Did the crane/heron leave a tip? Or at least a thank you note? A herding dog, if practicable, might keep the birds at bay if trained to protect the pond. Try this site: www.fullserviceaquatics.com/ and check for heron deterrents. That site also states that if your pond is less than two feet deep you are now the proud owner of "The Great Blue Huron Sushi Bar."
I thought about a Koi pond but I've got a pair of lynx, the neighbor's cats, bears and other wild and domestic animal life close by, so the fish wouldn't have chance unless I fenced the area off and capped it.
Up here we've got people that leave their dogs chained up outside during the day. Then they get all broken up when they come home from work all that's left is hair, teeth and eyeballs and bit of Fluffy's collar. Bear's gotta eat!
Last year a couple that live about a mile away come home to find both pet llamas had provided sustenance for a sow and two cubs. And, this was after numerous reports of the trio in the neighborhood for a good part of the summer. Bears gotta eat!
Living close to and co-existing with nature can be a challenge.
