Siamangs are the largest of the gibbons. Unlike other gibbons, they have a membrane that joins the second and third toe on each foot.

Subspecies
Two.

Life span
35 years.

Statistics
Head and body length: 73-88cm, Weight: Female: 10-11kg, Male 12.2-14.7kg.

Physical description
Siamangs are large and stocky, with black fur. Adults have a dark grey throat sac.

Distribution
They range across Sumatra and the Malay Peninsula.

Habitat
Siamangs inhabit primary and secondary forest.

Diet
The majority of their diet is made up of leaves, but they also feed on fruit, flowers and a small amount of animal prey.

Behaviour
Siamangs live in family groups, with one reproducing male and female and their offspring. They are diurnal and arboreal, and the female leads the troop. The male inflates his throat sac to scream his call, while the female barks. Like gibbons, siamangs are brachiators and move through the forest by hanging from branches by their arms and moving on to other branches in a suspensory fashion. They can also move bipedally over short distances.

Reproduction
After a gestation period of 189-239 days, the female gives birth to one infant. When the infant is eight months old, the male carries it around with him, returning it to its mother to nurse and sleep.

Conservation status
Siamangs are in the Lower Risk category of the IUCN Red List.