Primate Report

Northern White Cheeked Gibbon

Nomascus Leucongenys

Northern white-cheeked crested gibbon in Vietnam Terry Whittaker cc image


The northern white-cheeked gibbon or also known as the white-cheeked crested gibbon is classified as the genus Nomascus and the species of leucogenys. These mammals range through Vietnam, Laos and China, endemic to the dense rainforests of Southeast Asia. The recent declines suspect this primate is not going to sustain without immediate conservation, they are listed as critically endangered.

The lifespan of the white cheeked gibbon is 35 – 40 years. The male white-cheeked gibbon’s coat is black, and females are beige to yellow, both have white cheeks which reach up over the ears. However this species does not have hair on the fingers, the palms or the soles of their feet. Infants are yellow, as they mature they become black and when they reach adolescence, puberty at around 6 years of age they will turn into their actual color either female or male.

White cheeked gibbons are 1m – 1.2m in length and an adult gibbon will weigh 10kg – 12kg. Reaching 60cm to 70cm gibbons have the longest arms relative to their body size, out of all the primates. All gibbons lack a tail, though the hands and feet of the gibbon are long and thin helping them be very well adapted to arboreal life, living in the trees. Gibbons tend to have an opposable toe and thumb to help the gibbons grab objects. Their powerful legs also help them grab branches. The body of this species is slender and agile so that they can move swiftly.

Northern White-Cheeked Gibbon. Photography. Encyclopædia Britannica Image Quest. Web. 2 Apr 2013.

Observation of Primate

Vietnam, Lao People’s Democratic Republic, and China are home to the white cheeked gibbon. In Viet Nam it is present in Pu Huong Nature Reserve and Ben En National Park. The white cheek gibbons also occur south and west of the Black River, north-west and north-central parts of Vietnam. Another native territory of this species is Lao PDR, where they are found in the northern parts, and east of the Mekong River, except for a small area on the east bank where it is replaced by another species. In Lao PDR, it is present in Nam Et and Phou Loey, Nam Xam, Phou Khao Khoay, Phou Panang, Nam Kading, and Phou Dene Din National Protected Areas, Santong Training and also in Model Forest. In China, it was previously reported in Xishuangbanna National Nature Reserve, but only in the two sections southernmost part of Yunnan province, bordering Lao PDR.

Their habitats are primarily in fragmented (degraded forests, where the amount of trees are reduced) evergreen, semi evergreen and  forests at high altitudes with subtropical climates and abundant fruit trees. These tropical rainforests are warm mostly all year long. The average temperature in these forests are from 21˚C to 30˚ C, it infrequently changes, even between day and night. The environment is damp in these forests, maintaining the humidity of 77% to 88% all year round. The rainfall yearly can be from 200 to 1000cm.

At the Endangered Primate Rescue Centre (EPRC) located in Cuc Phuong National Park, Vietnam, there are 140 primates in 15 taxa, species and subspecies. These primates were victims of poaching, or illegal animal trade, which were confiscated by protection authorities all over the country.  This non-profitable organization is devoted to the rehabilitation, breeding, research, conservation of endangered primates, and their habitats. The enclosures for the primates are kept in their natural living conditions. The pair of white cheeked gibbons from the EPRC that live in captivity have an enclosure that is 15m in width and 5m in height. The space they live in is enclosed by metal wiring. There are bamboo sticks which are placed from one side of the cage to the other, creating many branches for them to swing on. There are playing toys in the enclosure which are mostly made for the swinging on but sometimes the gibbons would push it around. The cage that surrounds the enclosure is very sturdy because these primates must be kept in captivity, and sometimes they jumps violently on the cages too. There is a small open shed to block wind out at night where the primates can rest. The plants and trees in the white cheeked gibbon’s captive sanctuary are not dense. Except for the small plants that imitates the bedding of the rainforest floor. Surrounding the enclosures the EPRC, animal keepers grow the plants that the primates eat, making it organic as possible. The white cheeked gibbon’s home in the EPRC are larger than if they were to be kept as a pet; this creates more space and freedom for them.

