Pronghorn have taught themselves to use a new wildlife crossing in Wyoming, going from confused wandering last year to targeted crossing, without hesitation.
“Last year, scientists noted that it often took groups of pronghorn several hours to the better part of a day to cross the overpass,” the Wildlife Conservation Society said in a recent media release. “The groups would follow their established route, stop at the new fencing, and then spend time moving back and forth, in some cases passed the open overpass several times before finally crossing.”
The changes were seen on newly built overpasses crossing U.S. Highway 191 in Trapper’s Point, Wyoming, to assist pronghorn in their fall migration from Grand Teton National Park to the Upper Green River Basin. The animals’ adaptation is a boon not only because it helps them live through their migration but also because it reduces human fatalities, as well as vehicle damage. Wildlife-vehicle collisions are a nationwide problem, and crossings over or under major highways, while costing millions of dollars to build, are proving to be a workable solution—one that the animals themselves can get on board with.
Animals die, people die, and repairs to vehicles typically run into the thousands when big game animals are hit along the nation’s highways. Total costs run in the range of $8 billion annually. Such accidents can have severe impacts on the country’s wildlife populations, most notably deer herds but also elk, moose, antelope, bear and a myriad of smaller animals.
Problems commonly arise in areas where animals must move across highways during annual migrations as they travel between summer ranges in the mountains and winter ranges in the lower country with less snow. It may involve daily wandering to reach water. If there’s a road, especially a high-speed highway that bisects the two areas, collisions of vehicles and wildlife will occur.
The average deer collision causes $3,305 in damages, according to a report from State Farm Insurance. West Virginia was listed as the state with the highest risk for collisions, followed by South Dakota. Pennsylvania was number four, and Montana was number six. It’s a nationwide problem.
States and reservations have long been aware of the problems and have posted signs warning motorists to watch for wildlife in areas of particular concern. (Even that is not a cure-all, as collisions still pile up.) Wildlife crossings, a fairly recent idea that dates back just to the 1990s, are catching on nationwide.
These structures may be constructed like bridges over the highway, with fencing and wings to guide the animals to the structures. Many are planted with brush and small trees to provide visual security for the animals. Others are essentially large tunnel-type structures that allow animals to pass under the roadway.
Florida was among the first states to construct highway crossings, and the work there has served as a template for others. Even so, endangered Florida panthers are being killed by collisions with vehicles. Of the 21 known deaths of panthers in 2010, 16 were struck by cars, one fewer than the 17 killed the year before. Nineteen died by collisions in 2012, out of a total population of likely fewer than 150 endangered panthers.
The Banff area of western Canada, in British Columbia, was another area to recognize the severity of wildlife deaths, and wildlife crossings have been shown to work there as well.
“Roadkill has an immediate and direct effect on a population, easily seen within one or two generations,” Wild Travel Magazine reported in September. “Since fencing and crossing structures were first constructed, collisions have dropped by more than 80 percent.”
In Arizona, several thousand animals a year are saved by underpasses along Route 260 in the central part of the state. In Utah, along the border with Arizona on Highway 89, a famous mule deer area, wildlife collisions used to cause an estimated $440,000 annually. That was enough to convince state and federal agencies to retrofit seven underpasses along 12 of the deadliest miles. They also built an eight-foot-tall fence. That project is slated for completion this year.
Similar results can be found throughout the country, but perhaps no area has more concentration of wildlife crossing structures than the Flathead Reservation in Montana.
In a 52-mile stretch along Highway 93 through the reservation there are now 40 crossings, all but one of which are underpasses. The first structures were built about 2005, said Dale Becker, wildlife program manager for the tribes. It was done in cooperation with the Montana Department of Transportation and only came about after several years of discussion on what, how much and where. Transportation department officials wanted to put in a divided four-lane highway the entire distance, but the tribe had both wildlife and cultural concerns.
“In the end the agreement is a good one,” Becker said.
The tribe is now in the third year of a five-year monitoring project to determine the effectiveness of the crossings, so final numbers aren’t yet available, Becker said.
“Where we have fencing it’s looking pretty good and other areas with isolated structures and without fencing they’re getting used but we still have collisions,” he said. “We’ve had a lot of deer use and a fair amount of bear use and a whole gamut of other species. We see owls flying through, small mammals, a few reptiles, some amphibians, beavers, grizzly bears, black bears, river otter, mountain lions, coyotes and bobcats. We’ve seen a fair amount of moose activity, especially at the overcrossing.”
Back on U.S. Highway 191 in Wyoming, the pronghorns’ learning curve provided further testament to the value of wildlife crossings.
“While it was great to see pronghorn first using the overpass last year, it was clear that the fences and structures were confusing to them,” said Jeff Burrell, the Northern Rockies Program Coordinator for the Wildlife Conservation Society, in the group's statement. “This year, groups numbering from one to two hundred moved along a new route directly to, and over, the overpass with no delays, demonstrating their comfort with the overpass and the structure’s conservation value. The overpass not only reduces mortality but also allows the pronghorn to move with less energy and stress.”