Is there not a reasonable chance that a lot of birds are centred for more technical than stylistic reasons - that they were locked onto with a super sensitive centre AF point, for example, and/or the image quality in the shot is best around the centre of the frame? And that perhaps that was the only sharp shot that the photographer managed and as such, will have to do even if the composition isn't optimal?
I agree composition should be considered if there's more going on in the frame than the bird but I think if the subject is clearly the bird then it doesn't really matter so much.
My immediate answer when I saw this post was the same as this. At the time of shooting, the center point has better auto focus. Then it's a matter of cropping in post. Of course you need to shoot wide enough to have cropping options *and* you need to actally follow through and post-process your images. A few years ago, this center AF point reason was especially relevant. As cameras advance this becomes less true as focusing works across the entire frame.




