Bison are the largest land animals in North America. They can move fast and are very strong. Normally, they just roam the prairie munching on grasses. Because they are so big and strong, bison have few natural predators. Animals that can hunt bison, like wolves or brown bears, no longer exist in the area of Theodore Roosevelt National Park. Every few years, the park rounds up the bison and removes some. They are given to Native American tribes and other parks that need bison.