Camera Work/Technical: The colors you captured are terrific, but I think the overall image could use a little more sharpness.
Lighting: You did a really nice job using lighting to create a very strong silhouette. I think you captured a really strong balance between the shadows and the colorful background.
Composition/Content: I think here is where your score fell. Echoing other voters that have commented, the background is too busy. I think if you'd have shifted a bit to the left and shot him without that tree in the background, this capture would have finished much stronger. I know, nature is very hard to script.
My Opinion: Nice job meeting the challenge. I do believe that this one came pretty close to its potential as is. With a different composition, the score would have surely grown.
The background spoils the main attraction to this photograph but the sillhouette of the bird is very well photographed and it must of took you a bit of time to capture him!
A nice approach, and almost a nice shot; if you'd been a bit either luckier or more careful with the arrangement of the silhouetted trees, and if the background weren't so half-light, perhaps this would do well. It has an impression of lack of sharpness to the bird silhouette. Working with odd shapes, like this - I mean the surroundings rather than the bird, requires a careful eye and some real consideration of composition, which you haven't achieved here I'm afraid. In the end, it just looks messy.