Animal Diversity Web

Ge­o­graphic Range

Bornean orang­utans (Pongo pyg­maeus) are cur­rently found on the South­east Asian is­land of Bor­neo and gen­er­ally in­hab­its swampy and hilly trop­i­cal rain­forests. Bornean orang­utans have a patchy dis­tri­b­u­tion through­out the is­land and is com­pletely ab­sent from the south­east re­gion. Fos­sil ev­i­dence sug­gests that Bornean orang­utans were once wide­spread through­out South­east Asia and evenly dis­trib­uted across the en­tire is­land of Bor­neo. Due to il­le­gal log­ging and the de­struc­tion and con­ver­sion of trop­i­cal for­est to agri­cul­tural land this once ex­pan­sive range has de­creased dra­mat­i­cally. ("Great Apes and Other Pri­mates", 2011; An­cre­naz, et al., 2008; Lang, 2010; Schulz, et al., 2011)

• Biogeographic Regions
• oriental
  • native

• Other Geographic Terms
• island endemic

Habi­tat

Bornean orang­utans are ar­bo­real and rarely de­scend to the ground. They gen­er­ally live in the old growth forests rang­ing from the low­land swampy areas to the dipte­ro­carp forests. The peat swamps and flood-prone dipte­ro­carp forests pro­duce more fruit than the dry diper­to­carp forests and have a higher den­sity of Bornean orang­utans be­cause they mi­grate de­pend­ing on fruit avail­abil­ity. Bornean orang­utans in­habit the pri­mary trop­i­cal rain­for­est and sec­ondary for­est at lower el­e­va­tions and are rarely seen above el­e­va­tions of 1000 me­ters. (An­cre­naz, et al., 2008; Groves, 1971; Lang, 2010; Pa­mungkas and Mar­shall, 2005)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• rainforest

• Wetlands
• swamp

• Range elevation

  0 to 1000 m

  0.00 to 3280.84 ft

• Average elevation

  <500 m

  ft

Phys­i­cal De­scrip­tion

Bornean orang­utans have or­ange-red hair and long arms, which are ad­van­ta­geous for trav­el­ing through the canopy. Bornean orang­utans grasp with both their feet and hands, which suites their ar­bo­real life. Both sexes have throat pouches for call­ing but the male’s throat pouches are larger than the fe­males. Bornean orang­utans are sex­u­ally di­mor­phic, with males hav­ing an av­er­age height and weight of 970 mm and 87 kg re­spec­tively, and fe­males av­er­ag­ing 780 mm and 37 kg, re­spec­tively. Males also de­velop large cheek pads known as flanges and de­velop a sagit­tal crest where large tem­po­ral mus­cles at­tach. ("Great Apes and Other Pri­mates", 2011; An­cre­naz, et al., 2008; Groves, 1971; Lang, 2010)

Bornean orang­utans ex­hibit bi­ma­tur­ism, or two dif­fer­ent forms of ma­ture males. These two types of males are de­noted as being ei­ther flanged and un­flanged. Flanged males are twice the size of fe­males, have a large fa­cial disk with flanges, and a large throat patch. Un­flanged males look much more like the fe­males as they are the same size and do not dis­play the same call­ing be­hav­ior as flanged males. Both types of adult male orang­utans re­pro­duce in the pop­u­la­tion. Un­flanged males may be­come flanged at any time, as it is a re­flec­tion of so­cial hi­er­ar­chy as well as age. Males be­tween 8 and 15 years of age are gen­er­ally un­flanged and be­come flanged be­tween 15 and 20. (An­cre­naz, et al., 2008; Lang, 2010)

Bornean orang­utans are dis­tin­guish­able from their Suma­tran cousins in their mor­phol­ogy. After di­verg­ing 1.5 mil­lion years ago, Bornean orang­utans have be­come heav­ier and thicker, have darker red coats, long course hair, and the males have larger flanges cov­ered in bristly hair and larger throat pouches. (An­cre­naz, et al., 2008; Lang, 2010)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger
• ornamentation

