A major road and an artificial waterway are barriers to the rapidly declining western ringtail possum, Pseudocheirus occidentalis

[Truncated] Roads are known to pose negative impacts on wildlife by causing direct mortality, habitat destruction and habitat fragmentation. Other kinds of artificial linear structures, such as railways, powerline corridors and artificial waterways, have the potential to cause similar negative impacts. However, their impacts have been rarely studied, especially on arboreal species even though these animals are thought to be highly vulnerable to the effects of habitat fragmentation due to their fidelity to canopies. In this thesis, I studied the effects of a major road and an artificial waterway on movements and genetics of an endangered arboreal species, the western ringtail possum (Pseudocheirus occidentalis). Despite their endangered status and recent dramatic decline, not a lot is known about this species mainly because of the difficulties in capturing them. Using a specially designed dart gun, I captured and radio tracked possums over three consecutive years to study their movement and survival along Caves Road and an artificial waterway near Busselton, Western Australia. I studied the home ranges, dispersal pattern, genetic diversity and survival, and performed population viability analyses on a population with one of the highest known densities of P. occidentalis. I also carried out simulations to investigate the consequences of removing the main causes of mortality in radio collared adults, fox predation and road mortality, in order to identify effective management options. A rope bridge was built to provide this species with a safe passage across Caves Road in July 2013, and I present the results from 270 days of monitoring of the rope bridge and factors influencing the numbers of crossings.

No radio collared possums crossed the road successfully during my study, while two were killed on the road. No collared possums crossed the waterway, except for one accidentally falling into the waterway during a severe storm. None of the home ranges included the road or waterway, suggesting that they both act as physical barriers for possums. Even a 5 m wide firebreak was enough to limit the movements of some possums where canopy connection was not available. Individuals in partially cleared campsites mostly remained within groups of trees with continuous canopy connections. Home ranges were small (males: 0.31 ± 0.044 ha, females: 0.16 ± 0.017 ha), and their sizes were affected by sex and proximity to the waterway. These results highlight the exceptionally sedentary and arboreal nature of this species.