Tips for herons, egrets and other fishing birds:
- bird netting over the pond, usually the quickest method
- put in an pond shock fence, lays out over the water at the edge
- a motion activated sprinkler
(go to froogle.com to find these products and different vendors
and prices)
- Migratory Bird Act forbids lethal methods,
heavy fines and jail time take away from pond time ;-)

good luck!
kathy :-)
algae primer
http://hometown.aol.com/ka30p/myhomepage/garden.html