http://nuclearcdboxafziza4mgohcwhzfjiyg6zeslnry33pepsgtur2wyeyd.onion/social/thread/43.html
People form attachments to them, so it would be cruel to not just the pet but the family, even if justified to preserve the animals they threaten.
As for feral introduced species, Australia got it right: snipe camels from helicopters and give rabbits the pox.