First Impression: nice silhouette against a pretty sky.
Composition: You did a nice job on this picture with the placement of the bird. the close cropping really steers the viewers focus to the bird. That said, personally I think a little more space on the right, and possibly the top would strengthen the image.
Technical and PP: Exposure and colors look good. One commentator mentioned a little fringing around the silhouette which is noticable. I find this aspect hardly distracting to my eye because it is so slight. the small greenish cloud right behind the birds head is a little bit of a distraction. Advanced editing may have let you clone it out.?? The vignetting works well with this picture. Did you do some selective blurring on the BG?
Challenge results: 5.5xx is respectable. Maybe it didnt have that "hit the voter in the head" fantasy angle. Keep up the good work. You have some nice pics in your portfolio. I especially like your tribute entry.