In a Bigfoot case I can understand the Humans see what they want to see relevance because of the legend behind it. I'm not sure the whole humans see what they want to see really applies here. I don't want to see unwanted fish in my pond lol. Be it a Heron puking out a fish or a trespasser dumping unwanted fish in my pond or even a mix up in the fish stock it's not something we want to see. The unfortunate part is that in any one of these scenarios, there is no true testable evidence to confirm with 100% certainty. I can't go back in time to set out a trail camera and bust a trespasser. I cant go back and sort out all of the fish stock individually. That really only leaves one avenue left to explore which is the bird event. It just so happens to be the most interesting and debatable and glamorous possibility among them all. There are several fish loving birds in my particular pond because of the quiet remote location. While I have not witnessed any of them transporting fish, that doesn't necessarily mean they didn't do it. Nearly every time I approach the pond there is at least one bird roaming the banks. Very seldom have I approached the pond without finding a bird scanning the shores. If they did it or not who knows... I am no scientist but nevertheless the birds are a common denominator in my situation and others. They must be carefully considered as a suspect...
