{{Short description|Species of ape}} {{Speciesbox | name = Silvery gibbon | image = Moloch-20210525-Ctb.jpg | image_caption = A silvery gibbon foraging in a Ficus tree. Photograph taken in Mount Halimun Salak National Park | status = EN | status_system = IUCN3.1 | status_ref = <ref name=iucn>{{cite iucn |title=''Hylobates moloch'' |author=Nijman, V. |date=2020 |article-number=e.T10550A17966495 |doi=10.2305/IUCN.UK.2020-2.RLTS.T10550A17966495.en |access-date=17 January 2022}}</ref> | status2 = CITES_A1 | status2_system = CITES | status2_ref = <ref name=iucn/> | genus = Hylobates | species = moloch<ref name=MSW3>{{MSW3 Groves|pages=180|id=12100767 |heading=Species ''Hylobates moloch''}}</ref> | authority = (Audebert, 1798) | range_map = Silvery Gibbon area.png | range_map_caption = Silvery gibbon range }} thumb|skeleton The '''silvery gibbon''' ('''''Hylobates moloch'''''), also known as the '''Javan gibbon''', is a primate in the gibbon family Hylobatidae. It is endemic to the Indonesian island of Java, where it inhabits undisturbed rainforests up to an altitude of {{cvt|2450|m|ft}}. It has been listed as Endangered on the IUCN Red List since 2008, as the wild population is estimated to comprise less than 2500 mature individuals.<ref name=iucn/>
Its coat is bluish-grey, with a dark grey or black cap. Like all gibbons, the silvery gibbon lacks an external tail, has dorsally placed scapulae, and reduced flexibility in its lumbar region. It has long, curved fingers and very long forelimbs relative to its hind limbs. On average, it reaches {{cvt|8|kg}} in weight. It is diurnal and arboreal, climbing trees skilfully and brachiating through the forests. Brachiation is possible because of its mobile wrist joints, full rotation of the upper arm, and the ability to lock elbows in suspension. Its diet consists of fruits, leaves, and flowers.
Every three years, on average, the female gives birth to a single young, after a gestation of seven months. The offspring is nursed for about 18 months and lives with the family group until it is fully mature at about eight to ten years old.<ref>{{cite thesis |last1=Kappeler |first1=M. |year=1981 |title=The Javan silvery gibbon (''Hylobates lar moloch''), habitat, distribution, numbers |location=Basel |publisher=University of Basel |type=Ph.D.}}</ref>
==Behaviour and ecology== Like all gibbon species, the silvery gibbon lives in pairs and stakes out territory that the pair strongly defends; it has relatively small territories of about {{convert|42|acres|hectare}}. Females sing to declare their territory several times a day, and if strangers are spotted, the male screams in an attempt to scare them away. The majority of the solo song bouts or scream bouts are produced by females.<ref name="Geissmann-2009">{{Cite journal|title = Calling in Wild Silvery Gibbons (''Hylobates moloch'') in Java (Indonesia): Behavior, Phylogeny, and Conservation|last1 = Geissmann |first1 = T. |date =2009 |journal= American Journal of Primatology |doi=10.1002/ajp.20203|pmid = 16419119 |last2 = Nijman|first2 = V. |volume=68 |issue =1 |pages=1–19 |s2cid = 5900145}}</ref> The female vocal bouts occur after 0500 hr, with the vocal bout activity peaking around 0600 hr. In contrast, the male vocal bouts primarily occurred before 0500 hr was created in the style of a chorus, with a minimum of three participants. There are choruses around every 8.5 days. It took place sooner and lasted longer than female solo song fights. The majority of male songs begin in the dark, between 0355 and 0440 hours. The males are usually very aggressive toward others.<ref name="Geissmann-2009" />
==Threats and conservation== The silvery gibbon ranks among the most threatened primates. It is listed as Endangered on the 2009 IUCN Red List,<ref name="iucn" /> with the population appearing more stable than in a 2004 assessment of the species being Critically Endangered, which suggested there was a 50% chance of the silvery gibbon becoming extinct within the next decade.<ref name="Silvery_Gibbon_Project">{{cite web | title = The Silvery Gibbon Project | url = http://www.silvery.org.au/their-plight | access-date = 2007-12-11}}</ref> Habitat destruction on densely populated Java continues to reduce the natural range of the species. Many gibbons are also lost to the illegal pet trade when adults are hunted so their young can be sold in the markets as pets.<ref name="Silvery_Gibbon_Project" />
There are less than 2,000 silvery gibbons in the wild on eight sites that are considered to be genetically viable for the continuation of the species. There are also a dozen small, non-viable populations. Mount Halimun Salak National Park sustains the largest population of ca. 1,000 gibbons.<ref name="Silvery_Gibbon_Project" /> Other large populations of several hundred are found in the Gunung Ciremai National Park and Gunung Gede Pangrango National Park.<ref>{{cite journal | last1 = Supriatna | first1 = Jatna | title = Conservation Programs for the Endangered Javan Gibbon | url = http://www.primate-sg.org/storage/PDF/PC21.hylobates.moloch.pdf | journal = Primate Conservation | volume = 2006 | issue = 21| pages = 155–162 }}</ref> In the latter, there is a Javan Gibbon Centre that rehabilitates ex-captive gibbons.<ref>The Silvery Gibbon Project: [http://www.silvery.org.au/conservation-projects/ "Conservation Projects"] {{webarchive|url=https://archive.today/20131220054214/http://www.silvery.org.au/conservation-projects/ |date=2013-12-20 }}, retrieved 20 December 2013</ref>
Several zoos operate silvery gibbon breeding programs. Despite these efforts, the future survival of this species is in question.
==References== {{Reflist}}
==External links== *ARKive - [https://web.archive.org/web/20060506052222/http://www.arkive.org/species/GES/mammals/Hylobates_moloch/ images and movies of the Javan gibbon ''(Hylobates moloch)''] *http://www.gibbons.de
{{Hylobatidae nav}}
{{Taxonbar|from=Q663728}}
silvery gibbon Category:Fauna of Java Category:Endemic fauna of Indonesia Category:Endemic fauna of Java Category:Primates of Indonesia Category:Endangered fauna of Asia Category:Species that are or were threatened by the pet trade silvery gibbon silvery gibbon Category:Arboreal mammals