Orangutan means "man of the forest" in the Malay language. In the lowland forests in which they reside, orangutans live solitary existences. They feast on wild fruits like lychees, mangosteens, and figs, and slurp water from holes in trees.
They make nests in trees of vegetation to sleep at night and rest during the day. Adult male orangutans can weigh up to 200 pounds. Flanged males have prominent cheek pads called flanges and a throat sac used to make loud verbalizations called long calls.
An unflanged male looks like an adult female. In a biological phenomenon unique among primates, an unflanged male can change to a flanged male for reasons that are not yet fully understood.
Why are they endangered?
Orangutans are an easy target for hunters because they're large and slow targets. They are killed for food or in retaliation when they move into agricultural areas and destroy crops. This usually occurs when orangutans can't find the food they need in the forest.