Hylobates syndactylus

Limbs are long and slender with elongated fingers and toes. Fur is thick and black. Canine teeth are lengthy. Throat sac is gray or pink. Head and body length is 30 to 35 inches and weights average 23 lbs.








Sumatra and Malay Peninsula


Mountain forests and tropical rain forests

Life Expectancy


Sexual Maturity

5-7 years


In the wild, they eat insects, small mammals, fruit, eggs, leaves and sprouts. In the Zoo, they are fed monkey chow, fruit, citrus, vegetables and leafy greens.


IUCN - Endangered, CITES - Appendix I, AZA - green SSP


Siamangs form monogamous pair bonds to form a family unit made of one adult male and one adult female and their young. The adult pair usually produces a single offspring every two to three years. Gestation period is between 210-235 days (7 to 8 months). Offspring nurse until about the age of 2 years, and stay wrapped around the female’s waist. Young stay with their parents until conflict with the adult male helps to ease them out of the family unit by about 8 years of age. Subadult males often sing alone, apparently to attract a female. Either sons or daughters may end up near their parents. It is clear, however, that the first siamang to come along is not necessarily a suitable mate for life. Siamangs demonstrate a high cohesion of the family group throughout daily activities – group members are 33 feet apart on average, but never more than 100 feet apart. Male vocalizations consist of screams while the female has a bark series that lasts about 18 seconds. Singing in duets, these vocalizations serve to develop and maintain pair bonds and to exclude neighboring groups from the territory of the monogamous family unit. Even so, grooming is the most important social behavior, between both adults and subadults, and between adults and young; play, centered on the infant, is the next most common.


The siamang’s throat sac functions as a resonating chamber to amplify vocalizations. They have a spectacular arm-swinging form of locomotion (brachiation) that is a key adaptation for their unique suspensory skills. Their hands are designed for swinging from limb to limb.

Special Interests

Siamangs and gibbons have not been known to interbreed in the wild. However, in 1979, a female siamang and male gibbon did breed at Grant Park Zoo in Atlanta. This resulted in a hybrid, called a siabon.


Gibbons hold a special place in the society of forest peoples, because of their resemblances to man. Although hunted by these peoples, gibbons tend to be revered as good spirits of the forest home.


As forest dwellers, siamangs are neither pests nor effective carriers of disease. They are endangered primarily due to loss of habitat. Logging and clearing land for agricultural purposes mainly cause this.

Jacksonville Zoo History

The first siamang arrived here in May 1995. This species has successfully bred here.


Great Apes Exhibit Area