The harlequin duck (Histrionicus histrionicus) is a small sea duck. It takes its name from Harlequin (French Arlequin, Italian Arlecchino), 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.
Their breeding habitat is cold fast moving streams in north-western and north-eastern North America, Greenland, Iceland and western Russia. The nest is usually located in a well-concealed location on the ground near a stream. They are usually found near pounding surf and white water. They are short distance migrants and most winter near rocky shorelines on the Atlantic and Pacific coasts. They are very rare migrants to western Europe.
The eastern North American population is declining and is considered endangered. Possible causes include loss of habitat due to hydroelectric projects and loss of life due to oil spills near coastal areas. source