Orangutans are large apes with very long arms (much longer than their legs), which they use to swing from trees, and are covered in long, orange-red hair. Both sexes have large sacs in their throat that they use to vocalize loudly through the forest. Males are twice as big as females and have round cheek flaps that get larger as they age. Females of both species weigh 65 to 110 pounds, and males are 110 to 200 pounds; both sexes average 5 feet in length.
In the wild, orangutans live in the forested areas of two islands in Indonesia: Borneo and Sumatra. These are the only places on Earth, except for zoos, where these giant apes live. They live nearly their entire lives up in the trees, but are found at nearly every elevation.
Orangutans usually give birth to only one offspring at a time, but sometimes have two. The gestation period is similar to ours, ranging from 7 to 9 months. The babies weigh about 4 pounds at birth, and are not weaned until they are nearly 4 years old. Females reach sexual maturity at about 7 years of age; males at about 10.
Fruit is the main staple of the orangutans' diet in the wild, one of the reasons they spend so much time up in the trees. They will travel for very long distances in search of fruit. Some Sumatran orangutans have been seen eating meat in the wild. In zoos, orangutans are fed biscuits, chow, meat, seeds and nuts in addition to their favorite fruit.
Orangutans are not very social animals. They usually live alone, but sometimes in small groups consisting of two females and their young. Males and females do not interact with each other at all, except when they are ready to mate. Orangutans are active during the day, and each night build a platform nest out of branches and leaves to sleep in.