Wildlife crossings – the overpasses, underpasses, fencing, and other structures that traverse or surround linear infrastructure – are good at keeping wildlife connected. They help individuals move freely across the landscape, they protect large-scale migration routes, and they help prevent dangerous wildlife-vehicle collisions. With funding from government initiatives such as the Wildlife Crossings Pilot Program and the Infrastructure Investment and Jobs Act, more wildlife crossings than ever are being built across the U.S.
Beyond their known benefits, wildlife crossings are rarely considered in the context of climate change. As altered climatic conditions cause species to shift their ranges or migration routes, can wildlife crossings be built so that they are beneficial both now and in the future? Currently, few designs or studies of wildlife crossings explicitly incorporate climate connectivity.
Littlefield, C.E., Suraci, J.P., Kintsch, J., Callahan, R., Cramer, P., Cross, M.S., Dickson, B.G., Duncan, L.A., Fisher, J.R., Freeman, P.T. and Seidler, R., Wearn, A., Andrews, K.M., Brocki, M., Dodd, N., Gagnon, J., Johnson, A., Krosby, M., Skroch, M., and R. Sutherland. 2024. Evaluating and elevating the role of wildlife road crossings in climate adaptation. Frontiers in Ecology and the Environment. DOI: 10.1002/fee.2816.
A new publication highlights the potential for wildlife crossings to become part of the climate adaptation toolbox. First, through a review of current literature, it summarizes known benefits of wildlife crossings in the context of climate change, such as their ability to support individual fitness and reduce mortality as resources shift; to support gene flow as populations shift; to maintain predator-prey relationships under changing conditions; to protect access to shifting habitat and resources; to enable range shifts needed to adapt to changing conditions; and to support ecosystem functioning and resilience under variable environments.
A case study exemplifies how to incorporate climate change into wildlife crossing plans by looking at elk migration in Colorado and New Mexico, which is threatened by disrupted connectivity between low elevation winter ranges and high elevation summer ranges. GPS locations from 43 elk between 2013-2021 were used to model migratory connectivity under present and future climatic conditions and evaluate potential wildlife crossing locations.
The results show that migratory routes are likely to shift due to changes in climate and landscape permeability, and therefore change where elk might cross highways. Incorporating both present and future routes identified potential locations for wildlife crossings that would be valuable now and remain valuable in the long term. Planners that select sites where present and future benefits coincide are likely to build more effective wildlife crossings.
Overall, there are several considerations when adapting the idea of climate-informed wildlife crossings into practice:
- Taking a long-term, large-scale approach to funding initiatives and transportation programs
- Greater collaboration across jurisdictions and agencies, including Tribal nations and historically marginalized communities
- Encouraging climate-adaptive innovation and the long-term, cross-collaboration application of scientific findings
While there are still many unanswered questions about the effectiveness of wildlife crossings, there is extensive evidence showing their benefits. These benefits can be multiplied by explicitly incorporating climate change information to make sure crossings stay relevant in the future. As a result, even as linear infrastructure continues to fracture landscapes, wildlife populations can remain connected.
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