The Greater Yellowstone elk herd is the largest in the nation, and these graceful herbivores are a visitor favorite. However, a terrible and deadly disease is about to strike this huge and densely-populated herd, and the results could be catastrophic.

Bison
Bison have inhabited the Grand Teton and Yellowstone region since prehistoric times. They live in the area year-round, favoring grasslands in the summer, where they eat mostly grass and sedges.