Common Name: Siamang
Scientific Name: Hylobates syndactylus
Description: This lesser ape is the largest of all the gibbon species. Their arm span reaches up to 1.5 meters. Weight is 10 - 14 kg. Coat color is exclusively black and their hair is longer but not as dense as other gibbon species. A throat sac is present which expands during vocalizations. Calls have been heard over 4 km with females producing the longest sounds. The call itself is deep and resonating. The main song is a duet between the pair with additional notes provided by the offspring. Siamangs sing less frequently than the other gibbons. Songs are produced on about one-third of the days compared to three-quarters or more of the days for the other gibbons.
Range: Malaysian peninsula and Sumatra
Habitat: Rainforest. Predominantly arboreal. Typically found 25 or more meters high.
Diet: Approximately half the diet is leaves. Roughly forty percent is fruit. Other plant parts, insects, and small vertebrates make up the small remainder.
Social Life: All gibbon species are monogamous. Groups are made up of bonded pairs and up to three of their offspring. Gestation is just under 8 months with one offspring born. After the first birthday, mothers generally yield the juvenile's care to the male. Subadults leave the family after reaching adolescence between ages five and six. The single individuals observed in the forests are most likely subadults seeking mates, an activity which sometimes takes several years. Full maturity is reached between ages eight and nine.
Conservation: All gibbon species are greatly threatened by deforestation. Siamangs are listed as endangered by the USDI and on Appendix I of the CITES.