In this way, males can avoid each other. It also tells females where the males are when the females are ready to mate. Orangs have 11-13 other types of calls to convey their moods. The territory of a male usually includes that of up to four females. But males and females do not form pairs.
Adult males interact only with females who are in season.
This is probably because their food are scattered thinly throughout the rainforest, and they are such large creatures that need lots of food. So they forage independently. While males avoid each other and are aggressive when they meet, females may forage together in pairs for up to 3 days. Juveniles may also stay together in small mixed gender groups , or with an adult of either gender. The most unique is the male's loud groans wh ich can be heard up to 1km away.