Siamang Gibbon (Hylobates syndactylus)


Class: Mammalia
Order: Primates
Family:    Hylobatidae
Size:    Height: 3 feet (91 cm)
Weight: Up to 26 pounds (12 kg)
Diet: Leaves, fruit, buds, flowers and the occasional insect, bird’s egg and/or small vertebrate
Distribution: Sumatra and Malaysia
Young:  1 every 2 to 3 years
Animal Predators:  Unknown
IUCN Status: No special status
Terms: No special terms
Lifespan: Up to 40 years in the wild



·       The siamang gibbon is the loudest of all gibbons—its call can be heard two miles away.

·       The siamang is the largest gibbon—all nine species live in the rainforests of southern Asia.

·       Siamang gibbons sing for 15 minutes or more, several times a day.

·       Instead of grasping a branch with their fingers, they use their long fingers to hook over branches while swinging.



Male and female siamang gibbons are similar in appearance and size. They have long black hair and a blue-gray face. Siamangs have exceptionally long arms, averaging five feet (1.5 m) across when stretched out. They are extremely vocal animals, and have a large sac on the throat that inflates when they sing or call out.



Siamang gibbons inhabit only a very small portion of the world, living in the rainforests of Sumatra and Malaysia.


Feeding Habits

Their diets are almost completely vegetarian, consisting of 50 percent leaves, 40 percent fruit (figs are their favourite) and the remainder is made up of other plant material such as buds and flowers, but also the occasional insect, bird’s egg or small vertebrate. They forage for food during the day, usually in the morning and late afternoon, resting during the hot midday.



Once mated, siamang couples remain together for life. The female undergoes a seven-and-a-half month pregnancy before giving birth to a single baby. The baby clings to the mother for the first year of its life, while the father looks after the older siblings. After that time, parental care for the newborn switches to the father. At the age of six, young siamangs begin to demonstrate an interest in the opposite sex, and by eight, they find another siamang, pair up and begin their own families. 



Siamang gibbons live in family groups consisting of a mother and father and their offspring of various years that have not yet reached maturity (about the age of eight). Males make low booming sounds and emit loud screams, while females make booming and barking sounds, especially first thing in the morning. The family group sleeps perched high up in a tree at night, while sitting upright on branches. The members of the family show their affection for each other in various ways, including grooming each other and playing together. Gibbons move around by swinging from branch to branch using their long arms. When they walk on the ground, they often hold their hands up over their heads.



Along with all species of gibbons, siamangs are declining in population, mainly because of habitat destruction.



Siamang Gibbon Wildlife Fact File, IM Pub, US