The natural vegetation is divisible into two main sections directly related to the chief climatic regions of the country: (1) high forest, including both swamp and rain forests, and (2) savanna. Along the coastal area, the mangrove tree predominates, while immediately inland is freshwater swamp forest, which is somewhat more diversified and includes varieties of palms, the abura, and mahogany. North of the swamp forest lies near the rain forest, which forms a belt with an average width of some 130 km (80 mi). Here, trees reach as much as 60 m (200 ft) in height. Principal trees include the African mahogany, iroko, African walnut, and the most popular export wood, the obeche. Farther inland, the rain forest becomes displaced by tall grass and deciduous trees of small stature, characteristic of the savanna.
Few large animals are found in the rain forest; gorillas and chimpanzees in decreasing numbers are present, as well as baboons and monkeys. Reptiles abound, including crocodiles, lizards, and snakes of many species. Although many kinds of mammals can be found inland from the rain forest, these are not nearly so plentiful as in East or South Africa. Nigeria possesses two dozen species of antelope, but large concentrations of animals, even the common antelope, are rarely observed. The hippopotamus, elephant, giraffe, leopard, and lion now remain only in scattered localities and in diminishing number. Wildcats, however, are more common and widely distributed. Wildlife in the savanna includes antelope, lions, leopards, gazelles, and desert hyenas. Nigeria also abounds in bird life with a great number of species being represented.