Аннотация:The western hoolock gibbon (Hoolock hoolock) and eastern hoolock gibbon (Hoolock leuconedys) are the two representatives of gibbons in India. Their distribution is restricted to the south bank of the Dibang-Brahmaputra river system in the northeast. The western hoolock gibbon has the wider distribution of the two, occurring in all of the seven states of the Northeast region, namely Assam, Arunachal Pradesh, Meghalaya, Mizoram, Tripura, Nagaland and Manipur. It was thought that, in India, the eastern hoolock gibbon was restricted to the state of Arunachal Pradesh. Here, we report the occurrence of this species in three reserve forests of the Sadiya sub-division of the Tinsukia District of the state of Assam, extending the previously known range of the species in the country.
