First off, great capture! The seperation of the owl from the backgroud (to me) looks like a little too much post proccesing (gausian blur)and the light on the bird doesn't follow the rest of the image :(
Hard to get these wildlife shots. Good attempt, but you need to prefocus your spot a bit better. Maybe even put it on burst mode if you have that on your camera, which would take several consecutive shots together. Might have gotten a better face of the owl.