Western lowland gorillas live in small groups, averaging around five individuals. Gorilla group structure is well established. A mature male is called a silverback due to the lighter color of hair on the lower part of the back, which lightens from black as the gorilla ages. A silverback leads his troop (or family group) of several females with infants, younger males, and juveniles, determining where to forage each day and nest each night. The silverback is also responsible for protecting his troop. Mature females leave their natal group to join a single silverback or to join another troop. Juvenile males (termed black backs as the hair on their back has yet to lighten with age) either remain in their natal group or migrate. If the silverback is tolerant, a juvenile male may remain in his natal group and assume the role of silverback. Juvenile males may also leave their natal group, living in loosely-bonded bachelor groups with other young males until they meet females and form their own troop. Gorilla family groups are usually stable. However, rival males can display aggressive behavior when encountering another troop. Males may express agitation or excitement by beating their chests. Chest beating is a form of communication and has many meanings, depending upon the context. Not only is it used to ward-off threats, but to call to troop members as the sound carries long distances. Young gorillas often chest beat while playing. Females typically give birth to one infant after a gestation period of eight to nine months. At around three to four months of age, the infant rides on mom’s back and will do so until weaned at around four to five years of age. During the day, gorillas forage for food. Each night, they sleep in new nests built on the ground (larger males) or in trees (juveniles and lighter females). Gorillas are tool users and wild gorillas have been observed using rocks and sticks as rudimentary tools.
Gorilla are found in the lowlands and swamp forests of Cameroon, Central African Republic, Equatorial Guinea, the Democratic Republic of the Congo, Gabon, and Angola.
Gorillas eat primarily leaves, bark, vines, and stalks, as well as fruit. They will also eat insects. Western lowland gorillas enjoy termites and ants and will break open termite mounds to eat the larva, though this is a very small portion of their diet.
- Height: 4–6 feet
- Weight: 125–420 pounds