WHITE-CHEEKED GIBBON (CRESTED GIBBON) Hylobates concolor MAMMAL Order Primata Description Coat color varies with gender in this species; male is black with lighter cheeks while female is buff, sometimes with black patches. Head + body length 18-25 in, Weight about 12.5 lb. Extremely long arms, long legs.   Range Laos, Vietnam, Hainan, southeastern China, eastern Cambodia.   Status All gibbons are classified as endangered, and this species is more endangered than other gibbon species. Habitat conversion and logging as well as military activities have impacted habitats that support gibbons.

Ecology 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. Avg home range for gibbons is about 8.5 acres, but varies greatly. Life History Single offspring born about every 2-3 yr after 7-8 mo gestation. Weaning occurs early in 2nd yr, maturity by about 6th yr. Young males leave the family group by about 8 yr. Life span 25+ yr. 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).