A few weeks ago, I posted that I saw a white duck that didn't seem to be a Mallard. When I saw it, it was several hundred feet away, and I couldn't get a good look at it. At the time, I thought it had a smaller head than the other ducks.
While feeding the ducks, several of the ducks that came for bread were white with light brown trim on their bodies and wings. The rest of the ducks were the typical Mallard color (brown for females and black/green/blue for males). I don't know what kind of ducks the white ones are.