European Bison (Bison bonasus): Wisent Facts and Rewilding

Appearance

The European bison looks like a slightly leaner, longer-legged version of the American bison. It has a high hump over the shoulders, a massive head carried low, short curved horns that point forward and upward, and a beard hanging from the chin.

The coat is brown to dark brown. Long hair covers the head, neck, beard and front legs, while the back half of the body has shorter fur. In winter the coat grows thick and woolly, and in spring it is shed in large patches, giving bison a ragged look. Both bulls and cows have horns, but bulls have heavier heads, larger humps and much thicker horns.

European bison vs American bison

The two living bison species are close relatives and can interbreed, but they differ in several ways:

The word “buffalo” is often used for both, but true buffalo are different animals living in Africa and Asia; see bison vs buffalo.

How big is a European bison?

In the wild herd of the Białowieża Forest, adult bulls average about 630 kg (1,390 lb) and cows about 420 kg (930 lb). Exceptional bulls can top 1,000 kg (2,200 lb), especially in captivity, where animals are often fed more. Calves weigh about 15–35 kg (33–77 lb) at birth.

Compared with American bison, wisent are on average a little lighter but slightly taller at the shoulder, with longer legs and a longer tail.

Habitat and range

European bison are animals of mixed landscapes. They prefer deciduous and mixed forests of oak, hornbeam, lime and pine with plenty of open meadows, clearings, river valleys and young woodland where grasses and herbs grow. In winter they often gather near feeding sites or in forest clearings.

Historically, the species lived across most of lowland Europe, from France and Belgium to the Volga and the Caucasus, and as far north as southern Sweden. As forests were cleared and people hunted them, bison vanished from western Europe in the Middle Ages and survived into the 20th century only in the Białowieża Forest and the northern Caucasus.

Today, bison live in free-ranging and semi-wild herds in more than a dozen countries. The largest numbers are in Poland, Belarus, Russia and Ukraine, with growing herds in Lithuania, Romania, Slovakia, Bulgaria, Germany, Latvia, Spain and elsewhere. For a full guide, see are there bison in Europe?

What do European bison eat?

The European bison is a herbivore and a ruminant, meaning it has a four-chambered stomach and chews the cud. It eats mostly grasses, sedges and herbs, which can make up the bulk of its diet in open areas. Compared with American bison, it browses more, eating the leaves, shoots, twigs and bark of trees and shrubs such as hornbeam, willow, oak and ash. In autumn it eats acorns.

An adult bull may eat over 30 kg (66 lb) of fresh plants a day in summer. Bison need to drink every day and, in winter, can break thin ice with their hooves. In Białowieża and many other places, bison are given hay in winter, a practice that helps them survive but also gathers them in crowded groups.

Behavior and herd life

European bison live in herds of two main types. Mixed herds of cows, calves, young animals and sometimes young bulls usually number about 8–13 animals and are led by older cows. Adult bulls live alone or in small bachelor groups and join the mixed herds mainly in the rut. Herds are not fixed family units; they often meet, merge and split again.

Bison are mostly active in the early morning and evening, resting and chewing the cud in the middle of the day. They roll in dry soil to make dust baths, which help keep off insects, and they rub against trees, stripping the bark. Despite their bulk, wisent are good jumpers and can clear fences and fallen trees.

When alarmed, a bison may make a deep grunting or growling sound, and bulls give similar calls in the rut. Fights between bulls involve head-to-head pushing with locked horns.

Reproduction and life cycle

The rut runs from about August to October. A dominant bull follows a cow in heat, guarding her from rivals until she mates. Bulls are able to breed from two or three years old, but in the wild they usually do not get the chance until they are about six, because older bulls keep them away.

Pregnancy lasts about 264 days, around nine months, and a single calf is born from May to July. The cow usually leaves the herd to give birth and returns with her calf a few days later. Calves stand within an hour and are nursed for several months. Cows usually first give birth at about three or four years old and can breed until about 20.

Lifespan

Wild European bison can live about 20–25 years, and females usually live longer than males. Bulls often die younger after years of fighting in the rut. In captivity, bison have reached about 30 years of age.

Extinction in the wild and rescue

The European bison came closer to extinction than almost any other large mammal that has survived. During World War I, soldiers killed hundreds of the bison in the Białowieża Forest, and the last wild lowland bison there was shot in 1921. In the Caucasus, the last wild bison was killed by poachers in 1927.

By then only about 50 European bison were left, all in zoos and private parks. In 1923 conservationists founded the International Society for the Preservation of the Wisent and began a careful breeding program with a studbook. Every European bison alive today descends from just 12 of those animals.

Bison were returned to the Białowieża Forest in 1929, at first in enclosures. From the early 1950s, they were released into the open forest there, and since then they have been reintroduced to many other parts of Europe. To protect their genes, the herds are still managed in two lines: a “lowland” line descended from only 7 founders and a “lowland-Caucasian” line that includes all 12.

Predators and threats

Healthy adult bison have few natural predators. Wolves can kill calves and sometimes weakened adults, and brown bears are a minor threat where both live. For most of their history, though, people have been their main enemy.

The main threats today are:

• Low genetic diversity, the result of descending from so few animals, which may make bison more vulnerable to disease.
• Disease, including a bacterial infection of the male reproductive organs called balanoposthitis, as well as diseases shared with cattle.
• Fragmented habitat: most herds are small, isolated and hemmed in by farmland and roads.
• Conflict with people, as bison can damage crops and forestry, leading to culls in some areas.

Conservation status

The IUCN Red List classifies the European bison as Near Threatened, an improvement from Vulnerable, and before that Endangered. Its population is increasing. The world population has grown from a few dozen animals in the 1920s to roughly 10,000 in the early 2020s, about two-thirds of them free-ranging. Even so, conservationists stress that the species depends on continued management, and many herds remain too small to be secure on their own.

Relationship with people

The bison is a national symbol of Poland and Belarus, and its image appears on coins, coats of arms and in place names across central Europe. It was a favored royal game animal for centuries, and Polish-Lithuanian kings protected the Białowieża herd by law, which is one reason it survived there longest.

Bison also appear in prehistoric art. Cave paintings in France and Spain, such as those at Altamira, show bison drawn more than 14,000 years ago, although scientists debate how many of them depict the European bison rather than the extinct steppe bison.

Today the wisent is a flagship of European rewilding. Reintroduced bison are used to keep woodland glades open, create a mix of grass and trees, and draw visitors to rural areas, including in England’s Kent; see are there bison in the UK?

Wisent are wild animals and should be watched from a respectful distance. Like their American cousins described in are bison dangerous?, they can charge if surprised or crowded.