White-handed gibbon  (Hylobates lar)

A beautiful and captivating primate, the white-handed gibbon is a master of agility (5). As true brachiators, gibbons are much admired for their remarkably fast, yet seemingly effortless, suspensory motion through the trees (6). The white-handed gibbon possesses the long arms and hands typical of gibbon species, which are perfectly suited to this pendulous swinging from branch to branch. Despite lacking a tail, the gibbon's sense of balance is nevertheless acute, and it can even be found walking on its hind legs along branches high above the ground, characteristically raising its arms above its head for balance (5). Individuals vary in colour from dark brown or black to red-buff and pale fawn, but always with a white fringe framing the black face and white upper sides of the hands and feet (7) (8). Males and females are very similar in size and can have all colour variants (7). Its unmistakable call, a loud whooping sound, is enhanced by a sound-amplifying throat sac and can be heard from a great distance (5) (7).

Found in the tropical rainforests of southern and Southeast Asia (8), in the countries of China, Myanmar, Thailand, Malaysia and Indonesia (9). The Malaysian lar (Hylobates lar lar) is found in Malaysia and southern Thailand, the central lar (H. l. entelloides) in southern Myanmar and southern Thailand, Carpenter's lar (H. l. carpenteri) in eastern Myanmar, north-western Thailand and Laos, the Yunnan lar (H. l. yunnanensis) in the Yunnan province of southern China and the Sumatran lar (H. l. vestitus) in Indonesia (northern Sumatra) (1) (2).

This arboreal species inhabits primary or secondary semi-deciduous monsoon forests and tropical evergreen forests (9). Occupying only the upper canopy, these gibbons rarely, if ever, descend to the forest floor (8).

The white-handed gibbon was considered to make life-long pair bonds, but recent studies show some serial monogamy with occasional partner changes, and even non-monogamous groupings (10). Generally, however, groups consist of a mated pair and their offspring. An elaborate duet sung between males and females is thought to maintain pair bonds as well as to mark and defend the pair's territory. These gibbons breed year round, usually producing one young every two to three years (2) (8). The gestation period lasts seven to eight months and young are weaned at 18 months (10). Juveniles reach adult size at six years but remain with their natal group until they reach sexual maturity at around nine years old (8) (10). Parental care is predominantly given by the mother but the father and elder siblings also help raise young (8). Lifespan in the wild lasts 25 to 30 years (10).

These gibbons are active during the day, which is mostly spent foraging for food and feeding (10). Primarily frugivorous, the white-handed gibbon will also eat immature leaves, flowers, stems, shoots, buds, insects, eggs and the occasional bird (2) (9).

Rapid loss of habitat poses the principle threat to gibbons, placing their future in great peril (3) (8). With breathtaking speed the forests of Southeast Asia are being cut down due to logging and agriculture, leaving forest inhabitants an ever smaller region in which to live. This species is sometimes hunted for its meat (8) and the capture of young gibbons for the pet trade is rampant in some countries, particularly Thailand (5). Frequently the mother is shot so that the young can be taken (5).

The white-handed gibbon is protected from international trade by its listing on Appendix I of the Convention on International Trade in Endangered Species (CITES) (4). Other efforts are being made to save these primates, such as national parks and reserves, but they are not terribly effective as they are often poorly supervised and laws against capture un-enforced (8). The highest priority in protecting this primate must be given to preserving adequate areas of suitable habitat (3). Action is required now if we are to prevent this agile and intelligent lesser ape from becoming more critically endangered.

For further information on the white-handed gibbon see:

The Primata:
http://www.theprimata.com/factsheets.html

Macdonald, D. (2001) The New Encyclopedia of Mammals. Oxford University Press, Oxford.

Authenticated (07/11/2005) by Matt Richardson, independent primatologist and writer.