JP/18/GIBBON
Conservation a priority for endangered Javan gibbon
Jarot Arisona Contributor/Depok
The Javan, or silvery, gibbon (Hylobates moloch) is one of the world's rarest primates.
This lesser ape occurs nowhere but on Java, more precisely, in the western and central part of the island. It is confined to floristically rich patches of relatively undisturbed lowland to lower mountain rain forest of less than 1,600 meters in altitude.
During the last decade, the Javan gibbon population has declined rapidly throughout its range, mainly due to the loss of tropical forest habitat. According to Whitten and others (1999), Java has lost close to 90 percent of its tropical forest, leaving less than 19,828 square kilometers of forest, mostly mountain areas.
Furthermore, the economic crisis since 1997 and misinterpretation of the meaning of reform prompted people to clear many of the remaining forests for agriculture, causing more deforestation.
A study on the Javan gibbon population and distribution was carried out by the Indonesian Foundation for the Advancement of Biological Sciences (IFABS) and Center for Biodiversity & Conservation Studies, University of Indonesia (CBCS-UI), during 2002 and 2003.
The study surveyed 25 forest sites from Ujung Kulon National Park in West Java to the easternmost known distribution of the gibbon, namely the Dieng Plateau in Central Java. New localities for the Javan gibbon, especially in Central Java have been added, namely the Kendeng Mountains (Sekesod, Sokokembang, and Karang Gondang), Mount Jaran (Pandanarum village), and Mount Rendet/Mount Sulaeman (Sigugur village).
All the localities are located in protected forests, which have a lesser degree of protection than nature reserves or national parks. On the other hand, gibbons may have vanished from five localities (Lengkong, Mt. Porang, Mt. Kencana, Bojongpicung, and Pasir Susuru) where they had previously been reported.
The total number of gibbons estimated by this study to still exist ranges between 4,000 and 4,800 individuals. The populations are divided up into sub-populations, with mostly small numbers of individuals living in fragmented, small patches of forest.
Furthermore, the study listed seven locations at which the gibbon population has apparently fallen below 10 individuals, namely, in forest patches on Mt. Papandayan, Mt. Limbung-Halimun, Mt. Jaran, Mt. Rendet/Mt. Sulaeman, Mt. Slamet, Watukumpul, and Lewuweng Sancang.
Under these conditions of small and isolated populations, local extinction can result. Meanwhile, the total extent of the forest patches available to the gibbons is estimated to be only 1,144 sq. km.
The field study records that the gibbons are under threat from multiple direct and indirect threats, the most intense of which originate from forest clearance and agriculture. Meanwhile, geographically speaking, the most extensive source of threats comes from game hunting and land clearance.
This study strongly recommends in-situ gibbon conservation measures by exploring the prospects for establishing new reserves in Central Java as a priority, including in a forest patch of about 9,000 hectares on Mt. Kendeng, Dieng Plateau.
The development and recognition of community conservation areas is recommended, which would ensure long term community engagement toward increased local commitment and protection.
Furthermore, detailed studies and monitoring are needed in 15 most important gibbon sites, including: Mt. Jayanti, Mt. Salak, Telaga Warna, Mt. Malang, Mt. Sanggabuana, Mt. Simpang, Mt. Tilu, Mt. Limbung-Halimun, Mt. Kendeng (Dieng Plateau), Mt. Slamet, Mt. Wayang, Mt. Jaran, Mt. Watukumpul, and Mt. Pembarisan.
The study also supports the call for protected corridors, for instance, between Salak and the Halimun mountains. Overall, responding to the relatively high incidence of trading in gibbons, law enforcement needs to involve the prosecution of the middlemen and the people behind the illegal wildlife trade, with maximum sentencing employed as a deterrent
The writer is a researcher at the Indonesian Foundation for the Advancement of Biological Sciences (IFABS) and Center for Biodiversity & Conservation Studies, University of Indonesia (CBCS-UI).