If I were to leave my back door open, birds would fly in and out of my house all the time. They would build nests in the rafters (and maybe even displace the spiders and their webs). And if I left that door open, the blackberry brambles that have taken over my porch would creep their way on into the house. So I mostly leave the door closed (the screen, at least).
Iíve been lucky since Iíve lived here that Iíve never found a wild creature in the house. With all the inner wall space that I have here, I would have expected a rat or two, or maybe something worse, in all this time. The spiders I donít mind. I do kind of hate to see the occasional lizard get lost inside, because I have a hard time catching them until they crisp up and die (not necessarily in that order).
May years ago I lived in a duplex in a decent part of town. It was such a desirable place, in fact, that the owners kicked me out so their son could move in. Kind of tells you something, no? But it was at that place where, once upon a time, I was sitting on the couch and looked over only to see a gray mouse perched comfortably on the next cushion. Last thing I expected. (Well, one of the last, just a notch above an aardvark, an armadillo or Carmen Electra.)
But here, even though my lifestyle doesnít exactly discourage vermin, they pretty much keep to themselves, outdoor where nature intended. When they try to get in, I discourage them. It doesnít always work, of course. Iíve had one bird commit suicide by flying headfirst into a window. Come to think of it, I guess that was kind of discouraging.