Prioritizing human safety and multispecies connectivity across a regional road network

Abstract

The intersection of wildlife and people on roads raises two critical issues: the barrier and mortality effects of roads on wildlife and risks to people from animal-vehicle collisions (AVCs). Road mitigation decisions are typically made at the discretion of transportation departments that are mandated to primarily address motorist safety. Therefore, prioritization of road sections for mitigation currently focuses on identification of spatial clusters of AVCs. We sought to understand if AVC clusters align with multispecies connectivity across roads to accurately identify multipurpose mitigation hotspots. We developed a decision-support tool based on weighted priorities for mitigation planning across 7,900 km of roads over an 84,000-km 2 area of southern Alberta, Canada. To assess alignment, we built functional connectivity models for four focal species (prairie rattlesnake, grizzly bear, mule deer, and pronghorn) and a species-neutral structural connectivity model. We integrated AVC risk and wildlife connectivity indices into Mitigation Priority Indices that varied the weighting of individual indices. Our results demonstrated poor spatial alignment between road sections of high motorist safety risk and those of high value for wildlife connectivity. Transportation planning would benefit from integrating motorist safety risk and wildlife management needs to prioritize mitigation neighborhoods along roadways.

Is it the road or the fence? Influence of linear anthropogenic features on the movement and distribution of a partially migratory ungulate

“…To accomplish these mitigations requires collaborating with landowners and transportation agencies to ensure project success. For example, the area in the eastern portion of our study area has been identified as high value for pronghorn connectivity [ 48 ]. This area is bisected by the Trans-Canada Highway, with road sections of varying fence configurations (none, one, or both sides) and the surrounding area comprised of differing degrees of pasture fence densities.…”

“…This area is bisected by the Trans-Canada Highway, with road sections of varying fence configurations (none, one, or both sides) and the surrounding area comprised of differing degrees of pasture fence densities. This is a prime area to install an overpass with wing fencing along strategic road sections and to modify the adjacent pasture fences to facilitate movement [ 46 , 48 ]. Allowing pronghorn to freely move across the landscape will maintain functional connectivity to ensure population persistence of this endemic ungulate.…”

“…The three classes were paved divided (major highway with high-speed, high traffic volume), paved undivided (secondary highway with medium to large traffic volume) and gravel, dirt, or truck trail (county roads with low traffic volume). We combined all the road categories into one under the assumption that a barrier effect of roads would be constant for all road types and traffic volumes [ 48 ]. We buffered major and secondary highways by 40 m and county roads by 20 m to determine if the road was fenced or not.…”

Visualizing Connectivity for Wildlife in a World Without Roads

“…The approach developed here can be used experimentally to model improvement in connectivity when adding crossing structures in different places on the landscape. This technique can be applied in conjunction with, or in place of, the use of roadkill hotspots, which are generally limited to larger-bodied species such as deer and elk and do not necessarily align with best places for improving connectivity (Eberhardt et al, 2013;Teixeira et al, 2017;Lee et al, 2021), or standard GIS modeling approaches, which may not consider what connectivity would be like in the absence of the road barrier.…”

A before-after-control-impact study of wildlife fencing along a highway in the Canadian Rocky Mountains

“…Fencing may be accompanied by wildlife crossing structures, which are intended to maintain or restore the safe movement of wildlife across the highway via underpasses or overpasses. Because of its cost, fencing is usually prioritized along particular road segments or "hotspots" of WVCs (Ford et al, 2011;Huijser et al, 2016;Lee et al, 2020).…”