Wildlife crossings save animals’ lives by enabling them to cross roads in search of food, water and nesting sites safely, while also protecting biodiversity and reducing costly motor vehicle accidents. Without a safe place to cross the roads cutting through their habitat, animals suffer many negative consequences, explains my guest this week, environmental journalist Ben Goldfarb, the author of the book “Crossings: How Road Ecology Is Shaping the Future of Our Planet.”
Ben now lives in Colorado, but he grew up in New York and spent a lot of time hiking, camping and fishing in the Upper Hudson Valley, the Catskills and the Adirondacks. “I was fortunate to have a family who valued that sort of thing,” he says. He has always deeply cared about the natural world and conservation and says that every kid has an innate attraction to wild animals that he has never grown out of.
Environmental journalist Ben Goldfarb is the author of the book “Crossings: How Road Ecology Is Shaping the Future of Our Planet.”
“Crossings” received the Sierra Club’s 2024 Rachel Carson Award for Excellence in Environmental Writing and the Banff Mountain Book Competition’s Environmental Literature Award and Grand Prize. Ben’s first book is 2018’s “Eager: The Surprising, Secret Life of Beavers and Why They Matter,” winner of the PEN/E.O. Wilson Literary Science Writing Award. His conservation journalism has appeared in The New Yorker, The Atlantic, Smithsonian Magazine, The Washington Post, National Geographic, The New York Times, Orion Magazine and many other publications.
What Is Road Ecology?
Road ecology is a small but fast-growing field of science that looks at all of the different connections between roads and nature, Ben explains. This includes everything from the dead whitetail deer by the side of the highway to the impacts of road noise pollution and road salt on wildlife and ecology.
Road ecology looks at all of these different connections and what we do to manage or mitigate the negative interactions that transportation infrastructure has on nature.
“I had observed over the course of my career all of the ways in which roads were at the heart of various ecological problems,” Ben says.
He points out that before you can drill for oil and gas, you have to have a road network to get the machinery in. Before you can illegally log the Amazon, you have to road it first. Before you can poach an elephant, you have to have some way of accessing the elephant.
“So roads and the human access they create are kind of the prerequisite for all of these ecological issues,” he says.
In 2013, Ben toured wildlife crossings in Montana — famous underpasses and overpasses that allow animals to safely move back and forth across Highway 93, north of Missoula.
“It was just so cool to see a potential solution to some of these road problems that I’d observed over the course of my writing,” Ben says. “It was also very inspiring to think about the idea of spending millions of dollars to build dedicated infrastructure for animals.”
Collisions between whitetail deer and vehicles lead to millions of dollars of damage every year and can sometimes be fatal for the motorists as well.
Photo Credit: Ben Goldfarb
Road Ecology and Biodiversity
Better-designed roads with wildlife in mind will do a better job of biodiversity conservation. Roads in general, and especially poorly thought out roads, are a major contributor to wildlife loss.
“When we think about the forces that are imperiling wildlife around the world, we think about deforestation and climate change, of course, and mega fires, and dams on rivers,” Ben notes. “And certainly all of those are enormous issues. But there’s literally nothing that we do that kills more wild animals directly than drive. It’s the leading source of mortality for Florida panthers and ocelots and tiger salamanders and Hawaiian geese, and all of these threatened and endangered species all over the country and the world.”
Charismatic animals all around the world, such as Asiatic cheetahs in Iran and maned wolves in Brazil, are being literally driven to extinction, he says. The term “extinction vortex” was used in a scientific paper to describe California mountain lions that are slowly circling the drain due to habitat fragmentation.
“These are species that we’re going to lose from the planet in many cases if we don’t figure out ways to help them cross highways. And to me, dealing with this sixth mass extinction event in planetary history, which we’re in the middle of right now, necessarily means dealing with our road networks.”
A million vertebrate animals — birds, reptiles, amphibians, mammals, etc. — are killed each day in the United States by cars. And that says nothing of all the insects and spiders.
When highways prevent herds and packs of animals from roaming as far as they once did, they don’t find the diversity of mates they once did. Inbreeding can occur, leading to genetic abnormalities.
A million vertebrate animals — birds, reptiles, amphibians, mammals, etc. — are killed each day in the United States by cars. Photo Credit: Ben Goldfarb
Road Ecology and Ecosystem Health
“When highways disrupt the movement of animals, they also disrupt all of the ecological benefits and services and connections that those animals are making,” Ben says.
A Portuguese researcher who Ben interviewed studied road noise and its impact on birds.
“Birds live in this kind of acoustic world,” Ben says. “You imagine being a meadowlark who has to sing to attract a mate. And if your mate can’t hear you over the noise of traffic, you can’t live in that place.”
The researcher found that road noise drove away birds, and as a result, the birds were no longer present to eat insect pests. The uncontrolled pest populations began killing trees.
“There’s this whole kind of trophic cascade, this ecological chain reaction being caused by that disruption of animal movement that the road creates,” Ben says.
Road Ecology and Climate Resilience
“The American West, including Colorado, is getting hotter and drier and more flammable,” Ben says. “We’re experiencing these mega-fires that now happen many years.”
A migratory elk in Colorado, wandering in search of food and water, can lose large swaths of its habitat in a wildfire. But if an elk’s habitat is bisected by a highway, it’s not so easy to move from a scorched area to an unaffected area.
