A small bird of wooded habitats on Biak Island. Olive-brown back, gray head, pale yellow belly and broken white eye-ring. Forages actively in the mid-story in pairs or in mixed species flocks. Similar to the Biak race of Island Leaf-Warbler, but Biak Gerygone has black rather than orange lower bill and legs. Gives a messy, up-and-down, out-of-tune, whistled song mixed with a few scratchy notes.