Editing Orangutan (section)

== Ecology and behaviour ==

[[File:Video wild orangutan Borneo.webm|thumb|alt= Video of a wild orangutan in Malaysia|Wild orangutan in the Danum Valley ([[Sabah]], Malaysia, Borneo island)]]

Orangutans are mainly [[Arboreal locomotion|arboreal]] and inhabit [[tropical rainforest]], particularly lowland [[Dipterocarpaceae|dipterocarp]] and old [[secondary forest]].<ref name="MacDonald"/><ref name="international1" /> Populations are more concentrated near riverside habitats, such as [[Freshwater swamp forest|freshwater]] and [[peat swamp forest]], while drier forests away from the flooded areas have fewer apes. Population density also decreases at higher elevations.<ref name="RijksenMeijaard1999">{{cite book|author=Rijksen H. D.|last2= Meijaard, E.|year=1999|title=Our vanishing relative: the status of wild orang-utans at the close of the twentieth century|publisher=[[Springer Publishing|Springer]]|isbn=978-0792357551}}</ref>{{rp|92}} Orangutans occasionally enter grasslands, cultivated fields, gardens, young [[secondary forest]], and shallow lakes.<ref name="international1" />

Most of the day is spent feeding, resting, and travelling.<ref>{{cite book|author=Rodman, P. S.|year=1988|contribution=Diversity and consistency in ecology and behavior|editor=Schwartz, J. H.|title=Orang-utan biology|pages=31–51|publisher=Oxford University Press | isbn=978-0195043716}}</ref> They start the day feeding for two to three hours in the morning. They rest during midday, then travel in the late afternoon. When evening arrives, they prepare their nests for the night.<ref name="international1" /> Potential predators of orangutans include [[Sumatran tiger|tiger]]s, [[Sunda clouded leopard|clouded leopards]] and [[dhole|wild dogs]].<ref name="RijksenMeijaard1999"/>{{rp|91}} The most common orangutan parasites are [[nematode]]s of the genus ''[[Strongyloides]]'' and the [[ciliate]] ''[[Balantidium coli]]''. Among ''Strongyloides'', the species ''S. fuelleborni'' and ''S. stercoralis'' are reported in young individuals.<ref>{{cite book|author1=Foitová, Ivona |author2=Huffman, Michael A.|author3=Wisnu, Nurcahyo|author4=Olšanský, Milan|contribution=Parasites and their impacts on orangutan health|editor1-first=Serge A. |editor1-last=Wich |editor2-first=S. Suci Utami |editor2-last=Atmoko |editor3-first=Tatang Mitra |editor3-last=Setia |editor4-last=van Schaik|editor4-first=Carel P. |title=Orangutans: Geographic Variation in Behavioral Ecology and Conservation |year=2009 |url=https://archive.org/details/orangutansgeogra00wich |url-access=registration |publisher=Oxford University Press|page=[https://archive.org/details/orangutansgeogra00wich/page/n198 166]|isbn=978-0199213276}}</ref> Orangutans also use the plant species ''[[Dracaena (plant)|Dracaena cantleyi]]'' as an anti-inflammatory balm.<ref>{{cite journal |vauthors=Morrogh-Bernard HC, Foitová I, Yeen Z, Wilkin P, de Martin R, Rárová L, Doležal K, Nurcahyo W, Olšanský M |year=2017|title=Self-medication by orang-utans (''Pongo pygmaeus'') using bioactive properties of ''Dracaena cantleyi'' |journal=Scientific Reports |volume=7 |issue=16653 |page=16653|doi= 10.1038/s41598-017-16621-w|pmid=29192145|pmc=5709421|bibcode=2017NatSR...716653M|doi-access=free }}</ref> Captive animals may suffer an upper respiratory tract disease.<ref>{{cite journal|last1=Zimmermann|first1=N|last2=Pirovino|first2=M|last3=Zingg|first3=R|last4=Clauss|first4=M|last5=Kaup|first5=F. J.|last6=Heistermann|first6=M|last7=Hatt|first7=J. M.|last8=Steinmetz|first8=H. W.|year=2011|title=Upper respiratory tract disease in captive orangutans (Pongo sp.): prevalence in 20 European zoos and predisposing factors|journal=Journal of Medical Primatology|volume=40|issue=6|pages=365–375|doi=10.1111/j.1600-0684.2011.00490.x|pmid=21770970|s2cid=997385}}</ref>

