Animal Diversity Web

Ge­o­graphic Range

Tonkin snub-nosed mon­keys are found in sub­trop­i­cal areas of Viet­nam with ever­green forests. These areas are typ­i­cally as­so­ci­ated with karst lime­stone hills and moun­tains. Pop­u­la­tions have been con­firmed in the past in seven provinces of North­ern Viet­nam: Ha Giang, Tuyen Quang, Cao Bang, Yen Bai, Bac Kan, Thai Nguyen, and Quang Ninh. They have been found re­cently in Ha Giang, Tuyen Quang, and Bac Kan Provinces, and pos­si­bly in Thai Nguyen Province. (Boon­ratana and Le, 1998a; Le and Boon­ratana, 2006)

• Biogeographic Regions
• oriental
  • native

Habi­tat

Tonkin snub-nosed mon­keys only occur in sub­trop­i­cal broad-leaf and bam­boo forests that have mon­soon rain­fall and trop­i­cal tem­per­a­tures. These forests are usu­ally found on top of lime­stone hills at el­e­va­tions of less than 1000 m above sea level. Tonkin snub-nosed mon­keys are the only snub-nosed mon­keys that occur in sub­trop­i­cal areas. (Groves, 2007; Kirk­patrick, 1995)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• rainforest

• Range elevation

  1000 (high) m

  3280.84 (high) ft

Phys­i­cal De­scrip­tion

Both sexes of adult Tonkin snub-nosed mon­keys have up­turned noses. They also have fairly slen­der bod­ies with slen­der dig­its on the hands and feet in com­par­i­son to other species in the genus Rhino­p­ithe­cus. Coat color and pat­tern vari­a­tion has been re­ported among pop­u­la­tions and in­di­vid­u­als. The gen­eral pat­tern is black fur on the outer limbs and back, the dor­sal sur­face of the tail, and the hands and feet. The el­bows, chest, ven­tral side of the tail, in­side sur­faces of the limbs and parts of the face are creamy-white. Parts of the face are hair­less, par­tic­u­larly around the nose and eyes, and have pale blue skin. They also have or­ange col­oration on the throat and dark col­oration that out­lines the mouth. Males and fe­males dif­fer slightly in col­oration. Males show more pro­nounced or­ange around the throat and darker black around the mouth. In ju­ve­niles, the black parts of the fur ap­pear gray, they lack the or­ange in the throat re­gion, and the black around the mouth is not as pro­nounced as it is in adults. The av­er­age mass of males is 13.8 kg and the av­er­age mass of fe­males is 8.3 kg. The length from the top of the head to the end of the body ranges from 51 cm and 65 cm, and the length of the tail ranges from 66 to 92 cm. Den­tal for­mula in the genus Rhino­p­ithe­cus is I 2/2, C 1/1, P 2/2, M 3/3, for a total of 32 teeth. There is also sex­ual di­mor­phism in terms of ca­nine size, with males hav­ing larger ca­nines on both top and bot­tom jaw. (Boon­ratana and Le, 1998b; Jablon­ski and Ru­liang, 1995; Napier and Napier, 1967; Nowak, 1997; War­wick, 1960)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently

• Range mass

  8.3 to 13.8 kg

  18.28 to 30.40 lb

• Range length

  51 to 65 cm

  20.08 to 25.59 in

Re­pro­duc­tion

The so­cial struc­ture Tonkin snub-nosed mon­keys has been de­scribed as being one male mon­key with mul­ti­ple fe­males and ju­ve­niles or groups of all males, sug­gest­ing a polyg­y­nous mat­ing sys­tem. A fe­male will en­gage the male by get­ting him to fol­low her to var­i­ous branches; she will then move her tail above and to one side of her body prior to male mount­ing. Once the male has po­si­tioned his feet on the branch he will mount the fe­male from the rear ini­ti­at­ing cop­u­la­tion which was re­ported to have lasted ap­prox­i­mately 43 sec­onds. In one case, after cop­u­la­tion the fe­male moved to a neigh­bor­ing tree and the male moved to a lower branch where he moved his fore­limb in front to of his face and briefly shook his head. This de­scrip­tion is the only ob­served mat­ing event in Tonkin snub-nosed mon­keys. (Boon­ratana and Le, 1998b)

• Mating System
• polygynous

There has been lit­tle re­search on the re­pro­duc­tive be­hav­ior of these mon­keys as they are rare and dif­fi­cult to ob­serve. After a ges­ta­tion pe­riod of about 200 days, fe­males give birth to 1 or 2 off­spring in the spring or sum­mer. Males be­come sex­u­ally ma­ture at about 7 years of age and fe­males at about 4 years of age. There is noth­ing re­ported about the lac­ta­tion pe­riod of this species. (Dong, et al., 2011; Nowak, 1997)

• Key Reproductive Features
• iteroparous
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous

• Breeding interval

  Breeding intervals in Tonkin snub-nosed monkeys are not reported.