In their natural habitat, the white cheek gibbons would have many tree branches to swing onto. Since there are not enough trees at the EPRC, the density is not at all similar to the denseness of the forests, meaning that the primates will have to adapt a lot before introduced back to the wild. White cheeked gibbons in the wild live very high up in the canopy, and the branches in the enclosure are not nearly as high enough and they are too close, making their habitat very different. The enclosures lack privacy, the other enclosures are just meters away, and these animals are known to be aggressively territorial. The white cheek gibbon’s like to swing on the cages, however when they rot and the metal wiring can be fairly sharp. In the wild gibbons do hold on trees and the action of grabbing vertically onto the wiring will prepare them for that. The changes between the habitats and enclosures are large but since these primates were kept in captivity before they will find ways to adapt. There are good motives for the primates that live in captivity, for example the food is provided for them, though this means they won’t have any knowledge of how to find food in the wild.

White cheeked gibbon brachiating by Uyen Trinh cc images

The white cheeked gibbons are very well adapted to living in trees even without a tail. They spend most of their life in the high tree tops, the canopy layer, at approximately 24 to 30m above the forest floor, but can reach up to 60m above ground. They rarely descend to the forest floor. When they descend to the ground, they often do so on both feet, throwing their arms above their head for balance, which is called bipedalism. White cheeked gibbon form of locomotion is called brachiating, swinging from branch to branch. As they swing they use their weight to propel them forward and their arms alternate and grab onto the next branch. While they travel through trees, the gibbon does not actually clasp limbs but rather hook onto them, which is an adaptation that contributes to the animals speed while brachiating.

White cheeked gibbons are highly territorial. They are monogamous, a family of this species consist two adults which usually mate for life, and their offspring. Younger groups often consist of only two individuals. Hardly do the white cheeked gibbon groups exceed six individuals, though it is more common for the families to have two immature members. White cheeked gibbons often interact socially with each other while playing and grooming, they also sleep together in a huddle. They are allopatric, which means their ranges do not overlap. Each group occupies 20 to 45 hectares which they aggressively defend. They are among the 6% of primates that form strong pair bonds for life. Singing is very rare in mammals, and gibbons produce the most complex songs of all land mammals. The songs are also used to mark territory boundaries, and for mated gibbons singing strengthens their bond. White cheeked gibbons are diurnal, active during the day. Every morning for 30 minutes gibbons would announce its territory’s boundaries by hooting and singing loudly. Gibbon’s do this because they want to protect their local food sources such as figs, or fruit trees. White cheeked gibbons show aggression when they meet other groups of gibbons. They will leap aggressively, sometimes showing their teeth, as a warning. If neither group yields, a chase might result, this can last from several minutes to a few hours.

White cheeked gibbon’s move and feed mostly in the tropical forests canopy. These lesser apes are primarily vegetarian. 75% of their diets include fruits, and the other contents are leaves and insects. They are mainly frugivorous and folivorous. They eat leaves, flowers, seeds, tree bark, tender plant shoots, spiders, young birds, and small bird eggs, making them omnivores. Gibbons drink water by dipping their furry hand into the supply of water, or sometimes rubbing a hand on the wet leaves. Then they would slurp up the water from their coat. During the rainy season (May to October) many fruits are offered, so white cheeked gibbons move less, whereas the dry season (November to April), the gibbons eat more leaves and travel longer distances. White cheeked gibbons constantly swing out and grab fruits growing on the end of branches.


All 25 of the world’s gibbons are threatened of extinction, with the populations suffering from many habitual reasons as well as economic. Out of the world’s 25 different threatened gibbons, no populations are as vulnerable as the Indochinese crested gibbons, eight which includes the white cheeked gibbon. The white cheeked gibbon’s historical ranges are China, Vietnam and Lao PDR.  According to the International Union for Conservation of Nature and Natural Resources or IUCN, the white cheeked gibbons are listed critically endangered. Conferring to Vietnam’s Red Data Book, white cheeked gibbons are endangered. In Laos the population is unknown, while potentially large because of the remaining habitat. There have been no records of this species in China since 1990, but survey work, showing it is possibly extinct . Vietnam has the only dependable population.

Range Map IUCN White-Cheeked Crested Gibbon cc images

Considering the recent studies of the Nomascus genus, their habitat area could extend further south. Vietnam used to have a high level of diversity, but slowly the numbers of primates is decreasing immensely. Through auditory surveying and listening to the white cheeked gibbon’s loud morning calls, Conservation International (CI) has confirmed a surviving population of 130 groups (455 animals) in Pu Mat National Park, Vietnam. While in search to find and count the white cheeked gibbon, the CI has set up research points 6km away from each other. Scientists would climb up the mountain to their research spot at 5 am in the morning and detect sounds of gibbons. By analyzing the sounds of the gibbons, experts could identify and define each gibbon individuals. This new identification represents two thirds of the entire population in Vietnam, and is established as the only reliable population of this species left worldwide in the wild. Vietnam’s Pu Mat National Park is remote from human disturbance at 90,000 hectares, and is home to the largest community of white cheek gibbon in Vietnam.

