How to improve your photo
With wildlife, learning and understanding the behaviors of a given species will help you predict what is about to happen (based on body movements and position, alertness, and other signs) so you can frame your image better. It takes time, patience, and dedication, but the results are so much more impressive.
I don't know if you were using a tripod in this shot, but with long focal length lenses (as I'm sure you know), a steady platform (tripod or monopod, fencepost, rock, etc.) helps maintain a sharp image.
Selecting your framing orientation (horizontal or vertical) based on the prevalent orientation of your subject helps to emphasize and focus viewer attention on the subject. Not a concrete-set rule, only a guideline.