It wasn't until I got home and inspected my pictures on the computer that I realized it had green on its head just like a mallard! I did a little research on mallard hybrids but I couldn't find any that had this type of coloring on the head- mostly brown with only a stripe of green over the eyes.
Thanks goes out to Bennet for help in identifying this dabbling duck. Like I said, I saw the green and immediately started thinking mallard hybrid after reading that many other species are attracted the male's green head hence the many variations (such as the black duck x mallard hybrid). If I had taken time to go through the entire dabbling ducks section of my Sibley Guide I would have seen the Green-winged Teal, whose picture looks exactly like this duck. I learned that the Teal is one of smallest ducks along with the bufflehead and merganser. It certainly stands out in this picture among mallards.
I'm glad my boyfriend put up with me on this stop to photograph the red legs of the mallards on the ice- otherwise I would have never noticed this duck. How could you not when it looks like a seagull is hanging out among the mallards!