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Fact File

Continent: Asia
Habitat: Forests
Weight and Arm Length: 11.9kg (males) / 10.7kg (females), 1.8m
Diet: Omnivore
Gestation: 235 days
Number of Young: 1 at a time


Conservation Status: EN

STT - high res


  • Arboreal and move through the trees with an acrobatic hand over hand swinging motion called brachiation.
  • Most distinguishing characteristic is the enlarged throat sac that is used as a sound box to amplify their loud vocalisations.
  • Highly territorial, the male and female mark their territory by singing a duet. They sing in tune with one another and the male often swings through the trees during the song.
  • Siamangs move less and more slowly than most gibbon species. This may be because they consume more leaves than other gibbons. As a result of this they also have smaller territories.
  • Grooming is one of the most important social activities of a siamang.


Symphalangus syndactylus

Animals — Mammals — Primates — Hylobatidae (gibbons)

Siamangs are a large species of gibbon native to Sumatra and the Malay peninsula. They are in fact the largest gibbons, often twice the size of other species. They are always black, have two toes with a partial membrane and have large ‘gular sacs’ which they use to call loudly. They can be heard up to 2 miles away!

Siamangs are less active than other gibbons, likely because of the high leaf content of their diet. They are very social and tend to be found in family groups, though they often communicate with other family groups. They spend much of their time grooming each other. When fruit is most abundant they are most likely to breed.

They are endangered, being heavily affected by the pet trade. They are also strongly affected by habitat loss which has greatly reduced their numbers. The main reason for this destruction is palm oil plantations.

Habitat: Are found in lowland, hill and dipterocarp forest. They spend most of their time in the mid-upper canopy over 24 metres above the ground.

Vital Statistics: 
–Average weight: Male- 11.9kg, female- 10.7kg
–Average arm length: 1.8m

Life Expectancy:
In the wild up to: 25 years
In captivity up to: 40 years

Plant & meat eater. Eat mainly leaves with some fruit, and also insects, bird eggs and small vertebrates.

Distribution: Found throughout the barisan mountains of Sumatra and in the mountains of the malay peninsula.

Conservation: Safari Zoo has taken part in conservation work in Sumatra for the majority of its operation. We manage and are the sole funder of the Sumatran Tiger Trust Conservation Charity (STTCC), which was founded in 2000.

Our conservation in Sumatra currently works within two national parks: Way Kambas Tiger Reserve and Bukiet Tigapuluh National Park. Conservation activities include replanting of forest trees, anti poaching/logging patrols, snare and trap removal, environmental surveys, building of schools, hiring of teaching staff, and paying for medical staff visits.