OldMarine,
A suggestion... Determine what species this particular bird is for certian, obviously cannot shoot a blue heron or a whooping crane. Then check with your DNR and see if they can be hunted. If it is a sandhill crane or similar, they are supposed to be delicious. I have heard numerous people refer to them as "Ribeye in the Sky".
I don't think I could bring myself to shoot any of these birds, personally. But, if they were a major nuissance I might be tempted if the meat was good and would go to a could cause and not just be wasted.
If your predator is indeed a blue heron or other protected species, check into the tips listed here:
http://fullserviceaquatics.com/blue-heron/heron-deterrents-for-your-koi-pond/ , there are some good ones IMO.
J.W.'s talk radio idea is listed within as well!
Gordy