The mountain gorillas often live in an age-graded groups, on average, 9.2 individuals of multiple gorilla age groups. Usually, there is one adult male (though there may be more than one), multiple adult females, and their offspring. The minimum group size of the mountain gorillas are two individuals (usually a silverback and a female), except for males ranging alone. The maximum group size for mountain gorillas can exceed 20 individuals. Several people often confuse the gorilla age groups in gorillas, we shall elaborate them here. Don’t get confused:
Infant Gorilla (0-3.5 years):
Infants are dependent on the mother for survival. Infants are not yet weaned, although the frequency of nursing declines as infants get older. Infants are in a constant physical contact with their mothers for approximately six months of their lives. Infants begin to eat vegetation when they are about 9 months old and incorporate more plants in their diets they age. Infants are carried by their mothers regularly until they are about 2years old. Initially they are carried on their mother’s back when they are about 9-12 months old. Infants share their mothers’ night nests.
Juvenile Gorilla (3.5-6years):
Juveniles are immatures that are still heavily reliant on their mothers, but can survive if the mother dies or disperses another gorilla age groups. This is because they have stopped nursing and they are capable of foraging independently. They typically also construct their own night nest nearly every night, but may sometimes still share their mother’s nest.
Several infants playing together
Sub adult Gorilla (6-8years):
Immature gorillas are fully independent on their mothers, but they are not yet fully grown adults. Sub adults play much less than juveniles and infants.
A sub adult female in Rushegura Group, Bwindi Impenetrable National Park
Adult female Gorilla (8 years):
Females that are reproductively mature ’even if they have not yet had an offspring. They weigh approximately 100kgs.
An adult female mountain Gorilla
Blackback (8-12 years):
Males that are starting the process of becoming mature adults. Blackback males are initially the size of adult females, but continue to grow larger. They tend to have more square shoulders than adult females. As blackbacks mature, the hair on their backs starts to turn silver and their heads develops into the large sagittal crest.
A blackback gorilla
Silverback (>12 years):
Adult males. Mature silver backs have the characteristics silver back, large crest on their heads and are nearly double the size of adult females. All male gorillas that live into their teens become silver backs. The process of becoming a silver back takes a few years and males do not obtain their full adult size until they are 15 years old or later. They weigh approximately150kgs.