Mountain gorillas live in the mountainous rainforests of central Africa; about 320 individuals live on the extinct volcanoes forming the Virunga Range on the borders of Rwanda, Uganda and the Democratic Republic of Congo (DRC, formerly Zaire).
Most gorillas range within the Virunga National Park in the DRC and Volcans National Park in Rwanda. A few are also found in Mgahinga National Park in Uganda. About 292 mountain gorillas live in Bwindi Impenetrable National Park in southwest Uganda on the border of the DRC.
Gorillas walk on all fours, with the weight of their upper bodies carried on the backs of their knuckles. They rarely stand on their hind limbs except during chest-beating displays.
Like other gorilla species, mountain gorillas live and travel in family groups of five to thirty individuals. Mountain gorilla social units usually consist of one dominant silverback (the leader), one or two black-backed sub-adult males, several adult females, and up to ten offspring, juveniles and infants. Family units are usually peaceful. Only the silverback mates with the females. Maturing silverbacks (age 11 – 13 years) that are no longer tolerated by the dominant silverback leave the group and may live on their own before luring females from other natal groups to begin their own family groups.
Females reach sexual maturity between seven and eight years of age and give birth for the first time a few years later. Males do not usually breed until at least 15 years of age. Gestation lasts about 258 days. Females usually give birth every 3.5 to 4.5 years to a single offspring. Young are weaned at two years of age, but some continue to suckle until the next birth. Infants cling upside down holding onto the long chest hairs of their mother until they are about four months old. At this time, they begin to ride on the back.
Mountain gorillas have a home range of between five and 30 square kilometers (1.9 to 11.6 square miles) in which they feed on stems, shoots, fruits, bark, bamboo, wild celery and ants, snails and slugs. Mountain gorillas are mostly ground-dwelling but will feed and build nests in trees that can support their weight.
The total mountain gorilla population is estimated to be 647 animals. Gorillas may live 35 years in the wild.
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