New Thinking

Why are animals dying on our roads?

Photo credit: Image courtesy Paula MacKay
Wildlife-vehicle collisions pose a significant risk to a wide range of wildlife species and their populations throughout North America.

Disturbing accidents, such as this collision with a bear on the I-70 near Eagle, Colorado, occur on North American roadways every year. Photo credit: Shane Macomber, Vail Daily
Collisions between wildlife and vehicles have increased by 50 per cent in the past 15 years. These accidents now cost Americans $8 billion every year.

The prevalence of roadkill is both an obvious and unfortunate result of the conflict between the needs of humans and animals. The human need to get to where we are going safely and quickly is a basic expectation of modern society. Yet wild animals need to cross our roads in search of food, mates and shelter. Our expanding network of roads, highways and interchanges criss-crosses the continent, interrupting and fragmenting our landscapes—and with it, the territories of wild animals. Many are routinely struck and killed by vehicles in this most basic quest for survival.

Yes, this costly and tragic problem can be avoided using crossing structures. These are proven solutions that when designed and implemented strategically can radically reduce the number of collisions to save costs and, most significantly, human and animal lives.

This is where the work of ARC begins. ARC engages new thinking to design crossing structures that reconnect landscapes, safeguarding our wildlife populations, their habitats and our ecosystems.

The problems with roads

Traffic signage in Colorado warns motorists to be alert for wildlife on the road in high-risk areas. Photo credit: Nina-Marie Lister
“Because accidents between animals and people are scattered, happening here, there and everywhere over time, it’s difficult to grasp the scope of roadkill, and understand that it’s a systemic problem.” —Jeremy Guth, trustee, Woodcock Foundation, and ARC founding sponsor

We have been busy building roads for more than half a century in North America. Today, there are more than 4.8 million miles (7.8 million km) of roads on the continent. Americans have the highest rate of private automobile ownership on the planet, with more than a quarter billion vehicles using these roads. Given the dominance of the road in North America, and the fact that we now spend on average about 1.5 hours per day in the car, it has become disturbingly commonplace—even acceptable—for wildlife to be killed on our roads.

But this is not merely a wilderness or rural issue—it is a problem that affects everyone; those of us living and driving in busy suburban and urbanizing landscapes are more likely to witness or experience the conflicts first-hand. In fact, growing numbers of wildlife-vehicle collisions are leading to higher levels of personal injury and property damage, and rising insurance premiums. While human deaths are not high compared with other accidents, wildlife-vehicle collisions have increased significantly. A U.S. Federal Highway Administration study reports that there are approximately one million to two million collisions between cars and large mammals every year in the U.S. This represents a significant danger to human safety and wildlife populations. Wildlife-vehicle collisions are also increasing as a proportion of the total accidents on the continent’s roads. Even if not physically hurt or economically affected by a collision, many people report feeling traumatized after hitting an animal.

Alongside these obvious concerns for motorist safety are serious implications for wildlife. Road mortality is documented as one of the major threats to the survival of 21 federally listed threatened or endangered species in North America. At a much larger scale, road building results in significant losses of habitat for wild animals. Road networks carve up and fragment our landscapes into small, isolated patches in which wildlife must live and move. Worse yet, wildlife movement patterns often conflict with major transportation routes. Most of North America’s major highways cross the continent in an east-west orientation, but wildlife movements tend to flow north-south following mountain topography, such as the Rockies, the Appalachians and the coastal ranges. These landforms have always been important habitat and migration corridors, and they are becoming even more essential. Research on climate change suggests many wildlife species may be forced to migrate in new patterns across our landscapes in search of new habitats as resources become scarce in their current home ranges.

The solution: avoid the problem

Wildlife crossing structures in Banff, Alberta have been implemented with demonstrated success. Photo credit: Highway Wilding
“At what point in our evolution as a society did it become okay to run over wildlife? We need not tolerate hitting a deer on the way home from a ski trip. It’s a circumstance that’s avoidable.” —Ted Zoli, bridge engineer and MacArthur Fellow

Roadkill is not simply “bad luck” or an unfortunate consequence of driving, but an avoidable cost and a preventable loss. We know there are solutions that work; what we need is political will and social awareness to implement proven solutions in the right places.

Today, an emerging priority for transportation and natural resource agencies is to make highways safer for both drivers and wildlife. One of the proven solutions is to build wildlife crossing structures. Providing crossing infrastructure at key points along transportation corridors is known to improve safety, reconnect habitats and restore wildlife movement. Throughout Europe, Asia, Australia and North American, wildlife crossing structures have been implemented with demonstrable success.

Crossing structures include underpasses and overpasses, both of which have been constructed in a variety of sizes and designs. Although wildlife underpasses are less costly to build and more commonly used by a diversity of species, wildlife overpasses are preferred by certain wide-roaming and iconic species-at-risk, such as grizzly bears. Overpass structures are also more visible and noteworthy to motorists.

Images captured by research cameras stationed at wildlife crossing structures reveal the diversity of animals frequenting these structures. Photo credit: Tony Clevenger

VIEW GALLERY

Wildlife crossing structures present a timely opportunity to communicate both the problems and the solution to the general public. By making these structures visible, people can experience first-hand—and identify with—engineered landscape designs that create safer roads. At the same time, wildlife crossing solutions have the dual benefit of improving motorist safety and protecting wildlife populations. Eventually, with many crossing structures in place, we can begin to reconnect our landscapes and ultimately restore the important functions of North America’s wild ecosystems.

“People need to move around and they use highways to do that. When people learn that wildlife have the same needs that they do, and that the animals are often moving across those very same highways, they understand there’s a problem to solve.” —Harvey Locke, conservationist and ARC partner