The Ruddy DuckI have not seen these ducks on our lake before. They are a group that are migrating through. I have seen them in Wisconsin, so maybe they don't have too far to go.
Here the markings of the female and male are clear. The female has a slight line through the light section of her face and the male, with very distinct coloring, has a bright baby blue bill during mating season.
This little fella ... perhaps a juvenile. He/she has no markings and no up lifted tail ... but otherwise, looks like a Ruddy Duck.