The past three years the white cheek gibbon has been distributed in north-central Vietnam, none of these locations have populations of over a dozen. The other 27 recorded sites at which white cheek gibbons should have occurred in Vietnam, it was only confirmed surviving at four, and may survive in a further three. Some of the remaining white cheeked gibbons that were confiscated in Vietnam are currently kept in the Endangered Primate Rescue Centre. There may be as few as 200 groups of white cheeked gibbons in Vietnam. In 2000 the white cheeked gibbons were listed endangered on IUCN, showing that this species have suffered huge declines.

Endangerment and Conservation

The white cheeked gibbon has been continuously disappearing from a native distribution area to another. The population loss of the white cheek gibbon has been primarily because of hunting. There is a lot of hunting pressure for local consumption because of what is paid for this critically endangered species. White cheeked gibbons are caught for various reasons, including illegal trade, cultural value, scientific value, food, traditional medicines where parts of the primate are sold separately for money. Hunting has caused dramatic declines as well as created an issue to the security system. The roads that have been built through protected areas have made it easier for illegal activities such as hunting to go on. Still, hunting will let the park rangers know that, the area is not safe, and the can work on making it more secure. Most of the restricted areas which still have the remaining viable populations of gibbons, lack the standards of protection that ensure the survival of this species.

Gibbons are the most endangered apes, as well as the most endangered species of primates worldwide. Illegal pet trade is thriving across the whole South East Asia. Young gibbons are especially popular to keep as pets. Possibly because they are cattarhines, a group of primates with nostrils face forward and slightly downward. To be able to obtain a young animal, either the young animal’s mother or even father must be shot down from the treetops. Often both arboreal are killed during the process. Although, white cheeked gibbons are dexterous while moving in the trees and almost no predators can catch them, hunters have guns and since gibbon’s songs can be heard from several kilometres away, hunters can locate exactly where they are. Once gibbons are caught they have a small chance of being introduced back to the wild.

In order to preserve this species valuable genetics, local authorities must ban hunting and get assistance from other non-profitable organizations to secure and strictly protect the area that these astonishing creatures live in. The non-profitable organizations must investigate more. Through researching, collecting surveys throughout the range, tape recordings, genetic analysis, and photographic recordings, experts could gather more scientific information about this creature and where it lives. Adding to that primatologists have been setting up many research points in Vietnam to determine the distribution area of this species, and their populations, which will make it easier to secure that specific enclosure. Right now they are depending on Pu Mat National Park. This information will make it easier to help gibbons mate in captivity, and help to prevent hunting across the globe. The researchers will realize how important white cheeked gibbons are. Raising awareness to the public will also support these gibbons, for not many human actually know how much these gibbons are suffering. There are many actions that people are taking right now but it is not enough because there are too many critically endangered species out there.

This problem must be solved by research and analysing, not only will the solution impact the economy, and the environment but it will definitely be social as well. Socially, the information will have to be more precise, and exact for people to believe it. If scientists are able to protect and record examination of this species then people will be able to help more than they are right now. So if the facts are transferred onto media everybody will know it. Animal lovers will want to support, by donating or even personally coming to the protected location and help. Raising awareness globally will reduce the threats of extinction of the white cheeked gibbons as well as the other species so what similar to itself. Many sponsoring organizations will know more about these species, as so will people. The white cheeked gibbon species is in need of serious help because the locations they live are not protected. Using the money donated by others around the world, local governments could create an environment that is safer for them, by doing that other endangered species will be saved too.

Creating the primates sanctuary more secures means that hunters and poachers will lose their jobs, which is a good thing for the primates but a bad thing for them. Minimizing habitat disturbance will prevent wildlife trade from getting any worse. This means the black market and illegal trading will also start failing. Socially, hunters will have to realize what they are doing, and how many people are against them doing it. Hunters are always desperate for money so they depend on killing animals for money. Some hunters have changed into rangers because they know so much about the forests. This change will impact the other hunters and socially poachers will start to follow the laws. Many hunters out there are trespassing, logging and killing animals illegally. The increase of human access will affect the existence of gibbon population. The more remote the locations are, the more isolated human disturbance there is, meaning that these iconic tree dwellers will have a chance of surviving in the wild habitually. If hunters are stopped from entering protected areas then the social influence will be less.

