High Quality Content by WIKIPEDIA articles! The Yellowstone Park bison herd in Yellowstone National Park is probably the oldest and largest public bison herd in the United States of America. Yellowstone is known for its geothermal activity and large mammals, especially Elk, Wolves, American Bison, Bears, Pronghorn Antelope, Moose and Bighorn Sheep. The Yellowstone Park Bison Herd is estimated at approximately 3,700 individuals (2011) in two major herds. The Bison in the Yellowstone Park Bison Herd are American Bison, and of the Plains Bison subspecies. Yellowstone National Park may be the only location in the United States where free ranging bison were never extirpated, since they continued to exist in the wild and were not re-introduced as has been done in most other bison herd areas. Other large free ranging, publicly controlled herds of Bison in the United States include the Wind Cave Bison Herd (approximately 350 animals), the Antelope Island Bison Herd (approximately (550 to 700 animals), the Henry Mountains Bison Herd in Utah (400 to 500 animals), and the National Bison Range Herd near Flathead Lake, Montana (400 animals).