A mid-sized coucal of lowland and mid-hill forest. Black plumage with purplish sheen, dark rufous wings, and pale, greenish bill. Found in the dense undergrowth of humid forest where it is very skulking and difficult to see. Heard more often than seen. Similar to Greater Coucal, but Green-billed Coucal is smaller in size with pale bill. Call a series of deep, double “boop-boop” notes, or a regular, upslurred “ker-chuip” or “chuip” rather like a stone dropping into water.