The Yellowstone herd is both genetically and behaviorally unique, being the only herd with continuously wild ancestry from the days when 50 million buffalo migrated freely across the Great Plains. At the end of the 19th century, after tens of millions had been slaughtered, only 23 wild buffalo survived. Taking refuge in Yellowstone's remote Pelican Valley, this remnant herd ensured the survival of the species in the wild. Today there are a little more than 3,000 buffalo living in and around Yellowstone, comprising America's only free-roaming and unfenced population-bfc website