Enormous, ungainly ogre of a bird. Found around freshwater marshes and rivers in Amazonian lowlands. Dark gray and black overall with a scaly white neck and white belly. Named for the characteristic unicorn-like appendage on top of its head. Walks along river banks and perches in waterside vegetation, sometimes quite high. Honking song can be heard at great distances—a deep, reedy “ha-moo-co” often uttered in duet.