Scientists document mega Oregon-Nevada pronghorn migration

Three hikers will track ecological conditions on the route this June.

 

A helicopter hovered low over a flat, sagebrush expanse as a pronghorn gracefully bounded across the dusty earth ahead. A crewmember aimed a cannon-like device and fired a net. The pronghorn snagged beneath it and the copter landed, disgorging a handful of people who raced to untangle it. The researchers gently fitted the creature with a blindfold, then a lightweight GPS collar. They took blood to scan for disease and hair for genetic testing. In less than 10 minutes, the doe was free again – North America’s fastest land mammal flying across the high desert on her narrow legs.

A week later, she and 38 other collared does embarked with their kin on a much bigger journey that scientists working in southern Oregon’s Hart Mountain Antelope Refuge and northern Nevada’s Sheldon National Wildlife Refuge were hoping to finally understand. About 3,500 pronghorn occupy the jointly managed refuges, which respectively encompass 278,000 and 575,000 cattle- and wild horse-free acres, separated by a 20-mile wide strip of Bureau of Land Management land.

Sheldon Refuge pronghorn
Pronghorn race across Sheldon National Wildlife Refuge. Image Courtesy of Gail Collins, U.S. Fish and Wildlife Service.

The protected areas were established by Franklin D. Roosevelt in the 1930s to provide safe haven for the species; pronghorn numbers had fallen from historical estimates of 35 million animals to just 13,000 by 1915, thanks to overhunting and habitat loss. Even then, the lands they contained were known to provide important fawning grounds and summer range, Gail Collins, the complex’s supervisory wildlife biologist, explains. But until a few years ago, when tracking collars became light enough to avoid injuring the animals, she and her colleagues were forced to wonder: Where did the refuges' pronghorn spend their winters?

When the GPS collars broke away after two years, in 2013, they collected them and had their answer: Unlike their cousins in Wyoming, who use a 120-mile long migration route with defined pinch points to travel between summer range in Grand Teton National Park and winter range in the Red Desert, the Sheldon and Hart Mountain pronghorn migrated in several directions along common routes, about half of them to shared winter grounds in the unprotected land between the two ranges, in an area called Beatys Butte. One doe even traveled from Hart Mountain clear down to the foot of the Black Rock Range in Nevada to winter – a roundtrip journey of 200 miles. All told, they utilized some 3 million acres.

Though the pronghorn wintering outside the refuges compete with cows at Beatys Butte, as well as hundreds more feral horses than the BLM’s management plan for that area allows for, they don’t face the same acute habitat fragmentation threats – subdivision, busy highways, oil and gas development  that the Wyoming migrators do. Collins says the data – currently being prepared for publication – helps the U.S. Fish and Wildlife Service “establish a baseline, so that we understand what areas are important” if something like a pipeline is proposed.

“The takeaway is that our pronghorn use the lands around us,” she adds; as with so many protected areas, even these massive chunks are not big enough to contain all the resources a wide-ranging species needs. “We’ll work closely with our BLM partners to ensure that those areas where animals are moving are protected so that we don’t see breaks in those migrations.”

Bend, Oregon resident Alice Elshoff hopes to ensure the same, but in a different way. From June 8 to 14, Elshoff, a former elementary school teacher who is 80, plans to hike 10 miles per day with friends Julie Weikel and Helen Harbin all the way from Sheldon, through some of the migration areas, to Hart Mountain, to document habitat conditions in the area between the refuges and raise awareness about the creatures who rely on it, including greater sage grouse. “It’s just basically my love affair with the American pronghorn,” Elshoff, who sounds maybe 40 on the phone, says by way of explanation before listing the creature’s virtues. “This little speedster of the plains is just such a wonderful example of form following function”: spring-loaded toes, a windpipe the size of a vacuum hose, a massive and powerful heart.

The Oregon Natural Desert Association, an environmental group which Elshoff helped found in the ’80s, will bring the women’s gear to each camp. The route has yet to be solidified, but one thing is certain, says Weikel, a retired large animal vet who flies her own plane and is herself pushing 70. “Wherever we end up getting picked up at the end, we’re going straight to the Hart Mountain Hot Springs.”

Sarah Gilman is a contributing editor at High Country News.

An earlier version of this post incorrectly stated that ONDA was founded in the '60s. HCN regrets the error.