If you've ever been to Yellowstone National Park, you know that it can be the kind of experience that stays with you forever.

America's parks are natural treasures enjoyed by millions each year. From iconic Yellowstone, the country's first national park, to the Great Smoky Mountains National Park, the most visited, visitors ...

It huffs and blows air through its nose and mouth. Its tail goes up. It bluff charges, often followed by a real charge if the person doesn't give the bison more space.