Its interesting to see the different attitudes that folks have about this topic, and how excited they seem to get about it.
Personally I have lost a lot of chickens over the years by trying to let them free range. When we lived by the woods, I expected high losses. Then, I cooped the birds in what I thought was a secure manner. It wasn't. I woke up to killing fields fairly frequently, finding what I suspect was the work of intrepid coons or pussums. The story is the same everywhere you go, they test your security all the time. Different varmints have wiped me out before.
We now have a place in the middle of nowhere, with no neighbors. We've been here about a year, and its got to where I just grab a shotgun and head out the door anytime I hear the birds squawking like somethings after 'em. It doesn't bother me in the least to shoot pests that come up on the part of my property that is clearly inhabited by humans and domestic stock. I killed about 10 rattlesnakes out here so far this summer, and I'm getting a little callous.