Cars Harm Animals — Could Wildlife Crossings Be a Solution?

Freedom of movement is essential to the survival of species, but cars have disturbed the natural movements of animals. Is there a way to fix it?

An endangered red wolf
Credit: James Ford

Solutions Research Science

On April 15, an endangered juvenile red wolf named Muppet was struck by a vehicle while crossing a busy highway in eastern North Carolina. The two-year old Muppet —- named for his long, strikingly slender neck —-became the fourth red wolf to be killed by a vehicle strike in under a year. Just six months earlier, Muppet’s father died on the same stretch of Highway 64, which cuts through the only remaining red wolf territory in the world. Like Muppet, his father was named for a distinct feature of his lupine anatomy: large, alert ears that pointed jauntily skyward, earning him the moniker Airplane Ears.

With less than 20 red wolves left in the wild, the species is currently the most endangered wolf on the planet. Their remaining habitat has dwindled to two ecologically diverse wildlife refuges just miles from the shores of the Atlantic Ocean: the Alligator National Wildlife Refuge and Pocosin Lakes National Wildlife Refuge. The area is biologically rich, teeming with river otters, black bears, bobcats, snakes, turtles, frogs and the world’s last few red wolves.

This corner of North Carolina has simultaneously become a haven for red wolves — and a major contributor to their decline. Highway 64, which bisects the refuges, is a key travel corridor for tourists on their way to the popular beach destination, the Outer Banks, which sees about 5 million visitors a year. Vehicle strikes are now the second leading cause of mortality among red wolves, after gunshot wounds.

“At this point, we are seeing collisions with animals every couple of weeks on Highway 64, and traffic in this region is only going to increase,” Will Harlan, a Senior Scientist and Southeast Director at the Center for Biological Diversity tells Sentient. “Cars aren’t going anywhere. The wolves need some way to cross this death trap of a highway safely.”

While the situation is dire, advocates are hopeful that a simple solution could help save the red wolves from extinction: wildlife crossings.

What Wildlife Crossings Are, and Why They Matter

Wildlife crossings are human-made structures —- bridges, overpasses, tunnels, underpasses or culverts — that allow animals to safely traverse roads and the other pieces of infrastructure that cut through their habitats. As human development continues to encroach further into the world’s few remaining wildlife habitats, such connectivity areas can quite literally help bridge the divides between the human and animal worlds.

“If we are going to maintain wildlife and diversity as the planet steadily urbanizes and develops, we have to accommodate animals,” writer Ben Goldfarb, the author of the 2023 book Crossings: How Road Ecology is Shaping the Future of Our Planet, tells Sentient. “Wildlife crossings are a way of letting animals survive and coexist in the increasingly concretized, developed world that we are in the process of creating.”

How Cars Affect Wildlife

The United States is home to the largest road network in the world, encompassing more than four million total miles. The proliferation of these roadways — from hulking interstates spanning major cities, to dirt stretches cutting through wilderness areas —has helped make the United States one of the most car-dependent nations in the world. Most U.S. households own at least one vehicle; only eight percent do not. Despite the known climate impacts (cars and trucks account for about 28 percent of America’s greenhouse gas emissions), Americans drove more miles last year than ever before.

While cars epitomize a particularly American form of convenience, independence and speed, it is no secret that driving can also be incredibly deadly. According to the US Department of Transportation, there were over 40,000 vehicle-related fatalities in 2022 alone. Motor vehicle crashes are the leading cause of unintentional death in children and young people, and over two million people are injured in car crashes each year.

These statistics are dwarfed by the sheer number of animals who die on the road. Roadkill —that impersonal but chillingly accurate term —is an inescapable feature of modern life. According to one study, vehicles kill more than one million vertebrates every day in the United States. While vehicle safety for humans has undeniably improved since the days without seatbelts or turn signals, vehicle mortality rates for wildlife have quadrupled in the last 50 years. Cars and roadways threaten the survival of animals big and small, fast and slow, from low-lying snakes, frogs and turtles to large animals like elk, bears and wolves.

