Northern yellow-cheeked crested gibbon
| Northern yellow-cheeked crested gibbon | ||||||||||||
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| Nomascus annamensis | ||||||||||||
| Thinh, VN et al., 2010 |
The Northern buffed-cheeked gibbon ( Nomascus annamensis ) is a primate of the family of gibbons (Hylobatidae).
features
Male northern yellow-cheeked crested gibbons reach a head body length of up to 46 cm, while females remain somewhat smaller at 42 cm. The weight is 7 kg. This species is for the most part hardly of the southern yellow-cheeked gibbon ( Nomascus gabriellae ). Like all species of its genus, the northern yellow-cheeked gibbon has a pronounced sexual dimorphism . The males are black in color with a brown cast on the chest and yellow-brown cheeks, the hair of which is directed outwards. Females are pale to orange-yellow in color and have a black, different-sized vertex and a dark spot on the chest. Infants are born with whitish-yellow-brown fur, which then turns black. Males retain this coloration, while females develop yellow-brown fur as they mature.
distribution and habitat
The northern yellow-cheeked crested gibbon occurs in the central Annamite Mountains in southern Laos and in central Vietnam . The Mekong forms the western limit of its occurrence. The border to the distribution area of the southern yellow-cheeked gibbon ( N. gabriellae ) is formed by the Ba River, the rivers Banghiang in Laos and the Tach Han in Vietnam to the distribution area of the southern black-cheeked gibbon.
Evergreen and semi-evergreen deciduous forests form the habitat of this species. It occurs at heights of 50 to 1205 m above sea level.
Way of life and reproduction
Northern yellow-cheeked gibbons are diurnal tree dwellers. The activity begins shortly before dusk, mostly with loud calls that end around 7 a.m. A study showed that the species spends 38% of the day eating, 36% resting, 19% hiking through the area and 7% doing other things. They live in monogamous family groups consisting of a couple and their offspring. The area of one group was about 50 hectares.
There is only limited information on the menu of the northern yellow-cheeked gibbon. Two short studies show that this species mainly eats fruit, but also does not disdain leaves, young shoots and flowers. One case is known in which a female has captured and eaten a young Finlayson squirrel ( Callosciurus finlaysonii ). The sharing of food was also observed, as well as the capture of lizards .
Two births in the wild have been recorded in Cambodia. These were in November 2008 and August 2011, which leads to the conclusion that the interval between births is approximately three years.
threat
This newly described species is not yet classified by the IUCN . The northern yellow-cheeked gibbon occurs in 18 nature reserves. In 2011, around 200 groups were identified in Vietnam. Although data are lacking, the populations in Laos appear to be very significant, but it is certain that these are declining as they are not found in successfully managed nature reserves. Populations in Cambodia are also important, the largest being in Virachey National Park with over 10,000 individuals. In adjacent, currently administered regions, further animals live in around 500 groups. The northern yellow-cheeked crested gibbon is threatened by habitat loss, hunting, and the pet trade. In Cambodia, large areas of Virachey National Park have been cleared for mining and rubber plantations, although this is where the largest population lives. Compared to more northerly species of the genus Nomascus , the populations of the northern yellow-cheeked crested gibbon are relatively intact and robust.
Systematics
The species was only in 2010 from Southern White-cheeked Gibbon ( N. siki separated) and by scientists at the German Primate Center in Göttingen described . Due to the characteristic song of the animals, it was noticeable that it differs from that of the southern white-cheeked crested gibbon. In addition to the sound frequency, the genetic material in the intestinal cells extracted from excretions was also examined.
Individual evidence
- ^ A b 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. 788-789.
- ^ VA Melfi: Ex situ gibbon conservation: status, management and birth sex ratios. In: International Zoo Yearbook 46, No. 1, 2012, pp. 241-251, doi: 10.1111 / j.1748-1090.2011.00150.x .
- ↑ Van Ngoc Thinh, Alan R. Mootnick, Vu Ngoc Thanh, Tilo Nadler, Christian Roos: A new species of crested gibbon, from the central Annamite mountain range. (PDF) In: Vietnamese Journal of Primatology. 1, No. 4, 2010, pp. 1-12.
- ↑ Lee E. Harding: Nomascus leucogenys (Primates: Hylobatidae). In: Mammalian Species 44, No. 1, 2012, pp. 1-15, doi: 10.1644 / 890.1 .