Great-billed Heron Ardea sumatrana

Large plain heron. Dark gray overall with a paler, more brownish neck. Lacks the black head and neck markings of the slightly smaller Gray Heron. Tends to be solitary, only rarely seen in small flocks. Typically restricted to the coast, where it inhabits mangroves, lagoons, and offshore islands, but infrequently seen inland. Rather vocal for a heron, often giving a deep, horrifically resonant roar when flushed or on the nest.