Despite their hefty size, bison are quick on their feet. When the need arises they can run at speeds up to 40 miles (65 kilometers) an hour. Their curved, sharp horns can grow to be 2 feet (61 centimeters) long.

Females (cows) and adult males (bulls) generally live in small, separate bands and come together in very large herds during the summer breeding season. Males wage battles for mating rights, but such contests rarely turn dangerous. Females give birth to one calf after a nine-month pregnancy.

View Images

Bison once covered the Great Plains and much of North America, and were critically important to Plains Indian societies. During the 19th century, settlers killed some 50 million bison for food, sport, and to deprive Native Americans of their most important natural asset. The once enormous herds were reduced to only a few hundred animals. Today, bison numbers have rebounded somewhat, and about 200,000 bison live on preserves and ranches where they are raised for their meat.

Bison Headbutting Prepare yourself for the battle of the bulls in Yellowstone, when male bison battle head-to-head for a chance to mate with females.