Conservation Status– Critically endangered
Northern white cheeked gibbons show a high level of sexual dimorphism. The female is a reddy-tan colour with a black stripe along the centre of the head. The cheeks are white, a trait which they share with the males of the species. Males have a black coat. On the head they have a prominent ball of fur. White cheeked gibbons have incredibly long arms which are 1.2 to 1.4 times the length of their legs. This is long even for a gibbon.
Males and females are similar in size measuring from 45.7 to 63.5cm (1.5-2.08ft). The male has an average weight of 5.6kg (12.35lb) while females are mildly larger at 5.8kg (12.8lb).
Lifespan of this species in the wild is said to be 28 years.
White cheeked gibbons are classed as omnivores. The major portion of their diet is fruit though their dependence on this is less than other gibbons. They also feed on leaves, shoots, flowers and insects.
Throughout the year this species diet varies. In the wet season fruit is readily available and they do not need to travel as far to find this. During the dry season fruit is harder to acquire and they increase their dependence on leaves.
White cheeked gibbons are at home in Asia. They can be found in Laos and Vietnam where the world’s largest population is found. The gibbons in this area are said to form the only viable wild population. While they were previously found in a small region in China they are now believed to be extinct in this portion of their range.
These animals live in areas with a subtropical climate. They are found in primary and mature secondary forests. Most of their time is spent in the canopy of tropical rainforests.
Groups of white cheeked gibbons consist of a monogamous pair who will mate and their offspring. An important part of their mating is the calls which they make. The more times a pair call to each other the more likely they are to mate. The female has a 22 day ovarian cycle.
At one year of age both sexes turn to black in colour and develop a pale cheek patch. At four to five years of age females once again become buff while the males remain black. During this change the juveniles spend a large amount of time playing and will sing the call which females make regardless of gender.
At seven to eight years of age the Northern white cheeked gibbon becomes sexually mature. They have a baby every two to three years.
White cheeked gibbons are a social species. Their group may consist of six individuals with a mated pair and their juvenile offspring. They maintain a territory which is not particularly large. Most of their activity occurs during the day. At night time they cuddle together in a tall branch.
Males and females each have a distinct call which they use for duets. The female makes a set of nots followed by the male who replys. They then repeat the cycle and will do this for up to seventeen minutes. While much is not known about this species the southern species has been shown to sing at dawn and on sunny days only. Males can also may a booming noise and short single notes through the use of their gular sac. This display is part of defending their territory by showing off their position to other groups.
Gibbons live a highly arboreal lifestyle. Gibbons use a specialised movement method in the trees known as brachiation. This movement sees them using a hand over hand movement and creating a loose hook around the branches as they move through the trees. They show a preference for either the right or left hand when swinging through the trees.
It is believed that the only predator of this species is raptors. No definitive study exists to prove this though.
Northern white cheeked gibbons are able to recognise themselves in a mirror.