History of Bison in North America
The American bison was, at one time, possibly the most abundant large land mammal on earth. Only 200 years ago an estimated 30 million plains bison roamed the grasslands and shrub steps of North America from Central Canada to Mexico. Once an ecological keystone species, their migrations, grazing patterns, and behavior literally shaped the physical environment. Bison were also an inherent part of the cultural heritage of many Native American tribes and were central to national expansion and development.
However, intensive market hunting and commercial slaughter in the late 1800’s led to their near extermination. By 1902, numbers were reduced to less than two dozen. This last remaining wild herd of 23 animals found refuge in the high elevation interior (Pelican Valley) of Yellowstone National Park.
Today there is an estimated 500,000 bison across North America. However, the vast majority ~ 95% - could be considered “domestic” livestock as many are privately owned, raised in confinement for meat consumption, fenced, and most have some level of cattle gene introgression, meaning they’ve been bred with cattle and are not considered genetically pure bison. Furthermore, they only occupy a very small fraction of their former range (less than 1% according to some estimates) and are thus considered by many as being ecologically extinct throughout most of their historic range. Wood Buffalo National Park has the largest population of free-roaming woods bison (about 10,000), and Yellowstone National Park has the largest population of free-roaming plains bison (about 4,900).