Characterising the habitat of road trauma hotspots for threatened black cockatoos in metropolitan Perth, Western Australia

Context Threatened native black cockatoo species are affected by vehicular collisions in Western Australia. Aims We examined the interaction of a range of geospatial variables on black cockatoo collisions with vehicles during two time periods (2011–2015 and 2016–2020) to identify hotspots for vehicle trauma in the Perth metropolitan area. Methods A geospatial desktop analysis was conducted using publicly available datasets for road networks, traffic volumes, remnant native vegetation and water bodies, along with Perth Zoo Veterinary Department admission records for Carnaby’s and forest red-tailed black cockatoos. Key results Admission records for 547 black cockatoos showed significant non-random clustering of locations where black cockatoos collided with vehicles. Temporal regression modelling showed that the number of collisions with vehicles was positively correlated with road density and percentage of remnant vegetation but negatively correlated with distance to nocturnal roosting sites. Spatial regression modelling showed that the distribution of collisions with vehicles across both species was influenced by road density and distance to cockatoo roost sites, with percentage of vegetation and water bodies as explanatory variables. Conclusions A large number of black cockatoos have been injured or killed along major roadways in the Perth metropolitan region, with injuries and deaths tending to increase in frequency over the surveyed time. The distribution of collision locations was non-random and showed evidence of significant clustering around hotspots where future mitigation efforts may be most effective or most needed. Implications Identifying locations of trauma hotspots and contributing factors provides opportunity for decision-makers to better design road networks to ensure sustainable development and improve black cockatoo conservation.