Two male Red-breasted Mergansers and a female Common Merganser behind a Bonaparte's Gull and Ring-billed Gull
WD: Compare the Common Merganser female on the right to the Red-breasted Merganser male. She has a thicker bill, smoother crest and larger body. Note her white chin, reddish head and white collar which sharply bounds the head color--Red-breasted Merganser females have less white on the chin,
browner heads and a less distinct collar and boundary on the head color.