1 - Nice photo. Good comp & focus, clear subject, eye catching.
2 - Cool subject but looks busy. Crop out the shoreline from the top and the dock on the left. Also either increase the DOF so that all the birds are in sharp focus, or shoot wide open, focusing on a couple individual birds. The in between way (not enough DOF for all and too much DOF for just a single subject) looks half-hearted and confused.
3 - I can't quite pinpoint it but it just doesn't look catchy to me. It looks as if you tried to take a picture of the proverbial "kitchen sink." If I were you, I would have pointed the camera a bit more to the left to get rid of the distracting dock on the right and show the entire building on the left.
4 - Cool subject but I'm not a fan of harsh backlighting and semi-silhouetteness. I don't really understand your composition in this one too.