• Average mass

  87 kg

  191.63 lb

• Average mass

  64475 g

  2272.25 oz

  AnAge

• Average length

  970 mm

  38.19 in

Re­pro­duc­tion

Dom­i­nant flanged males often have an es­tab­lished ter­ri­tory that will en­com­pass mul­ti­ple fe­males' ter­ri­to­ries. The mul­ti­ple fe­males within the male’s ter­ri­tory will cop­u­late with him and pro­duce his off­spring. Younger un­flanged males often can­not sus­tain a home range of their own and are forced to wan­der through­out the forests. When these small, wan­der­ing males come into con­tact with a fe­male, the small un­flanged male will force cop­u­la­tion. This is dif­fer­ent from the flanged males which will long-call; a call to help re­cep­tive fe­males lo­cate him. Fe­males pre­fer to mate with flanged males, which may be a way to en­sure pro­tec­tion from un­flanged males. (An­cre­naz, et al., 2008; Groves, 1971; Lang, 2010)

• Mating System
• polygynous

Bornean orang­utans do not have a breed­ing sea­son, but fe­males show higher ovar­ian func­tion dur­ing pe­ri­ods of food abun­dance. Ovu­la­tion in Bornean orang­utans oc­curs on the 15th day of a 30-day cycle. Cop­u­la­tion gen­er­ally oc­curs with both par­ties hang­ing with their arms and fac­ing each other. Bornean orang­utan's ges­ta­tion pe­riod lasts about nine months after which they give birth to a sin­gle in­fant, al­though twins have been recorded. Re­search shows that fe­male orang­utans only breed every 6 to 8 years, and the young are nursed until age 6 and re­main at the mother's side until the next birth. The off­spring has con­tact with its mother after birth, but once fe­male off­spring start to dis­play sex­ual be­hav­iors, they begin trav­el­ing sep­a­rately. Once the fe­male off­spring is sep­a­rated from its mother com­pletely, it will move off and es­tab­lish a ter­ri­tory nearby its mother’s ter­ri­tory. Ado­les­cence in Bornean orang­utans starts at 5 years of age and lasts until around 8 years of age. Male off­spring re­main so­cially im­ma­ture de­spite being sex­u­ally ma­ture. The young males avoid con­tact with ma­ture males and start to wan­der the forests until they be­come a flanged male and es­tab­lish their own res­i­dent ter­ri­tory. Fe­male Bornean orang­utans will reach menopause around the age of 48 years. (An­cre­naz, et al., 2008; Groves, 1971; Lang, 2010)

• Key Reproductive Features
• iteroparous
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous

• Breeding interval

  Female orangutans breed every 8 years.

• Breeding season

  Bornean orangutans breed year-round.

• Range number of offspring

  1 to 2

• Average number of offspring

  1

• Average number of offspring

  1

  AnAge

• Range gestation period

  233 to 263 days

• Average gestation period

  245 days

• Range weaning age

  36 to 84 months

• Average weaning age

  42 months

• Range time to independence

  5 to 8 years

• Average time to independence

  7 years

• Range age at sexual or reproductive maturity (female)

  5.8 to 11.1 years

• Range age at sexual or reproductive maturity (male)

  8 to 15 years

Fe­male Bornean orang­utans in­vest a lot of time in their off­spring, tak­ing care of them until they reach ado­les­cence at around 6 years of age. Since Bornean orang­utans are semi-soli­tary in na­ture, the males have very lit­tle con­tact and no in­vest­ment in their young. From birth, the off­spring will be in con­stant con­tact with the mother for 4 months and will be car­ried every­where the mother goes. The off­spring re­mains com­pletely de­pen­dent upon the mother for the first 2 years of life. At about 5 years of age, the off­spring will begin to make short trips on its own, usu­ally stay­ing within sight of the mother. The orang­utan young may start to build its own nests as play, and will even­tu­ally start sleep­ing in the nests it builds. The off­spring are usu­ally weaned by 4 years of age and will begin ado­les­cence soon after. The off­spring will gen­er­ally stay around the mother until the next off­spring are born. After this, the young fe­males es­tab­lish their own ter­ri­tory and the young males travel the for­est until they can es­tab­lish their own home ter­ri­tory. ("Great Apes and Other Pri­mates", 2011; An­cre­naz, et al., 2008; Lang, 2010)

