Mystery of Missing Tadpoles - Solved

It has been a sad year for the frogs in our pond.  They have been virtually childless this year.  After the freakish amount of tadpoles we had last year, we were a little more prepared this summer for the overabundance of frog babies. Unfortunately, halfway through the summer - all of the tadpoles disappeared!  Thousands of tadpoles - gone. We were really concerned that somehow we had killed them ourselves even though we don't use any chemicals or fertilizers on our property.  The frogs made a couple desperate attempts to re-lay eggs over the balance of the summer but the egg sacks disappeared.

We couldn't figure out what might have happened until this weekend.  We have seen herons at our neighbor's pond but nothing on our property.  I woke up early Monday morning after a night of torrential rain and I took my cup of coffee out the front door to check on the water levels in our pond.   I wasn't quite awake as I walked down to the pond and suddenly this huge 6 foot monster bird opened it's wings and started flying over my head.  I think we both surprised each other.  It was so damn big.  It was Godzilla bird. Those tadpoles never had a chance.  Now, I don't have issues with doing anything and everything to get rid of a woodchuck but I really like birds - so what do I do?  Do I put up a scarecrow or something to keep the herons away from the frogs?  I have no clue.