A large, long-tailed, thick-billed bird, entirely dark bluish-black, with pale skin around a red eye. Found in most habitats, most commonly in old-growth lowland forest. Often flushed from trackside vegetation. Otherwise inconspicuous, but regularly feeds on the ground. Similar in appearance to Pacific Koel, but significantly larger, with a dark gray instead of ivory-colored bill. Unlikely to be confused. Vocally similar to other coucals, most commonly giving a confused series of hollow booming and barking notes.