Hi Gus- Jules is right, there is a pattern there- a graininess. I suspect it is caused by sharpening the noise in the image. The graininess is not really that noticeable on the bird because the feather detail covers it up. It is noticeable in the plain background. I think a round of noise reduction on the BG, by first masking out the subject, would work well here.
I like the pose and the "dreamy" background. The head is on straight but I wonder if a small CCW rotation would be a better head angle (I am frequently confused about this particular body angle/head angle combo).
Although I think the wide border is attractive for mounting I think it might distract a little from the critique point of view.