Hainan Black-Crested Gibbon, Nomascus nasutus hainanus

Hainan Black-Crested Gibbon
Nomascus nasutus hainanus (Thomas, 1892)
China (Hainan)
(2000, 2002, 2004)
Only a few dozen black-crested gibbons still survive on the island of Hainan — perhaps the world's most endangered primate population.

The black-crested gibbons of Vietnam and China are among the rarest primates in the world. Their taxonomy is currently in debate, but experts now believe that there are two species — the western black-crested gibbon, Nomascus concolor, with up to four subspecies in China, Laos and Vietnam, and the eastern black-crested gibbon, Nomascus nasutus, with two subspecies that are considered the most threatened of all the gibbon taxa (Geissmann, 2003).
The Hainan gibbon, Nomascus nasutus hainanus (Thomas, 1892) is restricted to the Island of Hainan, and the Cao Vit black-crested gibbon, N. nasutus nasutus (Kunckel d’Herculais, 1884), occurs on the continent in northeast Vietnam, and China. The correct scientific names of eastern black-crested gibbons are still under debate (Geissmann, 2000; Groves, 2001; Brandon-Jones et al., 2004). They differ in their territorial calls and hair color (La Quang Trung and Trinh Dinh Hoang, 2004). Further comparisons are needed besides genetic research, however, to determine whether they should be classified as separate species (Nadler, 2003).

Adult male N. n. nasutus are black with a slight tinge of brown hair on their chest, and adult male N. n. hainanus are entirely black (Geissmann et al., 2000; Mootnick, in press). The adult females on the mainland and Hainan Island vary from a buffish to a beige brown and have a black cap (Geissmann et al., 2000; Mootnick, in press). Adult female N. n. hainanus have a thin white face ring that is thicker above the mouth and below the orbital ridge. Depending on the amount of humidity, female Nomascus can obtain a more orangey color resulting from their sweat (Mootnick, in press).

There was an adult female “Patzi” in the Berlin Zoo whose vocalizations were similar to that of N. n. nasutus, but her pelage differed in that she had a very long and broad black crown streak that went past the nape, and extended to the brow, tapering to a thin face ring and becoming thicker at the chin (Geissmann et al., 2000; Mootnick, in press). This female had a narrow blackish brown chest plate slightly wider than the face, beginning at the throat and tapering at the top of the abdomen.

The Cao Vit black-crested gibbon formerly occurred east of the Red River in northern Guangdong and southwestern Guangxi provinces. It disappeared from southeastern China in the 1950s, and today it is restricted to the forests of the Phong Nam-Ngoc Khe Mountains, Trung Khanh District, northern Cao Bang Province in Vietnam (bordering China). Last seen in Vietnam in the 1960s, it was also feared extinct there, but was found again, after intensive searches in January 2002 by Fauna and Flora International (FFI) biologists La Quang Trung and Trinh Dinh Hoang (2004). They found five groups totaling at least 26 individuals in the remaining forest of 3000 ha. Further surveys by the Vietnam Primate Conservation Programme of FFI and Trung Kanh District rangers in November 2004 indicated 37 individuals (VNA, 2004).

In the 1950’s there were estimates of >2000 gibbons on the island of Hainan in 866,000 ha of forests across 12 counties (Wang and Quan, 1986). By 1989 the N. n. hainanus population was reduced to only 21 gibbons in four groups in 1200 ha of the Bawangling Nature Reserve (Liu et al., 1989). William Bleisch and Yingyi Zhang found 16 individuals in three groups on Hainan Island in November 2003 (pers. comm. to La Quang Trung and Trinh Dinh Hoang, 2004). Further recent surveys estimated between 12–19 individuals in three groups in the Bawangling Nature Reserve, and a fourth group sighted outside the preserve could have had between 2–7 individuals (Wu et al., 2004). Another survey found two groups, and two lone males, comprising a total of 13 individuals (Geissmann and Chan, 2004).

Gibbons generally establish long-term pair bonds, but in the Bawangling Nature Reserve there were observations of two females in the same group both carrying offspring (Liu et al., 1989; Bleisch and Chen, 1991). This could be a result of older offspring being unable to locate appropriate mates (Wu et al., 2004) and limited space to establish new groups (Liu et al., 1989). Efforts are underway by FFI to create new protected areas in forests such as those of Che Tao, Vietnam, where local support for the protection of endangered gibbons is apparently on the rise. There is an urgent need to secure the forests on the Island of Hainan, and the survival of the few remaining gibbons there.

