My first thought upon viewing the image was, effective use of fill flash. Before seeing Doug's comment, so good job there. The exposure really benefitted from the fill, on these notoriously challenging birds to expose.
Very effective use of fill flash. I wouldn't have known had it not been for Randy mentioning it. Brought the picture into PS. It appears to need some CW rotation. Really like the pose and the colors you captured here.
Excellent sharpness and eye contact. Love their eyes. Although I am not a big fan of this shooting angle, at times, one cannot get lower. And before I forget to mention.....superb job with exposure. These ducks are hard to expose correctly.