Nomascus leucogenys
Status A 13 day survey in July 2011 reported at least 10 groups in the north-west of Vu Quang National Park, which may be part of a significantly larger population as the majority of the national park has not been surveyed (Nguyen Manh Ha et al. 2011b). This is much higher than previous records in 2001 and 2004, which recorded three gibbon groups in Huong Khe and Huong Son Districts and two individuals in captivity (Nguyen Manh Ha 2005). Vocalisations were commonly heard in the core zone during elephant surveys in 1993-1994 (Dawson & Do Tuoc 1997). Other fragmentary records from before 2000 are listed in Geissmann et al. (2000). Threats and Conservation Actions Hunting and loss of forest habitats due to illegal logging are the principal threats to N. leucogenys and other wildlife in this national park. Hunting does not appear to target gibbons, but they are nonetheless occasionally hunted (Nguyen Manh Ha et al. 2011b). Vu Quang National Park maintains a good area of evergreen forest connected with Huong Son forest (see above) to the north and Nakai-Nam Theun National Protected Area (353,200 ha) to the south-west in Laos, where gibbons there are reported to be N. siki, although the species needs to be confirmed (MAF 2011). With an apparently large population of N. leucogenys for Vietnam and being part of a much larger transboundary conservation landscape, this site should be considered a priority for conservation of N. leucogenys in Vietnam. Nakai-Nam Theun NPA is supported with annual payments of US$1 million until 2037 from hydropower dam revenues. In Vietnam, the border area with Nakai-Nam Theun NPA, including Vu Quang National Park, is subject to an FFI project to strengthen transboundary cooperation for biodiversity conservation between the two countries. Further surveys throughout the national park are needed to ascertain the status of gibbons there and to confirm the species based upon records of calls or (less likely) through genetic analysis. Gibbons should be a focal and indicator species for conservation activities in this landscape.
5.3.13 Ke Go Nature Reserve Location: Huong Khe, Cam Xuyen and Ky Anh Districts, Ha Tinh Province Area: 21,759 hectares Status criteria: 1a, 2a, 3b, 4b, 5c Date of most recent survey: 2010 Date of most recent confirmed record: 2010 Minimum population: 4 groups (≼ 8 individuals) Status It is unclear whether the gibbons in this reserve are N. siki or N. leucogenys although vocal analysis provisionally suggests the former, (Van Ngoc Thinh et al. 2010a), assumptions about distributions of the taxa suggest the latter (Van Ngoc Thinh et al. 2010e). The population in the reserve is very low and near extirpation. In 2010 only four groups of about eight individuals were recorded in scattered locations in the nature reserve, during gibbon surveys covering 22 listening posts (Van Ngoc Thinh et al. 2010a). No more than one group was found at any one location, suggesting the remaining small population is highly fragmented and likely to be no longer viable. Threats and Conservation Actions Efforts by the reserve management board to control wildlife hunting have been unsuccessful (Van Ngoc Thinh et al. 2010a). Hunting in the reserve has been further facilitated through the construction of National Roads 21 and 22 (Van Ngoc Thinh et al. 2010a), which have increased hunter access. Logging and habitat clearance occurs in and around the reserve and is degrading gibbon habitats (Le Trong Trai et al. 1999b; Van Ngoc Thinh et al. 2010a). Together Ke Go Nature
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