European Bison (Bison bonasus)
The Eurasian species of bison, also known as wisent or the European wood bison, is the heaviest wild land animal in Europe - about 2.1 to 3.5 metres long, not counting a tail of 30 to 80 centimetres, and 1.6 to 1.95 metres tall. Body masses among adults (aged 6 years and over) can reach 634 kilogrammes on average in the cases of males, with a range of 400 to 920 kilogrammes - or even up to 1,000 kilogrammes, and of 424 kilogrammes among females, with a range of 300 to 540 kilogrammes.
At birth, calves are quite small, weighing between 15 and 35 kilogrammes. Body size in males increases proportionately to the age of six years. While females have a higher increase in body mass in their first year, their growth rate is comparatively slower than that of males by the age of three to five.
On average, the European species is slightly lighter in body mass and yet taller at the shoulder than the American bison (Bison bison). Compared to the American species, the wisent has shorter hair on the neck, head, and forequarters, but longer tail and horns.
The European bison is a herd animal, which lives in both mixed and solely male groups usually sited near meadows and water sources. Mixed groups consist of adult females, calves, young aged 2 to 3 years, and young adult bulls. The average herd size is eight to 13 animals, depending on environmental factors. 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.
The rutting season occurs from August through to October. Bulls aged four to six years, though sexually mature, are prevented from mating by older bulls. Cows, reaching sexual maturity in their third year, usually have a gestation period of 264 days, and typically give birth to one calf at a time. Productive breeding years are between four and 20 years of age in females, and only between six and twelve years of age in males.
Source: en.wikipedia.org/wiki/European_bison - 24.10.2017