My sons had 12 chicken and rooters in his pen. this morning all dead except one hen. I don't know what happen. we are in AL and there was frost on the ground this morning, it got down to 29, but all mind are OK. I will take his one hen and keep it in a smaller pen within the run, but because of the cold it is going to be hard.. for I can't but the small pen inside my coop just the run, how long do I need to keep them separate?? any ideals about what could of caused the death of all of them at ones??