Orangutans are the only great apes that live mostly alone. Gorillas and chimpanzees live in large groups that eat and travel together. But a mother and her offspring are the orangutan family unit.
A young orang stays with its mother until she has another baby. By that time, the first offspring is between 6 and 10 years old. Because it takes care of each child for so long, a female may only raise two or three offspring in her lifetime.
Adult males tolerate females and sometimes stay with a female for 20 days or more during courtship and mating, but they are aggressive toward other males and avoid them except to fight.
Female orangutans are caring, affectionate parents. This mother will keep contact with her youngster for up to ten years.
Orangutans that have large, overlapping home ranges recognize their neighbors when they meet—perhaps in a fruit tree—but they don’t interact much. Adult females are friendly with females of all ages and accept the males, but tend to look for food only with their most recent offspring.
When a mature male is ready to mate, he bellows loudly and sometimes breaks branches and flings them to the ground. This attracts females that are ready to mate, but sends mothers with young fleeing to the treetops. Less mature males in the area usually retreat.
By far, the friendliest orangutans are the juveniles and adolescents, who play and sometimes travel together.