The Bornean gibbon, also known as the grey gibbon, is a species of hominoid primate of the family Hylobatidae. It is currently listed by the IUCN as a threatened species due to habitat loss.

General characteristics

Unlike most gibbon species, the Bornean gibbon does not show sexual dimorphism in its coat colouring. Its fur is grey or brown with a ring of shiny hair around its face. On its head, it often has a dark-coloured “cap”.

Gibbons have padded buttocks, long canine teeth and no tail. The basal part of the thumb extends from the wrist rather than the palm, allowing it to extend its range of movement.

Feeding

Most of its diet consists of sugar-rich ripe fruits, although it may also consume leaves and some insects.

Behaviour

They are diurnal animals that move between trees using brachiation. Their long, strong-gripping arms allow for extremely graceful and fast movement through the trees. 

They are so well adapted to brachiation that when they are running through trees at high speed, they place their legs close to their bodies so as not to get in the way. On the rare occasions when these tree dwellers descend to the ground, they hold their arms above their heads to keep their balance and avoid dragging them along the ground while walking bipedally.   

They defend their territory with powerful, long songs. Single males sing longer songs to attract mates, but single females do not.

Reproduction

Gibbons are monogamous and reach sexual maturity at 8 to 9 years of age. The gestation period lasts approximately 210 days and usually only one calf is born.

Threats

It is a species in danger of extinction due to the increasing disappearance of the forests in Borneo. They are also a target for illegal hunting and trafficking.

Distribution

This gibbon is endemic to Kalimantan on the island of Borneo, inhabiting the rainforests of the north-eastern part of the island.  

Did you know? 

They are very fast. They reach speeds of up to 56km/h.

They can cover 15m on a single swing.

Although each gibbon’s songs may all sound the same to a human, in reality they are highly individualised.

Conservation status