Introduced predators and habitat structure influence range contraction of an endangered native predator, the northern quoll

Introduced predators such as feral cats (Felis catus) are responsible for declines of many small mammals across the globe. The impact of cats can be exacerbated by mesopredator release, when larger predators (e.g. canids) are suppressed. In response to increasing predation threat from cats, native species may change their use of landscapes. We studied how interactions among native and introduced predators affect the decline of the largest native predator in northern Australia, the endangered northern quoll (Dasyurus hallucatus). The northern quoll is a carnivorous marsupial 'that is undergoing rapid population declines in most of its range, and is retreating to rugged, rocky parts of the landscape. Widespread dingo (Canis dingo) control has been hypothesized to lead to mesopredator release of cats in parts of the continent. Using camera trapping and GIS mapping methods, we determined the temporal activity and spatial distributions of sympatric northern quolls, dingoes and cats in the semi-arid Pilbara region of Western Australia. We found that dingoes were scarce, and their role as top predators in our study areas was weak. Cats avoided dingoes in time at a fine scale, but their spatial distribution was not affected by dingoes. Cats frequently used flat, open habitats. Quolls avoided areas used by cats. We suggest that introduced predators influence the use of landscapes by northern quolls at both local and larger scales. Predator avoidance is likely to be a major reason for the contraction of the distribution of northern quolls to rocky areas across northern Australia.