Yellowstone National Park

Yellowstone National Park, a wilderness recreation area stretching for nearly 3,500 square miles atop a volcanic hot spot in Wyoming and parts of Montana and Idaho, may be in trouble.

Each year, Yellowstone attracts millions of visitors and provides a home to countless animal species, including the once-threatened grizzly bear and bison. But finding the right balance between tourism and preservation can be tricky.

Yellowstone National Park officials are proposing that 1,000 of the park's wild bison — mostly cows and calves — be killed this winter.

Bison have been culled from the park annually since 2000, as part of an agreement between Montana and the federal government to keep the bison population near 3,000.

There were about 5,000 bison in Yellowstone this summer, the Associated Press reports.

Wildlife experts say bear attacks are rising – but then, so is the number of people in bear country. Yellowstone National Park officials confirmed that a grizzly bear killed a hiker from Michigan. That's the second grizzly-caused death in the park this summer.

According to the Montana-based Center for Wildlife Information, run-ins with grizzly and black bears have increased in the last 20 years in North America. To some degree, that's expected. Bear populations have dramatically increased, and more people live and recreate in bear habitat now.