NIce low shooting angle, colors, angle of bird in frame.
Interesting effect of soft feathers and motion blur on the wings. I think that overall the bird is a little soft, perhaps another round of USM.
That is a lot of magnification that you are working with, and I don't think I could keep it steady at that shutter speed. I know that ISO performance can be an issue for the 7D, but I would have tried to push it up a bit to get more SS.
Cute, nice low angle, and good BG colours. I'd prefer a bit more room below as the head's reflection is nearly touching the bottom edge. I should go check my local spot for these guys!!