The Conservation Status of Gibbons in Vietnam - Gibbon Research ...

The Conservation Status of Gibbons in VietnamSummaryIn several respects, the status of gibbons in Vietnam can be considered to be an indicator for thegeneral status of the nation’s biodiversity and the natural environment. The geography ofVietnam lends itself to the extraordinary level of biodiversity for which it is known, and thediversity of gibbons in Vietnam is no exception. They can be found from the most northerly subtropicalforests which experience cold winters at high altitudes to tropical monsoon lowlandforests in the south.This conservation status review of gibbons in Vietnam, updates a similar review which was carriedout in 2000 by Geissmann et al. (2000). That milestone report drew from available literature,examinations of museum specimens and additional field surveys as a first attempt to documentthe status of gibbons in Vietnam. One decade later, this current report attempts to assess trendsin the populations of each gibbon species in Vietnam and the effectiveness of efforts so far toconserve them. This status review is part of a broader set of initiatives in this region which includeaction plans in both Laos and Yunnan Province, China, and is thus also able to give a regionalcontext. We have collated records of gibbons from all sites in Vietnam known to have gibbonsand where information can be assessed to be reliable. With so much more work carried out ongibbons during the past ten years, this report provides a clearer snapshot of the status of gibbonsin Vietnam than was possible a decade ago.Conservation Status by SpeciesAll gibbons in Vietnam belong to the genus of crested gibbons Nomascus. Current taxonomicunderstanding identifies seven species of Nomascus, all distributed east of the Mekong River (withthe exception of a small population) in Cambodia, China, Laos and Vietnam, six of which arefound in Vietnam (see Figure 1, page 7). The species in Vietnam being, from north to south:1. Eastern black gibbon Nomascus nasutus2. Western black gibbon Nomascus concolor3. Northern white-cheeked gibbon Nomascus leucogenys4. Southern white-cheeked gibbon Nomascus siki5. Northern yellow-cheeked gibbon Nomascus annamensis6. Southern yellow-cheeked gibbon Nomascus gabriellaeThe eastern black gibbon N. nasutus is the only gibbon species in Vietnam for which prospectsappear to have improved during the past decade. The species was rediscovered in 2002 on theborder with China in Trung Khanh District, Cao Bang Province and conservation efforts so farappear to be driving a gradual population recovery. This is the only location globally where thisspecies is currently known to exist and this population of only about 110 individuals is nowrestricted to approximately 1,000 hectares of limestone forest. It was previously distributed innorth-east Vietnam, with the Red River and its delta forming a natural boundary to the west andsouth. Fortunately, at this location there have been very few records of hunting with guns and norecords of gibbons being hunted since the population was discovered. N. nasutus is the onlygibbon species in Vietnam for which it can be said with any confidence that there has been anincrease in population. Despite, this, given the small size of its population and highly restricteddistribution, N. nasutus should be uplisted from Endangered to Critically Endangered in theVietnam Red Data Book. Globally it is listed as Critically Endangered on the IUCN Red List.The western black gibbon N. concolor has been the most closely monitored gibbon species inVietnam over the past decade. Within Vietnam it is distributed in the Hoang Lien mountain rangebetween the Black and Red rivers. Globally most of the population of this species occurs furthernorth in Yunnan Province, China and there is a small population in north-west Laos. In Vietnam,the population has undergone a population decline greater than 50% since surveys were firstxi