Hoolock Gibbons are lesser apes. They are the second largest of the Gibbons after Siamang. Earlier it was said that India (North East India) is home to two species namely Eastern Hoolock Gibbon and Western Hoolock Gibbon.
However, a recent study by Centre for Cellular and Molecular Biology has found that only western Hoolock Gibbon is found in India.
The Western and Eastern Hoolock Gibbons were kept separately in zoos and were not allowed to breed. Now they can be put together in the same cage and allowed to breed.
Highlights of the study:
- The divergence of the Hoolock gibbons from a common ancestor occurred 8.38 million years ago. The split of the western Hoolock Gibbon and the eastern Hoolock Gibbon occurred 1.49 million years ago.
- An American Naturalist R Harlan described the Hoolock Gibbons for the first time in 1834. The eastern Hoolock Gibbons and Western Hoolock Gibbons were considered as the sub species till 2005.
- In 2006, the first distribution of Eastern Hoolock Gibbons was published.
- The Western Hoolock Gibbons are distributed all over Northeast India, east and south Brahmaputra river and also along Myanmar and Bangladesh.
- The Eastern Hoolock Gibbons are distributed between Lohit and Dibang rivers in Arunachal Pradesh.
IUCN Status on Gibbons
According to IUCN (International Union for Conservation of Nature), the presence of Eastern Hoolock Gibbons in India is uncertain.
The IUCN has put the different species of Hoolock Gibbons under the following categories:
- Western Hoolock Gibbon: Endangered
- Eastern Hoolock Gibbon: Vulnerable
- Skywalker Gibbons: Threatened
There are three Hoolock Gibbon speocies. They are Western Hoolock Gibbon, Skywalker Hoolock Gibbon and Eastern Hoolock Gibbon.