Editing Proboscis monkey (section)

==Behavior and ecology==
===Social behavior===
[[File:Proboscis monkey (Nasalis larvatus) composite.jpg|thumb|Jumping ([[composite image]], from right to left), Labuk Bay, [[Sabah]]]]
[[File:011191 00001 Nasenaffen am Kinabatangan.jpg|thumb|A group of proboscis monkeys by the river Kinabatangan]]
Proboscis monkeys generally live in groups composed of one adult male, some adult females and their offspring.<ref name=Bennett1993/><ref name=Boonratana1993/><ref name=Booratana2002/> All-male groups may also exist.<ref name=Murai2004>{{cite journal|author=Murai, T. |year=2004|title= Social behaviors of all-male proboscis monkeys when joined by females|journal=Ecological Research |volume= 19| issue=4|pages=451–454|doi=10.1111/j.1440-1703.2004.00656.x|bibcode=2004EcoR...19..451M |s2cid=46315032}}</ref> Some individuals are solitary, mostly males.<ref name=Boonratana1999>{{cite journal|author=Boonratana R.|year=1999| title=Dispersal in proboscis monkeys (''Nasalis larvatus'') in the lower Kinabatangan, Northern Borneo| journal=Tropic Biodiversity |volume= 6| issue=3|pages=179–187 |url=https://www.researchgate.net/publication/225088971}}</ref> Monkey groups live in overlapping home ranges, with little territoriality,<ref name=Bennett1993/><ref name=Boonratana1993/> in a [[fission-fusion society]], with groups gathering at sleeping sites as night falls. There exist bands which arise when groups come together and slip apart yet sometimes groups may join to mate and groom.<ref name=Bennett1993/><ref name=Boonratana1993/><ref name=Booratana2002/> Groups gather during the day and travel together, but individuals only groom and play with those in their own group.<ref name=Booratana2002>{{cite journal|author=Boonratana R. |year=2002 |title=Social organisation of proboscis monkeys (''Nasalis larvatus'') in the lower Kinabatangan, Sabah, Malaysia |journal= Malay Nat. Journal |volume=56| issue=1|pages=57–75}}</ref> One-male groups consist of 3 to 19 individuals,<ref name=Murai2004/><ref name=Bennett1993/> while bands can consist of as many as 60 individuals.<ref name=Bennett1993/><ref name=Boonratana1999/> Serious aggression is uncommon among the monkeys but minor aggression does occur.<ref>{{cite journal|author=Yeager C. P. |year=1992| title=Proboscis monkey (''Nasalis larvatus'') social organization: nature and possible functions of intergroup patterns of association| journal=American Journal of Primatology |volume= 26| issue=2|pages=133–137 |doi=10.1002/ajp.1350260207 |pmid=31948161 |s2cid=84905354}}</ref> Overall, members of the same bands are fairly tolerant of each other. A linear dominance hierarchy exists between females.<ref name=Boonratana1993/> Males of one-male groups can stay in their groups for six to eight years. Replacements in the resident males appear to occur without serious aggression.<ref name=Murai2004/> Upon reaching adulthood, males leave their natal groups and join all-male groups.<ref name=Bennett1993/><ref name=Boonratana1999/>  Females also sometimes leave their natal groups, perhaps to avoid [[Infanticide (zoology)|infanticide]] or inbreeding, reduce competition for food, or elevation of their social status.<ref name=Murai2004/><ref name=Boonratana1999/>

In [[Sabah]], Malaysia, proboscis monkeys have been observed in mixed-species groups with [[silvery lutung]]s, and interspecific mating and a possible hybrid has been observed.<ref name=hybrid/>  Researchers believe this may be a result of the two species being confined to a small patch of [[riverine forest]] due to [[deforestation]] in order to plant [[oil palm]] trees.<ref name=hybrid>{{cite journal|title=Is Malaysia's "mystery monkey" a hybrid between ''Nasalis larvatus'' and ''Trachypithecus cristatus''? An assessment of photographs |journal=International Journal of Primatology |date=2022 |doi=10.1007/s10764-022-00293-z|pmid=35498121|author1=Lhota, S. |author2=Yap, J.L. |author3=Benedict, M.L. |author4=Ching, K. |volume=43 |issue=3 |pages=513–532 |pmc=9039274 |display-authors=3}}</ref>

