This species is listed in CITES Appendix I, and is protected in Viet Nam under the wildlife protection law (Government of Vietnam 2006, 2013) and is listed as Critically Endangered in the Vietnam Red Data Book (2007). The species occurs in several protected areas in Viet Nam, including Song Thanh Nature Reserve, Ngoc Linh Nature Reserve, Kon Ka Kinh National Park, and Kon Cha Rang Nature Reserve; however, protection against hunting and habitat disturbance is not completely enforced (Ha Thang Long 2004, 2009, Nadler and Brockman, 2014). A long-term study in Gia Lai Province included in the "Viet Nam Primate Conservation Program" of the Frankfurt Zoological Society has been in place since early in the last decade (Ha Thang Long 2004, 2007, 2009), and additional surveys in the distribution area are also included in the program, which may perhaps identify new populations. A number of conservation education programs have been offered in and around Kon Ka Kinh National Park over the past decade. There is an ongoing captive-breeding program for this species at the Endangered Primate Rescue Center at Cuc Phuong National Park in Viet Nam, which also incorporates an education component. Going forward conservation priorities include: establishing a protected area or appropriate conservation measure to conserve the sub-population in Kon Plong forest, Kon Tum Province; conducting surveys to estimate the population status of sub-populations that live outside the protected forests in Quang Nam, Quang Ngai, Binh Dinh and Phu Yen; establishing a green corridor between Kon Ka Kinh National Park and Kon Chu Rang Nature Reserve to allow gene flow between the two protected areas; integrating the primate monitoring program on protected forest Plan in Kon Ka Kinh NP, Song Thanh NR, Kon Chu Rang NR and Ngoc Linh NR; and conducting education initiative at the provincial level to inform public about the species and conservation value of the Grey-shanked Douc
This species occurs in central Viet Nam, in Quang Nam, Quang Ngai, Binh Dinh, Kon Tum, Gia La, and Phu Yeni provinces (Lippold and Vu Ngoc Thanh, 1995, 1999, 2002; Nadler et al. 2003; Ha Thang Long 2004, 2007, 2009; Nadler and Roos 2013; Nadler and Brockman 2014; Hoang Minh Duc et al. 2015). There is also a provisional report on its occurrence in adjacent areas of Cambodia (Roos et al. 2014).
The total population for this species is estimated at 550 to 700 individuals, but some areas with assumed occurrence are not yet surveyed (Ha Thang Long 2004).
The global population is unknown but is likely smaller than 2,000. The entire population estimate for Viet Nam is about 1,450-1,700 individuals. There are 14 isolated subpopulations currently confirmed with available data. Four subpopulations are in protected forests (Kon Ka Kinh National Park, Kon Chu Rang Nature Reserve, Ngoc Linh National Park, and Song Thanh Nature Reserve) with about 560-600 individuals within 1,200 km² of natural forest. Kon Ka Kinh NP has the largest Grey-shanked Douc subpopulation, with about 250 individuals within an area of 420 km² (Lippold and Vu Ngoc Thanh, 1995, 1999, 2002; Nadler et al. 2003; Ha Thang Long 2004; Nadler and Brockman 2014; Hoang Minh Duc et al. 2015). Nine subpopulations occur in unprotected forests; these contain nearly 50% of the global population of Pygathrix cinerea, with about 600 individuals. The most recent survey of a subpopulation of Grey-shanked Doucs occurred in Kon Plong district forest and it revealed approximately 450 individuals in this forest (B. Rawson, unpublished data).
The Central Highlands forests in Viet Nam where these animals occur lose almost 10,000 ha of forest annually due to logging, agricultural conversion, building hydropower stations, and construction of roads. This creates a progressively more fragmented habitat and population structure. Additionally, they are hunted for food, traditional "medicine" (for example it is used in the preparation of "monkey balm"), and for sale as pets (Ha Thang Long 2004, 2007). Their behavioural responses to hunting, hiding motionless in the canopy rather than fleeing, make them more vulnerable (Nadler et al. 2003); they also become susceptible to snaring when they come to the ground to move in degraded habitats.
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Nguyen Van Truong (category and featured image)