Habitat
High canopy of tropical rain forests. Hylobates means “tree dweller.”

Niche
Prefers small, scattered sources of ripened, pulpy fruit (which brings them into competition more with birds and squirrels than with other primates), but also eats buds, young leaves and some invertebrates.

Family members feed together at large food sources, but otherwise forage alone, coming together occasionally to groom, rest or (at night) sleep. Daily calling maintains pair bonds and excludes neighboring family groups from the family territory. Also, confrontations at territorial boundaries occur about once every 5 days; these include calling, acrobatic displays and, when necessary, males chasing intruders. Average home range for gibbons is about 8.5 acres, but varies greatly.

Life History
Single offspring born about every 2-3 years after 7-8-month gestation. Weaning occurs early in 2nd year, maturity by about 6 years old. Young males leave the family group by about 8 years. Life span 25+ years.

Special Adaptations

• Small body size and long arms are designed for hanging to feed from terminal branches and for brachiating through the forest.
• Base of thumb is free from palm and extends out from near the wrist, allowing a wide range of movement; thumb also stays out of the way during brachiation.
• Precision grip between thumb and index finger is used for picking fruit, permitting only the ripest fruit to be picked.
• Hind part of gut enlarged and specialized for fermentation of leaves (see also howler monkey).