It is difficult for me to explain, but I think it is mainly down to contrast.
Here is a repost which I hope explains what I mean, basically I boosted the contrast using linear contrast and sharpened a little more. I think I have overdone it a bit too much
Brendon,
I have never seen this bird so pretty hard for me to judge the correct color tones. Other than that, fantastic pose, great composition and wonderful wing position.