Animal Interactions

Orangutans are mainly a solitary animal that live high up in trees in the forests of Sumatra and Borneo.  Both species of Orangutans hardly encounter each other so it is not surprising that they rarely encounter other species of animals.  However, Orangutans have been seen threatening and even attacking Leopards and Lions (2) and must be aware of tigers roaming the forest floor. 

Interactions of Orangutans With Other Orangutans

Male Orangutans are the most solitary.  They are intolerant of each other in adulthood and will threaten one another using long calls, starring, shaking of tree branches, and inflating their laryngeal throat pouches.  Sometimes these encounters can escalade to hand to hand combat and even to the death.  Sexual contact with females is the only interaction that males have and it will only last for a few weeks when females are receptive to mating.  After contact, males will abandon females a few days after a female becomes pregnant. 

Females are usually accompanied by only one or two young when they travel.  Occasionally groups of females may be seen together with their young, but this does not persist for more than a day normally (3).  Females are less solitary than males and even semi-social.  It has been observed that females tend to travel with other females of whom they associated with as an adolescent (3).  Adult females have stable home ranges that may overlap, but each female recognizes clear boundaries to other home ranges (3).  A female's home range is usually 5 to 6 km2.

Adolescent females are the most sociable of all the Orangutans.  The females can often be seen grooming each other or the males that they may be consorting with.  Interestingly though, once an adolescent female gives birth to her first offspring, she becomes intolerant of other females that she previously had a friendly relationship with (2).  Adolescent females have been observed to establish home ranges that are close in proximity to their mother's range.

Male Orangutans have home ranges that are usually larger than their female counterparts.  Adult males will occupy home ranges that intercept two or more ovulating females or they will travel long distances to seek opportunistic females.  Males can be identified based on two criteria: Wanderer Males and Resident Males.  A Resident Male Orangutan will have a specified home range that is similar in size to an adult female's home range (3).  Wanderer Male Orangutans will travel over a larger area covering more ground looking for females or a steady food source.  Male Orangutans will typically disperse and settle on a home range father from their mothers than what a female would.  However, male settlement depends on the nearby female's ability to conceive and also on food sources.

In addition to adolescent females being social, juvenile Orangutans will establish friendships with their same sex & age mates.  Also, adult males will normally tolerate sub-adult males, but could easily displace them (2).  In addition, sub-adult males almost always tolerate one another in most instances.