• Breeding season

  The breeding season in Tonkin snub-nosed monkeys is not reported.

• Range number of offspring

  1 to 2

• Average gestation period

  200 days

• Average age at sexual or reproductive maturity (female)

  4 years

• Average age at sexual or reproductive maturity (male)

  7 years

There is not much known about the level of parental care ex­hib­ited by this species of snub-nosed mon­key. Adult fe­males al­logroom other mem­bers of the group. Allo-parental care has been ob­served in golden and black snub-nosed mon­keys, (Rhino­p­ithe­cus rox­el­lana and Rhino­p­ithe­cus bieti) re­spec­tively, so it is pos­si­bly an ale­ment of so­cial be­hav­ior in Tonkin snub-nosed mon­keys also. It is likely that fe­males in­vest heav­ily in young, as this is typ­i­cal of other species in this group. (Boon­ratana and Le, 1998b; Kirk­patrick and Grueter, 2010)

• Parental Investment
• female parental care
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • protecting
    • female
• post-independence association with parents

Lifes­pan/Longevity

The typ­i­cal lifes­pan in colobine mon­keys is about 20 years, with a lifes­pan of about 29 years in cap­tiv­ity. Lifes­pans of Tonkin snub-nosed mon­keys are not re­ported. (Mac­Don­ald, 2009)

Be­hav­ior

Tonkin snub-nosed mon­keys typ­i­cally or­ga­nize them­selves into ei­ther all male groups or groups of a sin­gle male with mul­ti­ple fe­males and ju­ve­niles; these groups typ­i­cally feed, sleep, and travel to­gether. These mon­keys are di­ur­nal and sleep­ing sites for this species are usu­ally on lower branches of trees near steep moun­tain sides so as to be pro­tected from cold winds at night. Groups some­times split into sep­a­rate groups or some groups come to­gether to form a larger group; this group fis­sion-fu­sion sug­gests that there is in­ter-group tol­er­ance. Be­cause groups frag­ment at times and fuse with other groups at other times, this species does not ap­pear to be ter­ri­to­r­ial. Fe­males al­logroom other mem­bers of the group. The type of lo­co­mo­tion used to move be­tween trees is al­most al­ways by quadrupedal walk­ing, but they also use climb­ing and leap­ing. Other types of be­hav­ior as­so­ci­ated with adult move­ment being leap­ing be­tween trees, hang­ing from the branches, and oc­ca­sional brachi­a­tion. (Boon­ratana and Le, 1998b; Napier and Napier, 1967)

• Key Behaviors
• arboreal
• scansorial
• diurnal
• motile
• sedentary
• social

Home Range

Home range size is not re­ported for Tonkin snub-nosed mon­keys. Some ob­ser­va­tions sug­gest that they will spend most of their time within a range of roughly 10 square kilo­me­ters. (Boon­ratana and Le, 1998b)

Com­mu­ni­ca­tion and Per­cep­tion

Vo­cal­iza­tions are the pri­mary means of com­mu­ni­ca­tion. The main vo­cal­iza­tion of this species sounds a lot like a hic­cup (“huu chhhk”) and is used ei­ther in alarm calls or to com­mu­ni­cate with other in­di­vid­u­als. This kind of com­mu­ni­ca­tion usu­ally oc­curs dur­ing trav­el­ing or when lo­cat­ing a re­source. Alarm calls are usu­ally done in the pres­ence of re­searchers. These mon­keys, like other pri­mates, prob­a­bly per­ceive the world well with binoc­u­lar, color vi­sion and use pheromones to com­mu­ni­cate with other mem­bers of this species, but there has been no re­search on com­mu­ni­ca­tion and per­cep­tion in Tonkin snub-nosed mon­keys. (Boon­ratana and Le, 1998b; Nguyen, 2000)

