As North Dakota transportation officials plan to incorporate wildlife crossings into a proposed expansion of U.S. Highway 85, state wildlife officials are evaluating the effectiveness of a critter crossing farther north.
A recent highway expansion near Williston included an underpass designed for moose in a critical habitat area south of the Lewis and Clark Bridge.
Now the North Dakota Department of Transportation is recommending two more underpasses on Highway 85 in the Badlands to accommodate bighorn sheep, mule deer and other animals.
“With the widening of the road, it creates a larger barrier for the movement of animals,” said Bruce Kreft, conservation biologist with the North Dakota Game and Fish Department. “A two-lane highway is a lot easier for the animals to cross.”
Having safe crossings for wildlife hadn’t been a huge issue in western North Dakota because traffic counts used to be lower, said Kreft. But increased traffic due to oil activity and population growth prompted wildlife officials to work with the transportation department on solutions.
“The ultimate goal from DOT was to provide a safe roadway for the traveling public,” Kreft said. “From the Game and Fish standpoint, we were looking to reduce collisions on the roadway and provide habitat connectivity.”
The wildlife crossing near Williston has been complete since last fall, Kreft said. It’s designed to be large enough for moose, but other species benefit from it as well.
Cameras that monitor the crossing have shown moose enter the underpass but they have not gone through it, according to Kreft, adding it’s too soon to evaluate the effectiveness of the crossing, in part because construction activity was still creating a disturbance in the area.
In addition, it may take a generation before animals are accustomed to using the crossing.
“Once a cow goes through there and realizes it’s safe, then when they have young, they will show the calf that it’s safe to go through there,” Kreft said. “It takes numerous years before that actually occurs.”
The Department of Transportation is recommending an expansion of Highway 85 from Belfield to Watford City from two lanes to four. A final decision on the $479 million project will be made by the Federal Highway Administration.
The state’s proposal includes an underpass designed for bighorn sheep south of the Long X Bridge. Another underpass is proposed farther south near the Summit Campground that would be geared for mule deer but also accommodate other animals, Kreft said.
In addition, the corridor under the Long X Bridge serves as another wildlife crossing.
The wildlife crossing system, which includes fencing and jump-outs, or one-way escape routes to prevent animals from getting stuck, is estimated to cost $7 million, according to a draft environmental impact statement.
The North Dakota Wildlife Federation is pushing for additional wildlife crossings, including at least two overpasses for bighorn sheep and pronghorn antelope, said Mike McEnroe, past president and lobbyist for the organization.
Agencies studied the possibility of a bighorn sheep overpass north of the Long X Bridge in the North Unit of Theodore Roosevelt National Park.
Matt Linneman, project manager with the Department of Transportation, said that was eliminated as a viable option because the agencies wanted to minimize the impact to the national park.
McEnroe said he’s concerned the bighorn sheep won’t use the underpasses.
Bighorn sheep, particularly ewes, would prefer to use an overpass, Kreft said.
“However there’s been other studies in other states that a large underpass, if put in the correct location, will be effective to allow the movement of ewes,” he said.
The Wildlife Federation also is advocating for wildlife crossings in the Grassy Butte and Fairfield areas to accommodate pronghorn antelope, McEnroe said. Currently, there are no wildlife crossings planned in those areas.
Migratory patterns of pronghorn antelope include crossing Highway 85, Kreft said. Because antelope rely on eyesight as a key defense mechanism, they do not like tunnels and would need a wildlife overpass, Kreft said.
However, overpasses are more expensive and difficult to construct.
“It would have to be quite a ways up above the roadway and very wide," Linneman said.
Transportation officials have committed to revisiting the possibility of overpasses for pronghorn antelope before that segment of highway is constructed.
“We don’t know how long it might be in the future before we actually build that stretch of the road,” Linneman said.
In the future, there may be more data available that justifies the expense of constructing large overpasses, he said.
The consequence of having no crossings for antelope would be an increase of vehicle collisions in addition to the potential for increased winter mortality if the antelope can’t reach their wintering grounds, Kreft said.
In addition to wildlife crossings, the Game and Fish Department also has worked with transportation officials to develop other wildlife accommodations, such as earthen wildlife trails under bridges that have been highly effective, Kreft said.