La Quang Trung; Trinh Dinh Hoang; Long, B. & Geissmann, T. 2002: Status review of black crested gibbons (Nomascus concolor and Nomascus sp. cf. nasutus) in Vietnam. In: Caring for primates. Abstracts of the XIXth congress of the International Primatological Society, 4th-9th August, 2002, Beijing, China, pp. 131-132. Mammalogical Society of China, Beijing.

Status review of black crested gibbons (Nomascus concolor and Nomascus sp. cf. nasutus) in Vietnam

La Quang Trung¹, Trinh Dinh Hoang¹, Barney Long² & Thomas Geissmann<sup>3

1</sup> Fauna & Flora International - Indochina Programme, IPO Box 78, 104B Pho Hue, Hanoi, Vietnam, e-mail: ffi@fpt.vn
² WWF Indochina Programme Office, 53 Tran Phu, Hanoi, Hanoi, Vietnam, e-mail: barneylong@cwcom.net
³ Institute of Zoology, Tierärztliche Hochschule Hannover, Bünteweg 17, 30559 Hannover, Germany, e-mail: thomas.geissmann@gibbons.de

Key Words: Nomascus, status, Vietnam

The status of the crested gibbons (genus Nomascus) in Vietnam is poorly known. No surveys in recent times have reliably recorded the presence of the two northern species, the western black crested gibbon Nomascus concolor and the eastern black crested gibbon N. sp. cf. nasutus. Since 1999, FFI-Indochina (Fauna & Flora - Indochina Programme) have been conducting numerous primate-focused surveys to assess the status of these species and identify priority sites for their conservation.

Our field surveys revealed the Che Tao - Nam Pam forests (between Yen Bai and Son La provinces) and the forests of Van Ban district (Lao Cai province) as the only known sites in Vietnam where the occurrence of the western black crested gibbon has been confirmed. The population in Che Tao - Nam Pam consists of at least 40 groups and 111 individuals. In Van Ban district, 14 groups have been identified, but some of them are isolated from the main core of surviving groups.

In January 2002 we were finally able to locate the first confirmed population of Nomascus sp. cf. nasutus in Vietnam since the 1960's. This population was discovered in Trung Khanh district (Cao Bang province) and consists of about 8 individuals totally (two groups and a single male). Even if vocal and DNA analyses should indicate that the Eastern black crested gibbon in Vietnam and the Chinese Hainan gibbon are the same species, the estimated global population of the species amounts to only about 32 individuals, meaning that this gibbon is the world's most endangered primate species.

The results of our surveys highlight the critical status of these Vietnamese apes due to hunting and habitat loss. Both species are on the brink of extinction in Vietnam and, without species-focused conservation efforts, will become extirpated in the next one to ten years.