We can ID this duck as an adult female Surf Scoter as follows:
- Two whitish patches on its face: one vertical whitish patch at the base of the bill and a second whitish ear patch. These two whitish patches differentiate the adult female Surf Scoter from the adult female Black Scoter, whose entire cheek is pale.
- Heavy, broad and relatively long triangular bill. This also differentiates the adult female Surf Scoter from the adult female Black Scoter, which has a shorter and thinner bill.