One of the most fascinating primate to see in the wild and what a gymnast they are. It is an awesome sight to see them move up in the trees and hear them. The eastern and western hollock gibbons are both found in India in the North east region. The newborns are milky white or yellowish and the turn dark brown in nine months and both the male and female turn dark black in two years time. Males stay black and a clear scrotum emerges by four years of age and become distinct by seven. Females, during their subadult phase may have varying light patches on their juvenile black coat till they turn golden blond colour with white brows and a white frame to their face between 18-24 months.
Gibbons are monogamous and are seen to pair for life. This and the fact that they are very territorial and do not move into a neighbouring territory even if for is scarce, make them more prone to extinction. Gibbons pair bond and then duet from dawn till late mornings or sometimes even noon. They may sing only once in a few days but when they do the forest resounds for 15-20 minutes with an introductory, an organising and a great call sequence.