"[T]he country in every direction around us was one vast plain in which innumerable herds of Buffalow were seen attended by their shepherds, the wolves; the solitary antelope which now had their young were distributed over its face; some herds of elk were also seen." -- Meriwether Lewis.
Though he recorded many detailed scientific observations of animals the Corps of Discovery encountered, Captain Meriwether Lewis got closer to one bison than he might have desired. On May 29, 1805, a bull swam across the Missouri River and thundered through camp, skirting several of the men's heads by inches, before Lewis's dog barked and the bison ran off. One of Clark's rifles was trampled, but everyone was glad to have escaped with such minimal damage.
This lone bull undoubtedly made an impression, but the bison, also called buffalo, were most noticeable in the vast herds that seemed the very life of the plains. They infused the grasslands, their many hooves beating the ground, the bulls' roaring echoing off the hills, their backs carpeting the prairie. For plains tribes and explorers alike, the bison were key to every aspect of life. Members of the Corps worried how they would feed themselves as they pressed west and left the bison behind.
Bison are more than symbols of the prairie: Biologically, they play an integral role. Native prairie grasses like little bluestem and buffalo grass evolved along with the bison and flourish with the grazing that prompts new growth. The buffalo's sharp hooves turn up the soil. Their wallows provide temporary spring ponds that fill with frogs. Unlike domestic cattle, bison avoid woody cover like buffaloberry, chokecherry, and plum, allowing this important vegetation to serve as winter cover and nesting areas for other wildlife and birds.
Bison naturally roam great distances, eating the grass and sage that make up the bulk of their diet. Females cluster with young, born in late spring, as well as adolescents and a few older males. Other males form herds of their own. The herds mingle in the breeding season of late summer, when males fight for access to the females. In the harsh prairie winter, woolly coats keep bison warm while they use their huge heads to brush away the snow to find food.