Tonkin snub-nosed monkey  (Rhinopithecus avunculus)

The Tonkin snub-nosed monkey is classified as Critically Endangered (CR) on the IUCN Red List (1) and listed on Appendix I of CITES (5).

The Tonkin snub-nosed monkey is one of the most endangered primates in the world, and indeed was presumed extinct for a time before its rediscovery in 1989 (6) (7). Vietnam’s largest primate species (8), it is an unusual and distinctive monkey, with a broad, flattened face, a flat, upturned nose, tufted ears, pale blue rings around the eyes, and thick, pink lips, giving an almost comical appearance. The back, outsides of the limbs and hands and feet are black, although the fur between the shoulders may be more brownish, while the underparts, inner sides of the limbs and the elbows are creamy white. The forehead and cheeks are also creamy, with bluish-black colouration around the mouth, and there is an orange throat patch, which is most prominent in adult males. The long tail is blackish-brown, with whitish tips to the hairs, and a white tuft at the tip (2) (3) (4) (8) (9) (10).

Infant Tonkin snub-nosed monkeys have grey rather than black fur, becoming darker with age, and lack the orange throat patch and the long, whitish hairs of the tail (4) (10) (11). Compared to other Rhinopithecus species, the Tonkin snub-nosed monkey is more slender, with more elongated digits, and shows a lesser degree of sexual dimorphism (8) (10). The calls of this species include a loud, distinct, hiccough-like ‘huu chhhk’, given when alarmed or as a contact call, as well as a softer ‘huu chhhk’, a soft ‘hoo’, and a rapid ‘chit’ (8) (10) (11).

The Tonkin snub-nosed monkey is the only Rhinopithecus species found outside of China, being endemic to northern Vietnam (1) (2) (3) (6) (8). Historically, it occurred east of the Red River (1) (6) (8), but its range has been drastically reduced in recent decades, and it is now known only from small areas of Tuyen Quang, Bac Kan, Ha Giang and Thai Nguyen Provinces (1) (8).

The Tonkin snub-nosed monkey inhabits subtropical evergreen forest associated with karst limestone hills and mountains, at elevations of between 200 and 1,200 metres (1) (8) (10) (11). The species is largely restricted to primary forest (1).

The Tonkin snub-nosed monkey is active during the day (1) (4) (8) (12), moving through the forest canopy by walking on all fours, climbing, leaping, or even hanging suspended from the branches, although some activity may also take place on the ground (1) (2) (4) (8) (11). The diet consists of a range of leaves, fruits, flowers and seeds (1) (4) (8) (10) (11) (13).

Massive deforestation and intensive hunting have drastically reduced the range of the Tonkin snub-nosed monkey, and the species is now known from just five isolated locations (6) (8) (11). The total population may number only around 200 to 250 individuals, and is fragmented into small subpopulations, which are unable to interbreed (1) (6) (7) (8) (11). As with many of Vietnam’s primates (8), hunting is the most immediate threat to this species (1) (2) (6) (14). Although described as bad-tasting, and not the main target of hunting trips, the Tonkin snub-nosed monkey is still commonly shot when encountered, and is either consumed or used in traditional medicine (1) (8) (11) (14). Groups often do not flee from hunters, making the species particularly vulnerable to being shot (1) (8) (12).

Habitat destruction, degradation and fragmentation are also major threats, with widespread deforestation occurring as a result of cultivation, development, road construction, legal and illegal logging, gold mining, and the commercial collection of non-timber forest products (1) (6) (7) (8) (11) (14). More recently, the development of a hydroelectric project on the Gam River in Na Hang has caused an influx of construction workers, leading to an increased demand for meat and resources, as well as resulting in the loss of forest habitat to construction, access roads and flooding (1) (6) (8) (11). Although the Tonkin snub-nosed monkey and its habitat are legally protected, hunting and habitat loss have unfortunately continued throughout its range, even within protected areas (1) (11).

International trade in the Tonkin snub-nosed monkey is prohibited under its listing on Appendix I of the Convention on International Trade in Endangered Species (CITES) (5). The Tonkin snub-nosed monkey is also protected by law in Vietnam, making it illegal to kill, capture or trade in the species, and is listed as Critically Endangered on the Red Data Book of Vietnam (11). The Tonkin snub-nosed monkey occurs in at least two protected areas, Na Hang and Cham Chu Nature Reserves, and may also occur in others, although populations in these areas are still under threat and continuing to decline, despite conservation efforts (1) (6) (8) (11). A population occurring in Khau Ca, an isolated forest within the buffer zone of the Du Gia Nature Reserve, will likely benefit from the creation of a Species and Habitat Conservation Area (1) (6) (11) (15), whilst a range of conservation activities have been put in place by Fauna & Flora International for a newly discovered population in Quan Ba District, near the border with China (7) (15).

A Conservation Action Plan is in place for the Tonkin snub-nosed monkey (11), and conservation measures for the species include further surveys and research, raising local awareness, establishing patrol groups, stricter law enforcement, imposing gun controls, expanding protected areas, habitat restoration, and potentially considering a captive breeding programme (1) (6) (7) (8) (11) (14). Although these measures give some hope for the species, the ongoing threats of hunting and habitat loss, together with its already tiny, fragmented population and range, mean the future of this unusual and highly endangered primate still hangs in the balance.

To find out more about the Tonkin snub-nosed monkey and other endangered primates, see:

• Mittermeier, R.A. et al. (2009) Primates in Peril: The World’s 25 Most Endangered Primates 2008-2010. IUCN/SSC Primate Specialist Group, International Primatological Society, and Conservation International, Arlington, VA. Available at:
  http://data.iucn.org/dbtw-wpd/edocs/2009-067.pdf
• Fauna & Flora International - Tonkin snub-nosed monkey:
  http://www.fauna-flora.org/asiapacific_tonkin.php
• IUCN/SSC Primate Specialist Group:
  http://www.primate-sg.org/