I am in the middle here. First thing I would do is deal with anything that is encouraging them.....so I would stop feeding the birds, be extra careful with stored refuse, clear areas of undergrowth and so on. I don't like to kill needlessly either but when you have had your compost bins eaten into, your garage liberally covered with rat wee and poo and found half a dead snake and a lobster shell head behind the freezer in the garage, then it makes you rethink a bit. You may need to get rid but if you just get rid and don't make the environment unwelcoming them more will move in; if you adjust the environment then they rats may move of their own accord without any need for raticide. IMO the one thing you should not do is let them be.