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

The Conservation Status of Gibbons in VietnamGenerally the future for gibbons in Vietnam remains precarious, but the status of each gibbonvaries dramatically and there is a marked difference between northern and southern Vietnam. Formost sites there is insufficient information to make a qualified judgement on a population trendover the past ten years, other than recognising that the presence of hunting is most likely to becausing population declines. Although, for about a quarter of sites reported here, a declininggibbon population has been demonstrated with certainty and the reality is probably that gibbonpopulations are declining at most sites. Here we will look at some of the general trends for eachspecies. For more details please refer to the relevant species chapters.The eastern black gibbon, N. nasutus, was rediscovered in 2002 on the border with China inTrung Khanh District, Cao Bang Province and conservation efforts at this site so far appear to bedemonstrating a gradual population recovery. This is the only location globally where this speciesis currently known to exist, although local extirpations in other areas may have occurred in thelast 10 years. Fortunately, at this location there have been very few records of hunting with gunsand no records of gibbons being hunted since the population was discovered. N. nasutus has, thusfar, been turned around from the brink of extinction both in Vietnam and globally following itsrediscovery. It is the only gibbon species in Vietnam for which it can be said with any confidencethat there has been an increase in population, but that is mainly due to the entire populationbeing so small, about 19 groups (including groups in China), and entirely in one place so it can beeasily monitored, and conservation efforts can be very focussed.There are few records of large gibbon population crashes occurring recently, but that may bemore as a result of lack of data, than the reality of the situation on the ground. The most closelymonitored gibbon populations in Vietnam are those of the western black gibbon, N. concolor,in the Hoang Lien Mountain range, which overall have undergone a population decline greaterthan 50% since surveys were first carried out in 2000 and 2001. At Hoang Lien-Van Ban NatureReserve, the gibbon population has dropped to a level where it is no longer viable and it ispossible that the Mu Cang Chai-Muong La population, slightly to the south, would haveundergone a similar decline without a concerted effort to protect them over the past ten years. Atthe latter location, following a strong decline in the first half of the decade the population withinMu Cang Chai Species and Habitat Conservation Area (SHCA), at least, appears to have stabilised.The experience of FFI working in the Hoang Lien Mountains should be a wake-up call for thecritical need for monitoring when working on species-level conservation for gibbons or otherspecies. The population decline of this species, despite long-term conservation attention, isillustrative of the level of threat that gibbons are under in Vietnam generally.For both N. nasutus and N. concolor the mid- to long-term prospects for their survival in Vietnamare far from certain, as they are both dependent upon the survival of single small populations. Theprospects for gibbons appear to improve as we proceed south through the country, and for eachof the other crested gibbon species there is more than one site with a potentially viablepopulation.A revised assessment of the distribution of the northern white-cheeked gibbon, N. leucogenys,indicates that it has a larger range than previously thought a decade ago, now extending furthersouth (Van Ngoc Thinh et al. 2010e). During recent years, survey work, mainly led by ConservationInternational (CI) and the Centre for Natural Resources and Environmental Studies (CRES), cannow give a much clearer picture of the status of this species in Vietnam. All significant recordscome from locations close or next to the Lao border and 79 groups have been reported since2000. Throughout the country there may be at least 190 groups, of which most are currentlyknown from Pu Mat National Park which probably maintains about 130 groups. These gibbons arenow restricted to remote border areas, where they appear to be protected by the harshmountainous terrain. This population is of global significance and may extend well into Laos.Muong Nhe Nature Reserve and Vu Quang National Park, again both on the border with Laos, mayalso hold significant populations of conservation priority. The population of gibbons in Vu QuangNational Park and neighbouring forests remains largely unknown and may be sizeable allowing usto speculate that the population of this species in Vietnam could be as high as 300 groups.Nevertheless, at all locations populations of N. leucogenys appear to be in decline, largely due tohunting, exacerbated by land conversion and forest fragmentation. It is known to have gone8