Hundreds of species of mammals, birds, fish, reptiles, and amphibians have been documented, including several that are either endangered or threatened.[11] The vast forests and grasslands also include unique species of plants. Yellowstone Park is the largest and most famous megafauna location in the contiguous United States. Grizzly bears, cougars, wolves, and free-ranging herds of bison and elk live in this park. The Yellowstone Park bison herd is the oldest and largest public bison herd in the United States. Forest fires occur in the park each year; in the large forest fires of 1988, nearly one-third of the park was burnt. Yellowstone has numerous recreational opportunities, including hiking, camping, boating, fishing, and sightseeing.