Siamangs are both the largest of the gibbons and the loudest: their territorial calls are amplified by a throat sac that can be inflated to the size their head. They are supremely well adapted to life in the treetops of the Malaysian and Indonesian rainforests, from their acrobatic, hand-over-hand swinging through the branches to using the branches as a bed. They are the only gibbons to have webbing between their second and third toes.
Scientific name: Symphalangus syndactylus
Rank: Species
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Singing and swinging
Siamang couples reaffirm their lifelong commitments in song.
Siamang couples reaffirm their lifelong commitments in song.
Freedom day
A rehabilitated siamang family is released back into the wild.
A rehabilitated siamang family is released back into the wild.
Island sanctuary
A family of siamangs is rehabilitated on the untouched island of Marak.
A family of siamangs is rehabilitated on the untouched island of Marak.
Species range provided by WWF's Wildfinder.
The Siamang can be found in a number of locations including: Asia. Find out more about these places and what else lives there.
The following habitats are found across the Siamang distribution range. Find out more about these environments, what it takes to live there and what else inhabits them.
Discover what these behaviours are and how different plants and animals use them.
Additional data source: Animal Diversity Web
Endangered
Population trend: Decreasing
Year assessed: 2008
Classified by: IUCN 3.1
The siamang (Symphalangus syndactylus) is a tailless, arboreal, black-furred gibbon native to the forests of Malaysia, Thailand, and Sumatra. The largest of the lesser apes, the siamang can be twice the size of other gibbons, reaching 1 m in height, and weighing up to 14 kg. The siamang is the only species in the genus Symphalangus.
The siamang is distinctive for two reasons. The first is that two digits on each foot are partially joined by a membrane—hence the name "syndactylus", from the Ancient Greek sun-, "united" + daktulos, "finger". The second is the large gular sac (found in both male and female of the species), which is a throat pouch that can be inflated to the size of the siamang's head, allowing the animal to make loud resonating calls or songs.
There may be two subspecies of the siamang. If so, they are the nominate Sumatran siamang (S. s. syndactylus) and the Malaysian siamang (S. s. continentis, in peninsular Malaysia). Otherwise, the Malaysian individuals are only a population. The siamang occurs sympatrically with other gibbons; its two ranges are entirely within the combined ranges of the agile gibbon and the lar gibbon. Although the siamang is given a name different from that of other gibbons, this division is not cladistically sound, since the genus Nomascus split from the rest of the gibbons before Symphalangus split.
The siamang can live more than 30 years in captivity.
While the illegal pet trade takes a toll on wild populations, the principal threat to the siamang is habitat loss in both Malaysia and Sumatra. The palm oil production industry is clearing large swaths of forest, reducing the habitat of the siamang, along with that of other species, such as the Sumatran tiger.
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