Fencing project aids pronghorn migration

GREAT FALLS – Two antelope met nose-to-nose one day in March in northeastern Montana, a barbed-wire fence keeping them on opposite sides of the prairie.

Unknown to the pronghorn, a camera mounted on a nearby fence post was capturing the fence-line rendezvous, one photograph per second.

Remote cameras, installed by the Nature Conservancy of Montana at its 60,000-acre Matador Ranch in south Phillips County, are documenting barriers conventional fences pose to wildlife in a project meant to spur modifications that are more “wildlife friendly.”

And fences like the one separating the two pronghorn are no small barrier to the fastest animal on the North American plains, which doesn’t jump well despite blazing speed, said Brian Martin, the conservancy’s director of science in Montana.

He said proof of the need for fencing improvements is in the photographs because “seeing is believing.”

“We’re not re-fencing all of southern Phillips County,” Martin said. “We just want to make sure there are places where pronghorn pass through.”

The cameras have also snapped close-up shots of unsuspecting elk, songbirds and raptors – and a lot of cows.

But the conservancy is focusing on the pronghorn in the fencing research because antelope in Montana move between Canada and the United States and fences can block the migrations of the speedy international ungulates.

Pronghorn don’t usually try to clear the fences because they evolved to outrun predators on the prairie and had no need to jump, Martin said. They can crawl underneath, but they often catch their backs on the barbs when they wiggle through, Martin said. The repeated scratching causes scarring and wears away fur, which Martin said makes the animals more susceptible to cold weather.

“Kind of like running around on a cold day with your jacket unzipped – it doesn’t feel very good,” Martin said.

Andrew Jakes, a doctoral candidate at the University of Calgary living in Helena, said fences can be life-and-death obstacles to pronghorn because their movement between seasonal habitats is as critical to their survival as the habitats themselves.

Jakes is studying pronghorn migrations between northern Montana and Saskatchewan and Alberta.

“They either are going to move or die,” Jakes said.

The conservancy’s fencing study is an outgrowth of Jakes’ work on antelope migrations. Last spring, 18 cameras were set up on the Matador Ranch and remained in place until October. The ranch is part of a migration corridor that Jakes identified in his work, Martin said.

To date, the conservancy has spent $80,000 on the project, mostly in fencing materials and contract expenses, with plans to spend another $20,000, Martin said.

Some of the funds have gone toward cost-sharing efforts with area ranchers who have agreed to modify a combined 25 miles of fencing in addition to fencing work on the conservancy’s Matador Ranch.

In the next phase of the project, this spring cameras will be placed on fences that have been modified to see how well they work in allowing wildlife to pass to the other side.

The cost-sharing approach to the research attracted Bruce Bruckner, who ranches eight miles east of Malta south of the Bowdoin National Wildlife Refuge.

“If you have a fence there that’s holding the cattle in, you’re not inclined to change it because that’s an expense and a lot of work,” Bruckner said.

Bruckner’s fence was old and he agreed to work with the conservancy to replace a mile and a half.

Now, the bottom wire on the new stretch is smooth, not barbed, and 18 inches off the ground so antelope can safely crawl underneath. The top wire is smooth, too, and there’s a wider gap between the top wire and the second wire from the top. As a result, deer or elk won’t get their legs tangled as easily when they jump over. That sometimes happens with barbed wire, he said.

“The fence looks a little funny, but it will hold cattle and it’s what they’re calling ‘wildlife friendly,’ ” Bruckner said.

He’s also agreed to leave gates open when cattle are not in the area, he said.

Montana Fish, Wildlife and Parks has contributed $10,000 to the research.

FWP is interested because it wants to assist landowners in reducing impediments to pronghorn movements, said Joe Weigand, a FWP private land wildlife specialist who operates the agency’s private land technical assistance program.

“It’s a landscape view seeing what we can do in a big picture to help both agriculture and pronghorn,” Weigand said.

The cameras have taken 70,000 pictures. Cows dominate.

One camera snapped a picture of an antelope jumping a fence but it was in a place where the fence was leaning, Martin said. Other photos show antelope standing at the fence or walking along them.

“The vast majority of them you see pictures where you’ll have antelope on both sides somewhat interacting,” Martin said. “I don’t know exactly what they’re doing per se.”

Data from Jakes’ pronghorn migration study, which involved tracking animals with GPS collars, showed that antelope sometimes spent a week or longer walking back and forth along fence lines, Martin said. That takes valuable energy, particularly during winter.

“They’re burning a lot of calories, which may not directly kill them but makes their chance for mortality much higher,” Martin said.

The project is focusing on east-west fences because pronghorn encounter them most in their north-south migrations.

In other locations, old sheep fencing is being modified or replaced. Sheep fencing has mesh wire at the bottom and is particularly troublesome for wildlife, Martin said. In many areas, that type of fencing is an “artifact” because cattle are now grazing on the landscape, Martin said.

Findings of the work will be published in two years in a scientific journal. The University of Montana is assisting the conservancy in preparing the data. Martin still is studying the photos.

Triggered by movement, the remote cameras take pictures up to 21 feet away every second. The shot of the face-to-face pronghorns was taken at 7:50 a.m. – and 16 seconds – on March 13.

The photos are especially interesting because the animals are not responding to a person with a camera, Martin said.

“You’re not going to see that if you’re out there,” Martin said of the two pronghorns. “You get to see some interaction that’s not likely with people.”