Indian Scimitar-Babbler

The Indian scimitar babbler is an Old World babbler. It is found in peninsular India in a range of forest habitats. They are most often detected by their distinctive calls, which include an antiphonal duet by a pair of birds. They are often hard to see as they forage through dense vegetation. The long, curved yellow, scimitar-shaped bills give them their name. It has been treated in the past as a subspecies of the white-browed scimitar babbler which is found along the Himalayas but now separated into two species, the peninsular Indian species and the Sri Lanka scimitar babbler.

Source: Wikipedia