White frost clings to the brown hair of an American Bison herd as they slowly lumber across a snow-covered hillside. Puffs of air can be seen as the animals breath. The nearby spruce trees shiver in the cold wind but the bison are unfazed due to their thick winter coats. Some of the bison use their large heads to dig through the snow to reach the vegetation below, others look off into the distance and smell the frigid winter air.
Historically bison played an essential role in the shaping of the ecology of the Great Plains and other Western Rangelands. These animals grazed heavily on native grasses, disturbing the soil as they roamed. This allowed many plant and animal species to flourish, including prairie dogs, and most of the native grasses and broad-leaf plants that are seen today. The trails that bison carved in their seasonal migrations formed some of the earliest traceable paths into the American wilderness and were used by Native Americans, explorers, and pioneers.
Bison are symbolic animal of Western Rangelands. These formidable beasts are the largest land mammals in North America, standing 5-6 feet tall at the shoulder and weighting in at over a 2000 pounds. Despite their massive size, bison are extremely agile and can run at speeds up to 40 miles per hour when needed. Bison move continually as they eat. The cows (females) lead the family herd and mature bulls (males) remain solitary or in small groups for most of the year except during mating season, which can range from June-September. Calves are born in April and May.
Bison herd have dominance hierarchies that exist for both cows and bulls. A bison’s dominance is actually related to its birthday, in that those born earlier in the season will more likely be larger and more dominant as adults. Thus bison are able to pass on their dominance to their offspring as dominant bison breed earlier in the season. This passing of dominance is crucial to herd behavior and sustainability. Bison have an excellent sense of small and it is essential in detecting danger. Bison can also hear very well. They communicate vocally through grunts and snorts. A bison’s eye sight is relatively poor when compared to the acuteness of its sense of smell and hearing. Due to their large size they have very few enemies besides wolves, humans, and occasionally grizzly bears and cougars.
Nobody really knows how many bison inhabited North America before the arrival of Europeans. Most estimates have a range between 30 and 70 million. Today wild populations of bison are limited to parks and reserves, but many people raise domesticated bison for meat and hides on privately owned ranches. These impressive animals played a unique role in the colonization of the American West and continue to awe visitors and residents who have the great fortune of seeing them.