I really like the birds pose and it is nice and sharp.
I am not to sure about the reflection of the bird with the head not really being visible. Not sure if I would keep it as is or crop into it.
Overall a lovely image.
I like the bird pose and the nice and clean BG. I think that the image works as is but you could also try a vertical crop. If this is almost full frame you should have enough pixels for that ,due to the D800 usage.