Bob,
Now that's a great neighbor! To be sure of the right bird:
If it dives under water for long periods, has a long neck (like a goose), struggles to get airborne, and returns to fly back over you right after getting airborne...you may have water turkeys.
If it sets in dead trees picking it's teeth and defecating remains of your fish....you may have water turkeys.
If your fish have slice marks on their "shoulders" and some are dead as a result...you may have water turkeys
If you see all your fish trying to congregate under a pier for protection...you may have water turkeys.
And last but not least...if you see a wild man named Meadowlark chasing after them...you may have water turkeys.
Propane Canon on the way; no water turkeys sighted yet