I've not seen a flight shot of a crested guan before Fernando. This picture is just OK in my opinion. The sky is a dull grey, and the bird isn't completely silhouetted. There is a little feather detail visible as well as some high-ISO noise in the dark areas. I do like the composition and the wing spread though. Thanks for posting!
The pose looks good and I would love to see this species sometime. I agree with Doug regarding the silhouette and a more pleasing BG color would have made this image even better. Thanks for sharing and keep them coming!