Hylobates agilis
agile gibbon

Gibbons are found throughout the tropical rainforests of South and Southeast Asia. Agile gibbons, Hylobates agilis, are found in Thailand, Indonesia, and Malaysia.

Hylobates agilis is found in the tropical rainforests of Thailand, Malaysia, and Indonesia. They live in the upper canopy of the forest, feeding on fruits, leaves, and insects. Members of Hylobates spend most of their lives in the trees, and rarely descend to the ground.

Lesser apes in the family Hylobatidae are generally small. The average weight of H. agilis is 5.4 kg for females and 5.8 kg for males. Agile gibbons come in a variety of different colors, including black, brown, light tan and reddish-brown. Both sexes have white eyebrows. Males and females can be easily distinguished by the white eyebrows and cheeks possessed by the males.

Gibbons lack tails. Hylobates agilis, like other gibbons, has extremely long arms and fingers. This adaptation aides in brachiation, the prnciple mean of locomotion for these animals. Brachiation consists of hanging from branches and swinging from tree to tree.

The reported lifespan in captivity for these lesser apes is 44 years. Wild animals probably do not live as long.

The average group size for H. agilis is four individuals. The group usually consists of the male and female mated pair, an infant, and a juvenile.

Gibbons exhibit two unique forms of behavior: monogamy and "singing". When an individual H. agilis disperses from its natal group (when it has reached sexual maturity), it finds a mate that it will spend the rest of its life with. These monogamous bonds are important for raising young and for defending the pair's territory. Hylobates agilis defend a territory by "singing". In the early morning, great calls can be heard throughout the upper canopy. These singing bouts are often duets and are a way of claiming home territory. When singing is not enough to keep intruders away, both male and female gibbons will chase the intruder away.

As in all primates, communication in this species is complex and involved several different modalities.

As mentioned in the "Behavior" section, above, these animals are highly vocal, and use great call vocalizations to defend their territories from other mated pairs.

Tactile communication is also important, between mates, and between parents and their offspring. Tactile communication involves grooming, mating, play and sometimes aggression.

In addition to vocal and tactile forms of communication, these animals use facial expressions, gestures, and body postures to communicate with conspecifics.

Hylobates agilis consumes large amounts of fruits. Like other gibbons, these animals are primarily frugivorous. Agile gibbons have also been observed eating a variety of other foods, including leaves, flowers, and insects. Due to their active lifestyle, it is necessary for them to eat food rich in calories. Fruits have a high caloric content.

Details on predation in this species are not available. However, snakes and raptors are probably the greatest threats to these animals. Because of their highly arboreal lifestyle, many potential predators are not likely to have access to these animals.

As these animals are not likely to be an important source of food for other animals, their greatest role in the ecosystem is probably seed dispersal for the fruits they eat.

There is no known negative economic effect of this species on humans.

Hylobates agilis is not an important economic resource for humans. These animals are sometimes hunted for food, and they are illegally captured for the pet trade. Poaching is a threat to H. agilis, for animals that are caught often die in transport from mishandling. Illegal poaching for meat and the pet trade are contributing factors in the declining numbers of H. agilis.

Hylobates agilis is listed by IUCN as an endangered species. Due to massive deforestation, their habitat is rapidly decreasing. This loss of habitat due to logging and agricultural demands is the main threat to gibbon species. Conservation measures have been taken, such as reserve game parks and breeding programs in zoos. Unfortunately, these measures are not enough, and more intense conservation efforts must be initiated in order to ensure the survival of these species.