Lesser Scaup... much like the Greater Scaup (which is why I misidentified it last time). The unique shape of the head (the sharper angle downward on the backside of the head) is what really sets the Lesser Scaup from the greater). Also the body is shorter and more compact as well. The female is shown here as well. Note the blue colored bill and the little black tip on the end. (I like the blue bill rather unique I think).