Deer, elk, and even moose have adapted to jump over low fences, but the simple barriers remain a seemingly insurmountable challenge for pronghorn. According to the Star-Tribune, researchers at the University of Wyoming are currently in the middle of a three-year study to determine why the state’s pronghorn population is dwindling. The problem is not restricted to Wyoming—states like Arizona are also seeing declines. Researchers are now looking into what they believe is the most likely cause: human development.
The fact that the pronghorn, one of North America’s fastest land animals, cannot jump over even a moderately-sized fence, may strike many as odd. Wildlife officials say it is simply a trait that the species never developed.
“People always want to know why they don’t just jump,” wildlife researcher Andrew Jakes told The Nature Conservancy. “They can jump, but it’s a learned trait. For eons, they just never had to adapt to jumping anything taller than sagebrush. They never lived in any other kind of terrain.”
With the encroachment of human development into their territory, pronghorn now find themselves trapped. This is especially noticeable in the winter, when cold weather and the search for food keeps a herd constantly on the move. A fence could stop the herd in its tracks, and eventually lead to starvation.
“They will walk up and down a fence until they die,” said Wyoming Game and Fish biologist Mark Zornes.
Hard winters and droughts have also played a role in the pronghorn’s decline, but in the past the species would recover. Those herds now find themselves in the high-stress environments of the urban sprawl, and researchers suspect that the animals are finding it hard to get food or raise their young. Attempts to relocate them to less developed areas have also proved problematic, as the animals are susceptible to capture myopathy. One thing researchers did find successful was modifying fences so that pronghorn can crawl under them. Adapting fences for pronghorn travel near migration routes, with the aid of wildlife corridors, may mean that the pronghorn can recover lost habitat.
“It will be ironic if it all gets developed and there’s no pronghorn out here,” Arizona Game and Fish wildlife manager Virginia Gouldsbury told Fronterasdesk.com. “But 20 years ago it was used as advertisement by a lot of the developers to say ‘come live with the pronghorn’ and a lot of people moved here for it.”