The conservation community has long understood that roads as well as other linear infrastructure (e.g., railways, pipelines) can imperil and impede wildlife. To date, however, investments by departments of transportation in wildlife crossings have largely been motivated by reducing costly wildlife-vehicle collisions and improving driver safety. Benefits to wildlife per se have not historically been the primary driver in many wildlife crossing investments. But this has begun to change, as several high-profile efforts—e.g., the Trans-Canada Highway crossings in Banff National Park, the I-90 Snoqualmie Pass Project in the North Cascades—are generating ample evidence that such investments are crucial for wildlife and for re-connecting landscapes more broadly. These wildlife crossings afford numerous benefits, from facilitating migration to ensuring dependable access to seasonal resources, from supporting gene flow to allowing meta-population dynamics to unfold, among other crucial processes.
Yet there is another tremendous benefit that wildlife crossings have the potential to afford that is not yet accounted for: supporting wildlife in adapting to climate change and enhancing ecosystem resilience. As effective as wildlife crossings can be, their siting and design rarely account for the movements necessary for wildlife to track suitable conditions that are shifting in time and space, among other climate impacts (e.g., extreme events).
We therefore sought to compile evidence—both empirical and theoretical—of the role that wildlife crossings may play in supporting climate change adaptation and ecosystem resilience. We did so through a literature review as well as a case study. As in practice, the science behind wildlife crossings and road ecology remains quite distinct from the science of climate adaptation. Still, our literature review revealed substantial potential for wildlife crossings to support or otherwise interact with individual fitness, population dynamics, species interactions, habitat provisioning, range shifts, and ecological processes in the face of climatic changes.
We sought to substantiate these lessons from the literature with a case study using collar data shared by the Southern Ute Tribe. Specifically, we modeled elk movement between summer and winter ranges in southwestern Colorado and northwestern New Mexico under future climatic conditions both with and without proposed wildlife crossing. We also accounted for probable changes to land cover (e.g., expanded human development, lack of forest recovery following wildfire) and traffic volumes. Here, we will present the results of our modeling effort, which underscore the important role that wildlife crossings can play in this era of unprecedented change.