Northern White-Cheeked Gibbon (Nomascus leucogenys )

Interesting :

There are 3 species of black gibbon, namely, 1) H.c. concolor, 2) H.c. leucogenys, and 3) H.c. gabrieliae. The specie of H.c. concolor can be found in Hainan. Male is purely black in color. At its face, there are white hairs spread around eyes, nose, and mouth. Female is light in color with black spot patched at the center of the head top. The specie of H.c. leucogenys can be found in Lao and Northern Vietnam. Male is black in color with white spot at its cheek. Female is light or gold in color with black spot patched at chest and the center of the head top. The specie of H.c. gabrieliae can be found in the Southern part of Vietnam bordered to Cambodia. Male is purely black in color but it also has red-gold hair scattered around. It has white marking spots at its face and cheek. Female black gibbon is light in color with black spot distinctively patched at chest. It has distinctive black hair pointed up at the head. Newborn black gibbon is gold in color. When it is 6 – 8 months, its hands, feet, and head is changed to black in color. After that the color of both male and female is changed into pure black. Its cheek will have white color when it is 6 – 7 years. For female, its color will turn into gold or light color. For H.c. leucogenys, its chest is black in color but for H.c. gabrieliae, its chest is also black in color and its hair is pointed up on its head. When standing, black gibbon does not bend its knees unlike any other gibbons. Male has larynx, which makes it bawl intermittently and persistently. Female does not have larynx. Thus, the bawl is different from that of male. Sexual organ of both male and female has cartilage bone inside. Thus, it is difficult to specify its sex when it is young or when its body hair is still black. Thus, to specify sex, its testis is an indicator. One that has testis is a male.

Habitat :

It is found in Lao, Indochina, Hainan, and Thailand. In Thailand, it is found in Loei at Chiang Kan district. It is a hardly found gibbon. HABITAT AND ECOLOGY This diurnal, arboreal and territorial species is found in tall primary and degraded evergreen and semi-evergreen forest. In northwestern Viet Nam and northern Lao PDR, the animals live in a subtropical climate with a short and not very cold winter without frost (Tien 1983). In Viet Nam, the species is found from 200 m to well over 1,000 m asl, with the highest record coming from Pu Mat NP from a listening post positioned at 1,500 m asl (Rawson et al. 2011), however, individuals are now found mostly above 700 m due to lowland deforestation (Rawson et al. 2011). In Lao PDR, gibbons are found from the Mekong plains up to at least 1,650 m in Nam Et-Phou Loei NPA (Duckworth et al. 1995, Duckworth 2008). Gibbons are strictly arboreal and mainly frugivorous (Ruppell 2013), but there is very little field data on the behavioural ecology of N. leucogenys. Dao Van Tien (1983) studied the stomach contents of six wild-shot crested gibbons (genus Nomascus) from Viet Nam, including three N. leucogenys, and found 90-100% fruits, associated with some leaves and insects. This data cannot be directly compared to field observations, which usually measure the time spent eating various food items (Geissmann et al. 2000). Food composition of individuals from Xishuangbanna (southern Yunnan) included fruits (39%), leaves (36%), and flowers (5%) (Hu et al. 1989). A 12-month behavioural ecology study of the species in Nam Kading NPA shows that the species here consumed more leaves (53-85% of monthly diet) than fruits, but the percentage of fruit in the diet increased from January to May when fruits were more abundant (Ruppell 2013). On average, the three groups studied annually spent 30% of their time resting, 33% feeding, 35% travelling and 2% singing (with a seasonal variation; Ruppell 2013). During the rainy season (May-October), when many fruits are available, gibbons travel less, whereas in the dry season (November-April), gibbons eat more leaves and travel for longer distances (Hu et al. 1989). Average group size in Yunnan province, China, was 3.78 (range 3-5, n = 9) (Hu et al. 1989). In anecdotal reports, group sizes of three gibbon groups from Thanh Hoa and Nghe An provinces (southern part of north Viet Nam) were specified as 3, 3, and 4 individuals, respectively (Ha et al. 2005). Mean home range size of the three groups in Nam Kading NPA was 38 ha (29 - 44 ha), and the mean daily path length was 1.5 km (Ruppell 2013).

