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

The Conservation Status of Gibbons in Vietnamknown population of the species in Vietnam and it appears to be stable. The effective protectionof this population is probably at least partly due to recent international conservation efforts in thebroader landscape implemented by WWF. The population of N. annamensis in Song ThanhNature Reserve may be significantly larger than is currently known, and thus may representanother priority site for this species. Kon Ka Kinh National Park, Kon Cha Rang Nature Reserveand surrounding forest may also represent an important landscape for conservation of thespecies.Southern Yellow-cheeked Gibbon - Nomascus gabriellaeCat Tien National Park and its landscape, including surrounding State Forest Enterprises andparts of Dong Nai Nature Reserve, have a large population of N. gabriellae, which at least appearsto be generally stable in Cat Tien National Park. This national park is one of the most secure inVietnam in terms of its capacity to protect biodiversity and thus appears to offer an importantlocation for long-term protection of this species. Another very large population of this speciespersists in Bu Gia Map National Park and surrounding forests. With the two largest knowngibbon populations in Vietnam, these two areas are of high national and internationalsignificance for conservation for this species. The complex of protected areas on the Da Latplateau, including Chu Yang Sin National Park, Bi Dup-Nui Ba National Park, Phuoc BinhNational Park and Hon Ba Nature Reserve, and their environs together may also maintain animportant gibbon population of as yet unknown size.2.4 Overall Threats to Gibbons2.4.1 HuntingHunting with guns stands out as a primary threat to gibbons at nearly all sites where they areknown to be still present in Vietnam, and is surely the primary reason for recent population losses.Only in Phong Dien Nature Reserve and the Cao Vit Gibbon Conservation Area is hunting notreported to be currently a threat to the local gibbon population. But, given the threat of huntingreported throughout Vietnam, it can be assumed that at all locations there is always a threat fromhunting, even if from outsiders making a one-off opportune hunting trip. The impact of huntingon gibbons in the recent past is undeniable. Even where there are still large gibbon populations inintact primary forest, they usually occur at much lower than expected population densities,suggesting hunting as the primary threat.Gun hunting is the most critical issue for gibbon conservation in Vietnam. Gibbons are particularlysusceptible to gun hunting pressure. Being arboreal and relatively large and agile, they have fewnon-human predators and are quite conspicuous and easy to find; initially from their loud anddistinct calls, and then closer up from their active nature and visibility, in particular the brightcolouration of the females. The low birth rate of gibbons compared to many other mammalsmeans a population will take longer to recover from an intensive period of hunting pressure or, ifthere is sustained hunting pressure, a continuous population decline as births cannot replace thenumbers being killed. The threat of females being removed to source infants as pets poses aparticular problem. Gibbons may be the first primates to be lost in an area where gun huntingoccurs. For example, this is the case at Than Sa-Phuong Hoang Nature Reserve where apopulation of Francois’ langurs Trachypithecus francoisi still remains (Le Dinh Duy 2010), andgibbons appear to have been quite recently extirpated (Luu Tuong Bach & Nguyen Van Truong2011a). Given this particular susceptibility, the health of a gibbon population can serve as a goodindicator for a protected area of general levels of gun hunting pressure, unless gun hunting isparticularly targeting other species. There are only very few locations in Vietnam where gibbonpopulations are likely to be large enough not to be seriously impacted by some level of huntingwith guns.14