Richard, you have a beautiful pose and lovely eye contact...good sharpness and a great clear sky BG. I do wonder if you don't have a bit of a green color cast on the feathers of the bird, though...you might try adjusting the white balance to see if you can get the browns to be a bit stronger.
As for comp, I'd go horizontal but put the bird closer to the right side of the frame and maybe even add a bit of canvas to the left side to give him enough space to look into.
Lovely image overall - what a treat to see this beautiful bird!