Dave - Really nice detail and colours. These are beautiful birds and you caught the hood well.
I’m not sure the vertical comp works as well as a horizontal one would, which would echo the horizontal water lines and width of the bird.
This is absolutely centered - usually not the best idea. Placing things off-center almost always adds more interest, and, in the case of animals/birds - leaving much more room in front for them to swim/fly, run into (virtually) works more aesthetically.
You’re posting some very nice images!
Sandy
Thanks Sandy for your input. I’ve not been responding too much to the critiques on my images but I have been reading, and sometimes applying the suggestions. I highly value these inputs for trying to improve my chops.
One of the more attractive ducks and you captured this nicely with good detail and handling of the blacks and whites. Would agree with Sandy regarding the comp.
Nice detail and an excellent job on the exposure, Dave. To my eye, the reflection doesn’t add much to this image. I think you could crop up quite a bit from the bottom and add some on the right and possibly the top, since it seems to be swimming away a bit.
Dave, no need to reply, unless you wish - all are just suggestions. You may choose to try them, or feel your original is what YOU wished to present and stick with that. Some people re-post the image in the same (or new ) thread with suggestions incorporated to see what people think then.
All up to you - 
Sandy
Bird looks really good. Exposure shows both the whites in the hood and the blacks well. The feather detail looks very good, though I think I am starting to see some image degradation due to the crop. I don’t particularly mind the comp. as-is, but I could def. see a horizontal version.