Contributions to Zoology, 75 (3/4) 161-168 (2006) In-Situ and Ex-Situ status of the Javan Gibbon and the role of zoos in conservation of the species Vincent Nijman Zoological Museum, University of Amsterdam, PO Box 94766, 1090 GT Amsterdam, The Netherlands, E-mail: [email protected] Key words: captive populations, conservation, Indonesia, PHVA, population management Abstract Introduction The Javan gibbon Hylobates moloch is confi ned to the last rem- The Javan gibbon Hylobates moloch (also known as nants of rainforest on the island of Java, Indonesia. As of 2002, silvery gibbon) is confi ned to patches of undisturbed the species has been recorded in 29 forest areas, and the wild lowland and lower montane rainforest below 1600- population is conservatively estimated at 4100-4500 individuals. 1800 m asl on the western part of island of Java, Over 95% of the gibbons are in populations of >100 individuals, and the four largest areas support populations of >500 individu- Indonesia. Java is densely populated with about 120 als each. In 2003, 56 Javan gibbons were maintained at eight million people at an average population density of Indonesian zoos, 15 at four Indonesian wildlife rescue centres, >900 people km-2. Although once fully covered in with fi ve potential breeding pairs. There is no evidence that the forest, it is now largely cultivated and forest remains species has bred successfully in captivity in Indonesia. Outside as scattered isolated pockets. Hence, populations of the range country, 48 Javan gibbons were maintained at ten in- stitutions in nine countries, with six breeding pairs. The total Javan gibbons are highly fragmented and are threat- ex-situ population is some 120 individuals, the majority of which ened mainly by loss and degradation of habitat. is wild-caught. At present most initiatives relating to the conser- Alongside 19 other primate taxa, the Javan gibbon vation of the Javan gibbon have targeted small isolated forest is listed as Critically Endangered by IUCN (note areas and the ex-situ population, whereas in-situ protection of however that this assessment was made in 2001 and the largest populations in the wild has been largely ignored. new information on the conservation status of many Signifi cant populations are currently found in unprotected forests. The large captive population of Javan gibbons within Indonesia taxa has emerged, for Southeast Asia see e.g. Geiss- allows, with improved co-operation, to set up an integrated cap- mann et al. 2004 and Nijman 2004b). The Javan tive-breeding programme. This should, not be seen, however, as gibbon is furthermore included on Appendix I of a means to improve the conservation status of the wild Javan CITES (Convention on International Trade in En- gibbons, which needs to be achieved through protection of re- dangered Species of Wild Fauna and Flora) (which maining habitat, but could be used for improving the prevailing low levels of conservation awareness in Java. prohibits all international trade of the species, its parts and derivatives, among contracting parties), and it was among the fi rst species to become pro- Contents tected by Indonesian law in 1925. In recent years, little research has been conducted on the Javan gib- Introduction .................................................................................... 161 bon, and that has been mostly on behavioural aspects Methods .......................................................................................... 162 (e.g. Dallmann and Geissmann 2001ab, Geismann Results ............................................................................................. 163 et al. 2005, Geissmann and Nijman 2006, Malone Wild population ...................................................................... 163 et al. 2004, Rinaldi 2003; but see Djanibudiman et Captive population ................................................................. 163 al. 2004). Discussion ...................................................................................... 164 Gates (1998) provided an overview of the in-situ Conclusions .................................................................................... 166 Acknowledgements ...................................................................... 167 and ex-situ status of the Javan gibbon. Most of his References ...................................................................................... 