I loose one once in awhile but between pellet rifle and .22 the prob usually solved pretty quick. I've never came close to loosing every chicken I have. One or two maybe and some yrs none.Free Range is the best way to lose every chicken you have! Even in a non-rural setting, there are coyotes, raccoons, o'possums, dogs, and any number of other predators, and if your chickens aren't secured, they're dinner for something!
Chicken security is being inside a pen with bottom, top, sides, etc. secured.