TAXONOMIC NAME: Hylobates lar
RANGE: Thailand, Malaysian Peninsula and Northern Sumatra.
HABITAT: Tropical and subtropical rain forests.
PHYSICAL CHARACTERISTICS: Average weight of 5-7 kg (11-15 lb). This slender, lesser ape has very long arms - nearly twice the length of its body. Like the larger apes, it has no tail. The coloration of its very thick fur varies from light buff to brown-black but always with white hands and feet. Many gibbons are almost white at birth and do not develop their full coloring until 2 to 4 years of age. Their small jaws hold some surprisingly long canine teeth.
LONGEVITY: Up to 30 years in the wild and up to 44 years in captivity.
SOCIAL STRUCTURE: Live in small family groups of a bonded male and female and up to four of their offspring.
ACTIVE TIME: Diurnal
DIET: Wild: Ripe fruit makes up most of their diet, followed by leaves, plant shoots, flowers, birds' eggs, (which they can catch in the air!), birds, insects and spiders.
Zoo: Leaf-eater biscuits, canned primate diet, fruits, vegetables and leafy greens.
BEHAVIOR: Well-adapted to a life in the trees, their long arms let them brachiate faster than we could run on the ground. Brachiation is a form of movement in which their long arms are extended far above their head to suspend and propel their body. They travel through the trees by swinging from branch to branch. They can use their hands and fingers like hooks instead of grasping the branches because their thumbs are well separated from the rest of their fingers. They often make long swing-like leaps in which neither arm is supporting them while they “fly” through the air to the next branch. They bound from springy branches high in the trees and can “soar” up to 36 feet through the air to the next set of branches. They are accomplished acrobats and exceed all other animals in agility. All species of gibbon are very territorial. They live in families that maintain territories as a group. To protect their territory and reinforce pair-bonds, a bonded male and female frequently sing a duet together in the mornings and sometimes in the evenings. The female has a swooping plaintive “great call” and the male sings more of a “quaver call”.
REPRODUCTION: Gibbons are very picky about their mating partners and can be difficult to breed in captivity for this reason. After a gestation period of around 7 months a single infant is born. It clings very tightly to its mother while she moves through the trees because if it lets go it will probably die from the fall. The young are not completely weaned until about 20 months. Once gibbons reach sexual maturity in 8 or 9 years, they meet up with other young gibbons at territory boundaries and form new family groups.
- Hylobates means “dweller of the trees.”
- Juveniles engage in play-biting matches to determine their rank later in life. The gibbon’s thick skin and dense fur protects it from serious injury.
- Surprisingly, gibbons fall during brachiation an astonishing amount. No matter how agile they are, decaying branches can break as they swing from them, making it difficult to regain their hold on another branch before falling. Many wild gibbons that have been examined have had several healed bone fractures.
- Gibbons share their food with each other, often the same piece of fruit. This kind of sharing is rare in apes and monkeys.
- Their very dense, soft fur has more than 1,700 hairs per cm2 (11,000 per in2) of skin on their backs more than 2 or 3x that found in most monkeys (900 hairs per cm2 in Old World monkeys).
- Drink water by licking rain of their fur after a storm, or dipping an arm into a water-filled tree hole or rubbing it on wet foliage.
CONSERVATION STATUS: All Gibbon species are considered endangered, largely due to foresting and palm oil harvesting.
RELATIONSHIP WITH PEOPLE: In many countries of their natural distribution, it is a status symbol to have a pet gibbon. In order to catch a young gibbon, however, the entire family is chased into an isolated tree and all the adults are killed. Dependent on old growth forests, the main cause of population decline for gibbons in the wild is habitat destruction due to logging and agriculture. Hunting gibbons for food or as pets worsens as habitat destruction continues because logging roads allow greater access into the forest.