BD, very nice image. My only comment is that there is very little detail in the birds feathers - not sure if that is an exposure thing or something that could be brought out in post with some more "contrast".
It was "awkward" lighting, overcast combined with the dark water made for an interesting exposure guideline. I was also using a borrowed lens that I think tends to lose some detail at 600mm. It is worth a second look to see if more can be pulled.