Assignment Earth

Researcher Aly Courtemanch starts her work day on skis. That’s how she gets around on the alpine terrain where she studies the Teton Range bighorn sheep herd. Using GPS devices and trail counters, Courtemanch a scientist at the Cooperative Fish & Wildlife Research Unit at the University of Wyoming, tracks the movemnts of both sheep and skiers. "We really want to get a better sense of how bighorn sheep survive in the Tetons, both summer and winter,” she said. “We don't know very much about this bighorn sheep herd, it's really small and really hard to study because they're so remote and hard to observe." While other wild sheep move down to more moderate terrain, this herd winteres at some of the highest elevations in Wyoming. But they’ve stopped migrating about 60 years ago due to human development, firs suppression and other factors. In this edition of This American Land researchers take a look at this species on the brink of extinction.

Yellowstone National Park has been described as a winter wonderland. “We find that a lot of people from across the United States enjoy going into the park on snowmobiles, because ... you're out in the fresh air,” said Bill Howell, part owner of a local snowmobile and snowcoach tour company. “You get to see things on a snowmobile. With your guide you can stop and take pictures." But conservation groups have been seeking to ban snowmobiles here for more than a decade. Even snowmobile enthusiasts now admit the machines became a problem in 1990s. “The amount of machines and the amount of people going into the park skyrocketed, a lot more than I think anybody had ever predicted or thought would happen,’ Howell said. “And as a result it probably did get a little out of hand." In this edition of This American Land we take a look at efforts to create a balance between the use of snowmobiles in Yellowstone and those who aim to limit motorized access to the park.