=== Diet and feeding ===

[[File:Orangutan -Zoologischer Garten Berlin-8a.jpg|thumb|upright=.75|right|alt=Orangutan on a branch eating some leaves|Although orangutans may consume leaves, shoots, and bird eggs, fruit is the most important part of their diet.]]

Orangutans are primarily [[frugivore|fruit-eaters]], which can take up 57–80% of their foraging time. Even during times of scarcity, fruit is 16% of their feeding time. Fruits with soft pulp, [[aril]]s or seed-walls are consumed the most, particularly [[Common fig|fig]]s but also [[drupe]]s and berries.<ref name="RijksenMeijaard1999"/>{{rp|65}} Orangutans are thought to be the sole fruit disperser for some plant species including the [[vine]] species ''[[Strychnos ignatii]]'' which contains the toxic [[alkaloid]] [[strychnine]].<ref>{{cite journal | last = Rijksen | first = H. D.| title = A field study on Sumatran orang utans (''Pongo pygmaeus abelii'', Lesson 1827): Ecology, Behaviour and Conservation | journal = [[The Quarterly Review of Biology]] | volume = 53 | issue = 4 | pages = 493–94|date=December 1978 | doi = 10.1086/410942 | jstor=2826733}}</ref>

Orangutans also include leaves in their diet, which take up 25% of their average foraging time. Leaves are eaten more when fruit is less available, but even during times of fruit abundance, orangutans will eat leaves 11–20% of the time. They appear to depend on the leaf and stem material of ''[[Borassodendron borneensis]]'' during times of low fruit abundance. Other food items consumed by the apes include [[Bark (botany)|bark]], [[honey]], bird eggs, insects and small vertebrates including [[slow loris]]es.<ref name="international1">{{cite journal | last = Galdikas |first = Birute M. F. | title = Orangutan Diet, Range, and Activity at Tanjung Puting, Central Borneo | journal = International Journal of Primatology | volume = 9 | year = 1988 | doi = 10.1007/BF02740195 | pages = 1–35 | issue = 1|s2cid = 40513842 }}</ref><ref name="RijksenMeijaard1999"/>{{rp|65–66}}

In some areas, orangutans may practise [[geophagy]], which involves consuming soil and other earth substances. They will uproot soil from the ground as well as eat [[Termite#Shelter tubes|shelter tubes]] from tree trunks. Orangutans also visit the sides of cliffs or earth depressions for their [[mineral lick]]s. Orangutans may eat soils for their anti-toxic [[kaolin]] minerals, since their diet contains toxic [[tannin]]s and [[phenolic acid]]s.<ref name="RijksenMeijaard1999"/>{{rp|67}}

=== Social life ===

[[File:Leuser-orangs 09N8683.jpg|thumb|left|upright|alt=Two orangutans swinging on tree branches|Orangutans are the least social of the great apes.]]

