Editing Proboscis monkey (section)

===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>