Hoolock Gibbon

Hoolock Gibbon (ulluk) a smaller arboreal ape, Bunopithecus hoolock, of the family Hylobatidae, order Primates.

It is also known as White-browed Gibbon. Its body is 45-63 cm long and weighs 6-7 kg. Hoolock lives in the natural and semi-natural forests of Chittagong, Cox';s Bazar, Chittagong Hill Tracts, Sylhet and Mymensingh (Karnojhora area of Balijhuri Forest Range adjacent to Tura Hills of India). It is tailless and its arms are longer than legs.

The Gibbon';s body has a dense and shaggy fur while it has beard-like tufts in the groin. Adults are sexually dichromatic. The male is jet black while the female is buff/blonde to various shades of greyish brown. The young are dark brown to black. Gibbons are diurnal and sleep at night on high tree branches; they awake before dawn and retire from day activities before dusk. They seldom come to cross open patches. 

Western Hoolock Gibbon Group size is 2-5. Gibbons give long and elaborate call like hoo-u, hoo-yu, hoo-koo-u, etc, for which they are is called Hoolock Gibbon; their calls are mostly performed in the morning and last for 1-46 min. They are frugivorous ie they feed mostly on ripe fruits. New birth occurs in between mid-September and January; their inter-birth interval is at least 3 years; and the gestation period is 4-8 months. [M Farid Ahsan] [Ahsan, Md Farid Professor of Zoology, Chittagong University]