Animal Overpass Helps Pronghorn Survive A Dangerous Migration

Dangerous Crossing
Photograph courtesy Joe Riis
The pronghorn antelope that migrate 170 miles (273 kilometers) south from Grand Teton National Park to their winter range face plenty of obstacles: rivers, fences, a high mountain pass, subdivisions, energy development. For years the most dangerous place in the migration corridor has been where the animals cross Highway 191 west of Pinedale, Wyoming.
For thousands of years this has been a tricky spot in the migration-a geographic bottleneck formed by two rivers that funnel animals onto a mile-wide strip of land. An archaeological site here unearthed 7,000-year-old charcoal pits and bones, the oldest evidence of humans hunting pronghorn antelope in the world. The bottleneck is called Trappers' Point, named for the mountain man rendezvous that took place here in the 19th century. Every spring and fall, thousands of migrating antelope and mule deer cross the highway here.
In modern times, cars and trucks, as well as semitrucks from the nearby natural gas fields, speeding along at 65 miles (105 kilometers) per hour, have increased the danger. A subdivision blocks half the bottleneck, and Highway 191, the main roadway connecting I-80 to Jackson Hole, runs across its middle flanked on both sides by barbed-wire fences. An average of 140 antelope and mule deer a year meet their end along this 12-mile (19-kilometer) stretch of road. Drivers are at risk too; collisions with wildlife can cause injury and death.
—Emilene Ostlind
Published December 4, 2012
Antelope Overpass
Photograph courtesy Joe Riis
Now, the migrating antelope have a safer way to cross the highway—their own overpass. The wide new bridge was built to preserve the animals' historic migration route.
Wildlife underpasses on other Wyoming highways have reduced vehicle mortalities for deer and other wildlife by more than 80 percent in some areas. But pronghorn, who rely on their powerful eyesight and fast running speeds to escape from danger, are reluctant to walk into the low, dark underpasses, so they needed a different solution.
The overpass was a gamble: No one knew for sure if the antelope would actually use it. But as this picture by wildlife photographer and National Geographic Young Explorer Joe Riis shows, the antelope knew just what to do when they came to the overpass at Trappers' Point. Eight-foot-tall (2.4-meter-tall) game fences funneled the animals to the overpass, and they sprinted over and continued south toward their winter range.
The Wyoming Department of Transportation, after failing to get federal funding for the project, wrote the $9.7 million check for the Trappers' Point overpass, as well as another overpass, six wildlife underpasses, and fencing on both sides of this 12-mile (19-kilometer) stretch of Highway 191. The savings to the state and drivers from avoiding vehicle damage while saving the lives of deer, antelope, and other species will pay for the project in a dozen years.
Published December 4, 2012
Migration Interrupted
Photograph courtesy Joe Riis
Back in 2008, before the new overpass was built, antelope had to crawl under fences on both sides of the highway to continue their winter migration at Trappers' Point. They travel to their winter range in the desert to escape deep snow elsewhere, and if an impenetrable fence blocks their way, it can be deadly.
Around the world, long-distance animal migrations are disappearing as development eats up habitat, and infrastructure like reservoirs and housing sprawl block corridors. The 170-mile-long (273-kilometer-long) trail of western Wyoming's pronghorn antelope, one of the longest land-animal migrations in the Western Hemisphere, is at risk of being cut off by new fences, subdivisions, or energy development. Already, six of the eight historic antelope corridors in the Greater Yellowstone Ecosystem have been blocked, and antelope no longer follow those paths or access those ranges.
The migration corridor from Grand Teton National Park to the Green River Basin crosses many different land jurisdictions, making it especially vulnerable to various kinds of development.
Published December 4, 2012
Help at Hand
Photograph from Bureau of Land Management via AP
To justify funding for the wildlife overpass at Trappers' Point, the Wyoming Department of Transportation needed to know the rest of the migration corridor was adequately protected. They wanted to ensure that if they built the structures, animals would continue to use them over the coming years. Doing that took years of work.
Here, Neil Miller from the Meadowlark Audubon Society and Randy Leisey, executive director of Friends of a Legacy, raise the bottom wire on a fence near Cody, Wyoming, so that pronghorn can slip through it more easily. Similar efforts have happened in the corridor for the Grand Teton National Park pronghorn. In addition, volunteers removed unnecessary fences, spooling up and packing out lengths of old barbed wire.
The effort took coordination among many state and federal agencies and conservation groups. The Bureau of Land Management made Trappers' Point an Area of Critical Environmental Concern, putting it off limits to gas drilling and other development. Biologists used wildlife collars to map the corridor and pinpoint road crossings. The Forest Service designated the first national migration corridor over the northernmost 45 miles (72 kilometers) of the route. Local land trusts put ranchlands along the Green River into conservation easements to keep them as pastures rather than subdivisions. And now the overpasses. "There are a lot of pieces in the puzzle that have come together over the last ten years," says Scott Smith, a state wildlife management coordinator. "I think it's a pretty neat story."
Published December 4, 2012
Onward South
Photograph courtesy Joe Riis
"The last time I was at Trappers' Point I was watching antelope cross the highway," says Riis, the photographer and National Geographic young explorer. "Now I show up four years later and they are going over a bridge."
Riis and writer Emilene Ostlind spent two years documenting this migration in photographs and stories in hopes that sharing the story would help rally support for protecting the corridor. Where antelope once dodged traffic on the highway, they now run over the top of the wide overpass. This structure adds to the many other efforts made over the last decade to keep this migration corridor intact.
Riis returned this fall to photograph antelope using the new structures for the first time. Aerial photos and close-ups of the animals on the overpass might help people understand the importance of this project to wildlife. "I'm just trying to show it functioning so other people working on these types of issues can think about their own projects where they live," Riis says. "These highway projects are just starting to get ramped up. In the future they will be commonplace."
"Perilous Passages," Emilene Ostlind and Joe Riis's High Country News cover story on this migration, received the National Association of Science Writers' 2012 Science in Society award and the 2012 Knight-Risser Prize for environmental journalism in the West. Find the story at emileneostlind.com, and see more photographs at joeriis.com.
Published December 4, 2012