While not as prolific as bison on the American plains, European bison were once a common site across the continent. By 1919 the species had been driven to extinction in the wild, but thanks to the captive breeding of 54 animals there are now 3,000 or so bison across their former range. That number will grow in April as reintroduction efforts continue.

The Dutch trust “Rewilding Europe” will release four bison in the Netherlands’ Veluwe region, and another 20 in Romania in May. The 20 will accompany four others recently released in Romania’s Maashorst nature preserve. According to New Scientist, Rewilding Europe hopes to have at least five herds of 100 bison each by 2022, with an overall population of 1,000 by 2032.

European bison once ranged as far west as southern England and as east as Russia. They inhabited all of the lowland areas of Europe, with populations in Sweden, Greece, and France, among others.

The differences between the European and American bison are slight but significant. Europeans have 14 ribs versus the American’s 15; the European is not as hairy but taller and lankier than the American; and the European’s horns face forward for better sparring with competitors, while Americans sweep up to enable the charging and goring of predators.

The European’s neck is also set differently than its American cousin. European bison browse more and graze less than Americans, and are harder to domesticate than Americans.

The European bison is a particularly rare species, making the reintroduction efforts all the more critical. By comparison, there are an estimated 30,000 American bison in various conservation herds across North America, with an additional 11,000 wood bison in Canada. The black rhino, constantly teetering on the edge of extinction, is thought to number at least 5,000 in the wild.

The term “rewilding” is used for large-scale conservation efforts. It focuses on restoring and protecting wilderness areas, apex predators, and keystone species.