Wildlife Crossings: Proven Success and Global Momentum
Nearly three years ago, journalist and author Ben Goldfarb released his book Crossings: How Road Ecology Is Shaping the Future of Our Planet, focusing on wildlife crossings and road ecology. These structures help reconnect habitats fragmented by road networks, reducing collisions, protecting threatened wildlife, and improving genetic diversity. Since that conversation, Goldfarb has observed the growing popularity of wildlife crossings worldwide. He returned to the Mongabay Newscast to detail how, where, and why they are increasingly being funded and built.
“Probably the biggest factor is that at this point, the evidence that wildlife crossing structures are effective is just overwhelming. Maybe 20 years ago, you could’ve theoretically said, ‘Well … we don’t necessarily know that …’ but here in 2026, we just have a lot of scientific research basically showing that animals of all shapes and sizes use wildlife crossings,” Goldfarb says. He notes that research confirms animals mate on both sides, restoring gene flow across highways that fragment populations, and that fences and crossings prevent numerous crashes, saving human lives and public money.
Effectiveness and Economic Benefits
Reducing Collisions and Saving Money
Goldfarb explains that wildlife crossings and fences reduce collisions with large animals by almost invariably more than 80%, and often by 95% to 100%. This reduction adds up to many nonhuman lives saved and likely many human lives as well, though data is incomplete because single-car crashes due to wildlife evasion often go unreported. Many wildlife crossings pay for themselves in under a decade by preventing expensive crashes, making them good investments for conservation and public safety.
Global Examples of Wildlife Crossings
Goldfarb takes us to locations in South America, North America, and Europe where this infrastructure enjoys rare nonpartisan political support.
- North America: In Colorado, Interstate 25 cuts off east-west movements of deer, black bears, elk, and pronghorn. The Colorado Department of Transportation built five underpasses and one giant overpass (currently the largest in the U.S., soon surpassed by one in California). The overpass saw its first elk use it in the week of the podcast recording. Eastern states like Vermont, Maine, and Massachusetts are also increasing funding.
- Europe: In Croatia, a highway built in the late 1990s incorporated many underpasses and bridges proposed by wildlife biologist Josip Kusak, resulting in one of the most ecologically permeable highways in the world. It was built at a time when the impacts of highways on wildlife were already understood.
- South America: Brazil’s first wildlife bridge connects habitat across the coastal four-lane BR-101 highway. Canopy bridges (rope ladders) are used in tropical forests for arboreal animals like sloths, howler monkeys, and orangutans. They are cost-effective at hundreds of dollars each.
Policy and Funding: The Wildlife Crossings Pilot Program
A bill is currently before the U.S. Congress to make the Wildlife Crossings Pilot Program permanent. This program was created by the 2021 Infrastructure Investment and Jobs Act, allocating $350 million over five years for competitive grants to states, Native tribes, and other entities. The program has been oversubscribed, with demand far exceeding funds. A reauthorization bill proposes $400 million over five years, while another (the Zinke bill) calls for $1 billion over five years. The funding also supports planning studies for states that have not yet conducted hotspot research.
Challenges: Malicious Restoration and Bridges to Nowhere
Malicious Restoration
Goldfarb warns that wildlife crossings can become a form of “malicious restoration” when used to justify building new highways through intact wildlife habitat. Roads cause many problems beyond fragmentation: noise pollution, tire particles toxic to fish, and enabling logging and mining. Crossings cannot mitigate all these harms.
Bridges to Nowhere
A “bridge to nowhere” occurs when the habitat on either side of a crossing is developed into subdivisions, farms, or strip malls. A deer underpass near Durango, Colorado, is currently effective, but surrounding land is slated for high-density housing. Investment in crossings must be matched by land conservation.
Public Sentiment and the Visual Power of Crossings
Public surveys show overwhelming support for wildlife crossings in the United States. In Colorado, 85% of residents support more crossings. Goldfarb attributes this to the effectiveness of camera traps in the early 2000s, which provided undeniable images of animals using the structures, and to the overpasses themselves being “billboards for connectivity.” He quotes an anonymous source who described overpasses as “billboards for connectivity” – striking visual reminders that we share the planet with wildlife. The Wallis Annenberg Wildlife Crossing over the 101 freeway in Los Angeles is a high-profile example, under construction and set to open in December 2026.
Goldfarb notes that the hunting community, especially in red states like Wyoming, has been integral to bipartisan support. Republican Senator John Barrasso and Representative Ryan Zinke have sponsored funding bills, making wildlife crossings a rare nonpartisan issue.
Innovations: Train Crossings and Cost-Effective Construction
Crossings are also being implemented for train infrastructure. In the Mojave Desert, overpasses for bighorn sheep are being built along a new high-speed rail line. In South Asia, underpasses and fences have been installed along train lines to reduce elephant collisions. Construction costs have risen due to inflation, from $5–10 million to $20 million per crossing. Researchers at the Western Transportation Institute are exploring recycled materials like fiber-reinforced polymers to lower costs.