High Quality Content by WIKIPEDIA articles! The Wind Cave bison herd is a herd of 250–400 American Bison in Wind Cave National Park, South Dakota, USA. It is believed to be one of only four free roaming and genetically pure herds on public lands in North America. The other three herds are the Yellowstone Park bison herd, the Henry Mountains bison herd in Central Utah, and on Elk Island in Alberta, Canada. The Wind Cave Herd are of the Plains Bison subspecies (Bison bison bison).