No.
I have never seen a bird give up food to become an aquaculturist. They are opportunists, feeding as they can. If they drop a fish into some water, it wasn't on purpose.
Since they can fly, fish eating birds move from pond to pond, or river to lake, or...to get the food they need.
I honestly don't know how fish get into a new pond.
I have seen fish swim from pond to pond via a small stream between the two during heavy rains. I have found small fish in cattle hoof prints in a field after a rain.
I have seen a bird catch a fish, take off flying, the fish flop and fall out of his mouth...into the dirt.
I have seen birds move fish from pond to pond on a hatchery, because all there is is pond next to pond, next to pond. But, I have never found hard evidence birds move fish from one pond to another in recreational ponds.
The theory that eggs are transported on bird legs doesn't fly with me, either. That's because eggs must have specific conditions to hatch. Most eggs are sticky. Shells are wet. Eggs breathe, and can't live in silt. That's why most fish eggs are either in a nest or stuck to a substrate, so they can breathe. Eggs stuck on a bird's leg have little hope of hatching. First, when a bird is airborne, there's a drying effect on the stuck eggs. Second, if the egg comes off the leg, it most likely happened in mud, where the egg can't breathe. But, let's say the egg hatches. There's another problem...we need a boy fish and a girl fish to make other little fishes.
So, two eggs must make it and hatch, and grow up, then meet and do what fish do.
To me, even after 26 years of doing this fish business stuff, how fish get into a new pond is more of a mystery now than ever.
