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Orangutans (Pongo spp.) Fact Sheet: Behavior & Ecology

Activity Cycle

  • Bimodal foraging pattern in the morning and afternoon, separated by a long rest period.
    • Rodman (1977) reported that daily peaks in the Kutai Reserve, Borneo occurred at 7:00-7:15 AM, and 4:15-4:30 PM.
    • Rijksen (1978) reported daily peaks in the Ketambe Nature Reserve, Sumatra at 2-3 hours after leaving the nocturnal nest, and at 3:00 PM.
  • Time spent on daily activities: 43% feeding, 41.5% resting, 13.5% traveling (often to find food) and 2% other (nest building, mating, vocalizing, socializing).
    • Actual times vary from place to place and season to season.
  • Orangutans sleep at night in arboreal nests that they construct, and usually move to a new spot every night.
  • Diurnal resting occurs in arboreal or ground nests, or by leaning on or draping over large branches. Body posture is upright or supine.

Social Groups

General

  • Orangutans were once thought to be solitary. More recent data analysis suggests that adult males are solitary, while females and young are more social.
  • Males spend 91% of their time alone; the rest of the time is spent consorting with a single female, or interacting agonistically with other males (usually for control of territory or females).
  • Females spend up to 7 years in continuous contact with each offspring; often she spends her time with two to three offspring of different ages; this is the most common social group.
  • Males do not spend any time caring for young.
  • Younger orangutans, especially adolescent females, have frequent social contacts with other immatures and adults
  • In areas of abundant food, orangutans sometimes congregate to forage. They arrive independently, or travel in foraging groups.

 Hierarchy

  • There is no strict social hierarchy, as seen in other apes.
  • Social contact appears to be loose and impermanent, and does not form a community structure.

Territorial Behavior

  • Males and females both have large home ranges, which may overlap
  • Territory of males (500 - 4000 ha) usually larger than territory of females (64 - 900 ha).
  • Females have stable home ranges
  • Adult male home ranges may be stable or transient.
  • Transient males occasionally challenge resident males for dominance and control of their territory.
  • Males are intolerant of other adult males living nearby, but are less aggressive towards sub adult males.
  • Once independent, young females set up their own home territory in or near their mother's. Young males travel much farther away.

Social Interactions

Aggression

  • Orangutans are generally non-aggressive toward humans and each other.
  • Many individuals reintroduced into the wild after having been in managed care are aggressive towards humans.
  • Male-male competition for mates and territory has been observed between adults.
  • Adult males are more tolerant of subadult males than of other adult males.

Play

  • Play has been observed only rarely in the wild, and usually between infant and mother.

Communication

Displays

  • Intimidation display: males break, shake or drop branches; dive, and lunge; press lips tightly; gape to expose teeth.

Visual Signs

  • Facial expressions are used to communicate submission, aggression, fear, and worry.
  • Gestures between mother and offspring relate to food and affection

 Vocalization

  • Click here for an audio sound of the Orangutan.
  • Up to 18 different vocalizations have been identified, including 4 types of distress calls made by young animals, 8 types of calls dealing with threat or fear, and 6 types of calls dealing with mating, territoriality, play, and contentment.
  • Males produce a very loud "long call" which attracts estrous females, and aids in maintaining territorial spacing of males. A shorter version, the "short call" is often used in reply to other calls.
  • Listen to  the "long call," courtesy of the BOS-USA (Balikpapan Orangutan Society), recorded by Soundelux Showorks.
  • A "kiss-squeak" expresses excitement or fear and is made with a sharp influx of air through pursed lips.

Olfaction/Scent Marking

  • Information lacking in the literature.

Locomotion

  • Primarily arboreal, but occasionally travel on the ground
  • Brachiation occurs over short distances; arms swing over, rather than under
  • Both hands and feet are used in arboreal locomotion
  • Bipedal locomotion is rare
  • Quadrupedal locomotion on the ground is somewhat common, but usually short in duration
  • Jumping and leaping are uncommon

Interspecies Interactions

  • When coming in visual contact with a snake or large monitor lizard, orangutans shake tree branches, make kissing vocalizations, throw twigs, or move away quickly.
  • Reaction to humans in the wild is usually avoidant. If a human watches or follows the orangutan persistently, the orangutan often waves, breaks, and drops branches.
  • Reaction to other primates feeding nearby is most often passive

Other Behaviors

  • Very dexterous, use both hands and feet while gathering food.
  • Tool use is uncommon and not well developed in the wild; examples include using leaves as cover when it rains or to wipe their face, and using sticks to clean their teeth and ears.
  • Tool use is more common in managed care, and much of it is learned by imitating their human caretakers.
  • Recent behavioral studies suggest that orangutans exhibit aspects of culture (van Shaik, 2003)
    • Many behavioral traits are specific to some populations and absent in others.
    • Behaviors are learned from one another, and passed on to subsequent generations
    • Behaviors not habitat dependent
    • Social groups have a larger behavioral repertoire than less social populations.

 

Sumatran Orangutan

an orangutan and baby

Indah and her young

Image credit: © San Diego Zoo Global. All rights reserved.

Page Citations

Galdikas, (1995)
Kaplan and Rogers, (1994)
Rijksen, (1978)
Rodman, (1977)
Tuttle, (1986)
Tuttle and Cortright, (1988 )

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