Making Space for Migratory Mammals on the Move | Article

Every year, hundreds of thousands of pronghorn, an antelope-like mammal, travel over a hundred miles—and back again—across Wyoming, making the longest land migration in the lower 48 states. As the state became more populated, multiplying roads, fences, and other developments blocked the routes pronghorn have traversed for thousands of years.

Development is more than a mere inconvenience for pronghorn. With traditional migratory pathways blocked by fences, roads, buildings, and other infrastructure, the animals could wander through towns in confusion and desperation, making them vulnerable to car collisions as they attempted to reach their seasonal habitat.

To address the issue, policymakers and scientists established the only federally-recognized migration corridor in the United States to date: the Path of the Pronghorn. Beginning in 2008, a series of underpasses and overpasses were constructed to facilitate safe passage of pronghorn across the roads that now bisect their migration paths.

These collaborative efforts to reconnect habitat have proven successful. At the Trappers Point pronghorn overpass, for example, wildlife-vehicle collisions have decreased by over 80 percent per year, protecting drivers and conserving this unique animal, along with dozens of other species, such as mule deer. Overall, officials say Wyoming Department of Transportation crossing projects have resulted in the safe passage of about 30,000 big-game animals annually.

Hank the Tank, a 500-pound black bear, made headlines in February 2022 when he was suspected of breaking into several homes in South Lake Tahoe, California. Wildlife authorities had indicated Hank might have to be euthanized if captured as he had begun associating human homes with food and so would not have been able to return to wild life.

A later investigation revealed the break-ins were not caused by Hank alone, but by at least three different bears. While Hank was spared from euthanasia or captivity because of these findings, the drama highlighted the issues caused by habitat fragmentation.

Photo Credit: BEAR League

Wildlife crossing structures have successfully provided safer passage for a whole host of other species across roadways throughout the nation. In addition to improving safety for both drivers and wildlife, these “wildlife crossings” have additional conservation benefits. Habitat fragmentation, caused when infrastructure slices through natural areas, can accelerate species extinction, and cause animals that may be threatening to humans, such as bobcats or bears, to come into unwanted contact with people. A changing climate is also causing species to shift their traditional ranges, meaning that providing them with room to roam is becoming increasingly important for their survival.

Infrastructure that maintains connections between wild areas can protect both people and animals. For these reasons, and due to the success of projects like the Path of the Pronghorn, wildlife corridors have gained political support at the federal level as a win-win for ecosystems and humans.

This federal support is key because the upfront costs of wildlife crossings are high. According to an article in Wyoming Wildlife Magazine, “A box culvert underpass usually runs about $675,000 to $950,000, with another $200,000 per mile in 8-foot fencing on either side to make sure the creatures actually use the underpass. A complete overpass project with multiple crossings can cost as much as $30 million.” The article notes that the investment pays off, though, with millions of dollars saved in avoided vehicle damage and wildlife costs.

The Infrastructure Investment and Jobs Act (P.L.117-58), passed into law in November 2021, provides $350 million for a dedicated five-year, grant-awarding Wildlife Crossings Pilot Program, administered by the U.S. Department of Transportation. State and local government entities applying for the grants will be selected based on a project’s ability to leverage non-federal funding contributions, integrate innovative designs to improve connectivity and reduce vehicular crashes, and incorporate research opportunities, among other criteria. At least 60 percent of grants will be awarded to projects in rural areas.

According to the Center for Large Landscape Conservation’s Federal Wildlife Crossings Pilot Program Toolkit, the legislation also provides other federal funding opportunities for wildlife crossings, including through the Surface Transportation Block Grant Program, Nationally Significant Freight and Highway Projects, Bridge Investment Program, and Federal Lands Transportation Program, among others.

Wildlife crossing in Nevada. Photo Credit: Nevada Department of Transportation

Nine states have already passed, and six states have introduced, bills encouraging habitat connectivity to enable wildlife movement. Since the Infrastructure Investment and Jobs Act was passed in November, more states, including New Mexico, Utah, Oregon, Colorado, and Pennsylvania have introduced or passed legislation dedicating millions of dollars to state wildlife agencies, which will support wildlife corridors and help match federal funds available through programs like the Wildlife Crossings Pilot Program.

Author: Amber Todoroff