Nice sharp capture. Of course, the sun is something we cannot control. You used a fast shutter speed, which is great. I think this photograph would appear less overexposed if a lower ISO were used. It would darken the scene a bit and reduce the clinical effects caused by a directly overhead sun. I think a little cropping from the bottom would help shape the composition and get rid of the rather empty space below. Thats my thought. Again, nice and sharp!
I dont think iso400 is bad at all, and I take higher is over blurry subject anytime. But I would crop a lot more to bring out the bird more, but still give him some space to fly into. Thanx for sharing.