• Parental Investment
• precocial
• female parental care
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female
• extended period of juvenile learning

Lifes­pan/Longevity

Bornean orang­utans are long lived like many of the other great ape species. They often live more than 50 years in the wild and have been doc­u­mented to live up to 59 years in cap­tiv­ity. ("AnAge entry for Pongo pyg­maeus", 2009; Lang, 2010)

• Range lifespan
  Status: wild

  50 (high) years

• Range lifespan
  Status: captivity

  59 (high) years

• Average lifespan
  Status: captivity

  59.0 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Sex: female
  Status: captivity

  57.3 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Status: wild

  59.0 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Sex: male
  Status: captivity

  58.8 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Status: wild

  35.0 years

  Max Planck Institute for Demographic Research

• Average lifespan
  Status: captivity

  50.0 years

  Max Planck Institute for Demographic Research

Be­hav­ior

Bornean orang­utans are di­ur­nal and rarely come down from the trees. Small groups of fe­males may travel with their in­fants in search of food, but adult males are usu­ally soli­tary. While all Bornean orang­utans are gen­er­ally soli­tary they may have oc­ca­sional so­cial con­nec­tions. Groups of 6 or more Bornean orang­utans are rare but can be found dur­ing times of mast fruit­ing; when a group of trees sud­denly fruit at the same time. Daily and sea­sonal move­ments change fre­quently and are in­flu­enced by the avail­abil­ity of fruit. Bornean orang­utans use mul­ti­ple meth­ods of lo­co­mo­tion. Brachi­a­tion is only seen in young orang­utans whereas older orang­utans walk quadrupedally, or oc­ca­sion­ally bipedally. When walk­ing quadrupedally, they walk on their fists rather than their knuck­les, un­like other great apes. Bornean orang­utans sleep in nest plat­forms made of veg­e­ta­tion 40 to 60 feet off the ground. Food is plucked with the fin­gers and the palm due to their in­abil­ity to use their thumbs. Bornean orang­utans can­not swim which make rivers and other water sources im­pass­able bound­aries, lim­it­ing their range. ("Great Apes and Other Pri­mates", 2011; An­cre­naz, et al., 2008; Groves, 1971; Lang, 2010; Pa­mungkas and Mar­shall, 2005; Schulz, et al., 2011)

• Key Behaviors
• arboreal
• diurnal
• motile
• solitary
• territorial
• dominance hierarchies

• Range territory size

  2 to 6 km^2

Home Range

Adult male Bornean orang­utans can have home ranges from 2 to 6 sq km and will often in­cor­po­rate mul­ti­ple fe­male home ranges. When a young fe­male is es­tab­lish­ing her home range, she will often choose a range nearby or bor­der­ing her mother's range. (An­cre­naz, et al., 2008; Lang, 2010)

Com­mu­ni­ca­tion and Per­cep­tion

Bornean orang­utans are not as so­cial as other species of great apes and do not have as many so­cial vo­cal­iza­tions. The most promi­nent form of com­mu­ni­ca­tion for Bornean orang­utans is the long-call, a one to two minute call per­formed only by flanged males. The long-call can be heard from sev­eral kilo­me­ters away in the right con­di­tions. The main pur­poses of long-calls are to in­form other males of the caller's pres­ence (when un­flanged males hear long-calls they flee the area) and to call out to sex­u­ally re­spon­sive fe­males. Long-calls are spon­ta­neous and do not fol­low any spe­cific pat­tern. Some ev­i­dence sug­gests that the long-call can even sup­press the de­vel­op­ment of un­flanged males. When the un­flanged males hear a long-call, stress hor­mones are pro­duced which in­hibit the de­vel­op­ment of the un­flanged males. The other type of call­ing pro­duced by Bornean orang­utans is a fast-call, which is most often made after male-to-male con­flict. In ad­di­tion to the long and fast calls, Bornean orang­utans smack their lips to pro­duce sounds when in small so­cial groups. When scared, Bornean orang­utans will fun­nel their lips and scream. (An­cre­naz, et al., 2008; Groves, 1971; Lang, 2010)

