After watching a while, I figures out it was jiggling its foot to scare up its breakfast.
See the rings it is creating as it shakes it foot underwater.
I set the camera on continuous shoot to try to get a shot of the egret catching something. He caught 4 somethings, and I got a lot of pictures like this..
I know, not even the bird is in the picture..
So you will just have to trust me , that in the half hour I watched him and the119 pictures I took
( thank goodness for digital) he did catch 4 or 5 things for breakfast.