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Southern White-cheeked Gibbon

Southern White-cheeked Gibbon

Class: Mammalia

Order: Primates

Family: Hylobatidae

Scientific Name: Nomascus siki

IUCN Red List status: Endangered

Protected by the following WLT project

Annamite Lowland Forest, Vietnam

Species Range (IUCN)

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The Southern White-cheeked Gibbon, like all gibbons, has long and flexible arms which can be more than twice the length of their body, the longest arms of any primate relative to body size.

Males are mostly black with a distinguishable beard-like white patch around their mouth. Males and females look different (sexual dimorphism). Southern White-cheeked Gibbons are born with a buff coat colour, which changes to black as they mature. Males maintain this black coat, while females undergo a second transition, obtaining pale yellow/orange to brown fur with a black streak on the crown or neck as they enter adulthood.


Spending most of their time on top of tree canopies, Southern White-cheeked Gibbons are more often heard than seen by scientists on the ground.  Calls may travel large distances and communicate different information: males often sing early in the morning to declare their territory and females begin a courtship song that is then joined by the males to create a 20-30 minute long duet.

They live in small groups that consist of an adult pair plus two or three young adults.

Southern White- cheeked Gibbons are mainly frugivorous (feed on fruit), but may also eat leaves and invertebrates to supplement their diet.  Due to their long limbs they can source fruit on thin branches that are beyond the reach of other primates.

Gibbons move between trees by swinging from hand to hand, using their long, powerful arms to propel themselves along. This method, known as brachiation, enables them to move between trees with ease, even where there are gaps in the canopy.

Pairs of Southern White-cheeked Gibbons are monogamous. They stay together for life and rear their offspring together. Young gibbons leave their parental territory on reaching maturity (between the age of three and six years old).   


Southern White-cheeked Gibbons are mainly found in lowland broadleaf evergreen and karst forests in southern Laos and north central Vietnam. 


The Southern White-cheeked Gibbon is classified as Endangered on the IUCN Red List of Species because its population has suffered a 50 percent decline over a 45 year period (three generations) prior to 2008.  

The species is threatened throughout its range by hunting for meat and traditional medicines or trapping for the illegal pet trade. The gibbons also suffer from the loss of habitat caused by logging and the spread of agriculture, particularly in Vietnam. The loss of forest habitat is particularly harmful for gibbons due to their dependency on specific territories. 

WLT’s Khe Nuoc Trong Forest project protects an important area for the Southern White-cheeked Gibbon as much of their habitat is so severely fragmented in Vietnam.

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