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

The Conservation Status of Gibbons in Vietnamextinct relatively recently in several protected areas, and may be on the point of extinction inseveral more.Compared to a decade ago, the southern white-cheeked gibbon, N. siki, is now understood tohave a much more restricted range (Van Ngoc Thinh et al. 2010e). There is insufficient data toquantitatively assess trends for N. siki however all indications are that with hunting being aprinciple threat there has been an on-going population decline for the species in Vietnam.Fortunately there remain relatively large populations in tracts of forest mainly centred on QuangBinh Province and along the border with Laos, with significant populations likely to be occurringin the forest complexes of Phong Nha-Ke Bang National Park-Truong Son State Forest Enterpriseand Khe Giua State Forest Enterprise-Bac Huong Hoa Nature Reserve. However, information gapsfor N. siki make the status of this species the most uncertain of all gibbon species in Vietnam,although a minimum of about 100 groups are reported here from compiled records.The northern yellow-cheeked gibbon, N. annamensis, was only recently described, which hasled to a revision of the species affinity for several sites previously thought to hold N. siki or N.gabriellae. The range of N. annamensis has been fairly well-surveyed, particularly in Thua ThienHue Province, which has been a focal area for the work of WWF. About 200 groups have beenrecorded throughout its range in Vietnam and there are likely to be more in unsurveyed areas.The contiguous protected area of Dak Rong and Phong Dien Nature Reserves hold the largestknown population with over 80 groups, but at much lower than natural densities as a result ofprevious hunting pressures. Song Thanh and Ngoc Linh Nature Reserves in Quang Ngai andQuang Nam Provinces, and Kon Ka Kinh National Park, Kon Cha Rang Nature Reserve andsurrounding production forests in Kon Tum Province may also hold significant populations.The numbers of southern yellow-cheeked gibbon, N. gabriellae, the most southerly distributedspecies, probably make up more than half the gibbons in Vietnam. There are at least 300 gibbongroups in just two areas: Bu Gia Map National Park and surrounding forests and the Cat TienNational Park-Dong Nai Nature Reserve complex and surrounding forests. The complex ofprotected areas and surrounding forests on the edge of the Da Lat plateau extending from ChuYang Sin National Park down to Hon Ba National Park potentially has a large population, but thereis still inadequate data on most of these locations. Additionally N. gabriellae is recorded innumerous State Forest Enterprises (SFEs) and there are likely to be more populations as yetunrecorded. Records in SFEs are likely to be under-represented as they fall outside of theprotected area system and are therefore less likely to be the attention of biodiversity surveys.There are no sites in Vietnam where a formerly viable gibbon population ten years ago can nowbe confirmed to be extinct. However there are several nature reserves, which had provisionalrecords or very small populations documented by Geissmann et al. (2000), where gibbons havelikely been extirpated. These include Kim Hy, Than Sa-Phuong Hoang, Xuan Son, Hang Kia-Pa Co,Pu Luong and Pu Hu Nature Reserves. Tragically two of these sites held the Critically EndangeredN. nasutus for which any other additional populations, however small, would be very importantfor possible long-term genetic management of the species.2.2 Protection Status for Vietnam’s GibbonsThis section describes the recognition that gibbon species in Vietnam receive as protected speciesboth nationally and internationally. While gibbons are afforded the highest level of legalprotection as species in Vietnam, awareness of this fact by the general public and evengovernment staff is low and law enforcement is weak, so as to render their legal status almostirrelevant. Nevertheless they are a starting point and indicate recognition of the need forprotection of gibbons at the highest levels of government. In particular we have taken theopportunity to assess the current status listing in the Vietnam Red Data Book and suggestrevisions based upon the findings of this conservation status review.9