The bison has often been described as the most ferocious animal in North America. This description is no doubt a result of its great size. Full-grown bulls weigh up to 2,000 pounds and stand six feet or more at the shoulder. Their massive heads, which are matted with a thick covering of wiry hair, hold a set of horns that are never shed. The shoulders carry a huge hump that gives the bison its characteristic top-heavy look, the hips being much smaller in relation to the rest of the body.
Cows usually conceive for the first time as three-year olds.
Calves are able to walk minutes after they are born and remain with their mothers for about a year, or until another calf is born. Bison are herbivores or plant eaters, and feed primarily on wheat grass, buffalo grass, blue grama, and other similar grasses. Though they generally have poor eyesight, bison have excellent hearing and a keen sense of smell. Bison reach maturity at seven or eight years of age and may live to the ripe old age of thirty. For centuries, both bison and human coexisted on the Great Plains.