I have two chickens in Seattle. I don't use a light in the coop and there isn't a heater in the coop. Will my two be OK (ie warm enough) without supplemental heat? We're in zone 8b, we will get a few hard frosts over the winter and occasionally snow, though it never lasts. The coop is well padded with wood chips and there is one perch and one nesting box in it. Thanks for any reply.