Who is this visitor? Well, it's not a buffalo; true buffalo only live in Asia and Africa. Your two-thousand pound neighbor is known as the American bison, or to scientists Bison bison. The bison is the largest land mammal in North America. Bulls are more massive in appearance than cows, and more bearded. For their size, bison are agile and quick, capable of speeds in excess of 30 mph. Each year, bison injure park visitors who approach too closely.