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American Bison - Bison bison

Classification

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Bovidae
Genus: Bison

ICUN Redlist - World Status:

Near Threatened

Description

The American bison is the largest land animal in North America. Males can stand six feet from hoof to shoulder and weigh between 1,000-2,000 pounds. Females are around five feet tall and weigh between 800-1,000 pounds. The bison has long, shaggy brown fur; a mane; a beard under its chin; and a long tail with a tuft of hair at the end. It has a big head with short, black horns and a hump on its shoulders.

Range

The American bison was once found in most of Canada, the United States, and parts of Mexico. It is estimated that there were close to 60 million bison in North America before Columbus landed. The American bison population had decreased to less than 1,000 by 1890, due to widespread hunting.

Wild populations are now limited to national parks and refuges. Bison can be found in Yellowstone National Park in Wyoming, National Bison Range in the Flathead Valley of Montana, the Wichita Mountains National Wildlife Refuge in southwest Oklahoma, the Fort Niobrara National Wildlife Refuge in northern Nebraska, Sullys Hill National Game Reserve in northwestern North Dakota, Neal Smith National Wildlife Refuge in central Iowa, and the Wood Buffalo National Park in Canada.

Habitat

The American bison lives on plains, prairies, and river valleys.

Diet

The American bison is a grazer. Its diet is made up of mostly grasses and sedges. It occasionally eats berries and lichen. In winter, the bison uses its head and hooves to move snow off vegetation.
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Life Cycle

Female bison are ready to mate when they are 2-3 years old. Males aren't ready to mate until they are about six. Mating season begins in July and can run through September. When mating season begins, male bison move into female groups and select a female. They then "tend" the female.

Males tend a female by staying between her and the rest of the herd. Tending can last for a few minutes or for several days. If a female isn't interested in a male, she walks away. Males threaten and sometimes attack other males that try to get too close to a female he is tending. Fights between males can involve head butting, shoving, or locking horns.

The female gives birth to one calf after about nine months. She goes to an isolated area to give birth. Newborn bison are reddish-brown and stand shortly after birth. The mother and her calf stay isolated from the herd for a couple of days. At about two months, the calf begins to develop shoulder humps and horns. The calf is usually weaned by the time it is seven months old, but it stays with its mother until it is a year old. The American bison lives 15-20 years in the wild.

Behavior

The American bison spends the warm hours of the day resting, chewing its cud, or wallowing in the dirt. It is most active in the early morning and late afternoon.

Bison live in a variety of groups. Females and young males may live in groups of up to 20 bison. Males also live in groups of up to 20 males, or they can live in smaller groups, or they can live alone. Mature males and females usually live apart, except during breeding season. Each bison group has a dominant male or female.

Audio Credit: National Park Service /Shan Burson