How will western North Dakota's bighorn sheep cross the road? A highway tunnel
Bighorn sheep do not like going underground and prefer high ground with good visibility, so part of the challenge is making the bridge wide and accessible enough so the sheep will use it.
WATFORD CITY, N.D. — North Dakota is home to approximately 350 bighorn sheep, many of which are brazen and accustomed to incoming traffic on busy roadways. While their bravery is laudable, it also leads to deadly sheep-vehicle collisions.
Now, to preserve the small population of bighorn sheep that claim North Dakota as their home, the state is building an underpass near Long X Bridge on U.S. Highway 85. The approximately $3 million project is designed to allow bighorn sheep and other wildlife to safely cross.
As of Monday, July 20, approximately 61 bighorn sheep live in the rugged, grassy habitat near the Long X Bridge located south of Watford City, said Brett Wiedmann, a North Dakota Game and Fish Department big game biologist. Construction is currently underway, with the North Dakota Department of Transportation supervising the creation of the bridge, the wildlife crossing and the roadway's expansion from two to four lanes.
U.S. Highway 85 is seeing increased traffic due to trucks carrying commerce and oil, Wiedmann said.
"It's really nice, really high-quality habitat, and the bighorns do very well there," Wiedmann said. "However, if you put in a four-lane highway like that with those rates of speed and that volume of traffic, (the bighorn sheep) are just going to get hit at such a rate, likely that it's going to have real negative effects on that local population of bighorn sheep and then ultimately, if you lose that herd, it's a big loss to the state's population."
Bighorn sheep do not like going underground and prefer high ground with good visibility, Weidmann said, so part of the challenge is making the bridge wide and accessible enough so the sheep will use it.
"We kind of had to build an underpass that was uniquely designed for bighorn sheep," he said, adding that building a bridge or an overpass is not a practical solution because of the area's terrain and it would be more costly for that kind of structure.
The structure itself is expected to be completed this fall, said Bruce Kreft, Game and Fish Department conservation biologist. However, the project will not be considered completed by the department until fencing is built around the roadway to funnel the sheep into the underpass. The fencing for the crossing was not included in the original proposal and the department is hoping to acquire additional funding for it.
Fencing is an important aspect of the crossing, Kreft said, because without it, the bighorn sheep will not learn to go through it.
"It usually takes at least three or four years for them to really kind of learn that this is a safe avenue for them to use," Kreft said. "Without the fence, it's hard to get them to go through a tunnel when they can try to go over the top of it, even with the road traffic and everything out there."
The United States has less than 8,000 bighorn sheep, according to the National Wildlife Federation, and it is considered an endangered species.
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