167 data from the wild population was derived from a 162 Nijman - Zoos and conservation of Javan gibbons Population and Habitat Viability Analysis (PHVA) and as part of an assessment of the trade in primates workshop that was held by the Conservation Breed- I compiled data on the number of captive Javan gib- ing Specialist Group of the IUCN (Supriatna et al., bons in Indonesia (Nijman, 2005ab, unpublished 1994). He summarised that the observed popula- data). The results from these studies differ substan- tion of about 400 individuals was found in 21 hab- tially from those presented by Gates (1998) and, as itat fragments, 18 of which contained fewer than almost ten years have passed since Gates’ review, an 30 animals, and none of these areas supported pop- updated assessment is presented of the in-situ and ulations of more than 100 individuals. A Vortex ex-situ status of the Javan gibbon. Furthermore, I will analysis revealed that a 100 individuals is the ap- present an alternative view on prioritising conserva- proximate threshold level below which popula- tion and management strategies, and discuss the role tions run a >1% chance of extinction over a 100- zoos can play in this. year time period (Supriatna et al., 1994). Gates (1998) also provided an update on the ex-situ sta- tus of the Javan gibbon as of 1996 and concluded Methods that 14 Javan gibbons were maintained in four In- donesian zoos and 27 Javan gibbons in six institu- I assessed the status of the wild Javan gibbon popu- tions outside Indonesia. He then discussed some of lation by surveying forest areas in 1994-2002 (Nij- the priorities for gibbon conservation and some of man, 1995, 2001, 2004a; Geissmann and Nijman the interventions that he deemed necessary to man- 2006). The status of the captive Javan gibbon popu- age the population. In short these priorities were: lation was assessed in 2003-2004 by visiting 14 1. The periodic transfer of 2-3 individuals between zoological gardens and 11 wildlife rescue centres in wild population fragments, as part of a regional western Indonesia. The origin of the gibbons was management strategy, and protection of small pop- requested from the directors and members of staff. ulations from illegal capture of animals. 2. In- Data on confi scation of illegally-held gibbons and creased protection of Mt Halimun National Park subsequent prosecution of owners and traders were and restoration of degraded areas within the na- requested from the Indonesian forestry department. tional park in order to allow for a signifi cant natu- Data on the captive Javan gibbon population out- ral increase in the gibbon population in the future. side Indonesia were retrieved from Thomas Geiss- 3. Establishment of ten breeding pairs in Indone- mann’s Gibbon Network (www.gibbons.de, last up- sian zoos. dated November 2003), with additional data from I recently completed a study on the conservation Cocks (2001), and corroborated through searches status of Javan gibbons in the wild (Nijman, 2004a), on the internet. Table 1. Ex-situ and in-situ population of the Javan gibbon Hylobates moloch, presenting a summary of Gates’ (1998) review1 and the present assessment2. Median refers to the median number of individuals per population. Gates (1994-1996) Nijman (2002-2003) Individuals Median Individuals Median (populations) (populations) Large populations3 250 (5) 36 3400-3800 (7) 560 Small populations 150 (16) 10 700-720 (22) 22 Total in situ 400 (21) 13 4100-4500 (29) 50 Wildlife rescue centres 0 (0) 0 15 (4) 3 Zoos in Indonesia 14 (4) 3.5 56 (8) 8 Zoos outside range country 27 (6) 2.5 48 (10) 2.5 Total ex situ 41 (10) 3 119 (22) 3 Total in-situ and ex situ 441 4119-4619 1 Additional data retrieved from Supriatna et al. (1994) and Cocks (2001) 2 Methods and number of institutions included in the assessments differ, precluding conclusions on possible changes between 1994- 1996 and 2002-2003. 3 Large populations are the top-quarter of populations. Contributions to Zoology, 75 (3/4) – 2006 163 Results species of gibbon. In most zoos housing conditions were extremely poor, especially when set against Wild population western standards, with the exception of the recent- ly opened Schmutzer Primate Centre in Jakarta and, The Javan gibbon is present in 29 forest areas in at least for Javan gibbons, Bali Zoo Park near Den- western Java (Fig. 1). The total population is con- pasar and Taman Safari Indonesia in Cisarua. These servatively estimated at 4100 to 4500 gibbons (Ta- three zoos were also the only that maintained at ble 1). Although there are a relatively large number least part of their Javan gibbons in pairs, in such of forest fragments with small numbers of gibbons, conditions that they could potentially produce off- >95% of the gibbons are in 11 discrete populations spring. Concerning the origin of the Javan gibbons of a hundred individuals or more. in these zoos, from 12 this was either unknown or I The four largest populations are located in Mt was unable to trace it, 15 were transferred from Halimun (>800 gibbons), Mt Simpang, Mts Dieng other zoos within Indonesia, 24 were donated by and