Food :

It eats fruits, treetops, bird eggs, and insects.

Behavior :

It likes to swing from branch to branch not running on trees. It stays on high trees all day. In order to drink water, it uses back finger to touch on water and suck on it or sometimes uses its tongue to lick in a small swamp. It likes staying in sunlight during early morning on the trees. During daytime or afternoon, where the weather is extremely hot, it will move down from the trees to avoid sunlight. When it is frightened, it swings quickly from branch to branch and hinds within dense shrubs. The important enemies of black gibbon are hawks and pythons.

Current Status :

This species is listed in CITES Appendix I. It is legally protected in Viet Nam (Appendix 1B of Decree 32, 2006) and in Lao PDR (‘Prohibition’ category in the list of protected species) and in China as a Class I Protected Animal under the Chinese Wildlife Conservation Law. However, despite these legal protections there has been little effective enforcement in any country to protect this species against forest encroachment and poaching. The population in China is likely functionally extinct and, as such, direct conservation action is not necessary. However, maintenance of habitat quality within protected areas in its former range should be pursued to allow for the possibility of population reintroductions in the future. In Viet Nam, the species is now largely restricted to the protected area network, including Muong Nhe NR, Sop Cop NR, Pu Hu NR, Xuan Lien NR, Pu Hoat NR, Pu Huong NR, Pu Mat NP, Vu Quang NP and Ke Go NR. Priority sites for conservation interventions are Pu Mat NP and Xuan Lien NR and surrounds (Rawson et al. 2011). Currently, no significant conservation interventions above and beyond those provided by protected areas operations are underway. Given the potential importance of these sites not just nationally, but globally, additional financial and technical investment is required, primarily to ensure effective protection as a first measure. In Lao PDR, the species is present in Nam Et-Phou Loey, Nam Xam, Phou Khao Khoay, Phou Panang, Nam Kading, and Phou Den Din National Protected Areas, and also in Santong Training and Model Forest and in the Nam Ngiep Subcatchment. There is an action plan for gibbon conservation in Lao PDR which includes N. leucogenys (MAF 2011). The action plan identifies Nam Et-Phou Loei NPA and Nam Kading NPA as first tier priorities with Phou Den Din, Nam Xan NPA and Phou Khao Khouay NPA as second tier priorities. Currently, WCS is implementing projects in both Nam Et-Phou Loei and Nam Kading NPAs with strong enforcement components. Across the species' range, hunting control is a vital conservation measure: populations are already small and fragmented and, therefore, extremely vulnerable to additional off-take. Additional measures include ensuring habitat protection and improved zoning and planning to take into account key areas for gibbons within existing protected areas. Environmental education for local communities and government authorities is required. Significant technical and financial investment will be required to ensure priority areas are controlled and maintained. While this is currently occurring in Lao PDR, in Viet Nam considerable additional (international) inputs are likely to be required. The species is commonly represented in zoo collections, both regionally and internationally, and as such there is future opportunity for reintroduction and/or population reinforcement, assuming required protocols can be met (Campbell et al. 2015).


CLASS : Mammalia

ORDER : Primates

FAMILY : Hylobatidae

GENUS : Nomascus

SPECIES : Northern White-cheeked Gibbon (Nomascus leucogenys)

Conservation status : Critically Endangered

Age :

It can live up to 30 years.

Reproductive :

It is mature and ready for mating at the age of 7 – 8 years. Gestation period is around 240 days. One litter contains only one young. Young black gibbon weans when it is 4 – 7 months and stays with its mother until it is 2 years old. Then, it will separate and live on its own.

Reference :

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Point of view :

Update : 11 April 2017