Transboundary conservation of the last remaining population of the cao vit gibbon Nomascus nasutus
CHAN G - YO N G MA *,HOA N G TRINH-DIN H *,VAN -TRUONG NGUYEN TRONG-DAT L E,VAN-DUNG L E,HUU-OANH L E ,J IANG YANG ZI -J IE ZHANG and P EN G -F EI FAN*
Abstract The cao vit gibbon Nomascus nasutus, also known as eastern black crested gibbon, is categorized as Critically Endangered on the IUCN Red List and was considered one of the world’s 25 most threatened primates. The only known population occurs along the border between China and VietNam. Accurate information on population size and dynamics is critical for the species’ conservation, but popu- lation surveys conducted in only one country may over- or underestimate total population size because the home ranges of cao vit gibbon groups often cross the international border. In 2007 and 2016 we conducted two collaborative transboundary censuses of the cao vit gibbon populations in the Trung Khanh Cao Vit Gibbon Species and Habitat Conservation Area in Viet Nam and the Bangliang Gibbon National Nature Reserve in China. The results showed a population size of 102–110 in 2007, which in- creased to 107–136 in 2016.Our results indicate that previous surveys conducted separately in Viet Nam and China underestimated the global population size of this species. According to our more comprehensive surveys, the gibbon population is increasing slowly. The gibbons and their habitat are legally protected in both countries. Hunting and charcoal making have not been reported in this area since 2007. As habitat carrying capacity is a limiting factor, habitat restoration is required. However, lack of funding to protect the cao vit gibbon remains a challenge.
Keywords Cao vit gibbon, China, Nomascus nasutus, popu- lation size, threats, transboundary conservation, Viet Nam
Supplementary material for this article is available at
https://doi.org/10.1017/S0030605318001576
Introduction
2018) and often artificially separate animal populations. Transboundary populations that live along international borders are often subject to different management regimes on each side of the border (Gervasi et al., 2016; Linnell et al., 2016; Thornton et al., 2018). Language barriers, lack of trust, and differences in sampling designs and data collection protocols can make transboundary information exchange difficult (Vitkalova et al., 2018), hindering the effective conservation of such populations. The cao vit gibbon or eastern black crested gibbon
P
Nomascus nasutus was once widespread in south China and north-east Viet Nam, east of the Red River (Tien 1983; Geissmann et al., 2000; Rawson et al., 2011). Hunting and habitat loss have led to a dramatic population decline (Geissmann et al., 2000) and by the 1960s the cao vit gibbon was thought to be extinct in both countries (Tan, 1985; Geissmann et al., 2003). The species was rediscovered in 2002 in a small karst forest patch in Trung Khanh District, Cao Bang Province, Viet Nam, close to the Chinese border (La & Trinh Dinh, 2002; Geissmann et al., 2003). In 2006 the species was observed in the same forest patch on the Chinese side (Chan et al., 2008), making it a transboundary population. Because only one small population survives, the cao vit
CHANG-YONG MA and PENG-FEI FAN (Corresponding author) School of Life Sciences, Sun Yat-sen University, No. 135, Guangzhou, 510275, China E-mail
fanpf@mail.sysu.edu.cn
HOANG TRINH-DINH,VAN-TRUONG NGUYEN,TRONG-DAT LE,VAN-DUNG LE and HUU-OANH LE, Fauna & Flora International—Viet Nam Programme, Hanoi, Viet Nam
JIANG YANG The Administration Bureau of Guangxi Banglinag Gibbon National Nature Reserve, Jingxi, China
ZI-JIE ZHANG Fauna & Flora International—China Programme, Nanning, China
*Contributed equally. Received 27 October 2018. Revision requested 28 November 2018. Accepted 20 December 2018. First published online 26 September 2019.
gibbon is considered the second rarest ape species. Only the Hainan gibbon Nomascus hainanus has a smaller popu- lation size (ca. 29 individuals; Bryant et al., 2016). The cao vit gibbon is categorized as Critically Endangered on the IUCN Red List (IUCN, 2017) and was considered one of the world’s 25 most threatened primates during 2008–2014 (Mittermeier et al., 2009, 2010, 2012). The species’ habitat has been seriously degraded as a result of selective logging, charcoal making, farming and livestock grazing (Fan et al., 2013). To conserve the last population of the cao vit gibbon, the Vietnamese government established the Trung Khanh Cao Vit Gibbon Species and Habitat Conservation Area in 2007, and the Chinese government set up the Bangliang Gibbon Autonomous Nature Reserve in 2009 and upgraded it to national protection level in 2013 (Fig. 1). Accurate information on population size and dynamics
is critical for conservation of threatened species. However, population surveys conducted on only one side of a political
Oryx, 2020, 54(6), 776–783 © 2019 Fauna & Flora International doi:10.1017/S0030605318001576
olitical borders rarely coincide with the natural boundaries of wildlife populations (Vitkalova et al.,
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