Effects of cover reduction on mulgara Dasycercus cristicauda (Marsupialia: Dasyuridae), rodent and invertebrate populations in central Australia: Implications for land management

This study investigates the effect of cover reduction on the mulgara, Dasycercus cristicauda, a small marsupial classified as vulnerable to extinction, which occurs in areas of central Australia dominated by hummock grasslands. Loss or degradation of spinifex has been implicated in population declines of this species previously, but the importance of cover in maintaining quality habitat remains speculative. To determine the effect on D. cristicauda of cover reduction, caused by the harvesting of spinifex, we monitored population changes and changes in prey resources (rodents and invertebrates) before and after spinifex harvesting took place at a site near the Ayers Rock Resort, Northern Territory, Australia. Ten plots, each of 8.75 ha, were established and sampled from May 1994 to October 1995. Harvesting took place on five plots in August 1994, which reduced spinifex cover from 46 to 21% and the amount of spinifex >0.25 m high from 42 to 2%. Harvesting did not significantly affect the number of D. cristicauda known to be alive or captured despite other studies indicating that cover is an important habitat attribute. There was also no evidence that cover reduction impacted on the biomass of the invertebrate food resources. However, there was a significant reduction in the number of rodents captured. The lack of a response to cover reduction by D. cristicauda is possibly because the cover of Triodia remained high enough (above 15%) to sustain animals, and harvested areas were relatively small. This study therefore suggests that D. cristicauda can tolerate a moderate local reduction in cover of its preferred habitat. However, it remains possible that other land use practices that cause severe reduction of cover (including clearing for mining or fire prevention, grazing which may result in spinifex reduction through trampling, and fire management) will have more dramatic effects on D. cristicauda. Evaluation of such effects should be a priority for future research.