Bison

Presentation

The American Bison (Bison Bison) is the largest land mammal in North America. Massive and stocky, it is distinguished by its muscular dorsal hump, its imposing head and its thick fleece at the front of the body. Once present in tens of millions in the Great Plains, it almost disappeared in the 19th century before being saved by conservation programs. It lives in herds and plays an important ecological role in maintaining grasslands. A close cousin, the European Bison (Bison bonasus), also occurs in the forests of Eastern Europe.

The Bison has a massive body with the forequarters more developed than the hindquarters, topped with a muscular hump. Its head is broad, with short, curved horns present in both sexes. Thick dark brown fur covers the head, neck and shoulders, contrasting with shorter coat on the rear of the body.

Characteristics

Indicative values: they vary by subspecies, sex and region.

Habitat and distribution

The Bison mainly frequents large prairies, grassy steppes and some open wooded areas of North America. It needs large areas offering both pasture and water points. Some populations survive today in national parks and protected reserves.

Behaviour

The Bison lives in herds whose size varies according to the season, the females and young forming groups distinct from the solitary males or in small groups. It is renowned for its robust character but can be unpredictable and aggressive, especially during the rutting period. Despite its size, it can reach high running speeds over short distances.

Reproduction

The Bison's mating season occurs in summer, during which males compete for access to females through fighting and vocalizations. Gestation lasts approximately nine months and ends with the birth of a single calf in the spring. The young stay with its mother for several months before joining the larger herd.

Peculiarities

The Bison can charge surprisingly quickly despite its heavy weight. Its dorsal hump is actually made up of powerful muscles supporting its massive head, useful for clearing snow from the ground in winter in search of food. The species experienced a dramatic decline in the 19th century, going from several million individuals to a few hundred.

Threats and conservation

The Bison was hunted extensively in the 19th century, leading to near extinction of the species. Today, the main threats concern habitat fragmentation and genetic management of remaining herds, often hybridized with domestic cattle. Conservation programs have helped stabilize wild populations.

References

Profile updated 27 August 2026 · Reviewed by the TunisieVet editorial team.