In light of new federal funding and surging public support, many US states are now undertaking planning efforts to determine the highest priority locations for wildlife road crossings. However, such planning efforts are complicated by the simple fact that wildlife crossing structures help to achieve not one but two primary benefits: reducing dangerous and costly collisions between vehicles and large mammals (often ungulates such as deer and elk), and promoting habitat connectivity for the broad spectrum of wildlife diversity. Studies have unfortunately confirmed that these two goals are not necessarily complementary. For example, deer populations and deer-vehicle collision rates are often quite high in suburban and exurban environments, areas that are generally considered to be of lower priority by conservation biologists seeking to create networks of intact, well-connected natural habitats such as mountain wilderness and wetlands.
Wildlands Network, a nonprofit organization dedicated to reconnecting natural areas across North America, has recently completed an effort to determine the highest priority locations for new wildlife road crossing structures across North Carolina, USA. The project dealt explicitly with the trade-offs mentioned above, by integrating relevant data sets covering deer-vehicle collisions and large-scale habitat connectivity priorities alike. We provided the different data layers to a large group of expert wildlife biologists who were tasked with ranking potential road crossing sites around the state, and eventually ended up with a list of the top 20 locations. Our report did not end there, however, we also provide NC DOT and other interested parties with a full list of 179 priority locations well-stratified across the extensive highway system of this wildlife-rich state.
We found during the prioritization process that wildlife experts often did not pick suburban deer collision hotspots, instead their focus tended to be on macro connections between large and well-known protected habitat areas. But there were some sites with overlap, such as Interstate 40 where that highway crosses through the elk and bear-laded Pigeon River Gorge, and US 64 where the road runs through the extensive and biodiversity-rich wetlands of Alligator River National Wildlife Refuge. Our top 20 sites represent places where the need is sufficiently urgent to justify efforts to install road crossings independent of other highway improvement activities. But the full list of sites can and should be incorporated into the full breadth and scope of transportation planning for North Carolina.
This presentation will highlight the trade-offs faced by this nonprofit-led effort to identify wildlife road crossing sites, presenting a case study that should prove quite useful for other states and jurisdictions attempting similar work across the country and around the world.