“The allure of the car is so strong that it has persuaded Americans to treat forty thousand human lives as expendable each year,” writes Ben Goldfarb in his book Crossings. “What chance does wildlife have?”

As more people rely on cars to get around and more roadways reach into areas previously reserved for nature, collisions between cars and wildlife have dramatically increased. In fact, such collisions are so common they have their own catchy abbreviation: WVCs, or wildlife-vehicle collisions.

The vast majority of WVCs — as much as 90 percent in some states — involve deer. According to one study, a deer is hit by a car every eight minutes in New York state.

In North Carolina, which is considered a high-risk state for wildlife collisions, roughly seven percent of all vehicle crashes are the result of animal strikes. Such collisions cost North Carolina a total of about $400-500 million dollars a year. An estimated 59,644 animals were killed on North Carolina roads from 2020 to 2022.

Though a very small number of these collisions are fatal to humans — less than one percent, according to some statistics —they are incredibly destructive to animals, threatening the survival of not only individual animals but entire species, as exemplified by the endangered red wolves.

Freedom of movement is essential to the survival of most species, but cars have disturbed the natural movements of animals. While people can travel faster and more widely than ever before, animal movement has increasingly become a fraught and fatal endeavor.

Other Ways Cars Impact Wildlife

Wildlife-vehicle collisions are certainly the most dramatic and obvious way roads impact animals, but there are a number of secondary or indirect consequences that also threaten the health and survival of wildlife.

Roads disrupt animal migration patterns and fragment crucial animal habitats. Fast moving highways can create what researchers call a “moving fence” that deters animals from traversing stretches that they otherwise might. Roads and related infrastructure strip animals of their natural vagility, or the ability to move through the landscape freely. Some researchers consider a road traversed by more than 10,000 vehicles per day an absolute barrier to wildlife. Roads can slice up entire ecosystems, stranding animals on one side or the other of that dangerous moving fence, which in turn makes it more difficult for animals to mate and create the genetic diversity that is necessary to the survival of any species.

Roads and cars also dramatically increase the risk of wildfires in wilderness areas, simultaneously creating conditions that destroy an animals’ habitat and limit their ability to freely roam to find a new one. What’s more, sonic pollution from roads and cars can negatively impact animal communication, stress levels, movement and community structures.

Shortly after the interstate highway system expanded into Western states like Colorado, Wyoming and Utah, researchers noted immediate consequences for migratory deer, antelope and other species. In 1971, for example, more than 3,000 pronghorns perished in Wyoming when they were unable or unwilling to cross a highway during a blizzard. In Idaho, hundreds of deer starved to death and their herd counts dropped precipitously after the opening of I-84 in the 1960s.

These problems will become especially acute in an era of climate change, when increasing habitat loss and dramatically shifting weather patterns will force more and more animals to move more frequently, and come into contact with more roads and cars as a result.

Habitat connectivity areas can help mitigate some of the worst impacts that climate change will have on wildlife.

“Wildlife crossings would be valuable on any planet, but in a planet that is rapidly warming up and experiencing climate chaos, they are even more crucial,” says Goldfarb.

The Construction of Wildlife Overpasses

In the 1950s, Canada began constructing the massive, 4,860-mile Trans-Canada Highway, which cuts through 1.6 million acres of Banff National Park in Alberta’s Rocky Mountains. By the time the highway was completed in 1962, road ecologists and researchers had nicknamed it “the Meatmaker” for the staggering number of animals that lost their lives on the pavement. After years of watching the Meatmaker devastate local elk and grizzly bear populations, researchers and engineers began constructing a vast network of nearly 50 fences, underpasses and expansive bridges across the highway.

The crossings —gorgeous, densely green structures spanning elegantly over stretches of dark gray asphalt —were as beautiful as they were effective. A little over 165,000 animals used this crossing according to Parks Canada, and wildlife deaths plummeted by as much as 80 percent. Banff’s wildlife crossings were heralded as a major success story, inspiring similar conservation efforts across the world.

Wildlife overpasses did not start appearing in the United States until 1975, when Utah created the first bridge to help mule deer cross I-15. The majority of habitat connectivity areas have been built across the long stretches of open highways that criss-cross the Western states, or in otherwise remote national parks and refuges, but they can also have a powerful role to play in bustling cities and suburbs.

