{{Short description|Species of ape}} {{Use dmy dates|date=September 2020}} {{Speciesbox | name = Western hoolock gibbon | image = Hoolock hoolock 001.jpg | image_caption = A female in the foreground, and a male in the background | status = EN | status_system = IUCN3.1 | status_ref = <ref name="iucn">{{cite iucn |author=Brockelman, W. |author2=Molur, S. |author3=Geissmann, T. |date=2019 |title=''Hoolock hoolock'' |volume=2019 |article-number=e.T39876A17968083 |doi=10.2305/IUCN.UK.2019-3.RLTS.T39876A17968083.en |access-date=19 November 2021}}</ref> | status2 = CITES_A1 | status2_system = CITES | status2_ref = <ref>{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}</ref> | genus = Hoolock | species = hoolock | authority = (Harlan, 1834)<ref>{{cite journal|last1=Harlan|first1=Richard|title=Description of a Species of Orang, from the North-Eastern Province of British East India, Lately the Kingdom of Assam|journal=Transactions of the American Philosophical Society|date=1834|volume=4|pages=52–59|doi=10.2307/1004829|jstor=1004829|jstor-access=free|url=https://www.biodiversitylibrary.org/page/24786617}}</ref> | range_map = Western Hoolock Gibbon area.png | range_map_caption = Western hoolock gibbon range | synonyms = ''Simia hoolock'' {{small|protonym}} }}
The '''western hoolock gibbon''' ('''''Hoolock hoolock''''') is a primate from the gibbon family, Hylobatidae. The species is found in Assam, Mizoram, and Meghalaya in India, Bangladesh, and Myanmar west of the Chindwin River.<ref>{{cite journal | author=Groves, C. P. | year= 1967 | title = Geographic variation in the hoolock or white-browed gibbon (''Hylobates hoolock harlan'' 1834). | journal = Folia Primatologica | volume=7 | issue= 3–4 | pages=276–283 | doi=10.1159/000155125 | pmid=5626313}}</ref>
==Classification== Mootnick and Groves<ref>{{cite journal | author = Mootnick, A. R. | author2 = C. P. Groves | author2-link = Colin Groves | name-list-style = amp | year = 2005 | title=A new generic name for the hoolock gibbon (Hylobatidae) | journal = Int. J. Primatol. | volume = 26 | issue = 4 | pages = 971–976 | doi=10.1007/s10764-005-5332-4| s2cid = 8394136 }}</ref> stated that hoolock gibbons do not belong in the genus ''Bunopithecus'', and placed them in a new genus, ''Hoolock''. This genus was argued to contain two and later three distinct species, which were previously thought to be subspecies: ''H. hoolock'', ''H. leuconedys'', and ''H. tianxing''. A larger evolutionary distance was later found to exist between these three species and the white-handed gibbons than between bonobos and chimpanzees.<ref>{{cite journal | author = Mootnick, A. R. | year = 2006 | title = Gibbon (Hylobatidae) species identification recommended for rescue or breeding centers | journal = Primate Conserv | volume = 21 | pages = 103–138 | doi = 10.1896/0898-6207.21.1.103| s2cid = 86331056 | doi-access = free }}</ref>
A new subspecies of the western hoolock gibbon has been described recently from northeastern India, which has been named the Mishmi Hills hoolock gibbon, ''H. h. mishmiensis''.<ref name="Choudhury2013b">{{cite journal |first=A. U. |last=Choudhury |title=Description of a new subspecies of hoolock gibbon ''Hoolock hoolock'' from North East India |journal=The Newsletter & Journal of the Rhino Foundation for Nat. In NE India |volume=9 |pages=49–59 |year=2013}}</ref> [[File:Western hoolock gibbon - Hollongapar Gibbon Sanctuary 2023-01-12 01.jpg|left|thumb|Western hoolock gibbon in canopy at Hoollongapar Gibbon Sanctuary.]]
