The Plains bison (Bison bison bison) is one of two subspecies/ecotypes of the American bison, the other being the wood bison (B. b. athabascae). Furthermore, it has been suggested that the Plains bison consists of a northern (B. b. montanae) and a southern subspecies, bringing the total to three. However, this is generally not supported. A natural population of Plains bison survives in Yellowstone National Park (the Yellowstone Park bison herd consisting of about 3,000