I like the timing of your shot. I probably would have a used a higher ISO, and thus a faster shutter speed. That might have frozen the wing tips on the right side of the frame. The head looks like some of whites have blown out, but that might be my laptop monitor. Do you mind showing the original?
HI Ian - pretty large crop - image quality seems to be suffering a little-personally I would like a little more room up front for him to fly into - think a horizontal format might have worked better here.
Agree about the SS - though the large crop is probably more of a limiting factor than the SS.
Keep em coming :)
I was planning on commenting on leaving more room in front of the bird when cropping, but I didn't want to assume you had room in your original. Here is how I would crop it for a standard shot. I'll follow this with a post showing a more unusual crop they you may or may not like.
Looks like you did quite well overall for the focal length you were limited to.