Pretty darn good Heron shot. 1/640 @ ISO 100 with the Sony, you could probably boost that shutter speed a little with ISO 200. That would stop any movement at all. Heron's tend to bob their head forward fairly fast when the walk, so a higher shutter speed would avoid that movement. Nice details and looking good. Raj is right as well, a little more to the left of the frame would look better. I tend to crop mine tight in the frame, but some don't like that, so its just a balance thing.
All the best.
Danny.