Silvery Gibbon (Hylobates moloch)

The Silvery Gibbon

The Silvery Gibbon (Hylobates moloch) is currently listed as critically endangered by the International Union for Conservation of Nature (IUCN). They are in danger mostly because of commercial clearing of the forest where they live. It is estimated that only 4% of their original native habitat is still available to the species. They are, of course, in danger from poachers who sell their meat, pelts, and take the babies for pets.

The Silvery Gibbon is only found on the island of Java in Indonesia. Because of their isolated location, it is estimated that there are less than 2000 of these animals currently living in the wild. They are usually found in the upper reaches of trees, and they travel in small family groups that consist of a mated pair and their offspring in various stages of development. They travel by swinging from branch to branch, using their long fingers to hook the branches as they swing forward for the next branch. At times, their swings are so powerful that it allows them to be completely airborne and reach greater distances in one swing. Gibbons are able to walk on the ground if they need to, and they walk on two legs, holding their arms up above their heads to help balance. In each family’s territory, there are trees that are used for specific purposes, like sleeping and calling. They repeatedly use the same trees for these functions.

Interesting Fact: Every morning, the female Silvery Gibbon will arise and announce her presence to the forest by shrieking and calling. These calls can be heard for at least a kilometer in all directions.

Silvery Gibbons, as their name suggests, are fluffy with grayish-white fur. The fur is very long and dark gray on the top of their round heads. The arms are extremely long, the span at least twice their height, and they are very slender, which allows them to travel through the trees more easily. The average weight for an adult Silvery Gibbon is approximately 13 pounds (6 kg), and the males and females are very similar in appearance and size.

Silvery Gibbons exist primarily on fruit. Since fruit-bearing trees are usually scattered in the jungle, they must travel extensively to find food, and each gibbon family usually has a territory that they travel through that averages about 42 acres (17 hectares). Sometimes these territories will overlap, allowing several families to share the same fruit trees. They have also been known to eat flowers and leaves.

Silvery Gibbons mate for life, and the female will produce offspring about every two to three years. Pregnancies usually last seven to eight months, and only one baby gibbon is born at a time. Gibbons are born essentially hairless with only a small tuft of hair on the top of their heads. Gibbon families are usually very closely linked, and they stay close together when traveling. Adolescent gibbons will stay with the family until they are ready to get off on their own and find a mate. If threatened in their territories, the gibbon female will sing and scream while the male chases off the intruder, usually with a lot of noise and crashing through branches.

Further Information on the Silvery Gibbon:

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Bibliography:
Gibbons. Encarta Encyclopedia, © 2000.
Animal Info - Silvery Gibbon. Accessed on August 15, 2004 at http://www.animalinfo.org/species/primate/hylomolo.htm.
ADW: Hylobates moloch: Information. Accessed on August 15, 2004 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hylobates_moloch.html.
Javan Silvery Gibbon (Hylobates Moloch). Accessed on August 15, 2004 at http://www.markuskappeler.ch/gib/gibs/chapter7.html.