The Javan (or Silvery) gibbon 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 there are fewer than 3,000 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 (Campbell et al, 2008).
The current conservation strategy for this species aims to:
- protect wild populations and habitat,
- rehabilitate and reintroduce ex-pet Javan gibbons into protected habitat,
- improve law enforcement and eliminate the illegal pet trade, and
- provide education programs regarding the importance of conservation of Indonesia’s wildlife and forests.
In 2009, a Global Cooperative Management Program (GCMP) 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.
The program aims to assist in the conservation of the species by:
- holding an insurance population and/or providing gibbons for release to the wild as part of a managed conservation reintroduction program
- conserve high levels of the genetic variability found in wild populations
- conserve the behavioural repertoire of the species
- support the development and documentation of husbandry techniques for the species
- supports regional fundraising efforts
- provides gibbons for zoo-based research
- ensure a captive population persists in zoos for the purposes of educational display and/or fundraising.
What is a Global Cooperative Management Program (GCMP)?
Traditionally, many captive species are 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 GCMP 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 GCMP, with a viable well managed captive population can not only provide suitable Javan gibbons for reintroduction but can also leverage significant funding for in situ conservation projects.
A GCMP can provide a tangible link between this 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 population can genuinely contribute through being ambassadors to raise funds for habitat and population protection, as well as providing suitable animals for reintroduction. It must be noted that animals should never be removed from the wild and placed in captivity as this would simply contravene any captive program’s primary goal of conserving the species in the wild.
The following diagram demonstrates how the Indonesian and International zoo populations, in conjunction with planned Gibbon Protection Units (GPU), to protect wild populations (funded by member institutions), can work together for the benefit of the wild population and negate the need for gibbons to be taken from the wild in future.
*Illegal to take from the wild
To summarise, the key outcomes of a GCMP should be:
- having a protected and sustainable population of wild Javan gibbons, and
- 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)
- maximum funding from international institutions for in situ conservation (institutions sign Cooperative Agreement, inc. funding commitment)
- Javan gibbons 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
- wherever possible gibbons are housed in natural groups.
Further Information
- Javan Gibbon GCMP Plan of Operations (pdf)
- Javan Gibbon Workshop Minutes April 2009 (pdf)
- Global Cooperative Management Program for Javan Gibbons (pdf)
What is Population Management?
Population Management is the science of managing captive animal populations in a manner suitable to achieve the stated aims of the population. Management often takes the form of genetic and demographic analyses of a given population with parameter values being tracked over time against goals. Goals might include components such as retaining a given level of genetic diversity over a given time period, reaching and maintaining a stable population size or the inclusion of an animal release component.
Often management of a population results in recommendations being made for the transfer of animals from one place to another in order to facilitate best practice animal pairings. Whilst the focus of Population Management work is largely science based the inevitable practicalities of managing a population which spans geographic area and consists of free thinking animals must also be factored in. Due attention must be paid to animal companionship and successful social integration as well as the needs of the various regions which support the managed population and the range state. This dynamic science provides an opportunity to contribute to species conservation in a measured and sustainable manner, helping to ensure the persistence of valuable threatened species.
‘Founders’ are those wild caught animals which have bred and have living offspring or descendants of living offspring in the current population. ‘Potential Founders’ are those animals which are wild caught and have yet to breed successfully and provide living descendants in the current population.
Why have a GCMP for Javan Gibbons?
The Javan gibbon captive population is relatively small and difficult to sustain in the long term without some form of co-operation between regions. Population analysis has determined that long term sustainability will require an improvement in breeding success and management of the entire captive population as one meta-population.
The Javan gibbon wild population is also relatively small with the likelihood of suitable areas available for reintroduction. Whilst the priority for Javan gibbons housed within rehabilitation centers should always be that these gibbons be reintroduced into the wild, there should also be some recognition that not all of these gibbons will achieve suitable rehabilitation and in some cases gibbons born and raised in good captive institutions may be more suitable for reintroduction.
The GCMP can also provide assistance to institutions to improve husbandry standards and breeding success negating the need for further acquisition of wild gibbons.
Management of an international studbook with detailed information about all Javan gibbons within the program will also assist to ensure closer scrutiny of gibbon acquisitions.
The goal of the Javan Gibbon GCMP is to maintain 90% gene diversity for 100 years. In many species programs this is only possibly with significant importation of animals from other regions or wild populations. The rate of importation required is influenced by many factors including:
- the level of breeding success and/or
- total allowable population size.
