Types of Bison in Montana

Technically, Montana has only one bison species: the American bison (Bison bison). However, wildlife managers recognize two subspecies that can live in the same region. Plains bison (B. b. bison) are more common and were historically found across Montana's grasslands and prairies. Wood bison (B. b. athabascae) are larger and adapted to forested areas, though most wood bison today live in Canada. Yellowstone's bison include both subspecies genetics due to historical cross-breeding. Most bison you encounter in Montana will be plains bison or plains-wood bison hybrids.

Plains bison are smaller and leaner than wood bison, typically weighing 800 to 1,200 pounds at maturity, with a more slender build and a lower hump. Wood bison are heavier, reaching 1,400 to 1,800 pounds, with a higher, more prominent shoulder hump and thicker fur. Both types are dark brown to nearly black, with long shaggy hair covering their head and neck. Their horns curve inward and are similar in size. From a distance, most observers cannot tell the subspecies apart. The visible differences are mainly weight and bulk, which you would only notice if comparing individuals directly.

Yellowstone National Park's herd is the largest wild bison population in North America, with roughly 4,000 to 5,000 animals. These are managed as part of an interagency agreement to prevent brucellosis spread to cattle. The National Bison Range near Missoula, managed by the U.S. Fish and Wildlife Service, holds approximately 350 to 400 bison. The Crow Tribe maintains a bison herd on tribal land. The Northern Cheyenne Tribe is building a herd as part of cultural and ecological restoration. Private ranches across Montana hold additional bison used for ranching and hunting. Most wild-viewed bison in Montana belong to Yellowstone's herd or the National Bison Range.

Yellowstone's bison herd is the most accessible and reliable for visitors. You can see them from the Grand Loop Road in many seasons, especially around Lamar Valley and Hayden Valley, which are prime grazing areas. The National Bison Range offers guided tours and driving routes where you have a good chance of seeing bison up close. Both locations provide the best opportunities for photography and safe observation. Private ranches near bison operations sometimes allow viewing from public roads, but always respect private property boundaries. Reservation-based herds on Crow and Northern Cheyenne lands require permission or participation in guided tours.

No. Yellowstone's bison have been interbred with domestic cattle in the past, and some herds have historical wood bison genetics mixed with plains bison. The National Bison Range maintains careful genetic records to preserve plains bison lineage and prevent unwanted cross-breeding. DNA testing has become standard practice for managed herds to track ancestry and genetic health. Most bison you see in Montana are healthy, viable animals regardless of their genetic history. Modern bison management prioritizes disease resistance and population stability over strict subspecies purity.

Brucellosis is a bacterial disease that affects cattle and wildlife, including bison. Yellowstone's bison sometimes carry brucellosis, which poses a risk to livestock ranchers in surrounding areas. This is why Yellowstone bison are closely monitored and managed to prevent spread to cattle herds. If you are a rancher or work with livestock, the presence of bison herds and wildlife corridors near your operations is important to know. Visitors and wildlife watchers are not at personal risk from brucellosis when viewing bison from a distance. The disease has shaped Montana's bison management policy significantly, influencing where herds are allowed to roam.

American bison are not closely related to African wild cattle like buffalo or wildebeest. Bison are bovines native to North America and have different evolutionary history, behavior, and ecology. Bison are solitary or found in small groups for much of the year, clustering into larger herds mainly during winter or breeding season. African buffalo form large herds year-round. Bison are adapted to grasslands, prairies, and open forests with cold winters. They have thick coats, smaller horns that curve differently, and a massive shoulder hump. If you have seen African wildlife documentaries, bison look and behave quite differently in their Montana habitat.

Winter and early spring are generally the best times to see bison in Montana. During these months, snow forces bison to lower elevations and concentrate around geothermal hot springs in Yellowstone or maintained feeding areas. They are more visible because vegetation is sparse and herds group together for warmth and access to forage. Summer bison disperse across higher elevations, making them harder to locate from roadside viewing areas. Fall is also decent for viewing, though bison begin moving to winter grounds. Early morning and late afternoon are best times of day regardless of season.

Yes, experienced observers can identify individual bison by horn shape, hump size, coloration patterns, and scars or markings. Wildlife managers use photographs and genetic testing to track individuals over time. The Yellowstone bison population has been studied for decades, and researchers have named and tracked many animals. As a visitor, you likely will not recognize the same bison twice, but you may notice variation in size, age, and condition between animals in a herd. Calves are lighter in color and much smaller than adults, making them easily recognizable during spring and early summer.