Capped Gibbon

Throwing itself from tree to tree over gaps of over nine metres, this tree-dwelling primate moves its forearms alternately to swing beneath the branches (3) (6). Despite exhibiting this brilliant form of locomotion, known as brachiation, the pileated gibbon is also able to move short distances by foot, and can also climb whilst moving slowly or feeding (5). The diet of the pileated gibbon consists primarily of fruits high in sugar, such as the fig (Ficus species), but it also supplements this sweet food with immature leaves, flowers and insects (5). Pileated gibbons are active during the day, spending the nights and other periods of rest in tall trees (5). They live in small family groups which consist of a breeding pair and their offspring. Single offspring are born into the group every two to three years (5) (7), and leave the group around adolescence (5). Although these apes are monogamous, polygyny has been observed where the white-handed gibbon (Hylobates lar) occurs in the same area, with some groups containing females of both species (5). Like all other gibbon species, pileated gibbons reinforce bonds between individuals in the group by social grooming, with one individual grooming another (5). Dominated by the female, the bond between breeding pairs is reinforced through 'duets'. It is believed that these vocalizations are also necessary to establish and maintain the family groups' territory (5), which they also defend with displays and threats (5) (6).

The pileated gibbon is protected from international trade by its listing on Appendix I of the Convention on International trade in endangered Species (CITES) (2). The World Association of Zoos and Aquariums (WAZA) established an International Studbook in 1990 for the pileated gibbon, and conservation breeding programmes were set up to ensure there is a viable reserve population (9). The Cardomom Project was set up with Fauna & Flora International (FFI) to preserve the Cardomom Mountains region in south west Cambodia to protect both the habitat from destruction and the wildlife from hunters. It is hoped that species such as the pileated gibbon will benefit from the work carried out by this project (7).

Known for their graceful and impressive method of locomotion, and their beautiful and complex duets, gibbons are spectacular to behold in the wild (3). Male pileated gibbons have short black hair with white hands, feet and brow band (3) (4), and there is a white circular streak around the crown cap on the sides of the head (4). Females range in colour from buffy to silvery-grey with a black chest, cheeks and cap (3) (4) and a white brow and facial ring (4). Infants of both sexes are similar in colour to the adult female, but slightly paler silvery-buff, making the pileated gibbon the only Hylobates species in which males undergo a colour change (4). Like other gibbons, the pileated gibbon has a slender body, long forearms and no tail (3) (5). A throat sac located beneath the chin enhances the spectacular calls which both male and female pileated gibbons make. The male calls with abrupt notes and a trill after the females call. The female call is much louder and distinctive and consists of rich short rising notes lasting around 18 seconds (3).

Occurs in semi deciduous monsoon forests and tropical evergreen forests (5).

The pileated gibbon is found in Cambodia, Laos and south-east Thailand (1) (3).

Classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix I of CITES (2).

The pileated gibbon has undergone a population decline since deforestation began in Southeast Asia (3) (8), and it is thought that the species is near extinction over large parts of its range (3). The additional pressure of hunting, for both food and for the pet trade, is adding to the problem (8). It is thought that up to ten animals will have died during capture or transit for every baby gibbon sold as a pet (8).