• Communication Channels
• visual
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Bornean orang­utans are fru­giv­o­rous, and spend two to three hours in the morn­ing feed­ing avidly. Their diet con­sists of for­est fruits, leaves and shoots, in­sects, sap, vines, spi­der webs, bird eggs, fungi, flow­ers, barks, and oc­ca­sion­ally nu­tri­ent rich soils. Bornean orang­utans have been doc­u­mented eat­ing more than 500 plant species as part of their diet. Fruits make up more than 60% of their total di­etary in­take and they will mi­grate de­pend­ing on fruit avail­abil­ity. ("Great Apes and Other Pri­mates", 2011; An­cre­naz, et al., 2008; Groves, 1971; Lang, 2010; Pa­mungkas and Mar­shall, 2005)

• Primary Diet
• herbivore
  • frugivore

• Animal Foods
• eggs
• insects
• terrestrial worms

• Plant Foods
• leaves
• roots and tubers
• wood, bark, or stems
• fruit
• nectar
• flowers
• sap or other plant fluids

• Other Foods
• fungus
• detritus

Pre­da­tion

The only preda­tor of Bornean orang­utans are hu­mans. Even hunt­ing for tra­di­tional pur­poses at a 2% hunt­ing rate, is not sus­tain­able for the cur­rent pop­u­la­tion of orang­utans. Bornean orang­utans are not sub­ject to pre­da­tion from large fe­lines like their Suma­tran cousins, al­though clouded leop­ards are able take down a young Bornean orang­utan. (An­cre­naz, et al., 2008; Groves, 1971; Lang, 2010)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • humans (Homo sapiens)
  • clouded leopards (Neofelis nebulosa)

Ecosys­tem Roles

Since fruits make up more than 60% the Bornean orang­utan diet, they play a vital role in seed dis­per­sal, es­pe­cially for the larger seeds which can­not be dis­persed by smaller an­i­mals. Bornean orang­utans play such a cru­cial role in seed dis­per­sal that they have been given the title "gar­den­ers of the for­est". (An­cre­naz, et al., 2008)

• Ecosystem Impact
• disperses seeds

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

The Bornean orang­utans keep the forests healthy by dis­pers­ing seeds, and eco tourism for the Bornean orang­utans draws in im­por­tant rev­enue for orang­utan con­ser­va­tion agen­cies. (An­cre­naz, et al., 2008; Lang, 2010)

• Positive Impacts
• ecotourism

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Bornean orang­utans have the high­est den­sity in areas where there is valu­able tim­ber such as the peat swamps. In the sec­ond half of the 19th cen­tury, the Bornean orang­utans lost 80% of its vi­able habi­tat. These forests are also being il­le­gally logged, as peo­ple are log­ging be­fore the 30 to 40 year rest pe­riod is over. Palm oil tree saplings are eaten after log­ging oc­curs and the orang­utans are search­ing for an­other food source. The Bornean orang­utans also com­pete with hu­mans for durian fruit and will on rare oc­ca­sions at­tack hu­mans. (An­cre­naz, et al., 2008; Groves, 1971)

• Negative Impacts
• injures humans
• crop pest

Con­ser­va­tion Sta­tus

Bornean orang­utans are an en­dan­gered species. Since all Bornean orang­utans are to­tally de­pe­nent on the trees for sur­vival, for­est degra­da­tion is dev­as­tat­ing to the pop­u­la­tion. Even though the fruit­ing trees are not the cov­eted tim­ber, the re­moval of trees from the area still neg­a­tively in­flu­ences the over­all qual­ity of the for­est. Be­cause Bornean orang­utans have to travel to find the fruit­ing trees, a patchy for­est hin­ders travel and dis­per­sal and in­creases com­pe­ti­tion for these lim­ited re­sources. ("Pongo pyg­maeus", 2012; An­cre­naz, et al., 2008; Lang, 2010)

If the Bornean orang­utan is going to re­cover, habi­tat de­struc­tion must be stopped. These orang­utans also need to be pro­tected, and any har­vest­ing for meat or for il­le­gal pet trade must be stopped. Both of these cur­rent prac­tices are not sus­tain­able and may lead to the ex­tinc­tion of the Bornean orang­utans. (Groves, 1971; Lang, 2010)

• IUCN Red List

  Endangered
  More information

• IUCN Red List

  Endangered
  More information

• US Federal List

  Endangered

• CITES

  Appendix I

Con­trib­u­tors

Ben­jamin Stro­bel (au­thor), Uni­ver­sity of Wis­con­sin-Stevens Point, Christo­pher Yahnke (ed­i­tor), Uni­ver­sity of Wis­con­sin-Stevens Point, Ale­cia Stew­art-Mal­one (ed­i­tor), Uni­ver­sity of Wis­con­sin-Stevens Point, Laura Podzikowski (ed­i­tor), Spe­cial Pro­jects.

