Facilitated movement over major roads is required to minimise extinction risk in an urban metapopulation of a gliding mammal
Taylor, BD & Goldingay, RL 2012, 'Facilitated movement over major roads is required to minimise extinction risk in an urban metapopulation of a gliding mammal', Wildlife Research, vol. 39, no. 8, pp. 685-695.
Published version available from: http://dx.doi.org/10.1071/WR12142
Context: Urbanisation is recognised as a primary cause of biodiversity loss. Roads are an inherent element of this, creating partial or complete barriers to animal movement. Urban landscapes of eastern Australia are typified by a dense road network interspersed with remnant patches of bushland. Inter-patch movement by tree-dependent gliding mammals may be halted and, consequently, population viability threatened, when canopy gaps over roads exceed gliding ability.
Aims: We test the notion that a metapopulation of the squirrel glider (Petaurus norfolcensis) in southern Brisbane can persist within a highly fragmented urban landscape with large road canopy gaps.
Methods: We used the population modelling software VORTEX to investigate the influence of inter-patch movement (dispersal) and wildfire on the probability of extinction. Wildfire is an inherent characteristic of this landscape.
Key results: Our modelling suggests that a lack of inter-patch movement as a result of road barriers, in tandem with wildfire, is associated with a high probability of local extinction. However, a small rate of inter-patch movement can substantially reduce the likelihood of extinction.
Conclusions: Road-crossing structures are the most plausible means available to link remnants to enable inter-patch movement for squirrel gliders in this landscape because of inadequate road-side tree height. Simulation studies such as the present study that test population viability are critical to convince land managers that action must be taken.
Implications: The need to conserve urban biodiversity will increase over time, so land managers must consider the likely benefits to population persistence conferred by installing wildlife crossing structures into existing roads.