• Communication Channels
• visual
• tactile
• acoustic
• chemical

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

Tonkin snub-nosed mon­keys eat leaves from trees, mainly bam­boo or other ever­green leaves. They are not strictly fo­liv­o­rous, as they eat a va­ri­ety of plant parts and fruits as well. The diet is com­prised of 28% leaf stems, 28% fruits, 11% young leaves, 22% un­ripe fruit, 8% flow­ers, and 3% seeds. Thirty-one food species have been iden­ti­fied be­long­ing to 21 fam­i­lies make up the diet of the Tonkin sub-nosed mon­key. The plant species Iodes seguini, Garcinia fa­graeoides, Acer tonk­i­nen­sis, Ex­cen­tro­den­dron tonk­i­nen­sis, and Bras­saiop­sis stel­late are con­sumed the most. They have a spe­cial­ized di­ges­tive sys­tem that is adapted for the di­ges­tion of leaves, in­clud­ing a sac­cu­lated stom­ach. Their strong jaw mus­cu­la­ture is re­lated to their di­etary pref­er­ences for tough plant foods. (Boon­ratana and Le, 1998b; Kirk­patrick, 1995; Napier and Napier, 1967; Quyet, et al., 2007)

• Primary Diet
• herbivore
  • folivore
  • frugivore

• Plant Foods
• leaves
• wood, bark, or stems
• seeds, grains, and nuts
• fruit
• flowers

Pre­da­tion

Hu­mans have been known to hunt and eat Tonkin snub-nosed mon­keys de­spite the meat’s ap­par­ently bad taste. No other preda­tors of Tonkin snub-nosed mon­keys are known, but it is likely that they are preyed on by ar­bo­real snakes and large birds of prey as well as for­est cats. (Kirk­patrick, 1995; Le and Boon­ratana, 2006)

• Known Predators

  • humans (Homo sapiens)

Ecosys­tem Roles

It is un­clear what role these an­i­mals play in the ecosys­tem as they are rare. Tonkin snub-nosed mon­keys are her­bi­vores so they may im­pact veg­e­ta­tion in their habi­tat. Since they eat fruits, they could aid in the dis­per­sal of seeds. (Kirk­patrick, 1995)

• Ecosystem Impact
• disperses seeds

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Tonkin snub-nosed mon­keys have been used by lo­cals as a food source and also to for tra­di­tional "med­i­cines," which have no true med­i­c­i­nal value. It is re­ported that body parts are some­times traded the bor­ders of Viet­nam and China. The hunt­ing of this species for these pur­poses poses one of the biggest threats to its con­ser­va­tion and has there­fore been made il­le­gal. (Boon­ratana and Le, 1998a)

• Positive Impacts
• food
• body parts are source of valuable material

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Tonkin snub-nosed mon­keys do not neg­a­tively im­pact hu­mans.

Con­ser­va­tion Sta­tus

Tonkin snub-nosed mon­keys are crit­i­cally en­dan­gered and com­pletely re­stricted to north­ern Viet­nam. The biggest threats to this species are hunt­ing and habi­tat degra­da­tion caused by hu­mans. Hu­mans hunt and trap these mon­keys for food, med­i­cine and trade. All of these acts are deemed il­le­gal but still oc­curs. Habi­tat de­struc­tion is also caus­ing a de­cline in the pop­u­la­tion of the species. Peo­ple who live in these areas har­vest bam­boo and cut down trees to har­vest the wood and fruit. Gold min­ing in the area has also de­stroyed parts of the habi­tat by clear­ing and ex­ca­vat­ing the land. Tonkin snub-nosed mon­keys have been rec­og­nized as one of the world’s 25 most en­dan­gered pri­mates since 2000 and were ranked as num­ber 8 in the 2006 to 2008 re­port. A sur­vey in 2006 es­ti­mated the total pop­u­la­tion for the en­tire species was about 150 in­di­vid­u­als, but it is pos­si­ble that it is lower. (Boon­ratana and Le, 1998a; Mit­ter­meier, et al., 2007; Nadler, et al., 2007; Nguyen, 2000)

• IUCN Red List

  Critically Endangered

• US Federal List

  Endangered

• CITES

  Appendix I

Con­trib­u­tors

Rachel Cherka (au­thor), Uni­ver­sity of Man­i­toba, Jane Wa­ter­man (ed­i­tor), Uni­ver­sity of Man­i­toba, Tanya Dewey (ed­i­tor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Boon­ratana, R., X. Le. 1998. Con­ser­va­tion of Tonkin Snub-nosed Mon­keys (Rhino­p­ithe­cus [Pres­byti­cus] avun­cu­lus) in Viet­nam. Pp. 315-322 in N Jablon­ski, ed. The Nat­ural His­tory of the Doucs and Snub-nosed Mon­keys. Sin­ga­pore: World Sci­en­tific Pub­lish­ing Co. Ltd..

