Reproduction

Lar gibbons do not have a defined breeding season though activity peaks in March.

Gibbons form a strong pair-bond with this pair maintaining a home range and living in a group with their immature young. Partners reinforce their bond each day through periods of mutual grooming.

Occasionally pairs may separate during their lives and find new partners.

A single infant is born after a gestation period of 210 days. At birth the infants are mostly hairless with a small cap of fur on top of the head. They will cling to their mother's chest where they are kept warm between the thighs and abdomen.

Soon after birth they develop the ability to vocalize. They first brachiate at 9 months old. Weaning occurs at 2 years old.

Females provide the majority of the care for the infant though the male may occasionally provide assistance.

At between six and eight years old the infant is driven out of its birth group.

Females achieve sexual maturity at 9 years old. Males mature between 8 and 12 years old.

Young are produced once every two to three years.

Behavior

White handed gibbons are best adapted for life in the trees. Their long arms are useful to help them move through the trees.

Inside the wrist they have a ball and socket joint rather than the saddle joint of humans which helps them to move through the trees. It is rare for individuals to ever move to the ground.

These gibbons are primarily active by day. At night they will find a spot in the trees where they sit on the ischial callosities and bury the heads in the knees or chest.

They live together in groups of two to six. The main members of this group are a monogamous pair which breed together for life. These groups are known as a troop.

Males work hard to defend the territory inhabited by the family. This is primarily achieved by calling and displaying which primarily occurs in the morning.

Pairs will also call in a duet to one another to reinforce their pair bond. Another call is generated to warn the group of approaching predators.

Occasionally lar gibbons are seen walking with on their two feet with the arms raised to keep them balanced.

Predators and Threats

Natural predators of the lar gibbon include leopards, tigers, pythons and eagles.

They experience some food competition with the larger siamang which can reduce their success.

Over the last 45 years the lar gibbon is believed to have declined in population by 50%.

In parts of their range they are hunted to supply the pet trade. Poachers will hunt the mother and then take the infant. They may also be captured for use as food.

Other threats including habitat clearing to create land for agriculture such as palm oil plantations. Increasing development of roads through their habitat both opens up new areas to hunting and habitat loss.

Quick facts

The lar gibbon is also known as the white-handed gibbon or common gibbon.

Their genus name Hylobates comes from a Greek language and means “forest walker.”

While well adapted to move through the trees the lar gibbon does occasionally fall. As a result some scientists believe most individuals suffer at least one fracture in their life.