Ecology of the Gorilla

During the afternoon, the group typically moves again before finding a place to spend the night. Each gorilla makes its own nest every night except for the infants, who sleep with their mother until weaned at age of 3-4 years. Nests are usually grouped around the dominant male. However, nests may be spread over 100 meters or more, particularly in groups where several silverbacks are present. Night nests are only used once then abandoned. Typically, gorillas defecate in their nests, and the freshness of the dung is a cue to the age of the nest. Some times gorillas may sleep late on rainy days, or on mornings after a long journey.
Gorilla groups move on average les than one kilometre per day, and rarely more than two. Longer movements typically follow an aggressive interaction or other event that has stressed the group. When tracking, you can often predict a long day’s hike by the absence of feeding sites and the presence of diarrhetic dung a typical sign of stressed animals.

Social Organisation
Gorillas mostly live in family groups. An average group contains about 12 animals, with one or two older silverback males, younger black males, several females and their offspring. Gorillas, how ever, follow no set pattern for group composition or size. Groups of thirty animals (with 5 silverbacks) been recorded, and smaller families are common. Likewise, there are groups composed entirely of males. In Virungas, up to 40% of the groups are multi-male.

Gorillas stay together in groups because of strong bonds between the individuals. In family groups the strongest bonds are between the females and the silver back male. He is a fully adult male whose hair is grey, a clear sign of his age which of course indicates his many years of survival, experience and health .The group may contain secondary silver backs who are often related to the leader , possibly being son or half brother . sometimes one of the younger silverbacks will usurp the position of his elder who may not be content to remain in the group at a subordinate position .The lead silverback is the groups primary defender , and probably fathers most infants born in the group.
Males in multi-male groups have weak relationships. They maintain their ties by avoiding conflict. They may coexist in groups for years but will leave if they find an opportunity to reside with females elsewhere.

Social relations among females are largely determined by kinship, and bonds between females can be very strong .A females status is a result of her age, kin, including the presence or absence of young, and her relationship to the dominant male. Black back males come next to the hierarchy although some might out rank particular adults females. Nearly all females and most black back males leave the group of their birth shortly after reaching maturity. Females might to other groups or with other males until they are strong enough to attract females of their own. These processes help to prevent inbreeding in this tiny population, and mating between closely related adults has been seen. Gorilla social behaviour is notably calm and stable compared to other primates. Conflict within gorilla groups is relatively rare, unlike the frequent dominance struggles which are common among chimpanzees and many monkeys. The most common conflicts within a gorilla group are minor confrontations over feeding areas or right of way. These are most noticeable in the fields as lunges and ‘pig-grunt’ vocalisation. A dominant silver back may fight with subordinate males if challenged, but usually keeps control through vocalisation and displays rather than violence. Transfer of power in a gorilla group can be violent when younger males or intruding silverbacks drive out the leader. However, often there is no violence and a dominant male grow old and even die of natural causes while still leading his group.

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Ecology of the Gorilla

Gorilla Safari guide, information on apes, chimpanzees and other primates of Uganda and Africa.