About the deer - if you eat meat and then pee around your periphery the herbivores won't cross the line into a predator's territory - doesn't work with vegetarian pee, and doesn't work against cats, either. And it isn't just that cat poop isn't good fertilizer, it contains things which are highly detrimental to human health and in which you ought not be digging. I have heard good things about cayenne or black pepper, both of which will deter anything which sniffs its way around. Wash your hands before touching your face (or other sensitive body parts) if that is what you use!