The Siamang is the largest of all gibbon species, and is confined to tall, montane or hill forest. The species is endangered due to the destruction of its  forest habitat by overlogging or conversion to oil palm plantations, as well as the illegal wildlife trade.

Siamang lead a fully arboreal lifestyle and are more often heard than seen. Males, females and juveniles all possess a large throat pouch which inflates to produce a powerful call which can be heard at a great distance : the call, which is usually made in the morning, comprises loud whoops, barks and yells.

The fur of adults and juveniles is long and jet black : there is a total absence of the white facial markings seen in other gibbons. Their thick fur allows them to live at high altitudes, reportedly as high as 3800 metres. Physically Siamang appear stocky, with long, thick powerful arms.

They feed predominantly on vegetation including young leaves, shoots of climbers, flowers, fruits and figs: this is supplemented by occasional high protein foods such as insects.

Unusually amongst primates, male Siamang play a significant role in caring for their young : fully weaned juveniles are carried by adult males during the day, only returning to their mothers at night.

Siamang occur in montane or hilly areas of extreme southern Thailand, Peninsular Malaysia and the Barisan Mountains of Sumatra. The Sumatra population is considered by some researchers to be a separate subspecies.   

 

Fig 1 : This free-living, but orphaned, immature Siamang  descends from the forest canopy each morning to feed on fruits at Fraser's Hill, Peninsular Malaysia.

Figs 2 and 3 : Foraging in the canopy for young leaves and shoots. Note the muscular arms.

Fig 4 : With throat pouch inflated.  Photo thanks to Vilma D'Rozario

Order : PRIMATES
Family : Hylobatidae
Species : Symphalangus syndactylus

Head-body length : 75-90 cm
Tail length : no tail
Weight : Females up to 11 kg, males up to 15 kg


References : M3, M5