At this size, the larger of the shots with the birds read better than the uncropped versions, although both have merit. The duck shot is nice, but next time try to leave more space in front of the bird when composing or cropping than in the rear of the bird. Nice work!
I had the same thought regarding the rule of space on the cropping of the first image. Leave more space the way the bird is looking rather than behind and that should add a little more interest.
Like the wave texture in the duck shot. I often see flat water, so it's a nice change.
The cropped versions emphasize the subject better than the uncropped. In cropping the sparrow I would suggest not centering it; leaving more room in front of the bird. Agree with John re: the water ripples. The bird (merganser?) seems not as sharp as it should be and could be lightened a little. The crop on the wading birds is good. Unfortunately they are not in focus.
President, Coastal Camera Club