Wildlife Crossings: Study Investigates Nebraska's Bighorn-Vehicle Collisions
February 20, 2024
TWENTY-SIX ROCK MOUNTAIN BIGHORN SHEEP HAVE BEEN DOCUMENTED ROAD KILLED IN WESTERN NEBRASKA SINCE 2009. AND 18 OF THEM HAVE DIED ALONG A SHORT STRETCH OF HIGHWAY 71, MOST WITHIN THE LAST THREE YEARS. Those are significant losses when considering Nebraska's entire bighorn population is fewer than 225.
The Nebraska Department of Transportation and the Nebraska Game and Parks Commission (NGPC) have secured a $400,000 federal grant to address the issue of wildlife-vehicle collisions in the Wildcat Hills area. The funds are being used to assess the feasibility of establishing crossings for bighorn sheep and other wildlife like deer, elk, and even a wayward moose that have collided with vehicles along this stretch.
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Bighorn Sheep Crossing sign along the highway. |
Todd Nordeen, the Big Game Research and Disease Program Manager at the Nebraska Game and Parks Commission, said the area's natural features in relation to the highway works against bighorns. "The geography of this area causes the bighorn sheep to cross the highway frequently. The worst spot is near the Wildlife Estates housing area, and with continued development along this corridor, there is increased potential for bighorn mortalities."
The Wild Sheep Foundation (WSF) provided a letter of support for the project to underscore the need to understand better the roadkill issue in Nebraska and the significance of this small but vital herd on the eastern edge of their range.
"We appreciate WSF support on this and other bighorn projects here in Nebraska. It has proven vital to our work to conserve Nebraska's wild sheep," Nordeen said.
According to NGPC officials, they will allocate a portion of the grant to procure ten new radio tracking collars. In addition to the three bighorn sheep in the area already fitted with collars, this data will be instrumental in evaluating the potential success of a wildlife crossing to connect their habitats. The study concludes in 2024 and will evaluate the estimated cost of wildlife crossing structures such as overpasses or underpasses.
The funding for this research initiative was made available through the federal Wildlife Crossings Pilot Program, which was established as part of the Bipartisan Infrastructure Law. This program provides $350 million over five years, bolstering projects that establish wildlife crossings, and aligns with the U.S. Department of Transportation's National Roadway Safety Strategy.
Greg Schildwachter, a WSF lobbyist, said wildlife collisions are an issue getting federal attention, and this could have a significant positive impact on bighorn sheep. "There's a lot of attention being paid to wildlife collisions at the federal level, and wildlife crossings are a fairly new and impactful way to deal with them. We know there are numerous areas where this is a significant problem for bighorns, and we are keeping an eye out as projects like this one in Nebraska develop," he said.
Bighorn-vehicle collisions are a concern in many areas of their range. According to an Arizona Fish & Game Department study cited in Human-Wildlife Interactions, vehicular-related mortalities comprise a significant source of mortality for sheep in some local areas. "Researchers Cunningham and Devos documented that 50 percent of mortalities in the Black Mountains of northwestern Arizona were caused by vehicle collisions."
A report in Saanich News said a stretch of highway in Radium Hot Springs, BC, has seen an uptick in bighorn deaths over the last decade, with 15 reported in 2021. That's 15 out of a local herd of around 150.
In an article in The Missoulian, Montana Fish, Wildlife & Parks biologist Bruce Sterling said between 2008 and 2012, 110 sheep (50 ewes and 60 rams) died in collisions. Vehicles claimed 107 on Montana Highway 200, and trains hit three in the area. This fits with recently released data from insurance giant State Farm who ranks Montana has number two in wildlife collisions behind deer-rich Virginia.
Schildwachter said WSF is also involved in talks on the related issue of migration corridors. Currently, federal designations for this topic are restricted to elk, pronghorn, and mule deer. "We're learning much about wildlife movements, migrations, and issues like habitat viability and vehicle collisions. WSF is committed to engaging officials on these issues as they relate to bighorns and lending our expertise to anything that can assist agencies' great work on wildlife crossings and migration corridors across the Western United States."
As human populations surge and highways become busier in the West, the significance of wildlife crossings and migration corridors is emerging as a significant conservation issue.
With innovative designs such as overpasses and underpasses, animals can traverse safely. These greatly reduce the risk of collisions, which may do negligible overall damage to whitetail deer or coyote populations, for example, but they can be a significant factor in much smaller bighorn herds.
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