I have had 2 of my hens killed by black snakes. I caught one in the act with half her body down his throat. I would not have believed it if I had not seen it myself. So my rule of thumb is, if I find one around my coop and my hubby is there, it will get relocated. If I’m at home by myself, whether in or out of the coops, with or without eggs or chickens in their mouths, then I kill it.