Great Cormorant: Very nice picture. The exposure and the color balance seem to be right on. I like the lighting because it seems to be coming pretty much straight from the left which gives the subject good depth. The background is well blurred and the detail is very good in all of the bird and the rock. My only problem with the overall image is that the composition is too static with him being so centered.
Grey Heron: Again, a very nice picture with a good exposure and color balance. I would say he is slightly overexposed. Not having been there to see him in the flesh, I could be wrong, but his colors seem to be slighted muted by the slight overexposure. The background is nicely blurred and the detail in the bird and the rock is all excellent. The fact that his mouth is open and gives us a flash of red adjacent to the green background and draws the eye directly to that tongue. I also feel that the rock is slightly overexposed. As in the Cormorant, I feel that the composition could be better if he were not so centered.
Squacko Heron: The sun is almost directly above - actually somewhere to the right and slightly behind the bird. The shadows created in the boat are very good and the lighting on the bird is good for a backlighted subject. Excellent exposure and color balance. Most subjects would become silhouettes in this lighting, but there are two factors mitigating here - first the fact that the sun is shining through his feathers and second, the reflected light from the white boat is lighting up his underside. I note the juxtaposition of the frayed anchor rope at top left with the similar ruffled feathers on the bird. The background is not as blurred as on the other two shots, but manages to not intrude.
I have to declare the Squacko Heron the clear winner on the basis of the superior composition, which is excellent. Also, the overall interest in this image is higher. This character is alive and in motion, whereas the others could be stuffed in comparison.