Bison mate in August and September; gestation is 285 days. A single reddish-brown calf nurses until the next calf is born. If the cow is not pregnant, a calf will nurse for 18 months. Cows nurse their calves for at least 7 or 8 months, but most calves seem to be weaned before the end of their first year. At three years of age, bison cows are mature enough to produce a calf. The birthing period for bison in boreal biomes is protracted compared to that of other northern ungulates, such as moose and caribou.
bison mate in august and september; gestation is 285 days a single reddish-brown calf nurses until the next calf is born if the cow is not pregnant a calf will nurse for 18 months cows nurse their calves for at least 7 or 8 months but most calves seem to be weaned before the end of their first year at three years of age bison cows are mature enough to produce a calf the birthing period for bison in boreal biomes is protracted compared to that of other northern ungulates such as moose and caribou