As the primary objective of the GCMP for Javan Gibbons is to manage the global population effectively and to provide tangible links between ex situ and in situ conservation efforts it would be inappropriate to source additional gibbons from wild populations. The use of wild caught animals to meet zoos requirements is unethical as well as being unsustainable.
In order to effectively manage the current global population of Javan gibbons and to meet the goals stated above whilst avoiding importation of additional wild gibbons the population would be required to grow to 680 Javan gibbons. Resource limits mean that this is not achievable. Despite this, a viable option is to improve the breeding success of Indonesian zoos and enhance genetic management through greater communication and cooperation between participating institutions.
The following tables provide current analysis of the captive population.
Table 1: Current genetic and demographic parameters of the Total Global Captive Population of Javan Gibbons at 01/06/2010.
| Total Global Population | |
| Number of Living Animals | 148 |
| Number of Institutions | 19 |
| Founders | 20 |
| Potential Founders | 88 |
| Mean F | 0.0006 (0.0002 – Potential Founders Included) |
| Mean MK | 0.0747 (0.0118 – Potential Founders Included) |
| GD | 92.53% (98.82% – Potential Founders Included) |
| Importation Required to Meet Goals (90%/100yrs) |
Yes |
| Rate of Importation Required | 1 animal every 5 years (see above) |
| Program Needs | Increased breeding success |
Table 2: Current genetic and demographic parameters of the Indonesian Captive Population of Javan Gibbons at 01/06/2010.
| Indonesian Population | |
| Number of Living Animals | 92 |
| Number of Institutions | 7 |
| Founders | 7 |
| Potential Founders | 83 |
| Mean F | 0.0000 |
| Mean MK | 0.1429 (0.0058 – Potential Founders Included) |
| GD | 85.71% (99.42% – Potential Founders Included) |
| Importation Required to Meet Goals (90%/100yrs) |
No |
| Rate of Importation Required | N/A |
| Program Needs | Increased breeding success |
Table 3: Current genetic and demographic parameters of the Global Captive Population of Javan Gibbons Excluding Indonesia at 01/06/2010.
| Global Population Excluding Indonesia | |
| Number of Living Animals | 56 |
| Number of Institutions | 12 |
| Founders | 13 |
| Potential Founders | 6 |
| Mean F | 0.0007 (0.0005 – Potential Founders Included) |
| Mean MK | 0.0855 (0.0642 – Potential Founders Included) |
| GD | 91.45% (93.58% – Potential Founders Included) |
| Importation Required to Meet Goals (90%/100yrs) |
Yes |
| Rate of Importation Required | 1 animal every 3 years |
| Program Needs | Access to founders |
Table 4: Current genetic and demographic parameters of the Regional Captive Populations of Javan Gibbons at 01/06/2010.
| Europe | North America | Australasia | Indonesia | |
| Number of Living Animals | 36 | 13 | 7 | 92 |
| Number of Institutions | 7 | 3 | 2 | 7 |
| Founders | 10 | 12 | 7 | 7 |
| Potential Founders | 6 | 1 | 1 | 83 |
| Mean Fecundity | 0.0000 | 0.0000 | 0.0045 (0.0039 – Potential Founders Included) |
0.0000 |
| Mean Mean Kinship | 0.1145 (0.0767 – Potential Founders Included) |
0.1176 (0.0941 – Potential Founders Included) |
0.2146 (0.1721 – Potential Founders Included) |
0.1429 (0.0058 – Potential Founders Included) |
| GD | 88.55% (92.33% – Potential Founders Included) |
88.24% (90.59% – Potential Founders Included) |
78.54% (82.79% – Potential Founders Included) |
85.71% (99.42% – Potential Founders Included) |
| Importation Required to Meet Goals (90%/100yrs) |
Yes | Yes | Yes | Yes |
| Rate of Importation Required | 1 animal every 2 years | 2 animals every 1 year | 2 animals every 1 year | N/A |
| Program Needs | Access to founders | Access to founders | Access to founders | Increased breeding success |
Related Documents and Websites
- Javan Gibbon Living Studbook (pdf)
- Javan Gibbon Living by Institution (pdf)
- Current Institutional Holdings of Javan Gibbons (pdf)
- Current Institutions in the JG GCMP (pdf)
- Javan Gibbon Historic Studbook (pdf)
- ISIS Website www.isis.org
