Mitigating Continental-Scale Bottlenecks: How Small-Scale Highway Mitigation Has Large-Scale Impacts

Roads are a primary contributor to habitat destruction and fragmentation yet have only recently become a major focus of conservation efforts. Road ecology originated from the realization that sprawling road systems can have substantial effects on species and ecosystems. Understanding these effects and developing science-based solutions to mitigate them will be central to large-scale landscape connectivity efforts. North American transportation agencies have been slow to adopt ecosystem and landscape-based approaches to planning. Large-landscape connectivity efforts focus on mitigating habitat fragmentation and increasing ecological connectivity at the landscape scale; however, local-scale mitigation is equally important. Wildlife crossing structures are an increasingly popular strategy for restoring connectivity across highways but are only as effective as the management strategies developed around them. Coordination is needed between land management and transportation agencies for local scale mitigation to be of value to landscape scale conservation planning. Because population viability is rarely threatened by transportation alone, cumulative human impacts need to be assessed and mitigated for connectivity conservation efforts to be successful at local scales. Here I provide an example where a multi-criteria decision-making process was used to assess potential transportation mitigation opportunities at a local scale but within a regional connectivity context. More work is required to assess the role of crossing structures in allowing animals to adapt and population to redistribute in response to changing climate.