Alan R. Mootnick, Anthony B. Rylands and William R. Konstant

References
Bleisch, W. V. and Chen, N. 1991. Ecology and behavior of wild black-crested gibbons in China with a reconsideration of evidence of polygyny. Primates 32: 539–548.
Brandon-Jones, D., Eudey, A. A., Geissmann, T., Groves, C. P., Melnick, D. J., Morales, J. C., Shekelle, M. and Stewart, C.-B. 2004. Asian primate classification. International Journal of Primatology 25: 97–164.
Geissmann, T., Nguyen Xuan Dang, Lormée, N. and Momberg, F. 2000. Vietnam Primate Conservation Status Review 2000. Part 1: Gibbons. Fauna and Flora International, Indochina Programe, Hanoi.
Geissmann, T., La Quang Trung, Trinh Dinh Hoang, Vu Dinh Thong, Dang Ngoc Can and Pham Duc Tien. 2003. Rarest ape rediscovered in Vietnam. Asian Primates 8(3/4): 8–10.
Geissmann, T. 2003. Symposium on Gibbon Diversity and Conservation: Concluding resolution. Asian Primates 8(3/4): 28-29. Available at:
http://www.tiho-hannover.de/gibbons/main/fullpapers/2003resolution.html.
Geissmann, T. and Chan, B. 2004. The Hainan black crested gibbon: Most critically endangered ape. Folia Primatologica 75 (Suppl. 1): 116. (Abstract.)
Groves, C. P. 2004. Taxonomy and biogeography of primates in Vietnam and neighbouring regions. In: Conservation of Primates in Vietnam, T. Nadler, U. Streicher, and Ha Thang Long (eds.), pp.15–22. Frankfurt Zoological Society, Hanoi.
La Quang Trung and Trinh Dinh Hoang. 2004. Status review of the Cao Vit black crested gibbon (Nomascus nasutus nasutus) in Vietnam. In: Conservation of Primates in Vietnam, T. Nadler, U. Streicher, and Ha Thang Long (eds.), pp.90–94. Frankfurt Zoological Society, Hanoi.
Liu, Z. H. and Tan, C. F. 1990. An analysis of habitat structure of the Hainan gibbon. Acta Theriologica Sinica 10: 163–169. In Chinese with English summary.
Liu, Z. H., Yu, S. M. and Yuian, X. C. 1984. Resources of the Hainan black gibbon and its present situation. Chinese Wildlife 6: 1–4. In Chinese.
Liu, Z. H., Zhang, Y. Z., Jian, H. S. and Southwick, C. H. 1989. Population structure of Hylobates concolor in Bawanglin Nature Reserve, Hainan, China. American Journal of Primatology 19: 247–254.
Mootnick, A. R. In press. Gibbon taxonomy recommended for rescue centers. In: All Apes Great and Small. Volume 2: Asian Apes, B. M. F. Galdikas, N. E. Briggs, L. K. Sheeran, G. L. Shapiro and J. Goodall (eds.). Kluwer Academic/ Plenum Publishers, New York.
Nadler, T. 2003. Rediscovery of the Eastern black crested gibbon Nomascus nasutus in Vietnam. The Gibbon’s Voice 6(1): 1–3.
Roos, C. 2004. Molecular evolution and systematics of Vietnamese primates. In: Conservation of Primates in Vietnam, T. Nadler, U. Streicher and Ha Thang Long (eds.), pp.23–28. Frankfurt Zoological Society, Hanoi.
VNA. 2004. Endangered gibbon and rare flora species found. Report on web site of Sci/Tech-Environment, Vietnam News Agency (VNA), Hanoi. http://www.vnagency.com.vn. Accessed November 17, 2004.
Wang, S. and Quan, G. 1986. Primate status and conservation in China. In: Primates: The Road to Self-sustaining Populations, K. Benirschke (ed.), pp. 213–220. Springer Verlag, New York.
Wu Wei, Wang Xiaoming, Claro, F., Ding Youzhoung, Souris, A.-C., Wang Chundong, Wang Changhe and Berzins, R. 2004. The current status of the Hainan black-crested gibbon Nomascus sp. cf. nasutus hainanus in Bawangling National Nature Reserve, Hainan, China. Oryx 38(4): 452–456.

Suggested citation:
Mootnick, A. R., Rylands, A. B. and Konstant, W. R. 2005. Hainan Black-crested Gibbon, Nomascus nasutus hainanus (Thomas, 1892). In: Primates in Peril: The World's 25 Most Endangered Primates 2004-2006, R. A. Mittermeier, C. Valladares-Pádua, A. B. Rylands, A. A. Eudey, T. M. Butynski, J. U. Ganzhorn, R. Kormos, J. M. Aguiar and S. Walker (eds.), pp.30-31. Report to IUCN/SSC Primate Specialist Group (PSG), International Primatological Society (IPS) and Conservation International (CI), Washington, DC.