Sandra,
Welcome to the forum.
Clearly you have good gear - the details are sharp. You also did a great job of processing from that original.
My only suggestions for improvement might be that you might want to try to get a little lower to the ground if possible. Having more of an eye level view gives wildlife more "personality". Of course, that might have meant swimming in this case.
I also think you cropped this a bit too tight. I like how you have kept the Green Heron looking into the frame, but I think a bit more space on all sides might look a bit less crowded and give it more space to look into.