Knowledge of the ecology of the chuditch (Dasyurus geoffroii) is largely restricted to its distribution in mesic jarrah forests. There is a need for information regarding its ecology in semiarid zones where rainfall and consequently productivity are lower than mesic forests. Given that spatial requirements are strongly influenced by resource availability, it was expected that the chuditch in the semiarid zone would be present at lower densities and would have larger core home ranges (defined by daytime refuges) than those in the jarrah forests. The diet was also investigated by examining the contents of scats. Chuditch at Forrestania were trapped and six individuals were radio-tracked. The population density was one-third that of the lowest estimate reported from the jarrah forest and core home-range estimates were substantially larger, particularly for males. The diet included mammals, birds, reptiles, invertebrates, plants and rubbish, which was consistent with it being a generalist predator. Chuditch did have greater spatial requirements than in the jarrah forest, therefore different management regimes may be needed for populations occurring in the semiarid zone.