Siamang gibbon

Common Name: Siamang gibbon

Scientific Name: Symphalangus syndactylus

 In Life Among the Trees, opposite the otter enclosure.

Family groups of siamangs sing to announce their territory and to show the pair bond between the adult male and female of the group.

Pairs of siamangs sing duets, with the male and female taking different parts. The duets are best developed in pairs that have been together longest. New pairs take time to coordinate their duets. Lone male siamangs sing solos.

Siamangs have a large inflatable throat-sac to increase the sound of their calls.

Siamangs show aggression by opening their mouths wide to show their canine teeth.

Fast Facts

  • Status


  • Size

    Head-body: 75-90 cm

  • Weight

    Males: 10.5-12.7 kg; females: 9.1-11.5 kg

  • Gestation

    189-239 days

  • Young


  • Life span

    Up to 44 years

In the wild

Siamangs mainly eat fruit, especially figs, but will also eat leaves, insects and flowers. These animals get most of the water they need from fleshy fruits. When they do need to drink they prefer to use water in tree-holes instead of climbing to the ground, where they are more at risk from predators. They drink by scooping water into their hands, or by dipping their hands into water and licking or sucking the water from their fur. They are also known to lick rainwater or dew from leaves.

Siamangs are found in Malaysia, Thailand and on the island of Sumatra in Indonesia. They live in tropical forests which are classed as primary forests (which haven’t been logged or managed by people) as well as secondary forests (which have been disturbed). Siamangs are most active in the middle and upper canopy of the forest, though they will forage lower down, especially during the hottest part of the day. They use very tall emergent trees, which grow above the height of the canopy, to rest and sleep.

Siamangs will usually give birth to one infant, but twins are born occasionally. Young siamangs are completely dependent on their mother for at least the first 12 months of their life. They start to eat solid food between 3 and 9 months, and are almost weaned by 12 months old. After this, the father takes over care of the infant, carrying it around until it can move independently. They are independent by the age of two. Siamangs reach maturity when they are about 8 years old.

Siamangs are thought to avoid predators by sleeping in tall trees and forming groups with other species of primate. Not much is known about the predators of siamangs, but clouded leopards have been known to take young siamang.

Siamang populations have decreased by at least 50% since the 1970s. The main threats they face are from hunting for the pet trade and habitat loss, mainly from land being used for agriculture, logging and road building.  However, siamangs are found in many protected areas, as well as being protected by local laws in every country they are found in. They are also included on CITES Appendix I, which means that international trade of the siamang and its parts are prohibited.

Meet Marwell's Siamang gibbon

Meet Marwell's Siamang gibbon

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