I think this is what got rid of my Herons. For many years I had Herons at my pond. For the first time starting this year my lily pads have completely sorrounded my pond and I haven't had any more Herons. Until my lilies come up and covered in late spring this year I did have Herons. So it would seem that they don't like to wade in the pads or can't see the fish very well.

John