Gorillas are large great apes from the rainforests of Central Africa. Adult males reach heights of up to 1.8 metres (5 feet 11 inches) when standing upright, making gorillas the second largest primates, after humans. Ground-dwelling animals, some inhabit the mountains, others the lowlands. Gorillas live in small but stable groups called troops, usually consisting of one male and several females and young. They feed only on ground-level vegetation: leaves, fruits and shoots. There are two species of gorilla that inhabit different parts of Africa: the Western and Eastern gorilla. Western gorillas live in swamp and lowland forests. Eastern gorillas are divided between the lowland and mountain kinds. Mountain gorillas have shorter arms and longer hair than their lowland relatives.

Lifestyle

Gorillas usually move around on all fours by knuckle-walking, like chimpanzees. They sometimes walk on two feet for short distances while carrying food or when threatening an attacker. Gorillas build nests out of branches and leaves for sleeping. Unlike chimpanzees or orang-utans, they prefer to sleep in nests on the ground.

Highly intelligent, gorillas can be taught sign language. They have been observed using branches as tools or weapons. They also use rocks for smashing open nuts.

Silverbacks

Adult males are known as silverbacks because of their “saddle” of silver hair. This comes when they reach the age of about 13 years. They threaten rivals by standing upright, roaring and beating their chests. A silverback will fiercely defend the group from other gorillas, humans or predatory leopards, fighting to the death if necessary.