European bison

European bison eat plants.

They eat grass and soft green plants. Sometimes they nibble twigs and bark.

About nine-tenths of a European bison's food is grasses, sedges and other soft plants called herbs. The rest is twigs, leaves and bark from trees and shrubs.

In snowy winters, people often put out hay for the bison in racks. Like cows, bison chew the cud: they rest for up to four hours at a time while they chew their food a second time. As they wander, bison spread the seeds of about 178 kinds of plants.

Rumen studies summarized by Animal Diversity Web show that grasses, sedges and herbs make up about 90% of the diet in every season, with trees and shrubs about 10%; mosses, horsetails and fungi together make up less than 1%. The IUCN describes the wisent as a mixed feeder or browser that keeps adjusting its diet to whatever easily digestible non-grass plants are available.

Where winters are snowy, many herds receive supplementary hay, which can draw bison into crowded feeding sites. Their day alternates foraging bouts of up to five hours with resting bouts of up to four hours, mostly spent ruminating (IUCN). Bison disperse the seeds of around 178 species of vascular plants.

Bison live in groups called herds.

Moms, young bison and calves stay together. Many grown-up males live alone.

European bison live in mixed herds of cows, young bison and calves, usually up to about 20 animals. Grown-up males often live alone or in small groups of two to eight bulls.

Herds are not fixed families. Groups meet, join together and split again, swapping some members. In the mating season, bulls join the cows, and in winter many bison gather in big groups where food is put out for them.

The basic social unit is a mixed group of up to about 20 animals: adult cows, two- to three-year-old subadults and calves (IUCN). Males are solitary or form bachelor groups of two to eight. Group size and make-up change with the seasons and are largest during the rut and in winter aggregations; groups are not family units and often merge and split.

From July, sexually active bulls join mixed groups. A dominant bull guards a cow in heat in a 'tending bond', and may fight rival mature bulls (Animal Diversity Web). Male bison have dispersed up to several hundred kilometers, and in growing populations mixed groups have begun to disperse too (IUCN).

Long ago, there were no wild European bison left.

People cared for the last bison in zoos. Now wild herds live in forests again.

By 1927, every wild European bison was gone. Fewer than 60 were still alive, in zoos and private parks. People bred them carefully, and in 1952 the first bison were set free in the wild again.

The plan worked. In 2019 there were more than 6,000 free-living bison, and the European Bison Pedigree Book counted 12,209 bison at the end of 2024, including 9,762 living in the wild. The species is now Near Threatened. All of today's bison come from just 12 ancestors, so they are closely related, and many herds are small and cut off from each other.

The IUCN lists Bison bonasus as Near Threatened under criterion C2a(i) (Plumb, Kowalczyk and Hernandez-Blanco; assessed 28 July 2020, published 2020), with an increasing trend. The lowland bison was extinct in the wild by 1919 and the Caucasian bison by 1927; restoration into the wild began in 1952. The free-living population grew from 1,848 in 2003 to 6,244 in 2019, yet only eight subpopulations exceeded a minimum viable size, holding 2,518 mature animals, none above 500.

The main concerns are very low genetic diversity (every bison descends from 12 founders), small and isolated herds, confinement to forest, parasites linked to winter feeding sites, culling and local poaching, and inconsistent national policies. The European Bison Pedigree Book recorded 12,209 animals worldwide at the end of 2024, 9,762 of them free-living.