===Reproduction===
Females become sexually mature at the age of five years. They experience [[sexual swelling]], which involves the genitals becoming pink or reddened.<ref name=Murai2004/><ref name=Murai2006/>  At one site, matings largely take place between February and November, while births occur between March and May.<ref name=Rajanathan1990>{{cite journal|author1=Rajanathan R. |author2=Bennett E. L. |year=1990| title=Notes on the social behaviour of wild proboscis monkeys (''Nasalis larvatus'')| journal=Malay Nat. Journal |volume= 44| issue=1|pages=35–44}}</ref> Copulations tend to last for half a minute.<ref name=Boonratana1993/><ref name=Murai2004/>  The male will grab the female by the ankles or torso and mount her from behind.<ref name=Boonratana1993/> Both sexes will encourage mating, but they are not always successful.<ref name=Murai2006>{{cite journal|author=Murai T.|year=2006| title=Mating behaviors of the proboscis monkey (''Nasalis larvatus'')| journal=American Journal of Primatology | volume= 68| issue=8|pages=832–837 |doi=10.1002/ajp.20266|pmid=16847976|s2cid=10625574}}</ref>  When soliciting, both sexes will make pouted faces. In addition, males will sometimes vocalize and females will present their backsides and shake their head from side to side.<ref name=Bennett1993/><ref name=Murai2006/><ref name=Rajanathan1990/><ref name=":0" /> Mating pairs are sometimes harassed by subadults.<ref name=Murai2006/> Proboscis monkeys may also engage in mounting with no reproductive purpose, such as playful and same-sex mounting, and females will attempt to initiate copulation even after they have conceived.<ref name=":0" /> Gestation usually last 166–200 days or slightly more.<ref name=Rajanathan1990/> Females tend to give birth at night or in the early morning. The mothers then eat the placenta and lick their infants clean.<ref name=Gorzitze1996>{{cite journal|author=Gorzitze A. B.|year=1996| title=Birth-related behavior in wild proboscis monkeys (''Nasalis larvatus'')| journal=Primates| volume= 37| issue=1|pages=75–78 |doi=10.1007/BF02382922 |s2cid=39403318}}</ref> The young begin to eat solid foods at six weeks and are weaned at seven months old. The nose of a young male grows slowly until reaching adulthood. The mother will allow other members of her group to hold her infant.<ref name=Boonratana1993/><ref name=Rajanathan1990/><ref name=Gorzitze1996/> When a resident male in a one-male group is replaced, the infants are at risk of infanticide.<ref>{{cite journal|author1=Agoramoorthy G. |author2=Hsu M. J. |year=2004| title=Occurrence of infanticide among wild proboscis monkeys (''Nasalis larvatus'') in Sabah, Northern Borneo| journal=Folia Primatol.| volume= 76| issue=3|pages=177–179 |doi=10.1159/000084380 |pmid=15900105|s2cid=20111145}}</ref>

===Communication===
Proboscis monkeys are known to make various vocalizations. When communicating the status of group, males will emit honks. They have a special honk emitted towards infants, which is also used for reassurance. Males will also produce alarm calls to signal danger. Both sexes give threat calls, but each are different. In addition, females and immature individuals will emit so-called "female calls" when angry.<ref>{{cite journal|author1=Messeri P. |author2=Trombi M. |year=2000| title=Vocal repertoire of proboscis monkey (''Nasalis larvatus'', L.) in Sarawak| journal=Folia Primatol.| volume= 71| issue=4|pages=268–287}}</ref> Honks, roars and snarls are made during low-intensity agonistic encounters. Nonvocal displays include leaping-branch shaking, bare-teeth open mouth threats and [[erection]] in males, made in the same situations.<ref name=Boonratana1993/>

