Chapotraphouse

Why exactly do you think it is so critical for us to perpetuate the existence of these animals?

I said it in my other answer but it's because I view them as equally valid forms of life as any other. Also paraphrasing my other answer: what you're describing are challenges to be overcome, not reasons why the task shouldn't be undertaken. Perhaps some problems must be bred out intentionally before an animal can be released, perhaps the animal sanctuaries for feral populations would have to be protected from predators in some way, I'm not advocating for dumping the mass of them in the woods and seeing what happens, I'm advocating for taking responsibility, and I view killing them all off as soon as they've outgrown their usefulness as an abandonment of that responsibility. As for resources - you opened this thread by describing an entirely vegan world, so I don't exactly feel burdened in this hypothetical by what is feasible from where I'm standing within the society I currently inhabit.