in Montana. Population estimates in 2010 ranged from 400,000 to 500,000, with approximately 20,500 animals in 62 conservation herds and the remainder in approximately 6,400 commercial herds. According to the
IUCN, roughly 15,000 bison are considered wild, free-range bison not primarily confined by fencing.
The Nature Conservancy (TNC) has reintroduced bison to over a dozen nature preserves around the United States. In October 2016, TNC established its easternmost bison herd in the country, at
Kankakee Sands nature preserve in
Morocco,
Newton County, Indiana. In 2014, U.S. Tribes and Canadian First Nations signed a treaty to help with the restoration of bison, the first to be signed in nearly 150 years.
Habitat and trails in
Moose, Wyoming. American bison live in river valleys, and on prairies and plains. Typical habitat is open or semiopen grasslands, as well as sagebrush, semiarid lands, and scrublands. Some lightly wooded areas are also known historically to have supported bison. Bison also graze in hilly or mountainous areas where the slopes are not steep. Though not particularly known as high-altitude animals, bison in the
Yellowstone Park bison herd are frequently found at elevations above , and the
Henry Mountains bison herd is found on the plains around the
Henry Mountains, Utah, as well as in mountain valleys of the Henry Mountains to an altitude of . Reintroduced plains bison in
Banff National Park have been observed to roam mountainous areas, including high ridges and steep drainages. Archaeological finds indicate some bison spent their lives within mountain ranges while others may have migrated in and out. Those in Yukon, Canada, typically summer in alpine plateaus above treeline. The first thoroughfares of North America, except for the time-obliterated paths of
mastodon or
muskox and the routes of the
mound builders, were the traces made by bison and
deer in seasonal migration and between feeding grounds and
salt licks. Many of these routes, hammered by countless hoofs instinctively following watersheds and the crests of ridges in avoidance of lower places' summer muck and winter snowdrifts, and often following the routes of least resistance across rolling terrain, were followed by the aboriginal North Americans as routes to hunting grounds and as warriors' paths. They were invaluable to explorers and were adopted by
pioneers. Bison traces were characteristically north and south along seasonal migration routes, but several key east–west buffalo trails were used later as routes for railways. Some of these include the
Cumberland Gap through the
Blue Ridge Mountains to upper
Kentucky. A heavily used
trace crossed the
Ohio River at the
Falls of the Ohio and ran west, crossing the
Wabash River near
Vincennes, Indiana. In Senator
Thomas Hart Benton's phrase saluting these sagacious path-makers, the bison paved the way for the railroads to the Pacific.
Mexico , Mexico. The southern extent of the historic range of the American bison includes northern Mexico and adjoining areas in the United States as documented by archeological records and historical accounts from Mexican archives from 700 CE to the 19th century. The Janos-Hidalgo bison herd has ranged between Chihuahua, Mexico, and New Mexico, United States, since at least the 1920s. The persistence of this herd suggests that habitat for bison is suitable in northern Mexico. In 2009, genetically pure bison were reintroduced to the
Janos Biosphere Reserve in northern
Chihuahua adding to the Mexican bison population. In 2020, the second herd was formed in
Maderas del Carmen. A private reserve named Jagüey de Ferniza has kept bison since before the above-mentioned reintroductions in Coahuila.
Introductions to Siberia Since 2006, an outherd of wood bison sent from Alberta's
Elk Island National Park was established in
Yakutia,
Russia as a practice of
pleistocene rewilding; wood bison are the most similar to the extinct
steppe bison species (
Bison priscus sp.). The bison are adapting well to the cold climate, and Yakutia's Red List officially registered the species in 2019; a second herd was formed in 2020. Plains bison were also translocated into the
Pleistocene Park, as more-favored wood bison could not be acquired. ==Behavior and ecology==