Javan Gibbon GSMP

The Javan (or silvery) gibbon (Hylobates moloch) is the last remaining ape species on Java. Like all gibbon species, it is under serious threat from the destruction of habitat and the illegal pet trade. Found only in the West and part of Central Java in highly fragmented habitat, recent surveys suggest that there are fewer than 3000 individuals remaining in up to 63 pockets of fragmented habitat. Many of these areas have little or no protection from habitat degradation or poaching and the Javan gibbon now appears to be one of the taxa most threatened with extinction (i.e. with one of the most restricted and threatened ranges).


In 2009, a Global Species Management Program (GSMP) for this species was borne out of a recognised need for improved management of the captive population in order to make a significant and genuine contribution to the conservation of the species.


Endorsed by WAZA, the program aims to assist in the conservation of the species by:


  • holding an insurance population and/or providing animals for release to the wild as part of a managed conservation reintroduction program;
  • acting as an insurance population in case of catastrophic declines in the wild;
  • conserving high levels of the genetic variability found in wild populations;
  • conserving the behavioural repertoire of the species;
  • supporting the development and documentation of husbandry techniques for the species;
  • supporting regional fundraising efforts;
  • providing animals for zoo-based research; and
  • ensuring a captive population persists in zoos for the purposes of educational display and/or fundraising.


Traditionally, as with many captive species, Javan gibbons have been managed regionally. Although some transfer has occurred between regions as required, the population has not been managed as one unit. Genetic analysis and subsequent recommendations on regional populations has now been identified as unsustainable. The GSMP provides the opportunity for the separate regional populations to be managed as one meta-population, providing the best outcomes for genetic pairings and breeding management. The GSMP, with a viable well managed captive population, can not only provide suitable animals for reintroduction but also leverage significant funding for in situ conservation projects. A key principle of the GSMP is that no Javan gibbon is to be removed from the wild to join a captive population.


A GSMP can provide a tangible link between ex situ management of a species and in situ conservation. In situations where both captive and wild populations are small, it makes sense to capitalise on any resource available and in many cases well managed captive populations can genuinely contribute to the conservation of a species as ambassadors to raise funds for habitat and population protection, as well as by providing suitable animals for reintroduction.


To summarise, the key outcomes of the Javan gibbon GSMP would be:


  • having a protected and sustainable population of wild gibbons; and
  • having a viable and well managed global captive population.


In order to achieve this, it is essential to have commitment from all regional programs and to operate under agreed values such as:


  • best species management of population (pair formation based on global genetics);
  • funding from international institutions for in situ conservation (institutions sign cooperative agreement including funding commitment);
  • animals available for reintroduction (if required);
  • ex situ population is managed to be sustainable without further wild founders;
  • the program actively supports actions to prevent further gibbons coming into captivity;
  • pairs are formed that are behaviourally compatible; and
  • wherever possible gibbons are housed in natural groups.


The Javan gibbon captive population is relatively small and difficult to sustain in the long term without some form of cooperation between regions. Population analysis has determined that long-term sustainability will require an improvement in breeding success within zoos and management of the entire captive population as one meta-population. The GSMP can provide assistance to institutions to improve husbandry standards and breeding success. Management of an international studbook with detailed information about all animals within the program will also assist to ensure closer scrutiny of animal acquisitions.


The Javan gibbon wild population is also relatively small and would benefit from a successful reintroduction program. The availability of suitable areas for reintroduction is looking promising. Whilst the priority for animals housed within rehabilitation centres should always be their reintroduction to the wild, there should also be some recognition that not all of these animals will achieve rehabilitation at a level sufficient for a return to the wild and in some cases animals born and raised in zoos with strong gibbon husbandry practices may be more suitable for reintroduction.


In August 2010, an international workshop was held in Java to finalise the plan of operation for the GSMP and to discuss the most effective ways in which the program can contribute to the in situ conservation of Javan gibbons. Plans are now progressing on the establishment of Gibbon Protection Units to protect wild populations (funded by member institutions) and reintroduction programs as well as capacity building and improvement of husbandry and breeding success. The workshop was organised by the Silvery Gibbon Project and supported by Perth Zoo, the Ministry of Forestry of Indonesia, the Javan Gibbon Foundation and the Aspinall Foundation.


Other developments include several births within the captive population. Perth Zoo, Howletts and Port Lympne Wild Animal Parks and the Gibbon Conservation Center have continued to breed successfully. A new pair established at Mogo Zoo in Australia also produced an offspring within a year of being paired.


One of the most significant developments has been the successful birth of an infant at the Javan Gibbon Centre in Java. It is anticipated that the Javan Gibbon Centre can serve as a centre of excellence in the region and assist with improvements in other zoos and rehabilitation centres in this region.


The Javan Gibbon Centre also conducted the first release of Javan gibbons in October 2009. The pair was released into a small isolated area of habitat within the Gunung Gede Pangrango National Park. The pair continues to be monitored and appears to be adapting well to life in the wild. They have explored the entire area, utilising all available food sources and have been observed grooming and copulating.


Clare Campbell – GSMP Convenor and International Studbook Keeper

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  • Javan Gibbon GSMP

    Javan Gibbon GSMP

    (1) © Karen Payne, (2) © Kate O'Connell, (3) © Karen Payne, (4) © Perth Zoo