fauna surveys were conducted in two areas of the Tanami Desert to investigate the relative importance of palaeodrainage habitat for fauna under different seasonal conditions. The two areas were at latitudes separated by approximately 400 km, and during the study period the northern study area (Tennant) received considerably more rainfall than the southern study area (Kintore). The species richness and abundance of a range of taxonomic groups were compared between the two study areas and between palaeodrainage habitat and adjacent sandplain habitat. The only significant difference between habitats was that small reptiles were more abundant in sandplain than palaeodrainage habitat. Overall, bilbies, bustards and macropods were significantly more abundant at Tennant than Kintore, but significantly more small mammals were captured at Kintore. In both habitats and areas, capture rates, track counts and species richness of reptiles varied significantly with season. The biomass of invertebrates captured also showed significant temporal fluctuations. Burrowing frogs were active only after rain, and birds showed significant fluctuations in abundance and species richness associated with rainfall. The abundance of small mammals did not vary significantly during this study. Overall, local seasonal conditions were generally more important determinants of the abundance of fauna in the spinifex grasslands of central Australia than was habitat type.