BIG HORN BISON CONSERVATION HERD
The largest terrestrial animal in North America, bison once roamed in herds numbering in the millions dominating prairie and forest ecosystems. Now reduced to a fraction of their current range and population, bison survive mainly in conservation herds. Yellowstone is the only place in the lower 48 states to have a continuously free-ranging bison population since prehistoric times. In the 1800s, market hunting and the US Army nearly caused the extinction of the bison. By 1902, poachers reduced Yellowstone’s herd to about two dozen animals. The US Army, which administered Yellowstone at the beginning of the 20th century, protected these bison from further poaching. Bison from private herds were used to establish a herd in northern Yellowstone. For decades, bison numbers were reduced due to the belief that they, along with elk and pronghorn, were over-grazing the park. By 1968, herd reductions of bison ceased. Reductions began again in the 2000s due to increasing numbers and litigation about migration into Montana. An estimated 20 to 30 million bison once roamed in North America from the Appalachians to the Rockies, and from the Gulf Coast to Alaska. Habitat loss and unregulated hunting reduced the population to under 2,000 animals by 1889. Today, approximately 500,000 bison live across North America, mostly on farms and ranches. Fewer than 30,000 wild bison live in conservation herds in national and state parks and reserves. Today’s bison ancestors appeared on the planet 5-10 million years ago (homo sapiens have only been dated back to 200,000 years) after splitting with the bovine lineage that eventually became the beef cow. Bison lived amongst mammoths, sabertooth tigers, and giant sloths. Today’s bison are much smaller than their larger ancestors and their main natural predators are wolves and mountain lions. Bison live in large numbers so as to provide safety and create more random harvesting by predators. They circle up when predators are present and push the calves into the center of the group. They are extremely aggressive animals using their horns, heavy heads, kicking action of their hooves and their thick skin to fight off attacks. We have found coyote skeletons with half of the skull sheared off, presumably by bison attacking them to protect the herd, and have never lost a bison of any age to a coyote attack.