This is Otto, an adult flanged male orangutan, avoiding fires and traveling through a smoke-filled forest in the Tuanan Orangutan Research Station in Indonesian Borneo. Disclaimer: AAAS and ...

There are two different types of adult male orang-utan: flanged and unflanged. Flanged males have prominent cheek pads called flanges and a throat sac used to make loud verbalizations called 'long ...

“Orangutans at the site rarely eat the plant ... intentional as he selectively treated his facial wound on his right flange, ...