Infant

The mother will carry her young until they are about 3-6 months old and begin to walk. Very few infants will survive at birth, 38-40% of infants will die within their first 3 years of life. This is largely due to trauma at birth or young ages. The addition of a new silverback is also a threat. When a new dominant male enters the group, he will kill off all the nursing infants.

Juveniles

Gorillas enter their juvenile stage around 3 to 4 years old and will stay in this stage until they are about 6-8 years old. Juveniles are independent but not yet fully mature. The males and females look almost identical at this stage and mature at the same rate.

Young Adult

At this stage, the gorilla becomes an adult. Females reach adulthood before the males. As young adults, the females will stop growing taller but will continue to gain weight until they weigh about 250 to 300 pounds. Young adult males will begin to get black hairs on their backs and are referred to as "blackbacks".

Mature Adult

When a male reaches adulthood, a silver patch of hair will begin to develop on its back and are referred to as "silverback". This characteristic distinguishes the males from the females. An adult male stops gaining weight at about 400-500 pounds.