Bwindi Mountains have an altitude range of between 1,160 and 2,607 m above see level. Because of this relatively small high the mountains are forested up to the summits. The Bwindi Impenetrable Forest is regarded to be one of the most biologically diverse forests in Africa, largely due to its antiquity (it dates to before the Pleistocene ice age, making it over 25,000 years old) and its altitude range. The forest harbors at least 120 mammals and 346 birds species.