Wood Bison (Bos bison athabascae)

Wood Bison


  • The wood bison is North America's largest land mammal, with males being much larger than females.
  • Body length can range from 2.4 to 3.9 metres (8 to 13 feet); shoulder height can measure from 1.3 to 1.8 metres (four to six feet).
  • Weight can range from 360 to 1090 kilograms (790 to 2400 pounds).


  • General characteristics include:
    • Massive, triangular heads
    • Large shoulders with a high hump
    • Dense, shaggy dark brown and black hair around the head and neck.
  • Both sexes have black horns, though female bison horns are thinner and more curved.
  • In Alberta, most free-ranging bison are considered wood bison and are found in Alberta's far north, in and around Wood Buffalo National Park, and in a large area centred on the Hay-Zama Lakes complex.
Natural History


  • Wetland-associated meadows, open savannah-like shrublands, and dry grasslands are the most important habitat types for wood bison in the boreal forest, but habitat requirements vary based on the season.


  • In winter, Alberta bison eat grasses and sedges. In other seasons, their diet can be more variable, including species such as grasses, sedges, willow leaves and lichens.
Reproduction and Growth

Breeding Behaviour

  • Male bison compete for mates during the rut, or mating season, which takes place from July to mid-September.
  • Though male bison reach reproductive maturity at one to two years of age, younger bulls usually do not have the opportunity to breed due to competition from older males.
  • Female bison are physically mature at two years of age and most calve for the first time at three years old.
  • Typically, a cow gives birth to a single calf in the month of May. Within hours of its birth, the calf can follow its mother.
Conservation and Management


Wood bison are classified as At Risk in the General Status of Alberta Wild Species report. See:

Also see the Status of the Wood Bison in Alberta report at:

This species is also listed as Endangered under the Wildlife Act, but only in a defined portion of north-western Alberta (the range of the Hay-Zama herd). See more information on this species and the assessment and listing process at:

Current Management

  • Only free-roaming wood bison found in northwestern Alberta's Bison Management Area are considered to be wildlife, and receive protection under the Wildlife Act. It is illegal to hunt, harm, or traffic in the bison within this area.
  • Free-roaming wood bison in and around Wood Buffalo National Park carry tuberculosis and brucellosis (introduced livestock diseases). To protect the Hay-Zama herd, and domestic livestock in northern Alberta, bison outside of the Bison Management Area receive no protection.
  • Beginning in 2008, a carefully-controlled hunt of the Hay-Zama herd was started, to control population growth, and to undertake disease surveillance. If the Hay-Zama recovery herd becomes infected, it will probably have to be destroyed. Until the disease threat from Wood Buffalo National Park can be eliminated, these control measures will probably need to be continued. For more information, visit the My Wild Alberta website at:
  • A disease containment approach has been developed to reduce the risk of tuberculosis and brucellosis spreading to domestic livestock and to the Hay-Zama herd. For details, see:
Similar Species
  • Plains Bison
    • Hair on the wood bison’s head is longer and less woolly than on the plains bison.
    • The beard, throat mane, cape and chaps are typically less pronounced in wood bison than for plains bison.

Are wood bison really wood bison?

Historically, there were two subspecies of bison found in Alberta – wood bison in northern boreal areas, and plains bison to the south. Although there has been some intermixing, the wild bison currently found in Alberta’s far north are considered wood bison.

Plains bison once occupied more open areas further south in Alberta (and across the Great Plains of North America). However, they remain extirpated as a free-roaming species from their original range in the province. Pure plains bison are currently found in Alberta only in a portion of Elk Island National Park.


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Updated: Jan 8, 2014