The social structure of the orangutan can be best described as [[solitary but social]]; they live a more solitary lifestyle than the other great apes.<ref name="Boekhorst 1990"/> Bornean orangutans are generally more solitary than Sumatran orangutans.<ref name="MacDonald">{{Cite book|author1=van Schaik, C.|author2=MacKinnon, J.|contribution=Orangutans|year=2001|title=The Encyclopedia of Mammals|edition=2nd|editor=MacDonald, D.|publisher=Oxford University Press|pages=[https://archive.org/details/encyclopediaofma00mals_0/page/420 420–23]|isbn=978-0-87196-871-5|url=https://archive.org/details/encyclopediaofma00mals_0/page/420}}</ref> Most social bonds occur between adult females and their dependent and weaned offspring. Resident females live with their offspring in defined home ranges that overlap with those of other adult females, which may be their immediate relatives. One to several resident female home ranges are encompassed within the home range of a resident male, who is their main mating partner.<ref name="Boekhorst 1990">{{cite journal | doi=10.1016/S0003-3472(05)80782-1 | title=Residential status and seasonal movements of wild orang-utans in the Gunung Leuser Reserve (Sumatera, Indonesia) |year=1990 | last1=Teboekhorst | first1=I. | last2=Schürmann | first2=C. | last3=Sugardjito | first3=J. |journal=[[Animal Behaviour (journal)|Animal Behaviour]] | volume=39 | issue=6 | pages=1098–1109| s2cid=54322235 }}</ref><ref name="Singleton 2002"/> Interactions between adult females range from friendly to avoidance to antagonistic.<ref>{{cite book|author=Galdikas, B. M. F.|year=1984|contribution= Adult female sociality among wild orangutans at Tanjung Puting Reserve|editor=Small, M. F.|title=Female Primates: Studies by Women Primatologists|publisher=[[Wiley (publisher)|Alan R. Liss]]|pages=217–35|isbn=978-0845134030}}</ref> Flanged males are often hostile to both other flanged males and unflanged males, while unflanged males are more peaceful towards each other.<ref name=male>{{cite book |last1=Atmoko |first1=S. Suci Utami|author2=Singleton, Ian |author3=van Noordwijk, Maria A. |author4=van Schaik, Carel P.|author5=Setia, Tatang Mitra |editor1-first=Serge A. |editor1-last=Wich |editor2-first=S. Suci Utami |editor2-last=Atmoko |editor3-first=Tatang Mitra |editor3-last=Setia |editor4-last=van Schaik|editor4-first=Carel P. |title=Orangutans: Geographic Variation in Behavioral Ecology and Conservation |chapter=Male–male relationships in orangutans |year=2009 |publisher=Oxford University Press |isbn=978-0-19-921327-6 |pages=227–29}}</ref>

