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UW Science Inspires Mule Deer Conservation at Fremont Lake

February 9, 2016
deer crossing creek
Mule deer cross Pine Creek just outside of Pinedale on their 150-mile Red Desert-to-Hoback migration in this camera trap photo. The Conservation Fund's recent purchase and restoration of a 364-acre property at this crossing helps conserve the migration route and allows deer to cross the creek over a wider area. (Joe Riis Photo)

Mule deer migrating in the Green River Basin this spring will have an easier path, thanks in part to research conducted at the University of Wyoming.

UW researchers produced the “Red Desert to Hoback Mule Deer Migration Assessment,” which led to improved conservation of the longest-known movement of mule deer in the United States.

The assessment came from UW’s Wyoming Migration Initiative (WMI), a project of zoology professor Matt Kauffman. His collaborators include project manager Bill Rudd, geographic information system specialist Matt Hayes and Hall Sawyer, a WMI partner who works as a consulting biologist.

The researchers identified the Fremont Lake area near Pinedale as a chokepoint for roughly 5,000 migrating mule deer that pass through each spring and fall.

The linchpin was a 364-acre parcel of private land that was available for development. Dean Clause, Wyoming Game and Fish Department biologist in Pinedale, says construction of houses on the property could further restrict movement in an already narrow migration corridor.

“If it got to a point where there was a barrier -- and mule deer couldn’t get to the winter ranges on the south -- that would be pretty devastating for that Sublette herd,” Clause says. Even worse, it could deepen an already serious statewide decline in the mule deer population.

deer behind fence

The Conservation Fund, together with Wyoming Game and Fish Department staff members and others, relocated elk fences like this at Fremont Lake after UW researchers identified the area as a mule deer migration bottleneck. (Joe Riis Photo)

The sobering science inspired the nonprofit Conservation Fund to lead a public-private campaign to purchase and restore the 364-acre parcel.

“Together, with the state of Wyoming and other key partners, this aggressive, proactive approach was the most appropriate conservation strategy,” says Mark Elsbree, senior vice president for the Conservation Fund’s western division.

Sawyer first discovered the migration bottleneck in 2011 as part of a study for West Ecosystems Technology. He put tracking collars on deer in the Red Desert near Interstate 80, then followed their migration north to the Hoback Basin in spring.

The collars yielded thousands of data points, mapping out a migration corridor that looks like a braided stream. By zooming in on those points, researchers could identify areas of concern where a few small changes could stop migrating deer in their tracks.

Fremont Lake was at the top of the list. The lake already constricted the migration corridor. Immediately adjacent was the parcel of private land, bounded by an 8-foot-high woven elk fence that keeps big game off the streets of Pinedale.

Migrating deer had two choices. They could either wade across Pine Creek and squeeze through tiny openings in the elk fence, or cross the outlet of Fremont Lake, which presents a drowning hazard when the lake is covered by thin ice.

Those challenges and the possibility of new development led the researchers to name the Fremont Lake property as the top area of concern on the entire 150-mile migration corridor.

WMI released its assessment to the public in March 2014.

map of mule deer migration route

The Red Desert-to-Hoback mule deer migration route, outlined in gray, went through a quarter-mile-wide bottleneck on private property at the outlet of Fremont Lake, just north of Pinedale. The Conservation Fund bought the property in 2015 and worked with partners including the Wyoming Game and Fish Department to restore the property along Pine Creek. (Wyoming Migration Initiative Map)

"We saw this assessment as a great way to fulfill UW’s land-grant mission to provide research useful to the state of Wyoming -- in this case, to improve the longest-recorded mule deer migration," Kauffman says.

The report attracted the attention of the late Luke Lynch, director of the Wyoming office of the Conservation Fund. Lynch began a campaign in September 2014 to raise $2.1 million to buy and restore the private parcel.  

The Knobloch Family Foundation in Jackson Hole -- a regular donor to UW and WMI -- learned about the Fremont Lake bottleneck in 2014. The foundation donated more than two-thirds of the $1.7 million purchase price, knowing that UW science had pinpointed where the foundation’s funding could best ease the journey of this iconic migration.

Public funders soon joined in. The Wyoming Game and Fish Commission put $250,000 toward the purchase. The Wyoming Natural Resources Trust Fund donated $160,000 toward the restoration of sagebrush habitat on the property.

The Conservation Fund completed the purchase by April 2015. Tragically, Luke Lynch died the following month in an avalanche while backcountry skiing in Jackson Hole. But, in August and September, Game and Fish staff and local volunteers gathered in his honor at the Fremont Lake property for two Luke Lynch Volunteer Days. Together, they helped take down 15,000 feet of fences that impeded the mule deer migration.

Later this spring, local contractors will complete restoration of the property by removing a radio tower, enhancing sagebrush habitat and relocating the elk fence to a location less likely to affect migrating deer.

That clears one obstacle for migrating mule deer in the Green River Basin. Meanwhile, WMI continues working with Game and Fish and other partners to map more migration corridors across the state.

Such research is a valuable tool for wildlife managers working to maintain Wyoming’s world-class big game populations.

overhead view of conservation area with caption to the right

The Conservation Fund property is at left in this photo, while Fremont Lake is at the right. Thanks to the restoration and removal of fences, deer will now have access to crossings along thousands of feet of Pine Creek. This helps deer avoid the hazardous existing routes across the creek or the lake outlet. (Wyoming Migration Initiative Infographic)

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