Ref­er­ences

2009. "AnAge entry for Pongo pyg­maeus" (On-line). AnAge. Ac­cessed Au­gust 20, 2011 at http://​genomics.​senescence.​info/​species/​entry.​php?​species=Pongo_​pygmaeus.

2011. "Great Apes and Other Pri­mates" (On-line). Smith­son­ian Na­tional Zo­o­log­i­cal Park. Ac­cessed Au­gust 15, 2011 at http://​nationalzoo.​si.​edu/​Animals/​Primates/​Facts/​FactSheets/​Orangutans/​default.​cfm.

2012. "Pongo pyg­maeus" (On-line). The IUCN Red List of Threat­ened Speces. Ac­cessed Oc­to­ber 26, 2012 at http://​www.​iucnredlist.​org/​details/​17975/​0.

An­cre­naz, M., A. Mar­shall, B. Goossens, C. Van Schaik, J. Sug­ard­jito, M. Gumal, S. Wich. 2008. "The IUCN Red List of Threat­ened Species" (On-line). Pongo pyg­maeus. Ac­cessed Au­gust 15, 2011 at http://​www.​iucnredlist.​org/​apps/​redlist/​details/​17975/​0.

Call, J. 2004. In­fer­ences about the lo­ca­tion of food in the Great Apes (Pan panis­cus, Pan tro­godytes, Go­rilla go­rilla, and Pongo pyg­maeus). Jour­nal of Com­par­a­tive Psy­chol­ogy, 118: 232-241. Ac­cessed Au­gust 15, 2011 at http://​www.​cs.​arizona.​edu/​projects/​wonac/​papers/​Call2004JCP.​pdf.

Groves, C. 1971. Pongo pyg­maeus. Amer­i­can So­ci­ety of Mam­mal­o­gists, 4: 1-6. Ac­cessed Au­gust 15, 2011 at http://​www.​science.​smith.​edu/​msi/​pdf/​i0076-3519-004-01-0001.​pdf.

Lang, K. 2010. "Na­tional Pri­mate Re­search Cen­ter, Uni­ver­sity of Wis­con­sin - Mad­sion" (On-line). Pri­mate Info Net. Ac­cessed Au­gust 15, 2011 at http://​pin.​primate.​wisc.​edu/​factsheets/​entry/​orangutan/​taxon.

Pa­mungkas, B., A. Mar­shall. 2005. A sur­vey of the orang­utan (Pongo pyg­maeus wur­bii) pop­u­la­tion in and around Gu­nung Palung Na­tional Park, West Kali­man­tan, In­done­sia based on nest counts. Bi­o­log­i­cal Con­ser­va­tion, 121: 495-507. Ac­cessed Au­gust 15, 2011 at http://​anthropology.​ucdavis.​edu/​people/​andrew-j.​-marshall-1/​publications-1/​Johnson%20et%20al.​%202005-GP%20orangutan%20census.​pdf.

Schulz, K., L. Shapiro, M. Frаnkis. 2011. "En­cy­clo­pe­dia of Life" (On-line). Pongo pyg­maeus. Ac­cessed Au­gust 15, 2011 at http://​www.​eol.​org/​pages/​326450.

Zhang, Y., O. Ryder, Y. Zhang. 2001. Ge­netic Di­ver­gence of Orang­utan Sub­species (Pongo pyg­maeus). Jour­nal of Mol­e­c­u­lar Evo­lu­tion, 52: 516-526. Ac­cessed Au­gust 15, 2011 at http://​159.​226.​149.​45/​zhang/​achievements/​publications/​2001/​Zhang%20YW-JME2001.​pdf.