Cow groups are composed of females, males under three years of age, and a few older males. More males enter these groups as the rut approaches. Males live either individually or in groups that may be as large as 30 head. Dominance between the bulls is linear. Bulls that have a higher rank in the society breed more often than those of a lower rank.
Cows also live in a linear dominance hierarchy, which is established early in life.
Grazing takes place during several periods each day and is conducted in loose groups. When bison travel, they form a line. The traveling pattern of bison is determined by the terrain and habitat condition. An adult cow supplies the leadership. The olfactory sense of bison is excellent and is essential in detecting danger.