Orangutan

The orangutan lives a solitary life in the treetops of the rainforest. With the exception of adult males, orangutans rarely descend to the ground. The orangutan is a diurnal animal that is, active during daylight hours. At night, females and youngsters sleep in a nest of braches placed in the fork of a tree. Because males are heavier, they generally prefer to sleep on the ground. All orangutans sleep on their sides with their arms cushioning their heads. At daybreak, orangutans leave their nests and search for food.

Orangutans are the least vocal of the great apes, but they do have a system of auditory communication. Their most dramatic vocalization is the long call, given only by adult males. The call has been likened to the sound produced by large volumes of water roaring through steel pipes. The precise function of the long call is not known, but it probably serves to space out adult males in territories. It likely also serves other functions, including a display to attract sexually receptive females, and a signal to inform the community of the location of the dominant male. Males tend to call in bad weather, when another male is visible or calling, when close to a sexually receptive female, or as an element of copulatory behavior. Calls are audible up to 1.2 miles from the source.

A dominant male orangutan may have large breeding territory and mate with several females. Mating occurs year-round and females give birth to a single offspring every 3-6 years. A baby orangutan grows very slowly. It may become somewhat independent at 3 years of age, but it will stay with its mother until she gives birth again.

Fruit, nuts, leaves, bark, insects, and eggs form the diet of an orangutan. When the food supply in a particular area is plentiful, an orangutan may remain in one place for a period of time to feed. Although several orangutans may feed from the same tree, there is little social interaction or competition among them.