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Social structure and territorial behaviours

The European bison is a herd animal, which lives in both mixed and solely male groups. Mixed groups consist of adult females, calves, young aged 2–3 years, and young adult bulls. The average herd size is dependent on environmental factors, though on average, they number eight to 13 animals per herd. Herds consisting solely of bulls are smaller than mixed ones, containing two individuals on average. European bison herds are not family units. Different herds frequently interact, combine, and quickly split after exchanging individuals.

Bison social structure has been described by specialists as a matriarchy, as it is the cows of the herd that lead it, and decide where the entire group moves to graze. Although larger and heavier than the females, the oldest and most powerful male bulls are usually satellites that hang around the edges of the herd to protect the group. Bulls begin to serve a more active role in the herd when a danger to the group's safety appears, as well as during the mating season – when they compete with each other.

Territory held by bulls is correlated by age, with young bulls aged between five and six tending to form larger home ranges than older males. The European bison does not defend territory, and herd ranges tend to greatly overlap. Core areas of territory are usually sited near meadows and water sources.