Orangutans [[biological dispersal|disperse]] and establish their home ranges by age 11. Females tend to live near their birth range, while males disperse farther but may still visit their birth range within their larger home range.<ref name="Singleton 2002">{{cite journal | last1 = Singleton | first1 = I. | last2 = van Schaik | first2 = C. P. | year = 2002 | title = The Social Organisation of a population of Sumatran orang-utans| journal = [[Folia Primatologica]]| volume = 73 | issue = 1| pages = 1–20 | doi = 10.1159/000060415 | pmid = 12065937| s2cid = 13557435 }}</ref><ref name="van Noordwijk">{{cite book|last1=van Noordwijk |first1=Maria A. |author2=Sauren, Simone E.B. |author3=Nuzuar |author4=Abulani, Ahbam|author5=Morrogh-Bernard, Helen C. |author6=Atmoko, S. Suci Utami| author7=van Schaik, Carel P. |contribution=Development of Independence|editor1-first=Serge A. |editor1-last=Wich |editor2-first=S. Suci Utami |editor2-last=Atmoko |editor3-first=Tatang Mitra |editor3-last=Setia |editor4-last=van Schaik|editor4-first=Carel P. |title=Orangutans: Geographic Variation in Behavioral Ecology and Conservation|year=2009|url=https://archive.org/details/orangutansgeogra00wich|url-access=registration|publisher=Oxford University Press|page=199|isbn=978-0199213276}}</ref> They enter a transient phase, which lasts until a male can challenge and displace a dominant, resident male from his home range.<ref name="Delgrado 2000">{{cite journal | last1 = Delgado | first1 = R. A. Jr. | last2 = van Schaik | first2 = C. P. | year = 2000 | title = The behavioral ecology and conservation of the orangutan (''Pongo pygmaeus''): a tale of two islands | journal = [[Evolutionary Anthropology: Issues, News, and Reviews]]| volume = 9 | issue = 1| pages = 201–18 | doi = 10.1002/1520-6505(2000)9:5<201::AID-EVAN2>3.0.CO;2-Y| s2cid = 84778685 }}</ref> Both resident and transient orangutans aggregate on large fruiting trees to feed. The fruits tend to be abundant, so competition is low and individuals may engage in social interactions.<ref name="van Schaik2004"/><ref>{{cite journal|author=van Schaik, C. P.|year=1999|title=The socioecology of fission-fusion sociality in orangutans|journal=[[Primates (journal)|Primates]]|volume=40|issue=1|pages=69–86|doi=10.1007/BF02557703|pmid=23179533|s2cid=13366732}}</ref><ref>{{cite journal|last1=Mitani|first1=J. C.|last2=Grether|first2=G. F.|last3=Rodman|first3=P. S.|last4=Priatna|first4=D.|year=1991|title=Associations among wild orang-utans: sociality, passive aggregations or chance|journal=Animal Behaviour|volume=42|issue=1|pages=33–46|doi=10.1016/S0003-3472(05)80603-7|s2cid=40824300}}</ref> Orangutans will also form travelling groups with members moving between different food sources.<ref name="Delgrado 2000" /> They are often consortships between an adult male and a female.<ref name="van Schaik2004">{{cite book|last1=van Schaik, C. P.|last2= Preuschoft, S.|last3= Watts, D. P.|year=2004|contribution= Great ape social systems|editor=Russon, A. E. |editor2=Begun, D. R. |title=The Evolution of Thought: Evolutionary Origins of Great Ape Intelligence|url=https://archive.org/details/evolutionthought00russ|url-access=registration|publisher=[[Cambridge University Press]]|pages=[https://archive.org/details/evolutionthought00russ/page/n200 193–94]|isbn=978-0521039925}}</ref> [[Social grooming]] is uncommon among orangutans.<ref name="Munn 1997"/>

===Communication===
{{listen
| filename     = Call-Cultures-in-Orang-Utans?-pone.0036180.s001.ogg
| title        = Nest smack
| description  = Nest smack, [[ogg]]/[[Vorbis]] format.
| format       = [[Vorbis]]
| filename2    = Call-Cultures-in-Orang-Utans?-pone.0036180.s002.ogg
| title2       = Raspberry
| description2 = Raspberry [[ogg]]/[[Vorbis]] format.
| format2      = [[Vorbis]]
| filename3    = Call-Cultures-in-Orang-Utans?-pone.0036180.s004.ogg
| title3       = Throatscrape
| description3 = Throatscrape [[ogg]]/[[Vorbis]] format.
| format3      = [[Vorbis]]
}}
Orangutans communicate with various vocals and sounds. Males will make long calls, both to attract females and to advertise themselves to other males.<ref name="Utami 2002" /> These calls have three components; they begin with grumbles, peak with pulses and end with bubbles. Both sexes will try to intimidate conspecifics with a series of low frequency noises known collectively as the "rolling call". When uncomfortable, an orangutan will produce a "kiss squeak", which involves sucking in air through pursed lips. Mothers produce throatscrapes to keep in contact with their offspring. Infants make soft hoots when distressed. When building a nest, orangutans will produce smacks or [[blowing a raspberry|blow raspberries]].<ref name=vocal>{{cite web|title=Orangutan call repertoires|publisher=[[Universität Zürich]] – Department of Anthropology|url=https://www.aim.uzh.ch/de/orangutannetwork/orangutancallrepertoires.html|access-date=23 April 2020|archive-date=3 October 2020|archive-url=https://web.archive.org/web/20201003083144/https://www.aim.uzh.ch/de/orangutannetwork/orangutancallrepertoires.html|url-status=live}}</ref> Orangutan calls display consonant- and vowel-like components and they maintain their meaning over great distances.<ref>{{cite journal|last1=Lameira|first1=A. R.|display-authors=etal|year=2021|title=Orangutan information broadcast via consonant-like and vowel-like calls breaches mathematical models of linguistic evolution|journal=Biology Letters|volume=17|issue=9|doi=10.1098/rsbl.2021.0302|pmid=34582737 |pmc=8478518 }}</ref> They also display [[Recursion#In_language|recursion]] via three layers of rhythmic sounds.<ref>{{cite journal|last1=De Gregorio|first1=C|last2=Gamba|first2=M|last3=Lameira|first3=A. R.|year=2025|title=Third-order self-embedded vocal motifs in wild orangutans, and the selective evolution of recursion|journal=Annals of the New York Academy of Sciences|doi=10.1111/nyas.15373}}</ref>

