Исландский гоголь Bucephala islandica

Striking diving duck of coastal harbors, mountain lakes, and large rivers. Very similar to Common Goldeneye. Males are easiest: Barrow’s has more black on the back, a downward-pointing spur on the side, and a crescent-shaped (not circular) white patch on the face. Females can be very difficult. Barrow’s usually has a yellow bill, but Common can rarely show a dull yellowish bill. Head and bill shape are important: Barrow’s has a steeper forehead and a puffy nape, and a shorter bill with a more rounded lower edge. Fairly common in western U.S. and Canada; much less common in the northeast. Small population in Iceland. Frequently found in mixed flocks with Common Goldeneye.