===Feeding and activities===
As a seasonal folivore and frugivore, the proboscis monkey eats primarily fruit and leaves.<ref name=Boonratana1993/> It also eats flowers, seeds and insects to a lesser extent. At least 55 different plant species are consumed, "with a marked preference for ''[[Eugenia]]'' sp., ''[[Ganua motleyana]]'' and ''[[Lophopetalum javanicum]]''".<ref name=Yeager/> Young leaves are preferred over mature leaves and unripe fruits are preferred over ripe fruit.<ref name=Boonratana1993/> Being a seasonal eater, the proboscis monkey eats mostly fruit from January to May and mostly leaves from June to December.<ref name=Yeager>{{cite journal|author=Yeager C. P.|year=1989 |journal= International Journal of Primatology |issue=6|pages=497–530 |doi=10.1007/BF02739363|title=Feeding ecology of the proboscis monkey (''Nasalis larvatus'') |volume=10 |s2cid=23442969}}</ref> Groups usually sleep in adjacent trees.<ref>{{cite journal |author=Yeager C. P.|year=1990| title=Proboscis monkey (''Nasalis larvatus'') social organization: group structure |journal=American Journal of Primatology |volume=20 |issue=2 |pages=95–106 |doi=10.1002/ajp.1350200204 |pmid=31963992 |s2cid=85675872}}</ref> Monkeys tend to sleep near rivers, if they are nearby. Proboscis monkeys will start the day foraging and then rest further inland. Their daily activities consist of resting, traveling, feeding and keeping vigilant.<ref name=Boonratana1993/>  Occasionally, they chew their [[cud]] to allow more efficient digestion and food intake.<ref name=Matsuda2011>{{Cite journal |last1=Matsuda |first1=I. |last2=Murai |first2=T. |last3=Clauss |first3=M. |last4=Yamada |first4=T. |last5=Tuuga |first5=A. |last6=Bernard |first6=H. |last7=Higashi |first7=S. |doi=10.1098/rsbl.2011.0197 |title=Regurgitation and remastication in the foregut-fermenting proboscis monkey (''Nasalis larvatus'') |journal=Biology Letters |volume=7 |issue=5 | pages=786–789 |year=2011 |pmid=21450728 |pmc=3169055}}</ref>  As night approaches, the monkeys move back near the river and forage again. Predators (potential or confirmed) of the proboscis monkey include [[crocodilian]]s like [[false gharial]]s and [[saltwater crocodile]]s, the [[Sunda clouded leopard]], [[sun bear]]s and [[reticulated python]]s as well as, for probably young or sickly monkeys, large [[eagle]]s (such as the [[crested serpent eagle]] or [[black eagle]]), large [[owl]]s, and [[Monitor lizard|monitor lizards]].<ref>{{cite journal|author=Feilen, K. L. |author2=Marshall, A. J. |date=2014 |title=Sleeping site selection by proboscis monkeys (''Nasalis larvatus'') in West Kalimantan, Indonesia |journal=American Journal of Primatology|volume=76 |issue=12 |pages=1127–1139|doi=10.1002/ajp.22298 |pmid=24810395 |s2cid=26318484 }}</ref><ref>{{cite journal|author=Stuebing, R. B. |author2=Bezuijen, M. R. |author3=Auliya, M. |author4=Voris, H. K.  |year=2006 |title=The current and historic distribution of ''Tomistoma schlegelii'' (the False Gharial)(Müller, 1838)(Crocodylia, Reptilia) |journal=The Raffles Bulletin of Zoology |volume=54 |issue=1 |pages=181–197}}</ref> Monkeys will cross rivers at narrows or cross arboreally if possible. This may serve as predator avoidance.<ref>{{cite journal|author=Yeager C. P. |year=1991| title=Possible antipredator behavior associated with river crossings by proboscis monkeys (''Nasalis larvatus'')| journal=American Journal of Primatology |volume=24| issue=1|pages=61–66 |doi=10.1002/ajp.1350240107 |s2cid=84996963}}</ref>