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

The Conservation Status of Gibbons in Vietnamforest in neighbouring Muong La District, Son La Province, and Hoang Lien-Van Ban NatureReserve, Lao Cai Province.N. concolor was considered to overlap with N. leucogenys in Vietnam and southern Yunnan (DaoVan Tien 1983; Ma & Wang 1986) however a reassessment suggested there was insufficientevidence of this (Fooden 1996; Geissmann et al. 2000) although the possibility still remains (seeMuong Nhe site account in N. leucogenys chapter).4.2 Summary of Status and Distribution in Vietnam4.2.1 Change in Status Since 2000Since the first gibbon status review in 2000 (Geissmann et al. 2000), new status surveys andconservation activities have been conducted for N. concolor, but a significant decline in thenational population has nonetheless occurred. The current population in Vietnam is estimated tobe 64-70 individuals, within a minimum of 22-25 groups. In 2000 the population was estimated tobe less than 100 individuals (Geissmann et al. 2000), but baseline population estimatesestablished in 2000-2001 at three sites, Hoang Lien-Van Ban Nature Reserve, Mu Cang Chai SHCAand Muong La Watershed Protection Forest gave a combined population estimate of about 53groups and more than 140 individuals (see data in site records below). Since then, two to fourcensus surveys have been conducted using consistent methods and experienced researchers ateach site. In 2000-2001, these three sites supported similar numbers of gibbons, but over the pastdecade have experienced dramatically different declines in the numbers of gibbons and groups.The contiguous forest of Mu Cang Chai SHCA and Muong La supports the most gibbons withapproximately 59 individuals within 20 groups. This population has declined by at least 50% overthe past decade, but may now be recovering. In Hoang Lien-Van Ban Nature Reserve the localgibbon population is very fragmented and has only two to five groups remaining.There are two recent anomalous vocalization records of N. concolor from one survey in MuongNhe Nature Reserve (Nguyen Manh Ha et al. 2010a), west of the Black River, where the majority ofthe population is N. leucogenys (see Muong Nhe site account). However these records need to betreated with caution until confirmed.4.2.2 Key Sites for ConservationMu Cang Chai SHCA and Muong La Watershed Protection Forest are treated here as two separatesites owing to differences in management regime, but the forest of these two sites is contiguousand the gibbon population extends between them. Due to a severe decline in gibbon numbersover the past decade in Hoang Lien-Van Ban Nature Reserve, the Mu Cang Chai SHCA-Muong LaWatershed Protection Forest complex is now the only area in Vietnam where N. concolor has arealistic chance of survival. Even so, the population there is quite small and fragmented. There is amarked difference between population trends inside and outside Mu Cang Chai SHCA, whichindicates that the protected area and conservation interventions have protected the gibbonswhen compared to the watershed protection forest in Muong La District (which still supports onethird of the gibbon groups).4.2.3 ThreatsGibbon hunting and deforestation are the principle threats to N. concolor in all sites where thisspecies persists. Hunting is intense in Muong La Watershed Protection Forest, and if not haltedwill cause the local extirpation of remaining gibbon groups and the threat may then spill over intoMu Cang Chai SHCA. A new and key threat is the impending completion of a road from Mu CangChai Town to Che Tao Village, and another new road which will go through or close to Muong LaWatershed Protection Forest and continue adjacent to Mu Cang Chai SHCA. Until recently theremoteness of both sites conferred some degree of protection, but the completion of these roads31