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The New West: Impacts we have on wildlife

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CREDIT: David J Swift


Twice in the same week at different events in Jackson Hole, Bruce S. Thompson projected graphics onto a screen. Each time there were accompanying gasps in the audience. These were not moments of shock, but rather epiphanies that invited instant personal reflection.

Thompson, who is a professional natural sciences education specialist who also spent 17 years as education director of the nationally-renowned Teton Science Schools, was making vivid a phenomenon that many outdoor-oriented people suspect, but which has been hard to put a finger on.

The phenomenon is recreational impact on wildlife, a topic treated by some as almost taboo. 

Many people assume or claim that because they don’t actually witness animals running away at their approach, there must not be impacts, he said. Indeed, federal land management agencies, like the U.S. Forest Service, have been slow to respond to the impacts of growing recreation pressure. Yet as Thompson points out, absence of evidence doesn’t equate to absence of impact.

Right now there seems to be an awakening happening around the realization that wildlife displacement is happening.

Thompson, who lives in Dubois, Wyoming, says his research in to recreational impacts on wildlife was piqued by a push from commissioners in Fremont County, Wyoming, to transform the 4,520-acre Dubois Badlands Wilderness Study Area, stewarded by the Bureau of Land Management, into a National Conservation Area.

Not long ago, Thompson presented what he found: that hikers with dogs are formidable wildlife disruptors. In dog-crazy communities, of which the Greater Yellowstone Ecosystem has an abundance, people who head out with their domestic canines need to be aware of the impacts they cause.

A single hiker walking down a trail causes wildlife displacement of 150 feet. But a hiker with a dog on a leash results in wildlife displacement of 280 feet in one direction. When the panoramic radius on both sides of the trail is combined to create total diameter, it means dogs cause a displacement zone of 560 feet. 

It’s one thing if it causes an animal to flee but then it’s able to return after the person and dog are gone, but the disruption can become chronic, if not permanent, when the trail receives a stream of near-constant or heavy use. Not only does it cause the animal stress and expended energy, but it results in the animal abandoning the prime places where it finds the best forage and security cover, Thompson said.

Often, mountain bikers insist they are no more disruptive to wildlife than hikers and equestrians, Thompson said. Though, there is a problem. Bikers travel faster and cover much longer distances than hikers; they tend not to make noise; while navigating trails, they’re more concerned about avoiding rocks and trees than being fully attentive to their surroundings; and the way they ride makes their presence less predictable, he explained.

If a single mountain biker is traveling twice the distance as a hiker, then it could be argued, Thompson says, that the cyclist is having twice the spatial impact in terms of potential wildlife disruption. And, with a rising number of mountain bikers and local clubs pressuring the Forest Service to let them upgrade and build new trails, the impacts are hardly benign.

“The obvious thing at stake in Greater Yellowstone, the simple answer, is that what we have in this place is not present in those other places,” Thompson told me. “We are confronting the old tale of dwindling wilderness and natural systems. We’ve become a prominent symbol of the metaphor and no one knows yet if we’ll be able to hang on to what we have [and] avoid the mistakes those other places have made.”

No user group likes being called out. Both the Custer Gallatin National Forest, headquartered in Bozeman, and the Bridger-Teton are presently involved with updating their long-term management plans.

Significant scrutiny is being directed toward the Custer Gallatin and its management of the 155,000-acre Hyalite Porcupine Buffalo Horn Wilderness Study Area that, ecologists say, contains incredible wildlife diversity and superior habitat in the Gallatin Mountains between Yellowstone and Bozeman.

In 1996, conservationists sued the Forest Service for allowing motorized recreation, mountain biking and illegal trail building to occur in the Hyalite Porcupine Buffalo Horn, ultimately resulting in a settlement in 2001 that forced the Custer Gallatin to assemble a travel management plan. Illegal trespass by motorized users and mountain bikers remains a persistent problem in the roadless Gallatin Range near Big Sky.

How much consideration are the Custer Gallatin and Bridger-Teton giving to wildlife persistence now and in the decades to come? What is the science telling them about the impacts of human intrusion?

“On one level, it seems completely intuitive that we’re having impacts,” Thompson said. “But as you put the statistical information together, it really becomes compelling. I wasn’t planning on getting involved with this issue in my retirement, but the more I learn, it’s not something I can persuade myself to let go of.”

Todd Wilkinson is founder of Bozeman-based Mountain Journal ( devoted to protecting the Greater Yellowstone Ecosystem and is a correspondent for National Geographic. He’s also the author of “Grizzlies of Pilgrim Creek” about famous Jackson Hole grizzly bear 399, which is available only at

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