Factors influencing the effectiveness of wildlife underpasses in Banff National Park, Alberta, Canada

Clevenger and Waltho analyzed how the design and placement of wildlife underpasses beneath the Trans-Canada Highway in Banff National Park affected their use by different species, drawing on one of the longest-running monitoring programs of crossing structures in the world. They found that structural attributes, such as openness, dimensions, length, and proximity to cover, along with human activity levels, strongly influenced which animals used a given passage, with some species favoring high, open structures and others preferring more constricted ones. The work provided evidence-based guidance for designing crossings that actually function for the target wildlife, including carnivores. It became foundational to road-ecology practice, showing that crossing structures are not one-size-fits-all and that thoughtful, species-specific design is essential for restoring movement across highways.