Nyerere National Park has the largest number of elephants out of all the reserved wildlife areas in the country. The park offers a variety of environments ranging from hot volcanic springs, dense thickets, and open wooded grasslands. This diversity is also home a broad range of game, including buffalo, gnu, hartebeest, Greater kudu, sable, warthog and zebra. Also lion, hippo, spotted hyena and black rhino are spotted, while African wild dog and cheetah are sometimes seen. Nyerere National Park also boasts over 350 species of bird and reptiles such as crocodiles and various snakes and lizards. Walking is permitted (with an armed ranger). Nyerere National Park is one of the more exclusive areas in Tanzania. Its size and location afford privacy and seclusion from the masses of tourists associated with the more well-known parks such as Ngorongoro and Serengeti. The dry season is the best time for game viewing, while the rainy season provides ample bird watching opportunities; however, many of the roads are impassable after heavy rainfall. Lodges close between March and May.