== Vocalisation == Like other gibbons, hoolock gibbon pairs produce a loud, elaborate song, usually as a duet from the forest canopy, in which younger individuals of the family group may join. The song includes an introductory sequence, an organising sequence, and a great call sequence, with the male also contributing to the latter (unlike in some other gibbon species).<ref>{{Cite book|title=Mammals of South Asia|last1=Kakati|first1=Kashmira|last2=Alfred|first2=J. R. B.|last3=Sati|first3=J. P.|publisher=Universities Press|year=2013|isbn=978-81-7371-590-7|editor-last=Johnsingh|editor-first=A. J. T.|volume=1|location=Hyderabad|pages=332–354|chapter=Hoolock gibbon|editor-last2=Manjrekar|editor-first2=N.}}</ref>
thumb|Western hoolock gibbons calling from the rainforest canopy in Dampa Tiger Reserve, Mizoram, India
==Habitat and Diet== In India and Bangladesh, the western hoolock gibbon is found where the canopy is contiguous, broad-leaved, wet evergreen and mixed evergreen forests, including dipterocarp forests and often in mountainous terrain. The species is an important seed disperser; its diet includes mostly ripe fruits, with some flowers, leaves, and shoots.<ref name=":0">{{Cite journal |last1=Borah |first1=Mrigakhi |last2=Devi |first2=Ashalata |last3=Kumar |first3=Awadhesh |date=11 September 2017 |title=Diet and feeding ecology of the western hoolock gibbon (Hoolock hoolock) in a tropical forest fragment of Northeast India |url=http://link.springer.com/10.1007/s10329-017-0627-6 |journal=Primates |language=en |volume=59 |issue=1 |pages=31–44 |doi=10.1007/s10329-017-0627-6 |pmid=28894949 |s2cid=12152723 |issn=0032-8332|url-access=subscription }}</ref> The western hoolock gibbon also feeds on non-plant items such as silkworms, ants, and various other insect species.<ref name=":0" /> During the monsoon season of northeast India, insects are recorded to be this species' second preferred food item, behind Artocarpus ''chaplasha'''','' a fruit bearing tree in the same genus of jack fruit.<ref>{{Cite journal |last=Borah; Mrigakhi; Asglata, Devi; Awadhesh, Kumar |date=2014 |title=Feeding on Non-Plant Food Items by Western Hoolock Gibbon (Hoolock Hoolock) |url=https://www.currentscience.ac.in/Volumes/107/10/1657.pdf |journal=Current Science (Bangalore) |volume=107 |issue=10 |pages=1657–660 |via=Current Science}}</ref><ref>{{Cite journal |last1=Ray |first1=Parimal Chandra |last2=Kumar |first2=Awadhesh |last3=Devi |first3=Ashalata |last4=Krishna |first4=Murali C. |last5=Khan |first5=M. L. |last6=Brockelman |first6=W. Y. |date=2015 |title=Habitat Characteristics and Their Effects on the Density of Groups of Western Hoolock Gibbon (Hoolock hoolock) in Namdapha National Park, Arunachal Pradesh, India |url=http://link.springer.com/10.1007/s10764-015-9834-4 |journal=International Journal of Primatology |language=en |volume=36 |issue=3 |pages=445–459 |doi=10.1007/s10764-015-9834-4 |s2cid=7098362 |issn=0164-0291|url-access=subscription }}</ref> [[File:Western hoolock gibbon - Hollongapar Gibbon Sanctuary 2023-01-12 03.jpg|center|thumb|Female Western hoolock gibbon at Hoollangapar Gibbon Sanctuary.]]
