The first shot seems slightly underexposed with some noise and lack of detail in the background...was this a 100% crop? I agree with TwoRails...the grey sky can be cropped off to improve the image. That is one big bird.
The second shot is okay...no real main point of interest though. Your horizon is nice and straight. The palm/coconut tree on the left is distracting. The water looks very clear and inviting...would have liked to see a shot taken to the right of this one.
The third shot looks a little underexposed. The water washing up against it and the bubbles in the water make this a much more interesting shot than if it was just the rock by itself. Don't care for that shadow on the bottom right corner.
Batman Returns?
The last shot had a lot of potential, but the light just doesn't do it any favors. Shot at a different time of day with a low sun from the right and maybe from a the point of view farther back and to the left (or the right) and it might be a winner.