In fact, Margie and I were also at La Manche when a probable Great Blue Heron flew overhead. I got pictures, but I went from shooting in the dark undergrowth straight to a shot in the sky, needless to say, the shots were so bad no ID could be made on that either.
Here is an example of just how bad it can be. In the middle of this picture is a very olive-colored bird with a white streak on its face and a very white belly. It got away without an ID:-(
Then there was the one with the sunshine yellow belly that totally got away. I keep looking, shooting and hoping for a clear enough rendition to be able to study and identify later, when the feathers have settled. This was one of those rare moments when there are so many different birds around you, it is hard to know where to look.