In the 1950s, President Eisenhower led the creation of a national system of interstate highways across the United States. Though the system was originally conceived as a necessary part of defending the country, today it is the primary basis of our nation’s commerce and travel. Until recently, little thought was devoted to the implications of building roads through wildlife migration corridors.
These corridors – the paths that wildlife follow to access seasonal resources such as various foods, water and mating opportunities – ensure the persistence of a wide range of migratory animals across the globe. As society expands its reach and wild places are increasingly targeted for development, centuries-old corridors have been disrupted and habitat compromised.
During most of the 20th century, new road building decisions focused on issues like terrain, soil, and other location considerations, along with logistics and cost. It was not until late in the twentieth century that projects started to consider the needs of wildlife in relation to road construction and maintenance. As a result, many roadways pass through what were once the best habitats, for example along rivers.
One such roadway, U.S. Highway 191 in western Wyoming’s Greater Yellowstone Ecosystem, cuts through the 93-mile long “Path of the Pronghorn,” along which pronghorn move between their wintering grounds in the Upper Green River Basin and summering grounds in Jackson and Grand Teton National Park. The path is the first and only federally designated migration corridor in the United States.
Pronghorn numbered an estimated 35 million in the early 19th century. Today, approximately 700,000 remain and more than half of those live in Wyoming. Those that follow the ‘Path of the Pronghorn’ to and from Grand Teton National Park ensure that the park’s ecosystem remains ecologically intact and that a 6,000 year-old migration remains a part of our national heritage.
Roadways like Highway 191 represent one of the biggest threats to wildlife and motorists alike today. Fortunately, advances in the science of road ecology and the development of new tools can help us achieve both greater human safety and wildlife conservation priorities on new and existing interstates and other roadways.
Last fall, new overpasses constructed by the Wyoming Department of Transportation began providing passage for thousands of migrating pronghorn near Trapper’s Point. This marked the culmination of years of cooperation among conservationists, government officials, and land and transportation planners, and a new era of reduced risk of wildlife-vehicular collisions in the region.
Overpass locations were determined using data collected by WCS, the Wyoming Cooperative Fish and Wildlife Research Unit, Grand Teton National Park, and the Wyoming Game and Fish Department. Our tracking collars collected information during a five-year period on the location and timing of pronghorn movements and impediments to migration such as roadways, fences and energy infrastructure.
The area near Trapper’s Point has long posed a “bottleneck” risk along the migration route for pronghorn, leading thousands of the animals to cross traffic lanes and creating a perilous situation for humans and wildlife alike. With the new GPS information, the Wyoming Department of Transportation led the effort and was able to site overpasses and underpasses such that both motorists and wildlife in the Greater Yellowstone Ecosystem were protected.
The Trapper’s Point overpass is one of eight safe passages constructed along a 13-mile stretch of the highway. Eight-foot-high barrier fencing has been placed along the highway to channel the animals to the crossing points. In all, two overpasses and six underpasses have been constructed and will accommodate not only pronghorn, but also mule deer, moose, elk and other animals.
Last summer, President Obama signed the “Moving Ahead for Progress in the 21st Century” transportation bill. With the leadership of Sen. Max Baucus, D-Mont., the new law includes language that will further enable state and federal transportation managers to address safety improvements and improve wildlife connectivity through measures to maintain ecological corridors.
With more than
200 Americans killed and close to 30,000 injured in vehicle-wildlife collisions annually, at an estimated expense of more than
$8 billion, the importance of developing new highway infrastructure to facilitate animal crossings cannot be overstated. These efforts in turn inspire our colleagues in other nations to seek similar solutions. In April scientists from Mongolia will take a research trip to Wyoming in hopes of reducing negative impacts of roads built to facilitate mining operations in the Gobi Desert.
In the meantime our animal crossings help to ensure that North Americans’ love of the road, and the freedom and adventures to be found there, need not be a source of conflict with other species in these landscapes. Like the folks in Steppenwolf’s timeless rock classic who get their motors running and head out on the highway, pronghorn were born to be wild.