The mother and her calf will stay isolated from the herd for a couple of days. At about two months, the calves will begin to develop shoulder humps and horns. The calves are usually weaned by the time they are seven months old. The American bison spends the warm hours of the day resting, chewing its cud, or wallowing in dirt. It is most active in the early morning and late afternoon.
Bison live in a variety of groups.
Females and young males may live in groups of up to 20 bison. Males also can live in groups of up to 20 males, or they can live in smaller groups or individually. Mature males and females usually live apart except during breeding season. Each bison group has a dominant male or female. The American bison is an endangered species.