Hylobates lar weighs 5.5 kg on average. Individuals are
either dark brown to black in color, or red buff color with
white face-rings, hands, and feet. Colors are not specific to
sex. Males and females can show either color, but their white
"accents" are always present.
are mainly frugivores, but they will also eat other plant matter.
They consume ripe fruit only, and only new leaves and buds.
They have several adaptations for feeding. One of them is brachiating
locomotion, which involves swinging from branch to branch by
their arms. This style of motion allows them to reach the periphery
of the tree canopy, where most of their food is found. Other
adaptations include high cusps on their back teeth to help grind
plant matter, and a gut adapted for a folivorous diet.
They rarely, if ever, descend to the forest floor.
Gibbons have no fixed season for breeding. The gestation period
lasts around seven months, and females produce approximately
one young every two years. Young are weaned by the time they
are about two years old. In most gibbons, reproductive maturity
is reached around 8 years of age. Although they are probably
completely capable of caring for themselves at an earlier age,
young gibbons do not leave their family group until they reach
sexual maturity. Although infants are weaned within a two year
period, young stay with the family group for a few additional
years. Although the bulk of parental care, including nursing
and grooming, is the responsibility of the mother, the father
and older siblings also help out.
lar is found in the tropical rainforests, where
it occupies only the upper canopy, between
the Slween and Mekong Rivers from S Yunnan (China) south to
the Mun River (Thailand) and the Mudah and Thepha Rivers on
the Malay Peninsula; S Malay Peninsula south to the Perak and
Kelantan Rivers; Sumatra (Indonesia) NW of Lake Toba and the
Singkil River; E and E Burma.