Field Notes from Wyoming: Preserving Ungulate Migrations for the Future

June 7, 2017

By Kathleen Kennedy, CSDP Associate Director

Did you know that mule deer, pronghorn antelope, and elk migrate hundreds of miles each year in Wyoming? Fairly recently, scientists discovered that various herds of these ungulates migrate every summer and winter. Many of them summer in Yellowstone National Park, then fan out to the north, south, east, and west as they migrate to their winter ranges. Intermingling in Yellowstone in the summer leads to increased genetic diversity as the different herds meet up. Roads, however, threaten these migrations when thousands of animals cross certain sections of roadway in a short amount of time. Pronghorn antelope, for instance, cross Highway 191 near Pinedale, WY by the thousands, leading to safety risks for both the pronghorn and motorists. 

A few weeks ago I had the privilege of attending the International Conference on Ecology and Transportation (ICOET) in Salt Lake City, UT. Together with Coalition Director, Carolyn Campbell, we presented on the Oracle Road wildlife crossings project (in collaboration with Arizona Game and Fish Department) and on how wildlife crossing infrastructure is funded in Pima County. We were also able to attend a wide variety of presentations by academics, other non-profits, state and federal agencies, and private consultants on the latest and best science around the intersection of ecology and transportation. Presentation topics included research on wildlife fencing, wildlife crossings, different wildlife species in various ecosystems, funding mechanisms for crossings, and a host of other topics. 

On Day Three of the conference, I woke up at 5am and hopped on the 5:45am lightrail train to get to the conference center by 6am. This was our departure time for a long day-trip into southwest Wyoming to learn first-hand about ungulate migrations and see the different wildlife crossings that Wyoming has built to preserve these migratory patterns. Our first stop was in Nugget Canyon on Highway 30. This is the location of a large mule deer migration. From late April to late May, thousands of mule deer migrate from south of Nugget Canyon north to Yellowstone over 150 miles. Once this migration was discovered in the 1990s, the state began by installing wildlife fencing. This reduced wildlife-vehicle collisions where the fencing was located but collisions continued in the un-fenced area (hundreds each year). By 2012, the Wyoming Department of Transportation had installed 7 wildlife underpasses and installed more wildlife fencing to connect them. This dramatically reduced wildlife-vehicle collisions, with thousands of mule deer using the crossings safely each year. 

Our second stop of the day, after winding through the Wyoming Range through intermittent snowstorms and following the Snake River for a ways south of Grand Teton National Park, was Trappers Point. Trappers Point is home to two wildlife overpasses over Highway 191 built for pronghorn antelope and six wildlife underpasses primarily used by mule deer, but also elk and moose. These wildlife overpasses were finished in 2012 and are now used by thousands of pronghorn as they migrate from their winter range east of Big Piney, WY to their summer range near Grand Teton National Park. As we arrived at the wildlife overpass and stepped off the bus, four pronghorn could be seen running towards the overpass – it was quite a welcome to this important project site. 

Wyoming is a rugged and sparsely populated state. But like anywhere, it is not immune to the pressures of more roads, oil & gas development, and growing population centers. It was inspiring to see first-hand what the Wyoming Department of Transportation is doing and has done to mitigate the impacts of habitat fragmentation through the construction of wildlife crossings and fencing. Their wildlife crossings are preserving migratory patterns that are older than we know and that are passed down each year from mother to young. We can all be grateful for that. 

Note: I found it interesting that in Wyoming, mule deer prefer wildlife underpasses while here in the Sonoran Desert, at least on the Oracle Road wildlife crossings project, they vastly prefer wildlife overpasses. To me, this points to the need for a variety of crossing types and continued research in different ecosystems. What works in one place won’t necessarily work in another place. We must always be in tune to the nuances of the ecosystem we’re working in. 

Wildlife Underpass in Nugget Canyon, WY used primarily by mule deer and elk during their migrations. Photo by Kathleen Kennedy.

Wildlife fencing in Nugget Canyon, WY. Photo by Kathleen Kennedy.

Wildlife overpass at Trappers Point, WY built for the migration of pronghorn antelope. Photo by Kathleen Kennedy.

The view northeast from on top of the Trappers Point wildlife overpass, looking at the Wind River Mountain Range. Photo by Kathleen Kennedy.

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