1 Anthropological Institute,
University Zurich-Irchel, Winterthurerstrasse 190, CH - 8057 Zurich, SWITZERLAND
2 Fauna & Flora International, Asia Pacific Programme, Hanoi, VIETNAM
3 Institute of Ecology and Biological Resources, Hanoi, VIETNAM
This section has been published as:
Geissmann, T.; La Quang Trung, Trinh Dinh Hoang, Vu Dinh Thong, Dang Ngoc Can & Pham Duc Tien, 2003: Rarest ape species rediscovered in Vietnam. Asian Primates 8(3-4): 8-9.
A printable pdf-file of this paper can be downloaded here.
Unlike what most people believe, the rarest apes of the world are not the popular great apes which include chimpanzees, gorillas and orangutans. The gibbons or small apes are usually overlooked by media and scientists alike. Yet, several gibbon species are much more critically endangered than even the rarest of the great apes. Whereas even the rarest great ape (the Sumatran orangutan Pongo abelii) still exhibits a population size of 12,000 individuals, the populations of several gibbon species are considerably smaller (see Geissmann, 2002).
The rarest ape species - and actually the most critically endangered primate species of the world - is a gibbon, the eastern black crested gibbon (Nomascus sp. cf. nasutus). This gibbon was recognized as a species distinct from the western black crested gibbon (Nomascus concolor) in 1997 (Geissmann, 1997). Originally, the species was widely distributed in northeastern Vietnam east of the Red River, in southeastern China and on Hainan Island. However, the species became extinct on the Chinese mainland in the 1950's, and the Hainan population has become reduced to less than 20 individuals (Geissmann et al., 2001). In Vietnam, the last reliable record for the occurrence of the species stems from the 1960's. Since the recognition of the eastern black crested gibbon as a distinct species, numerous field surveys were carried out in all areas where the species had previously been recorded (Geissmann and Vu Ngoc Thanh, 2001; Goldthorpe et al., 2002; Ngo Van Tri and Lormée, 2000; Phung Van Khoa and Lormée, 2000; Tordoff et al., 2000). In spite of these efforts, no live individual was sighted or heard, and it became increasingly likely that the species may actually have become extinct in Vietnam.
In January 2002, however, a small remnant population of the eastern black crested gibbon was re-discovered by FFI biologists La Quang Trung and Trinh Dinh Hoang in Trung Khanh district of Cao Bang Province (NE Vietnam) (La Quang Trung et al. 2002). In August 2002, we carried out the first overall population survey. We discovered that at least five groups comprising at least 26 individuals survive in the remaining forest area of less than 3000 hectares. As a result, the gibbons in Cao Bang do not solely represent the only population of the species in Vietnam but also the most important population of the whole species. Moreover, because these Vietnamese gibbons and their Hainan island counterparts differ in both fur colouration and their territorial calls, they also represent two distinct subspecies.
Because of its characteristic morning songs, the Vietnamese subspecies is termed the Cao-Vit black crested gibbon. It is the only ape taxon endemic to Vietnam. However, its future seems highly uncertain. Not only is the size of their remaining forest area very small, but the gibbons are highly threatened by illegal logging for firewood and for charcoal production, both from the neighbouring villages as well as from the neighbouring Chinese communities, and by hunting. In order to save the Cao-Vit, FFI together with the Forest Protection Department (FPD) is proposing to create a species/habitat conservation area for the area and to develop a joint forest protection system with local communities.
Geissmann, T. (1997). New sounds from the crested gibbons (Hylobates concolor group): First results of a systematic revision. P. 170 in D Zissler, ed, Verhandlungen der Deutschen Zoologischen Gesellschaft: Kurzpublikationen - Short Communications, 90. Jahresversammlung 1997 in Mainz, Gustav Fischer, Stuttgart.
Geissmann, T. (2002). Gibbon diversity and conservation. Pp. 112-113 in Caring for primates. Abstracts of the XIXth congress of the International Primatological Society, 4th-9th August, 2002, Beijing, China, Mammalogical Society of China, Beijing.
Geissmann, T.; Nguyen Xuan Dang; Lormée, N. and Momberg, F. (2000). Vietnam primate conservation status review 2000 - Part 1: Gibbons. English edition. Fauna & Flora International, Indochina Programme, Hanoi. 130 pp. ISBN: 1-903703-03-4.
Geissmann, T. and Vu Ngoc Thanh (2001). Preliminary results of a primate survey in northeastern Vietnam, with special reference to gibbons. Asian Primates 7(3&4): 0-4.
Goldthorpe, G.; Pham Duc Tien and Roos, C. (2002). New record for Nomascus sp. cf. nasutus in Kim Hy forest, Bac Kan province, northern Vietnam (working title). Report to Frontier-Vietnam (Society for Environmental Exploration), Hanoi.
La Quang Trung; Trinh Dinh Hoang; Long, B. and Geissmann, T. (2002). Status review of black crested gibbons (Nomascus concolor and Nomascus sp. cf. nasutus) in Vietnam. Pp. 131-132 in Caring for primates. Abstracts of the XIXth congress of the International Primatological Society, 4th-9th August, 2002, Beijing, China, Mammalogical Society of China, Beijing.
Ngo Van Tri and Lormée, N. (2000). Survey on primates in Kim Hy proposed nature reserve, Na Ry district, Bac Can province, north-eastern Vietnam. Report to Fauna & Flora International, Indochina Programme Office, Hanoi.
Phung Van Khoa and Lormée, N. (2000). Primate status assessment in Bac Kan province, North Vietnam, January 2000, with a special reference to the black gibbon (Hylobates concolor). Report to Fauna & Flora International, Indochina Programme Office, Hanoi.
Tordoff, A. W.; Tran Quang Ngoc; Le Van Cham and Dang Thang Long (2000). A rapid field survey of five sites in Bac Kan, Cao Bang and Quang Ninh provinces, Vietnam: A review of the Northern Indochina Subtropical Forests Ecoregion. Report to BirdLife International Vietnam Programme, and FIPI, Hanoi.