Los Angeles is currently constructing the Liberty Canyon Overpass, which will span Highway 101 and become the largest wildlife crossing in the world. While a wide variety of creatures will benefit from Liberty Canyon, it will prove especially vital in connecting the isolated populations of mountain lions that currently live in the Santa Monica Mountains to populations on the other side of the highway.

Surrounded on all sides by ocean, urban sprawl and traffic-clogged freeway, the Santa Monica Mountains have become an island of dense chaparral and scrubland where a steadily dwindling population of mountain lions are left marooned. This has fueled a higher risk of extinction, what researchers call an “extinction vortex” — only about 10-15 mountain lions remain in the area.

A mountain lion was struck by a car as recently as January of this year. Those mountain lions that haven’t been hit by cars while trying to cross the 101 are left stranded on the other side, unable to find mates. Last year, P-22, the most famous mountain lion in the city, perhaps in the world, was euthanized by Park Service officials, who found that the daring 12-year old animal was suffering from injuries from a vehicle strike, as well as other chronic ailments.

P-22 became the poster child for both the plight of the cougars in Southern California and the promise of wildlife crossings to save them. Though P-22 will not be around to benefit from it, the city hopes that Liberty Canyon will be complete by 2025 and help the mountain lion population bounce back.

Such crossings have been successful in other heavily urbanized areas as well. The Netherlands, which has one of the densest road networks in the world, is home to the huge Natuurbrug Zanderij Crailoo, the longest of over 600 “ecoducts.” Other major metropolises, like Singapore, have created grassy bridges that span the highways of their dense, heavily trafficked urban areas.

Though cities are often considered the antithesis of nature, wildlife crossings like those in Los Angeles, the Netherlands and Singapore are a welcome reminder that animals and humans can continue to coexist, even in dense, heavily-trafficked urban areas.

A Bi-Partisan Solution

Until recently, most of the funding for wildlife crossings has come from out-of-state and federal transportation budgets. But in 2021, Congress passed a massive $1.2 trillion bi-partisan infrastructure bill. The bill allocated $350 million for the Wildlife Crossings Pilot Program, which will provide federal funds for states and cities looking to build habitat connectivity areas.

Advocates in North Carolina are hoping to get a grant from the Wildlife Crossings Pilot Program to fund bridges, fences and underpasses along Highway 64.

“It’s truly a win-win for everyone,” says Will Harlan from the Center for Biological Diversity, who is pushing for habitat connectivity areas through red wolf territory in North Carolina. “Wildlife crossings along Highway 64 would provide immense safety benefits to both motorists and to the spectacularly diverse wildlife in this region, saving money and lives.”

But with the red wolf population dropping at such an alarming rate, any delay could be fatal. Even if the crossings prove successful in curbing the deaths of endangered red wolves, advocates worry that $350 million dollars is hardly sufficient to quickly and effectively construct enough bridges to protect other vulnerable populations across the nation. 

Unwinding the myriad of problems caused by America’s four million miles of roads will be a complex, multi-pronged process. Advocates call for decommissioning certain roads while revitalizing and reimagining the city spaces that have been fragmented and devastated by highways, which were often built through communities of color. Improving public transportation systems and bike lanes will also be crucial to stemming America’s overreliance on cars. 

But, as Harlan said, cars aren’t going anywhere. For better or worse, driving remains the most logical choice for people in many parts of the country. Cars will likely remain the dominant means of transportation for many Americans, especially those living in remote or rural areas with limited public transportation options, like eastern North Carolina, where the few remaining red wolves roam.

For endangered animals like the remaining members of Muppet’s pack, wildlife crossings remain a simple but profound solution. Such crossings help support a kind of symbiosis between the natural and man-made worlds, allowing animals to move freely without human disruption. In an increasingly fast, urbanized environment, wildlife crossings offer a new way of thinking about the roads we drive, and the many different creatures we share them with.

Support Us

Independent Journalism Needs You

Donate » -opens in new tab. Donate via PayPal More options »