While I had to be away for an unexpected death in the family, the temps at home dropped to air temps of -15f at night. My fill in chicken caregivers did their best, but 2 of my girls suffered minor frostbite on their combs. I discovered it upon my return and have brought them inside and been treating it. They are acting much happier and are eating and drinking well. My question is at what temps can they go back outside, at least during the day? Their run is protected from wind, so that is not an issue.