A bison has a shaggy, long, dark-brown winter coat, and a lighter-weight, lighter-brown summer coat.
Male bison are significantly larger and heavier than females.
Wood bison is potentially more primitive in phenotype than plains bison while the latter probably evolved from mixing of Bison occidentalis and Bison antiquus.
Plains bison are often in the smaller range of sizes, and wood bison in the larger range.
Head-rump lengths at maximum up to 3.5 m (11 ft 6 in) for males and 2.85 m (9 ft 4 in) for females long and the tail adding 30 to 95 cm (1 ft 0 in to 3 ft 1 in).

Heights at withers in the species can range from 152 to 186 cm (5 ft 0 in to 6 ft 1 in) for B. b. bison while B. b. athabascae reaches over 2 m (6 ft 7 in).
Typically weights can range from 318 to 1,179 kg (701 to 2,599 lb), 460 to 988 kg (1,014 to 2,178 lb) with medians of 730 to 792.5 kg (1,609 to 1,747 lb) (B.b.
bison) and 943.6 kg (2,080 lb) (B.b.athabascae) in males, and 360 to 640 kg (790 to 1,410 lb) with medians of medians of 450 to 497.6 kg (992 to 1,097 lb) in females, although the lowest weights probably representing typical weight around the age of sexual maturity at 2 to 3 years of age.
The heaviest wild bull for B.b.bison ever recorded weighed 1,270 kg (2,800 lb) while there had been bulls estimated to be 1,360 kg (3,000 lb).
B.b.athabascae is significantly larger and heavier on average than B.b.bison while the number of recorded samples for the former was limited after the rediscovery of a relatively pure herd.
When raised in captivity and farmed for meat, the bison can grow unnaturally heavy and the largest semidomestic bison weighed 1,724 kg (3,801 lb).
The heads and forequarters are massive, and both sexes have short, curved horns that can grow up to 60 cm (2 ft)  long with 90 cm (3 ft) to 124 cm (4 ft) width, which they use in fighting for status within the herd and for defense.

Bison are herbivores, grazing on the grasses and sedges of the North American prairies.
Their daily schedule involves two-hour periods of grazing, resting, and cud chewing, then moving to a new location to graze again.
Sexually mature young bulls may try to start mating with cows by the age of two or three years, but if more mature bulls are present, they may not be able to compete until they reach five years of age.

For the first two months of life, calves are lighter in color than mature bison.
One very rare condition is the white buffalo, in which the calf turns entirely white.
A bison has a shaggy, long, dark-brown winter coat, and a lighter-weight, lighter-brown summer coat. Male bison are significantly larger and heavier than females. Wood bison is potentially more primitive in phenotype than plains bison while the latter probably evolved from mixing of Bison occidentalis and Bison antiquus. Plains bison are often in the smaller range of sizes, and wood bison in the larger range. Head-rump lengths at maximum up to 3.5 m (11 ft 6 in) for males and 2.85 m (9 ft 4 in) for females long and the tail adding 30 to 95 cm (1 ft 0 in to 3 ft 1 in).
Heights at withers in the species can range from 152 to 186 cm (5 ft 0 in to 6 ft 1 in) for B. b. bison while B. b. athabascae reaches over 2 m (6 ft 7 in). Typically weights can range from 318 to 1,179 kg (701 to 2,599 lb), 460 to 988 kg (1,014 to 2,178 lb) with medians of 730 to 792.5 kg (1,609 to 1,747 lb) (B.b. bison) and 943.6 kg (2,080 lb) (B.b.athabascae) in males, and 360 to 640 kg (790 to 1,410 lb) with medians of medians of 450 to 497.6 kg (992 to 1,097 lb) in females, although the lowest weights probably representing typical weight around the age of sexual maturity at 2 to 3 years of age. The heaviest wild bull for B.b.bison ever recorded weighed 1,270 kg (2,800 lb) while there had been bulls estimated to be 1,360 kg (3,000 lb). B.b.athabascae is significantly larger and heavier on average than B.b.bison while the number of recorded samples for the former was limited after the rediscovery of a relatively pure herd. When raised in captivity and farmed for meat, the bison can grow unnaturally heavy and the largest semidomestic bison weighed 1,724 kg (3,801 lb). The heads and forequarters are massive, and both sexes have short, curved horns that can grow up to 60 cm (2 ft)  long with 90 cm (3 ft) to 124 cm (4 ft) width, which they use in fighting for status within the herd and for defense.
Bison are herbivores, grazing on the grasses and sedges of the North American prairies. Their daily schedule involves two-hour periods of grazing, resting, and cud chewing, then moving to a new location to graze again. Sexually mature young bulls may try to start mating with cows by the age of two or three years, but if more mature bulls are present, they may not be able to compete until they reach five years of age.
For the first two months of life, calves are lighter in color than mature bison. One very rare condition is the white buffalo, in which the calf turns entirely white.
American bison