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

The Conservation Status of Gibbons in Vietnam2.2.1 Decree 32/2006/NP-CP on Management of Endangered, Preciousand Rare Forest Plants and AnimalsPrime Minister’s Decree 32/2006 classifies and defines the level of protection for protected wildanimals and plants in Vietnam within two groups; I and II. Gibbons are classified under IB, thehighest level of protection for animals which are “strictly banned from exploitation and use forcommercial purposes, including plants and animals of scientific or environmental value or higheconomic value, with very small populations in nature or in high danger of extinction”. Nomascusconcolor, N. leucogenys, N. nasutus and N. gabriellae are all explicitly listed and it may be assumedthat the listing of N. leucogenys covers N. siki as the sub-species N. leucogenys siki, as it is recordedin the Vietnam Red Data Book and elsewhere in literature from that time.This decree is soon to be supplemented by a decree on “Criteria for Species Identification,Management and Protection of Species listed as Endangered, Precious, Rare and Prioritized forProtection”, which brings formal levels of protection more into line with the categories andcriteria of the Vietnam Red Data Book.2.2.2 Vietnam Red Data BookAll gibbon taxa listed in the current 2007 Vietnam Red Data Book come under the categoryEndangered with the criteria A1cd C2a, which broadly indicates that there has been a 50% declineand severe fragmentation of the population of each species, and that the species is facing a veryhigh risk of extinction in the wild. N. nasutus and N. annamensis are not directly referred to. N.nasutus falls within the distribution map presented for N. concolor and N. annamensis was notdescribed as a distinct species at the time.However, the actual population status and levels of threat of extinction vary widely for thedifferent gibbon species in Vietnam, and with the more comprehensive information now availableit is clear that this one category and set of criteria is inappropriate for all species. The national RedData Book should clearly indicate relative levels of threat to each species and so supportprioritisation of conservation measures through policy and direct action. A more appropriatecategorisation for each gibbon species following the criteria of the Vietnam Red Data Book (SeeAnnex 2) is proposed here. It is not intended to be definitive but to provide a starting point forfuture revisions of the Vietnam Red Data Book.In proposing these categories and criteria, certain assumptions have to be made where there islarge uncertainty in the available data. This uncertainty is compounded by the fact of a gibbongeneration being long compared to most mammals. In this document a gibbon generation isconsidered to be about 15 years, following the standard used for gibbons on the IUCN Red List ofThreatened Species. The low fecundity of gibbons means long periods of time need to beconsidered in order to track declines and forecast potential recovery. One generation, i.e. 15 years,is already long enough that sufficient records are not available to make quantitative analyses ofpopulation trends based on existing data, so past population trends need to be inferred.However, overall it is assumed with confidence that there have been drastic declines in gibbonpopulations within the last few gibbon generations, based upon the previous known extent ofgibbon occurrence, land-use change and past and present levels of hunting pressure.Eastern Black Gibbon - Nomascus nasutusProposed category and criteria: Critically Endangered A1cd, B1+2cdThe current population of N. nasutus in Vietnam is well documented. There has been a decline inthe population of this species over the past three generations greater than 80%, based on thearea of occupancy and extent of occurrence being reduced to one population in an area of about1000 ha. Recent likely local extirpations, such as at Kim Hy and Than Sa-Phuong Hoang NatureReserves, have no doubt been due to hunting and indicate continued recent declines. N. nasutusthus certainly qualifies for the status of Critically Endangered in Vietnam.10