Hi Doug- I like the way the bird is positioned looking out over the habitat. The subject is sharp and the head angle is good. A couple of things to think about- try to position yourself or wait for the right moment so that habitat elements are not between the camera and the subject. The cattail down below is OK but the one arching around the neck is a bit distracting. Also I would consider a looser crop to give the bird a bit more breathing space. Herons have long legs and feet and a crop you might consider is one where the "virtual" feet are included in the image- if you have them to begin with.
I notice pretty severe chromatic aberration in many parts of the image causing a halo of red/green. I think you would find that modern camera lenses are much better corrected for this.