Discovery of isolated populations of the ‘Critically Endangered’ grey-shanked douc langur (Pygathrix cinerea) in Quang Nam Province, Vietnam

The grey-shanked douc langur (Pygathrix cinerea) is one of the world’s rarest primate species. Following up on scarce information about the occurrence of this species in the southern part of Quang Nam Province, we carried out surveys to verify the existence of the species and to estimate the population size. We confirmed four extremely small, isolated populations with a total of 48 to 50 individuals.

The results of the survey induced provincial and local authorities to immediately implement actions to protect the douc langurs and the remaining habitat as well. A “Community Forest Protection Team” was established to patrol the area daily and any deforestation to extent an Acacia plantation is now strictly prohibited. Furthermore the provincial authorities plan to develop a conservation action plan for the remaining douc langur populations and to grant the protection status for the four hills, which they inhabit. To this purpose about 80 ha of Acacia plantation will be repurchased from locals in order to set up a 10 years reforestation project and to create forest corridors between the currently isolated hills.

The grey-shanked douc langur (Pygathrix cinerea) counts among the ‘World’s 25 Most Endangered Primates’ (Mittermeier et al. 2012) and is listed as ‘Critically Endangered’ on international (IUCN Red-List of Threatened Species 2019) as well as national level (Ministry of Science and Technology & Vietnamese Academy of Science and Technology 2007). The population in Vietnam is highly fragmented and the species is in the focus of the country’s protection and conservation activities (Prime Minister of Government 2017).

Following up on scarce information from locals about the occurrence of this species in the southernmost part of Quang Nam Province, we carried out surveys to verify the existence of the species, to estimate the population size, to assess the threats and to recommend measures for its conservation. The occurrence of the species in the central and northern part of the province had been confirmed during a survey in 2004 (Minh Hoang et al. 2004). But a large group close to one of the new discovered populations disappeared already together with the rest of the forest in the area, replaced with Acacia plantations.

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