Boon­ratana, R., X. Le. 1998. Pre­lim­i­nary Ob­ser­va­tions on the Ecol­ogy and Be­hav­iour of the Tonkin Snub-nosed Mon­key (Rhino­p­ithe­cus [Pres­byti­cus] avun­cu­lus) in North­ern Viet­nam. Pp. 207-215 in N Jablon­ski, ed. The Nat­ural His­tory of the Doucs and Snub-nosed Mon­keys. Sin­ga­pore: World Sci­en­tific Pub­lish­ing Co. Ltd..

Covert, H., L. Quyet, B. Wright. 2008. On the Brink of Ex­tinc­tion: Re­search for the Con­ser­va­tion of the Tonkin Snub-nosed Mon­key (Rhino­p­ithe­cus avun­cu­lus). Pp. 409-427 in J Flea­gle, C Gilbert, eds. Elwyn Si­mons: A Search for Ori­gins. New York: Springer Sci­ence and Busi­ness Media, LLC.

Dong, T., S. Hua, R. Boon­ratana. 2011. A first ob­ser­va­tion on the sex­ual be­hav­ior of the Tonkin Snub-nosed Mon­key (Rhino­p­ithe­cus avun­cu­lus) in Viet­nam. Asian Pri­mates Jour­nal, 2(1): 8-9.

Groves, C. 2007. Spe­ci­a­tion and Bio­geog­ra­phy of Viet­nam’s pri­mates. Viet­namese Jour­nal of Pri­ma­tol­ogy, 1: 27-40.

Jablon­ski, N., P. Ru­liang. 1995. Sex­ual Di­mor­phism in the Snub-Nosed Lan­gurs (Colobi­nae: Rhino­p­ithe­cus). Amer­i­can Jour­nal of Phys­i­cal An­thro­pol­ogy, 96: 251-272.

Kirk­patrick, C. 1995. The Nat­ural His­tory and Con­ser­va­tion of the Snub-nosed Mon­keys (Genus Rhino­p­ithe­cus). Bi­o­log­i­cal Con­ser­va­tion, 72: 363-369.

Kirk­patrick, R., C. Grueter. 2010. Snub-nosed Mon­keys: Mul­ti­level So­ci­eties Across Var­ied En­vi­ron­ments. Evo­lu­tion­ary An­thro­pol­ogy, 19: 98-113.

Le, X., R. Boon­ratana. 2006.

A Con­ser­va­tion Ac­tion Plan for the Tonkin Snub-nosed Mon­key in Viet­nam

Mac­Don­ald, D. 2009. The En­cy­clo­pe­dia of Mam­mals. Prince­ton, New Jer­sey: Prince­ton Uni­ver­sity Press.

Mit­ter­meier, R., J. Rat­sim­bazafy, A. Ry­lands, L. Williamson, J. Oates, D. Mbora, J. Ganzhorn, E. Rodríguez-Luna, E. Pala­cios, E. Hey­mann, M. Kierulff, L. Yongcheng, J. Supri­atna, C. Roos, S. Walker, J. Aguiar. 2007. Pri­mates in Peril: The World’s 25 Most En­dan­gered Pri­mates 2006–2008. Re­port. Ar­ling­ton, Vir­ginia: IUCN/SSC Pri­mate Spe­cial­ist Group, In­ter­na­tional Pri­ma­to­log­i­cal So­ci­ety, and Con­ser­va­tion In­ter­na­tional.

Nadler, T., V. Thanh, U. Stre­icher. 2007. Con­ser­va­tion Sta­tus of Viet­namese Pri­mates. Jour­nal of Pri­ma­tol­ogy, 1: 7-26.

Napier, J., P. Napier. 1967. A Hand­book of the Liv­ing Pri­mates. Lon­don: Aca­d­e­mic Press.

Nguyen, N. 2000. A sur­vey of Tonkin snub-nosed mon­keys (Rhino­p­ithe­cus avun­cu­lus) in north­ern Viet­nam. Folia Pri­ma­tol, 71: 157-160.

Nowak, R. 1997. Walker’s Mam­mals of the World. Mary­land: The Johns Hop­kins Uni­ver­sity Press.

Quyet, L., N. Anh Duc, V. Anh Tai, B. Wright, H. Covert. 2007. Diet of the Tonkin Snub-nosed Money (Rhino­p­ithe­cus avun­cu­lus) in the Khau Ca area, Ha Giang Province, Noth­east­ern Viet­nam. Viet­namese Jour­nal of Pri­ma­tol­ogy, 1: 75-83.

War­wick, J. 1960. The Jaws and Teeth of Pri­mates. Lon­don: Pit­man Med­ical Pub­lish­ing.