It looks like your getting a little achromatic aberrations (purple fringing) with your lens - I get it too especially with long shots. I've noticed if I turn down the magentas it makes it go away mostly. Also, it looks a little over sharpened especially along the branch. It's a nice capture and good timing. Hey wait, I just realized I have a photo with the same name: . Just a different kind of bird! Good luck to ya!
I don't know if there is enough sharpness to do a flattering tighter crop on the bird but, the rest of the picture really doesn't add anyting to the shot.