Mother orangutans and offspring also use several different gestures and expressions such as beckoning, stomping, lower lip pushing, object shaking and "presenting" a body part. These communicate goals such as "acquire object", "climb on me", "climb on you", "climb over", "move away", "play change: decrease intensity", "resume play" and "stop that".<ref>{{cite journal|last1=Knox|first1=A|last2=Markx|first2=J|last3=How|first3=E|last4=Azis|first4=A|last5=Hobaiter|first5=C|last6=an Veen|first6=F. J. F|last7=Morrogh-Bernard|first7=H|year=2019|title=Gesture use in communication between mothers and offspring in wild Orang-Utans (''Pongo pygmaeus wurmbii'') from the Sabangau Peat-Swamp Forest, Borneo|journal=International Journal of Primatology|volume=40|issue=3|pages=393–416|doi=10.1007/s10764-019-00095-w|s2cid=195329265|doi-access=free|hdl=10023/18054|hdl-access=free}}</ref>

=== Reproduction and development ===

{{multiple image
 | direction = horizontal
 | width = 200
 | align = right
 | image1 = Male Bornean Orangutan - Big Cheeks.jpg
 | image2 = Here's Looking At You, Kid (5656539778).jpg
 | caption1 = Flanged male orangutan
 | alt caption1= Male orangutan exhibiting the facial flange and throat pouch
 | caption2 = Unflanged male orangutan
 |alt caption2 = A male orangutan with no facial flange or throat pouch
}}

Males become sexually mature at around age 15. They may exhibit [[Neoteny|arrested development]] by not developing the distinctive cheek pads, pronounced throat pouches, long fur, or long calls until a resident dominant male is absent. The transformation from unflanged to flanged can occur quickly. Flanged males attract females in [[oestrous]] with their characteristic long calls, which may also suppress development in younger males.<ref name="Utami 2002">{{cite journal | last1 = Utami | first1 = S. S. | last2 = Goossens | first2 = B. | last3 = Bruford | first3 = M. W. | last4 = de Ruiter | first4 = J. R. | last5 = van Hooff | first5 = J. A. R. A. M. | author-link5 = Jan van Hooff | year = 2002 | title = Male bimaturism and reproductive success in Sumatran orangutans | journal = Behavioral Ecology | volume = 13 | issue = 5| pages = 643–52 | doi = 10.1093/beheco/13.5.643| doi-access = free }}</ref><ref name=Payne/>{{rp|100}}

