Does a highway through a conservation reserve disrupt populations of medium-sized mammals in eastern Australia?

Major roads are common within conservation reserves in Australia; however, few studies have described their impacts on wildlife. We investigated whether eight species of native mammals were influenced by a highway through a conservation reserve in north-east New South Wales. We conducted camera-trapping over a 17-month period at sites along the highway and at sites at varying distance (0.5–10 km) along service roads through adjoining forest. Evidence of a highway response on the basis of the probability of occupancy was strongest in the Vulnerable parma wallaby (Notamacropus parma), with occupancy increasing from 0.5 (0.26–0.66, 95%CI) at highway sites to 0.96 (0.74–1.0) at sites >3 km into the forest interior. For the Vulnerable long-nosed potoroo (Potorous tridactylus) and the swamp wallaby (Wallabia bicolor), the probability of detection increased by 10% from the highway to forest interior, but other factors (season or recent wildfire) induced greater variation in detection. The mountain brushtail possum (Trichosurus caninus) differed from all other species in showing higher detection near the highway (0.35, 0.30–0.41) than in the forest interior (0.18, 0.15–0.22). Enhanced habitat quality associated with the highway may explain this pattern. The Endangered spotted-tailed quoll (Dasyurus maculatus) was detected at 80% of sites, although too infrequently to adequately assess its response to the highway. Our study showed that an occupancy approach can be used to investigate responses of wildlife to roads. Further studies are needed to better understand if major roads through conservation reserves have an adverse influence of wildlife populations.