Love the texture around the head and the wind blown feather in this one. Agree about missing the focus. Also I feel the angle is a bit steep, might be result from the top of the head seem softer than the rest.
Pretty bird. I might have shifted the bird down in the frame just a bit, to put the eye on the ROT intersection. Focus problem might be partly a DOF issue. I find that with a bird really close to me, I need a smaller aperture to get him all in focus; and with a stationary bird and blue sky BG you didn't have any motion or background to worry about, and could have traded some SS for a smaller aperture.
I agree with Bill on this one....more aperture!. Also keeping the plane of the camera sensor parallel to the eye would have helped here...angle does look too steep!
Thank you everyone. As you can imagine, with a caged bird, my vantage point was pretty controlled. I do agree that a smaller aperture would have helped significantly.