Unflanged males wander widely in search of oestrous females and upon finding one, may [[Sexual coercion among animals|force copulation]] on her, the occurrence of which is unusually high among mammals. Females prefer to mate with the fitter flanged males, forming pairs with them and benefiting from their protection.<ref name="Fox 2002">{{cite journal | last1 = Fox | first1 = E. A. | year = 2002 | title = Female tactics to reduce sexual harassment in the Sumatran orangutan (''Pongo pygmaeus abelii'') | journal = [[Behavioral Ecology and Sociobiology]] | volume = 52 | issue = 2| pages = 93–101 | doi = 10.1007/s00265-002-0495-x| s2cid = 13583879 }}</ref><ref name="Delgrado 2000" /><ref name=Knott2009>{{cite journal|last1=Knott|first1=Cheryl Denise|last2=Thompson|first2=Melissa Emery|last3=Stumpf|first3=Rebecca M|last4=McIntyre|first4=Matthew H|year=2009|title=Female reproductive strategies in orangutans, evidence for female choice and counterstrategies to infanticide in a species with frequent sexual coercion|journal=Proceedings of the Royal Society B: Biological Sciences|volume=277|issue=1678|pages=105–13|doi=10.1098/rspb.2009.1552|pmid=19812079|pmc=2842634|doi-access=free}}</ref> Non-[[ovulation|ovulating]] females do not usually resist copulation with unflanged males, as the chance of conception is low.<ref name=Knott2009/> [[Homosexual behavior in animals|Homosexual behaviour]] has been recorded in the context of both affiliative and aggressive interactions.<ref>{{cite journal|last=Fox|first=Elizabeth A|year=2001|title=Homosexual behavior in wild Sumatran orangutans (''Pongo pygmaeus abelii'')|journal=American Journal of Primatology|volume=55|issue=3|pages=177–81|doi=10.1002/ajp.1051|pmid=11746281|s2cid=21561581}}</ref>
[[File:Bukit Lawang, orangutans (6785217748).jpg|thumb|left|upright|alt=A mother orangutan with her offspring|Mother orangutan with young]]
Unlike females of other non-human great ape species, orangutans do not exhibit [[sexual swelling]]s to signal fertility.<ref name=Knott2009/> A female first gives birth around 15 years of age and they have a six- to nine-year interbirth interval, the longest among the great apes.<ref name=Wich>{{cite book|last1=Wich |first1=Serge A. |author2=de Vries, Hans |author3=Ancrenaz, Marc |author4=Perkins, Lori |author5=Shumaker, Robert W. |author6=Suzuki, Akira| author7=van Schaik, Carel P. |contribution=Orangutan life history variation|editor1-first=Serge A. |editor1-last=Wich |editor2-first=S. Suci Utami |editor2-last=Atmoko |editor3-first=Tatang Mitra |editor3-last=Setia |editor4-last=van Schaik|editor4-first=Carel P. |title=Orangutans: Geographic Variation in Behavioral Ecology and Conservation|year=2009|url=https://archive.org/details/orangutansgeogra00wich|url-access=registration|publisher=Oxford University Press|pages=67–68|isbn=978-0199213276}}</ref> Gestation is around nine months long and infants are born at a weight of {{convert|1.5|–|2|kg|lb|abbr=on}}.<ref name=Payne/>{{rp|99}} Usually only a single infant is born; twins are a rare occurrence.<ref>{{cite journal|last1=Goossens|first1=B|last2=Mohd|first2=D|last3=Kapar|last4=Kahar|first4=S|year=2011|title=First Sighting of Bornean Orangutan Twins in the Wild|journal=Asian Primates Journal|volume=2|issue=1|pages=10–12|url=https://www.researchgate.net/publication/245023318}}</ref> Unlike many other primates, male orangutans do not seem to practise [[Infanticide (zoology)|infanticide]]. This may be because they cannot ensure they will sire a female's next offspring, because she does not immediately begin ovulating again after her infant dies.<ref>{{cite journal |last1=Beaudrot |first1=LH |last2=Kahlenberg |first2=SM |last3=Marshall |first3=AJ |year=2009 |title=Why male orangutans do not kill infants |journal=Behavioral Ecology and Sociobiology |volume=63 |issue=11 |pages=1549–62 |pmid=19701484 |pmc=2728907 |doi=10.1007/s00265-009-0827-1}}</ref> There is evidence that females with offspring under six years old generally avoid adult males.<ref>{{cite journal|last1=Scott|first1=A. M.|last2=Knott|first2=C. D.|last3=Susanto|first3=T. W.|year=2019|title=Are Male Orangutans a Threat to Infants? Evidence of Mother–Offspring Counterstrategies to Infanticide in Bornean Orangutans (''Pongo pygmaeus wurmbii'')|journal=International Journal of Primatology|volume=44|issue=3|pages=435–55|doi=10.1007/s10764-019-00097-8|hdl=2144/39274|s2cid=198190605|hdl-access=free}}</ref>

