The wisent or European bison (Bos bonasus; often also Bison bonasus) is a European species of cattle (Bovini). Bison were found in the primeval forests of western, central and south-eastern Europe up until the early Middle Ages. Their habitat is temperate deciduous, coniferous and mixed forests. Bisons are herd animals, but according to their habitat they are only found in small groups. Typical herds number 12 to 20 animals and consist of cows and young animals. Sexually mature bulls stay with the herds only during the rutting season. The outwardly similar American bison (Bos bison) can be crossed with the wisent without any restrictions.
In Europe, in addition to the actual wisent (Bos bonasus), sometimes also called the lowland wisent, there was also the mountain wisent (Bos caucasicus), which has been exterminated (sometimes it is only regarded as a subspecies of the wisent and is then referred to as Bos bonasus caucasicus), or in a mixed form (hybrid) with the actual wisent. In bison breeding, a distinction is made between three breeding lines: the lowland line (homogeneous lowland bison), the lowland-Caucasus line (crossing of lowland bison and mountain bison) and the highland line (crossing of lowland bison and mountain bison with further cross-breeding with American bison). All pure-blooded animals are registered in the world bison studbook kept in the Białowieża National Park.
Source: Wikipedia