Daytime losses or night time losses? During the day, if a predator gets into your coop the chickens don't have a chance of escape - I get that. Just lost a hen that way this year. If they're free ranging, they stand a better chance. At night, it's not going to matter if they're loose or not. Chickens are basically helpless at night. They seem to be totally unaware of their surroundings. I can walk right up to them and pluck them off the roost. Can't get near 'em during the day. If they're locked up at night in a secure coop/run, they are much safer since the predators don't have access (or at least not easy access) to them. If they're not secured, once they are found, your flock could potentially be wiped out in a matter of minutes. Raccoons don't necessarily just take one. Coyotes will grab several at a time. Owls pop their heads off, knocking their bodies from trees they're roosting in (voice of experience on that one!). If they're low enough to the ground, skunks will take them. Opossums (I think I forgot to mention those in my list of potential predators) will climb up to where ever they're roosting and get them. And the chickens will just sit there and let it happen because they are totally defenseless at night.