Information provided by the research will also help other scientist and experts across the entire globe to have a better idea of what these amazing species are capable of. They will be able to save them gradually, and sooner. Globally people will understand the importance of these beautiful apes. Even though raising awareness seem easy, the social pressure by the public will make the experts look further into their primate’s endangerment. There are many endemic species out there and it’s very important to protect them, preserve their valuable genetics, and understand their effects on nature. The research will impact everybody’s knowledge of gibbons, not many know how threatened white cheeked gibbons are. Scientist will also be able to help the population more. With people caring about white cheek gibbons there will be more help directed to save these primates.

Conservation projects such as Conservation International, Endangered Primate Rescue Centre etc… have started already, but they only have enough money to save the most endangered. The white cheeked gibbon is legally protected in Vietnam though enforcement against forest poaching is not proper in most cases. In China it is protected by wildlife protection law. Surveys are conducted and the more people do the more the population will be kept. Even though, the increase of human access will affect the existence of gibbon decimated population, these primates need assistance on surviving. After all it isn’t their fault.


There is a lot of pressure of saving these primates because of their presence in the wild and impact on the environment. It’s important to protect white cheeked gibbons because not only do they limit the amount of plant’s but also wildlife, so that no birds take over the forest. The white cheeked gibbons are important to the functioning of the environment, especially the food web. White cheeked gibbons eat a lot of plants and if they get extinct, then all those plants will over populate taking up all the energy from the sun, meaning other plants won’t be able to photosynthesize and die. If the white cheeked gibbon’s species get wiped out, the food chain will be ruined because every living thing is a crucial part of nature and if one dies, then others will fail to live slowly.  There are a lot of biodiversity in the natural habitats of Vietnam but there are many primates out there that are threatened of extinction, meaning that each and every one of them supports the environment by reproducing, digesting, and wasting. The only motivation of keeping the forests of Vietnam is to save the wildlife that live in them. If every single one of those primates becomes extinct the greenery will be chopped down for agriculture or for timber. Those national parks aren’t only vital for survival of primates but it also benefits to people as a watershed which provides more than 50,000 people with water for drinking and agriculture. The trees in these habitats benefit everyone in the world by providing oxygen, without them it would be harder to breathe as well as more pollution.

People believe if we don’t start now the future generation will never be able to experience this amazing creature. Yet the future will always be uncertain.

Works Cited

“All About Gibbons.” Enchanted Learning. EnchantedLearning. 30 Mar. 2013
Bleisch, B., T. Geissmann, N. Manh Ha, B. Rawson, and R. J. Timmins. “Nomascus Leucogenys.” The IUCN Red List of Threatened Species. 2008. International Union for Conservation of Nature and Natural Resources. 29 Mar. 2013
“Gibbon Conservation Alliance.” Gibbon Conservation Alliance. Ed. Thomas Geissmann. Gibbon Conservation Alliance, Zürich, Switzerland. 29 Mar. 2013
“Gibbon.” National Geographic. National Geographic Society. 30 Mar. 2013
“Gibbons.” WWF. WWF. 30 Mar. 2013
” Largest Population of Critically Endangered Gibbon Discovered in Vietnam.” Conservation International. 18 July 2011. Conservation International. 29 Mar. 2013
“Rainforests.” Kids Do Ecology. Kids Do Ecology NCEAS. 02 Apr. 2013 <>.
Rakowski, Sarah. “Extinction Looms for Gibbons in Vietnam, Scientists Say.” Fauna & Flora International. 21 May 2012. Fauna & Flora International. 30 Mar. 2013
Rawson, Ben. “Gibbon Discovery Gives Hope for Survival of Species.” Human Nature Conservation International Blog. 18 July 2011. Conservation International. 30 Mar. 2013
THANHNIENNEWS. “Vietnam’s Gibbons Face Extinction: Report .” TalkVietnam. 23 May 2012. TalkVietnam. 29 Mar. 2013
VIETNAMNET. “How White-Cheeked Crested Gibbons Discovered in Vietnam?” TalkVietnam. 1 Aug. 2011. TalkVietnam. 30 Mar. 2013 <>.
“gibbon.Britannica Student Encyclopedia. Encyclopædia Britannica Online School Edition.
Encyclopædia Britannica, Inc., 2013. Web. 1 Apr. 2013.
Print Friendly, PDF & Email

Leave a Reply

Your email address will not be published. Required fields are marked *