The Harlequin Duck (Histrionicus histrionicus) is a small sea duck. It takes its name from Arlecchino, Arlequin in French, a colourfully dressed character in Commedia dell'arte. The species name comes from the Latin word "histrio", "actor". In North America it is also known as Lords and ladies. Other names include painted duck, totem pole duck, rock duck, glacier duck, mountain duck, white-eyed diver, squeaker and blue streak.
A bird of fast-moving water, the Harlequin Duck breeds on fast-flowing streams and winters along rocky coastlines in the crashing surf.
More than half of eastern North American population of Harlequin Ducks winters in coastal Maine, particularly outer reaches of Penobscot and Jericho bays.
When engaged in behavioral interactions, the Harlequin Duck gives distinctly unducklike squeaks, the source of one of its local names: sea mouse.