American Bison

The destruction was fast and deliberate: tens of millions of animals reduced to fewer than a thousand by the 1880s, in a campaign aimed as much at Plains nations as at the bison itself. Recovery brought the total to several hundred thousand, but most of those are commercial herds. The conservation figure — genetically pure, free-ranging animals managed as wildlife — is closer to twenty thousand, which is why the listing has not moved further.

Bison graze in a way cattle do not, moving in dense groups, cropping grass hard, then leaving it alone for long enough to recover. They wallow, and the bare hollows fill with water and hold different plants. Reintroduce bison to prairie and the plant community reorganises around them; the grassland is a product of the animal as much as the reverse.