Created yes. Maintained not so much. Feral cats can make more feral cats on their own just fine. In fact, outdoor housecats are really bad for feral cats, because they hunt prey, fight for territory, and contribute to overpopulation of small predators without having to deal with the constant dangers that an actual feral cat does.

This doesn't work as a general argument against having an outdoor cat, because you can just have them fixed.