Gorillas - Ecology & Habitat

Mostly vegetarian

Gorillas are mostly found in lowland tropical rainforests, although some subspecies are found in montane rainforest (between 1,500 and 3,500 meters) and in bamboo forest (between 2,500 to 3,000 meters).

Social Structure
Gorillas have a well-developed social structure, living and travelling in family groups which vary from 2 to 35 individuals, but more frequently number 5 to 10 individuals. They have a home range of between 5 to 30km².

Gorillas form stable groups with the dominant male keeping his position for years. If a male leaves a group, he wanders alone for a number of years, then sometimes establishes a range adjacent to or overlapping that of the former group.

Adult males that stay in a group are probably the offspring of the dominant male and eventually will take over leadership of the group. Nearly all female gorillas leave their natal group at maturity to join other groups or single males.

Life Cycle
The mortality rate for gorillas less than one year old is high, while for adults the rate is only 5%. In the wild, lifespan may reach 50 years; a captive gorilla in the US was reported to have lived for 54 years.

Breeding
Females become sexually mature at 7-8 years old but do not start to breed until several years later. Males mature later than females, with few breeding before the age of 15 years.

High infant mortality, a long gestation (251-295 days) and inter-breeding period, a tendency to single births, and a prolonged period of maternal care mean that on average only one infant is reared in a 6 to 8 year period. Females generally give birth to only 2-3 surviving young during their reproductive life.

Diet
Gorillas are mainly herbivorous (vegetarian), spending almost half of the day feeding on stems, bamboo shoots, and a variety of fruits, supplemented with bark and invertebrates. In Gabon, gorillas are reported to frequently feed on termite nests.