I am pretty sure this is a Bufflehead. I got a good look at it before it took off. When it saw me coming down the trail by the water at Delta Ponds it made tracks out of there, like a rock skipping across the water! I was fortunate to capture its tracks. :) Now that was fun!
Note for the curious: The image is as shot, with only contrast, color, sharpness, and crop adjustments.