Where I live on the west coast of Canada, we seem to have several species of ducks that are black and white. I have trouble identifying them unless I have a species chart with me. I've learned that noticing their specific markings, especially on their heads, is very important for identifying who I am looking at. I also find that if I take a close-up photo of the bird, I can then take my time identifying which one it is with my field guide and/or with Merlin. Now I just need to commit each species of black and white ducks to memory (Bufflehead, Barrow's Goldeneye and Common Merganser).