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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 . 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.

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 . 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. 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. 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. In the latter, there is a Javan Gibbon Centre that rehabilitates ex-captive gibbons.

Several zoos operate silvery gibbon breeding programs. Despite these efforts, the future survival of this species is in question.

References

  • ARKive - images and movies of the Javan gibbon (Hylobates moloch)
  • http://www.gibbons.de