There is a rookery to the west of us, their feeding grounds appear to be the east of us. We are in their direct flight path. Before I finally netted the pond, they came every day and stalked the ponds looking for food. The floating alligator heads worked for a while, but with all my lilies they quit moving, mr heron learned they were safe. I tried fishing line, they went through it, fencing hopped over it.
The net is easy to lift up so I can work on the lilies, get in the pond, also it does not trap frogs, small birds, dragon flies, etc.
The net is all that has finally stopped them from coming. It is a large weave fishing gill net (4-5 inch), hung 3 feet or so over the pond. The heron can not strike through it. We watch them fly over, quite often tree level over our ponds, they pause look down, keep going.