“In less than three hours, Church responded with a detailed plan to return “a flock of millions to billions” of passenger pigeons to the planet.”
Just what are the unintended consequences of that? What ecological niche will it inhabit or takeover? What will be kicked out of that niche?
Ebb and flow. That is nature itself.
It will be a lot of work to just produce a few passenger pigeons. Apparently they needed a flock of at least 1,000 just to generate the sexual excitement and hormones need to make breeding take place. They would probably do well in the south where they were common, and be a good game source of food. They had their niche, and anything that has occupied it since can probably accommodate a few PPs.