Feral cats are domesticated cats that have escaped and are no longer considered domesticated. The point is that if it weren't for humans we wouldn't have so many feral cats.
Also, feral cats tend to congregate close to human populations.
I'm not sure what your point is about equilibriums. Of course equilibria are reached naturally, but with the human factor these equilibria have been distorted beyond any natural capacity. In short, any human-impacted equilibria tends toward the rapid decrease in species populations, often to the point of species extinction.
