Mr. Bill, do you mind explaining how you trap tadpoles? Many of us have no experience with this.
Also, there have been lively discussions on the forum on how bluegill end up in other ponds. Birds are usually blamed but many have felt this is impossible or at least low likelihood for a bird to mouth a bluegill, not damage it, dump it or drop it in the new location, and then return back to the old location for more. This process would continue until enough live male and female bluegill are in the new location to successfully spawn etc.
I never thought of putting the blame on muskrat. You propose egg transfer on muskrat. Anyone have ideas on if this happens?
How else could enough mixed sex bluegill get into your pond #2? could highwater event flow some fish into pond #2?
Idea of the layout of the land, grade and location of ponds or pictures might help with this.
I'm not trying to pick on you, it is just that getting unwanted bluegill into a pond really puts a damper on many of our best laid plans (I imagine yours too..) so if we all understood better how these things happened maybe we could prevent it.
I assume someone fishing in one pond and dumping them in the other isn't a likelihood for you? Strangers bucket stocking fish after catching them in another body of water off your property a chance?
This story/scenario comes up so often, and the explanation always so consistently hard to believe (must have been kingfisher who dropped a meal, ducks who carried eggs..eggs must have been prefertilized? what fish took care of the eggs on the 'nest' until they matured?, animal transfer, osprey dropped..etc) that it really gets my 'want to know' going when we hear so many scenarios like yours.
Would love to see pictures. Your story sounds like we all can learn a lot from you!