==Conservation== Numerous threats exist for western hoolock gibbons in the wild, and they are now entirely dependent on human action for their survival. Threats include habitat encroachment by humans, forest clearance for tea cultivation, the practice of ''jhuming'' (slash-and-burn cultivation), hunting for food and "medicine", capture for trade, and forest degradation.<ref name="iucn" /> [[File:Western hoolock gibbon - Hollongapar Gibbon Sanctuary 2023-01-12 02.jpg|left|thumb|Male Western hoolock gibbon hanging from lower branches at Hoollongapar Gibbon Sanctuary.]] Since the 1980s, western hoolock gibbon numbers are estimated to have dropped from more than 100,000 (Assam alone was estimated to have around 80,000 in the early 1970s) to less than 5,000 individuals (a decline of more than 90%).<ref>{{cite web | title = Western Hoolock Gibbon, ''Hoolock hoolock'' | url = http://www.primate-sg.org/hoolock07.htm | access-date = 2008-03-10}}</ref> In 2009 it was considered to be one of the 25 most endangered primates,<ref name="2008-2010Top25">{{cite book | editor1-last = Mittermeier | editor1-first = R.A. | editor2-last = Wallis | editor2-first = J. | editor3-last = Rylands | editor3-first = A.B. | editor4-last = Ganzhorn | editor4-first = J.U. | editor5-last = Oates | editor5-first = J.F. | editor6-last = Williamson | editor6-first = E.A. | editor7-last = Palacios | editor7-first = E. | editor8-last = Heymann | editor8-first = E.W. | editor9-last = Kierulff | editor9-first = M.C.M. | editor10-last = Long | editor10-first = Yongcheng | editor11-last = Supriatna | editor11-first = J. | editor12-last = Roos | editor12-first = C. | editor13-last = Walker | editor13-first = S. | editor14-last = Cortés-Ortiz | editor14-first = L. | editor15-last = Schwitzer | editor15-first = C. | others = Illustrated by S.D. Nash | editor-link = Russell Mittermeier | year = 2009 | title = Primates in Peril: The World's 25 Most Endangered Primates 2008–2010 | publisher = IUCN/SSC Primate Specialist Group (PSG), International Primatological Society (IPS), and Conservation International (CI) | location = Arlington, VA | pages = 1–92 | isbn = 978-1-934151-34-1 | url = http://www.primate-sg.org/PDF/Primates.in.Peril.2008–2010.pdf}}</ref> though it has been dropped from the later editions of the list,<ref>{{cite book| editor1-last = Mittermeier | editor1-first = R.A. | editor2-last = Schwitzer | editor2-first = C. | editor3-last = Rylands | editor3-first = A.B. | editor4-last = Taylor| editor4-first = L.A. | editor5-last = Chiozza | editor5-first = F. | editor6-last = Williamson | editor6-first = E.A. | editor7-last = Wallis | editor7-first = J. | others = Illustrated by S.D. Nash | editor-link = Russell Mittermeier | year = 2012 | title = Primates in Peril: The World's 25 Most Endangered Primates 2012–2014 | publisher = IUCN/SSC Primate Specialist Group (PSG), International Primatological Society (IPS), Conservation International (CI), and Bristol Conservation and Science Foundation | pages = 1–40 | url = https://static1.1.sqspcdn.com/static/f/1200343/25117808/1403888374823/Primates_in_Peril_2012-2014_Full_Report.pdf?token=SWlE8nHhRTZJh%2F%2BZ%2FQ3kXz%2BX9R8%3D |isbn=978-1-934151-69-3}}</ref> and is rated as endangered by the IUCN.<ref name=iucn/>
Multiple conservation agencies work to protect the western hoolock gibbon's habitat. A few organizations that help to fund the protection of their habitats are World Land Trust <ref>{{Cite web |last=Farrows |title=WESTERN HOOLOCK GIBBON |url=https://www.worldlandtrust.org/species/mammals/western-hoolock-gibbon/ |access-date=2023-12-11 |website=World Land Trust |language=en}}</ref> and Gibbon Conservation Alliance.<ref>{{Cite web |title=Gibbon Conservation Alliance - Projects |url=http://www.gibbonconservation.org/05_projects_engl.html |access-date=2023-12-11 |website=www.gibbonconservation.org}}</ref>
==See also== *Lawachara National Park
==References== {{Reflist}}
{{Hylobatidae nav}} {{Taxonbar|from=Q577084}}
western hoolock gibbon Category:Arboreal mammals Category:Primates of South Asia Category:Mammals of Bangladesh Category:Mammals of Myanmar Category:Mammals of India Category:Endangered fauna of Asia Category:Species that are or were threatened by the pet trade western hoolock gibbon Category:Taxa named by Richard Harlan Category:Endangered Fauna of China