American Bison (Bison bison)
Physical Description: American Bison are covered in dark brown dense fur, which they shed in spring and early summer. Their coats' thickness insulates them from harsh winter weather with two layers of hair and a thick hide. The coarse outer layer serves as protection from cold and moisture. The inner layer consists of fine fibers, creating an insulation that traps air and warmth. American Bison have 10 times more hair per square inch than domestic cattle.
Adult American Bison are 7 to 11.5 feet long from head to rump with their tail adding an extra 20 to 24 inches. Males are called bulls and can weigh up to 2,000 pounds and stand 6 feet tall. Females, called cows, weigh up to 1,000 pounds and stand between 4 and 5 feet tall. Both male and females have horns. While they have poor eyesight, they have excellent senses of smell and hearing. They grunt, growl and snort to communicate. During mating season, bulls can be heard bellowing across long distances.
At birth a calf usually weighs between 30 and 70 pounds. Calves are orange-red in color, earning them the nickname "red dogs." After a few months, their hair starts to change to dark brown and their characteristic shoulder hump and horns begin to grow.
American Bison can run up to 40 mph and jump vertically as high as six feet. They are quite agile and can spin quickly. They are strong swimmers too. Its tail usually indicates a Bison’s mood. When it hangs down and switches naturally, the animal is usually calm. If the tail is standing straight up it may be upset and ready to charge.
Habitat: They live in open grasslands and plains, sometimes bordering large forests and mountains.
Range: The American Bison lives in the mid and western United States up through Canada and Alaska. Since the late 19th century, the Department of the Interior has been the primary national conservation steward of the bison. Public lands managed by them support 17 bison herds—or approximately 10,000 bison — in 12 states, including Alaska. Yellowstone National Park is the only place in the U.S. where American Bison have continuously lived since prehistoric times. What makes Yellowstone's America Bison so special is that they're the pure descendants (free of cattle genes) of early America Bison that roamed the land.
Diet: As grazers, they use their huge heads as snowplows in winter to uncover vegetation to eat.
Lifespan: They live 25 years in the wild and up to 35 years in human care.
Social Structure: American Bison like to live and travel in groups. For most of the year herds are divided by gender, with females and calves in one herd and males in another herd. When the breeding season begins in the summer, many males temporarily join the female herd and begin looking for a mate.
Female American Bison are pregnant for about nine months and give birth to one offspring. Within an hour after birth the calf stands and, soon after, begins to walk. The cows will care for their young for about a year, however, calves learn to be independent very quickly. By the middle of their first winter, juvenile American Bison are feeding independently and have the typical brown fur of the adults.
Status: Red List: Near Threatened1, Green Status: Critically Depleted1
Other: The American Bison became the first national mammal of the United States when President Barack Obama signed the National Bison Legacy Act into law on May 9, 2016.