Although their range covers a small percentage of Africa, gorillas cover a wide range of elevations.The mountain gorilla inhabits the Albertine Rift montane cloud forests of the Virunga Volcanoes, ranging in altitude from 2,200–4,300 metres (7,200–14,100 ft).
A gorilla's day is synchronized, divided between rest periods and travel or feeding periods. Mountain gorillas mostly eat foliage, such as leaves, stems, pith, and shoots, while fruit makes up a very small part of their diets.Lowland gorillas live in dense forests and lowland swamps and marshes as low as sea level, with western lowland gorillas living in Central West African countries and eastern lowland gorillas living in the Democratic Republic of the Congo near its border with Rwanda.The American physician and missionary Thomas Staughton Savage and naturalist Jeffries Wyman first described the western gorilla (they called it Troglodytes gorilla) in 1847 from specimens obtained in Liberia.The separate species and subspecies developed from a single type of gorilla during the Ice Age, when their forest habitats shrank and became isolated from each other.The proposed third subspecies of Gorilla beringei, which has not yet received a trinomen, is the Bwindi population of the mountain gorilla, sometimes called the Bwindi gorilla.Adult males are 1.7 to 1.8 m (5 ft 7 in to 5 ft 11 in) tall, with an arm span that stretches from 2.3 to 2.6 m (7 ft 7 in to 8 ft 6 in).
Female gorillas are shorter, with smaller arm spans.Obese gorillas in captivity can weigh as much as 270 kg (600 lb).Gorilla facial structure is described as mandibular prognathism, that is, the mandible protrudes farther out than the maxilla. The eastern gorilla is more darkly coloured than the western gorilla, with the mountain gorilla being the darkest of all. The western lowland gorilla can be brown or grayish with a reddish forehead.Western lowland gorillas live in swamp and lowland forests ranging up to 1,600 m (5,200 ft), and Cross River gorillas live in low-lying and submontane forests ranging from 150–1,600 m (490–5,250 ft).Gorillas construct nests for daytime and night use.The western gorilla lives in west central Africa, while the eastern gorilla lives in east central Africa.