The intersection of wildlife and people on highways raises two critical issues: impacts of roads on the movement and mortality of wildlife, and risks to people from animal-vehicle collisions (AVCs). In Alberta, as in many areas, these two issues are addressed by different government agencies, with Alberta Transportation (AT) mandated to address motorist safety and Alberta Environment and Parks (AEP) mandated to manage Alberta's wildlife. AVCs are responsible for ~50% of all vehicle collisions in rural areas, and therefore represent an important human safety concern. AEP has several policy objectives relating to maintaining wildlife connectivity in support of species recovery and biodiversity management goals.
There is a need to better understand wildlife connectivity across the highway network in southern Alberta, identify areas of high human safety risk, and prioritize highway sections where mitigation solutions should be implemented. To meet these needs, we developed a coupled AEP-AT decision support tool that incorporates wildlife connectivity concerns into future road development and highway upgrade projects, linking Alberta's transportation planning and land use planning processes.
We developed an AVC Risk Index using Royal Canadian Mounted Police records of animal carcasses from AVCs along roads in southern Alberta, which enabled the identification of highway sections with relatively high AVC density and therefore high human safety risk. We developed functional connectivity models for four focal species (pronghorn, rattlesnake, grizzly bear, and mule deer) and a species-neutral structural connectivity model using Linkage Mapper software, and then derived Connectivity Value Indices by extracting values from connectivity model outputs for grid cells along highway sections. We compared the AVC Risk Index and Connectivity Value Indices to determine whether and where priority highway sections identified by different indices overlapped.
Our results indicated poor spatial overlap between highway sections of high human safety concern and those of high value for wildlife connectivity. AVC risk was highest along urban fringes where deer are common and traffic volumes are high, which are often ecologically marginal areas. Functional connectivity models for focal species highlighted areas more distant from urban centers where wildlife agencies may want to focus finer-scale assessments, especially in cases where road mortality and avoidance behaviour are concerns for at-risk species. Species-agnostic structural connectivity models based on landscape naturalness may be most effective as a tool for communicating the importance of connectivity and supporting broader biodiversity objectives in fragmented landscapes. Future mitigation investment decisions should take into account both AVC risk and wildlife connectivity needs - which may suggest different priority locations - in order to protect the well-being of human and wildlife populations