Eastern black crested gibbon
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Eastern black crested gibbon ( Nomascus nasutus ) |
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| Nomascus nasutus | ||||||||||||
| ( Kunkel d'Herculais , 1884) |
The Eastern Black Crested Gibbon ( Nomascus nasutus ) is a primate of the family of gibbons (Hylobatidae).
features
Exact body measurements are not known, but the eastern crested gibbon is believed to be the same size as other species in the genus Nomascus . Just like them, this one also has a pronounced gender dimorphism . Males are completely black with a brownish tinge on the chest, while females are yellow to beige-brown in color. Females also have a large, white face ring and a large, black vertex that extends to the neck and often even to the shoulders. The chest is sometimes adorned with gray, brown, or black hair. Young Eastern black crested gibbons are black in contrast to other crested gibbons. The change of coat color in females to yellow-beige-brown occurs with sexual maturity.
distribution and habitat
The distribution area of the Eastern Black Crested Gibbon is now limited to a small region on the Sino - Vietnamese border ( Cao Bang Province, Vietnam and Guangxi Province, China). The historical distribution, however, reached from southeast China to north Vietnam south and west to the Red River .
Actually, mountain and karst forests at a height of 50 to 930 m represented the habitat of this species. Now it is only in tropical monsoon limestone forests at 500 to 930 m in the Cao Vit Gibbon Conversation Area, Vietnam, and in the adjacent Bangliang -Nature reserve, China, to be found on an area of only approx. 2000 ha.
Way of life
The eastern black crested gibbon is a diurnal tree dweller. The activity starts just before dusk and with loud chants. The species forms groups that defend their territories, although there are some that overlap. Initial estimates of three territories by three groups are between 128 and 133 hectares, which is quite large for gibbons. The formation of a new group was observed only once and consisted of a male and two young animals, which occupied an as yet unoccupied area and which shortly afterwards a female arrived. The first long-term observations suggest that this species, in contrast to most other species, but similar to the western black crested gibbon and the Hainan crested gibbon, lives polygamously. A group therefore consists of a male, one or two females and their offspring. Groups with two females are considered stable and even two pups that are still dependent on the mother at the same time were observed in two groups. The average size of a group is six individuals.
Long-term observations have shown that eastern black crested gibbons feed mainly on fruits (36%) and figs (21%). The menu is supplemented with leaves (16%), buds (14%), animals (7%), flowers (3%) and other parts of plants. About 81 plant species are eaten. 19 of them are locally rare, but make up the largest part. The animal component consists of large invertebrates, but lizards are not spurned either.
Four births of Eastern Black Crested Gibbons in the wild have been recorded to date. They all took place between October and February and don't seem to be seasonal.
threat
The Eastern Black Crested Gibbon is classified by the IUCN as "critically endangered" (threatened with extinction). It is protected in China and Vietnam and occurs in two nature reserves, in the Cao Vit Gibbon Conversation Area in Vietnam and in the adjacent Bangliang Nature Reserve in China. Only 110 individuals in 18 groups, four of them in China, the rest in Vietnam, exist today. Four groups were only discovered in China in 2006, another in Vietnam in 2002. The Cao Vit Gibbon Conversation Area in Vietnam was established in 2007, the adjacent Bangliang Conservation Area in China in 2009. Additional searches in Vietnam were unsuccessful and it is possible that the Eastern one Black crested gibbon is extinct in all other places where it historically occurred. All conservation efforts are now focused on the only known population. The species is endangered by the habitat destruction of the locals who use the wood for building and as firewood. The hunt is under control with not a single animal killed since 2003. Other threats include inbreeding, disease outbreaks and natural disasters. To ensure the conservation of the species, forests are being planted in China and Vietnam.
literature
- Thomas Geissmann: Comparative Primatology . Springer, Berlin 2003, ISBN 3-540-43645-6 .
- Russell A. Mittermeier, Anthony B. Rylands, Don E. Wilson: Handbook of the Mammals of the World. Volume 3: Primates. Lynx Edition, Barcelona 2013, ISBN 978-84-96553-89-7 , pp. 787-788.
Web links
- Information from the Gibbons Research Lab. (English)
- Information of the Primate Specialist Group (English)
- Nomascus nasutus in the endangered Red List species the IUCN 2006 Posted by: T. Geissmann, 2003. Accessed July 26 of 2007.
Individual evidence
- ↑ Chan Bosco Pui Lok, Tan Xue-feng, Tan Wu-jing: Page no longer available , search in web archives: Rediscovery of the critically endangered eastern black crested gibbon Nomascus nasutus (Hylobatidae) in China, with preliminary notes on population size, ecology and conservation status. (PDF) In: Asian Primates Journal 1, No. 1, 2008, pp. 17-25.
- Jump up ↑ Pengfei Fan, H. Fei, Z. Xiang, W. Zhang, C. Ma, T. Huang: Social structure and group dynamics of the cao vit gibbon (Nomascus nasutus) in Bangliang, Jingxi, China. In: Folia Primatologica 81, No. 5, 2010, pp. 245-253, doi: 10.1159 / 000322351 .