The siamang (Symphalangus syndactylus) is a large gibbon that inhabits lowland forests such as the Malay Peninsula and Sumatra. Body length is 70–90 cm and the arms are very long; it moves between trees by brachiation. A well-developed gular pouch can be greatly inflated for vocalization, and males and females exchange complex "songs" that carry over long distances to indicate territory and pair bonds. Groups consist of a pair and their offspring and show strict territoriality. Their diet is mainly fruit and leaves, and they also consume insects and flowers. Reproduction is nonseasonal; gestation lasts about 230–235 days, weaning occurs at 1.5–2 years, and their conservation status is Endangered (IUCN Category I B).