The White-winged Scoter is not as commonly scene as the Surf Scoter in the Bay Area. I have only seen one once myself. Hopefully, I will see some others and take some better pictures.

The White-winged Scoter doesn't have the harlequin color bill as the Surf Scoter but the male has a comma shaped eye white patch around the eye during breeding season. White-winged Surf Scoters primarily feed on crustaceans, molluscs, and insects.