“The ability to cross roads would be important on any planet, but a planet that’s getting hotter and drier and resources are becoming increasingly scarce, it’s just vital that we give animals the ability and the options to move around the landscape and find those seasonal resources. And roads are one of the things that impedes that.”
Underpasses allow wildlife, including fish in some cases, so pass under roads.
Photo Credit: Ben Goldfarb
Human Safety and the Economy
The average vehicle vs. deer collision costs $9,000 in medical bills, vehicle repairs, tow trucks and other associated costs.
“The average elk collision is more than $20,000. The average moose collision is more than $40,000,” Ben adds. “There are hundreds of driver fatalities every year in animal crashes. The single most dangerous wild animal in North America is the whitetail deer.”
Collectively, animal collisions cost Americans more than $10 billion a year, Ben says,
“If you can build infrastructure in the form of roadside fences and wildlife passages that allow animals to safely cross highways without being hit by cars, you can save some lives and save the public a lot of money,” he says. “There’s lots of good research showing very clearly that these wildlife crossings pay for themselves in many cases very quickly.”
Not only is it better for human safety, it would also reduce unnecessary wildlife death and suffering, which is another selling point for wildlife crossings.
Animal collisions on roads cost Americans $10 billion annually.
Photo Credit: Ben Goldfarb
Reptile and Amphibian Migration
On warm, wet spring nights in the Northeast, there can be thousands of amphibians crossing roads simultaneously for their migration from their upland forest habitat to their wetland breeding habitat.
“These are not the most traffic-aware animals on earth,” Ben notes. “They’re not going to dodge like a black bear and get out of the way of an oncoming car.”
Historically, the United States hasn’t done much to protect reptiles and amphibians on roads because they don’t pose a risk to driver safety.
“These are animals that are of conservation concern, but they’re not a driver-safety concern. So we don’t think about them all that much. And we haven’t really done a whole lot for them,” Ben says. “Certainly we need to think more about the large animals, but let’s spare a thought for those smaller ones too.”
Historically, the United States hasn’t done much to protect reptiles and amphibians on roads because they don’t pose a risk to driver safety.
Photo Credit: Ben Goldfarb
Animals That Have Learned To Live With Highways
Coyotes in Chicago famously look both ways before crossing the street and use the crosswalks. Crows in Japan have learned that if they leave walnuts in intersections, the cars will crack the shells open for them, and then they can retrieve the walnut meat inside.
Through natural selection, cliff swallows are evolving shorter wings, which are better than long wings for agility. And better agility makes it easier for them to avoid an oncoming vehicle.
Where there are wildlife crossings, fences are integral. Rather than crossing the highway at any spot, the animals track along the fence until they come to an opening at a wildlife crossing. Ben says some animals learn to use the crossings quickly, while others, like bears, may take years to become accustomed to the crossings.
“There is this learning process or this habitation process that has to happen at these crossings,” Ben says.
Some animals have become very adept at crossing streets, waiting for cars to pass before they try.
Photo Credit: Ben Goldfarb
Wildlife Crossings as Greenwashing
Wildlife crossings should not be used as a justification for new road construction through pristine wilderness.
“They don’t solve all these problems, and what they really don’t solve is the fact that when new roads go in, they totally change the way the surrounding land is used,” Ben says. “You put a highway through a place, and suddenly all of this new industry and development and human colonization is suddenly possible — facilitated by that road.”
Wildlife crossings are a valuable technology, he says. “We know they work, we know they’re good. We know we need a lot more of them, but they’re not, by themselves, sufficient.” In the American West, we lose about a football field’s worth of habitat every several minutes to development, he points out. “If you build a bunch of wildlife crossings, but turn all the surrounding landscape into condos, you’ve basically built bridges to nowhere.”
Wildlife crossings are great additions to existing highways but not a good justification for news highways.
Photo Credit: Ben Goldfarb
Many Wildlife Crossing Designs Can Be Used
Wildlife crossings can be overpasses or underpasses that take various forms and come in various sizes depending on the animals they are intended to service, from animals as large as elk to as small as crabs and turtles. These can be tunnels, culverts, canopies, catwalks, “critter shelfs,” etc.
“Not every wildlife crossing project has to be some $10 million overpass,” Ben says. “There’s a lot we can do to just kind of tweak and modify at very low cost the infrastructure that’s already on the landscape to make it more amenable to wildlife.”
The best wildlife crossings protect movement pathways and migration corridors that intersect with roads.
Wildlife crossings are politically popular because they are pro-conservation physical infrastructure projects that motorists, hunters and animal welfare advocates all like.
Wildlife crossings can be big or small, depending on the animals they are designed for.
Photo Credit: Ben Goldfarb
I hope you enjoyed my conversations with Ben Goldfarb on “Crossings: How Road Ecology Is Shaping the Future of Our Planet.” If you haven’t listened yet, you can do so now by scrolling to the top of the page and clicking the Play icon in the green bar under the page title.
What innovative wildlife crossing does your city or town have? Let us know in the comments below.
Links & Resources
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“Crossings: How Road Ecology Is Shaping the Future of Our Planet” by Ben Goldfarb
“Eager: The Surprising, Secret Life of Beavers and Why They Matter” by Ben Goldfarb
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