Bison

The male (or bull) bison can reach 6.5 ft (2 m) in height and measure up to 12 ft (3.7 m) long, and is twice as large as the female (or cow). Male bison commonly weigh 2,000 lb (900 kg), but animals twice as large have been reported. American bison have a huge hump across the shoulders that rises 1 ft (30 cm) or more above the top of their head. The dark brown hair growing on the hump is long and shaggy, and the thick body fur allows bison to tolerate air temperatures as low as -49°F (-45°C). In the spring, bison molt their winter coat and great quantities of their hair falls off. The back half of their body has short, lighter-colored hair. The head is covered with a helmet of thick black hair that terminates under the chin as a "goatee." Extremely rare white bison are revered by Native Americans of the Plains. When one was born in 1994, people traveled long distances to Wisconsin to see it. As the calf grew older, however, its fur turned darker.

Bison have large, curved, hollow horns growing sideways from their big, heavy head, which are never shed. The horns may reach a length of 24-26 in (60-65 cm), but are usually much shorter. The horns of females curve back toward the head more than that of males. Bison have no front teeth, and eat grass and other herbaceous plants by wrapping them around their tongue and pulling to break them off the rootstock. Bison are ruminant animals. As such, they have a four-chambered stomach and chew a cud.

Their short tail is used both as a flyswatter and as an indicator of excitement, for the normally drooping tail rises into the air when a bison is angry or otherwise excited. Bison are subject to attack by numerous biting flies and ticks, and they have a habit of rolling in dirt or mud to relieve their itchiness. Because of their hump they cannot roll over completely, so they rock and kick first on one side and then on the other. This maneuver is called wallowing, and it also helps get rid of molting hair.