A recent blog post by the Pew Trusts highlights how the growing success of wildlife crossings – bridges, underpasses, and culverts designed to help animals avoid vehicle traffic – across the U.S. is drawing a surge of interest from policymakers seeking to reduce wildlife-vehicle collisions and protect animals.
[Above photo by the Colorado DOT]
For example, Pew touted the success of the crossing along State Highway 9 in Colorado – built by the Colorado Department of Transportation and the Colorado Parks and Wildlife agency – that reduced wildlife-vehicle such collisions by 90 percent from 2015 to 2020.
Another example comes from Oregon along U.S. 97 near Lava Butte, where a crossing project built by the Oregon Department of Transportation reduced wildlife-vehicle collisions by roughly 85 percent between 2015 and 2017.
To broaden awareness of wildlife crossing benefits and needs, Pew held a conference of wildlife and climate experts in November 2022 to analyze and address how such crossings can address climate change issues and contribute to resilient ecosystems.
Those experts, who included researchers and policy professionals from the public and private sectors, co-authored a consensus statement and recommendations for including wildlife crossings in local, state, and federal climate adaptation strategies.
The ability for animals to migrate and move in response to changing conditions or extreme weather is fundamental to ecosystem resilience, helping to ensure not only one species’ survival but the broader balance of predators and prey, and healthy habitat, noted Matt Skroch, a project director with Pew.
Throughout the country, roads and highways often bisect – and in some cases fully block – those natural routes. By contrast, wildlife crossings can maintain or restore key ecological connections while lowering the risk of road accidents, he said – adding that, in many places, governments are replacing or upgrading culverts to accommodate an increase in flooding.
In doing so, they have an opportunity to factor wildlife passage into the design, making both the infrastructure and ecology of the surrounding area more resilient, Skroch pointed out.
State departments of transportation across the country continue investing in a variety of wildlife crossing projects.
For example, to date, Colorado DOT said it has built more than 60 wildlife mitigation structures crossing above or under highways throughout the state. Additionally, it has installed 400 miles of high big game fencing along state and U.S. highways or next to the interstates.
In August 2022, the agency completed a wildlife overpass and underpass on U.S. Highway 160 in the southwestern part of the state; a stretch of road where more than 60 percent of all crashes are due to wildlife-vehicle collisions.
Fortunately, Colorado DOT said its new wildlife crossing on U.S. Highway 160 should reduce the potential for wildlife-vehicle collisions by 85 percent.
Meanwhile, a research document released in July 2022 by an international pool funded study led by the Nevada Department of Transportation provides an “authoritative review” of the most effective measures to reduce animal-vehicle collisions, improve motorist safety, and build safer wildlife crossings.
With as many as two million collisions with large mammals in the United States leading to approximately 200 human deaths every year, the review compiled, evaluated, and synthesized studies, scientific reports, journal articles, technical papers, and other publications from within the United States and beyond to determine effectiveness of 30 different mitigation measures.
Ultimately, the report provides best management practices to reduce animal-vehicle collisions, increase habitat connectivity, and implement cost-effective solutions.