Females do most of the caring of the young. The mother will carry the infant while travelling, suckle it and sleep with it.<ref name=Payne/>{{rp|100}} During its first four months, the infant is almost never without physical contact and clings to its mother's belly. In the following months, the amount of physical contact the infant has with its mother declines. When an orangutan reaches the age of one-and-a-half years, its climbing skills improve and it will travel through the canopy holding hands with other orangutans, a behaviour known as "buddy travel".<ref name="Munn 1997">{{cite book |last1=Munn|first1= C. |last2=Fernandez|first2= M.|year=1997|contribution=Infant development |title=Orangutan Species Survival Plan Husbandry Manual |editor-first=Carol |editor-last=Sodaro |publisher=[[Chicago Zoological Park]] |pages=59–66 |oclc=40349739}}</ref> After two years of age, juvenile orangutans will begin to move away from their mothers temporarily. They reach adolescence at six or seven years of age and are able to live alone but retain some connections with their mothers.<ref name=Payne/>{{rp|100}} Females may nurse their offspring for up to eight years, which is more than any other mammal.<ref>{{cite journal|last1=Smith|first1=Tanya M.|last2=Austin|first2=Christine|last3=Hinde|first3=Katie|last4=Vogel|first4=Erin R.|last5=Arora|first5=Manish|year=2017|title=Cyclical nursing patterns in wild orangutans|journal=Evolutionary Biology|volume=3|issue=5|page=e1601517|doi=10.1126/sciadv.1601517|pmid=28560319|pmc=5435413|bibcode=2017SciA....3E1517S|doi-access=free}}</ref> Typically, orangutans live over 30 years both in the wild and in captivity.<ref name=Payne />{{rp|15}}
{{Clear}}

=== Nesting ===

[[File:Bornean Orangutan in nest.jpg|thumb|right|An orangutan lying in its nest|alt=Orangutan lying on its back in a nest]]

Orangutans [[Nest-building in primates|build nests]] specialised for either day or night use. These are carefully constructed; young orangutans learn from observing their mother's nest-building behaviour. In fact, nest-building allows young orangutans to become less dependent on their mother. From six months of age onwards, orangutans practise nest-building and gain proficiency by the time they are three years old.<ref name="WichAtmoko2009">{{cite book |last1=Didik |first1=Prasetyo |author2=Ancrenaz, Marc |author3=Morrogh-Bernard, Helen C. |author4=Atmoko, S. Suci Utami |author5=Wich, Serge A. |author6=van Schaik, Carel P. |editor1-first=Serge A. |editor1-last=Wich |editor2-first=S. Suci Utami |editor2-last=Atmoko |editor3-first=Tatang Mitra |editor3-last=Setia |editor4-last=van Schaik |editor4-first=Carel P. |title=Orangutans: Geographic Variation in Behavioral Ecology and Conservation |chapter-url=https://books.google.com/books?id=ZHsNfZC3DfYC&pg=PA270 |chapter=Nest building in orangutans |year=2009 |publisher=Oxford University Press |isbn=978-0-19-921327-6 |pages=270–75 |access-date=16 December 2015 |archive-date=24 April 2016 |archive-url=https://web.archive.org/web/20160424082644/https://books.google.com/books?id=ZHsNfZC3DfYC&pg=PA270 |url-status=live }}</ref>

Construction of a night nest is done by following a sequence of steps. Initially, a suitable tree is located. Orangutans are choosy about sites, though nests can be found in many tree species. To establish a foundation, the ape grabs the large branches under it and bends them so they join. The orangutan then does the same to smaller, leafier branches to create a "mattress". After this, the ape stands and braids the tips of branches into the mattress. Doing this increases the stability of the nest. Orangutans make their nests more comfortable by creating "pillows", "blankets", "roofs" and "bunk-beds".<ref name="WichAtmoko2009" />