When they hide in the same place you are chances are the Heron will see you first. Often they freeze and let you walk right by.
Other times they jump up and if lucky there is time for a quick focus.
This Great Blue was fast enough to be out of focus with about one bounding-flap of his wings.
Besides, these birds are so long a small shift in direction and the shot is blurry.
Old Rice Field, Donnelley, South Carolina.