Description: The American bison, commonly referred to as buffalo, are large ungulate mammals with males ranging in size from 3.6 to 3.8 meters (11.8-12.5 feet) long and 1.67-1.86 meters (5.5- 6 ft) tall. Females are smaller, reaching 2.1-3.2 m (7-10.5 ft) long and 1.52-1.57 m (~5 ft) tall. Bison, depending on their sex, weigh between 318-900 kilograms (700-2000 pounds). Bison have brown fur with hair longer in the front than rear. Bison have a predominant head and shoulder hump, and black curving horns are present on both males and females.
Life History: Bison graze year round, primarily on prairie grass species. Bison live, on average, 15-20 years in the wild and up to 40 years in captivity. Both males and females become sexually mature at 2-3 years of age, however, males (bulls) will not breed until they reach the size where they can compete with other bulls, usually around six years of age. Bison breed once a year from late June through September and give birth to one offspring from mid April through May. Calves are 15-25 kg (30-40 lbs) at birth and become independent after one year. Bison live in groups, with females and young males (under three years of age) living in herds and males of breeding age either living alone or in their own herds.
Habitat: Bison live predominately in grassland and savanna habitats, but can also live in montane wooded and semi-desert habitats, if enough food is available.
Distribution: Bison bison were once found throughout North America from northwest Canada down to Mexico and east to the Appalachian Mountains. Wild populations of bison now exist only in national parks and refuges in the west.
Status: Populations of bison were once estimated at 60 million in pre-settlement North America. Today, there is an estimated 500,000 bison in North America with 350,000 bison in the US. There are approximately 30,000 free-roaming bison found in national parks and refuges, with the remaining bison commercially raised for meat. Bison are a keystone species of the prairie ecosystem and thus, are beginning to be re-introduced on prairie preserves and prairie restoration projects. There are only about 12,000 genetically pure bison left, with the remainder existing as cattle-bison crossbreeds.
University of Michigan, Animal Diversity Web
IUCN Redlist of Threatened Species
The Nature Conservancy, Tallgrass Prairie Preserve