Since I have moved to my country home by a little creek, 6 years now, I have spooked many GBH's while walking near the waters. Two of which spit out a fish just after taking flight. I have seen this one other time while fishing a conservation lake nearby. This particular spit fish was rather large - 6-8 inches. I was able to retrieve one of other fish off of a dry gravel bed, still flopping about, I returned it to the creek to live another day. I can see how a heron could take a fish to another nearby BOW, get spooked, and there you go...a new species in the pond.
Now that has to happen twice, beating the 50/50 odds for male vs female, in a short enough period of time that spawning can happen to create a population, but it only has to happen once to introduce that one bass.
The chances of eggs sticking to bird's feet and then surviving are very, very slim in my opinion.
