Our hens are never separated from the roosters, and I disagree that it stresses the hen. Lots of times the roos will stand by the nest and chase away other hens who harass the setting mom. After the babies hatch, the roos will go to great lengths sometimes to help the mother protect, and care for, the babies. As far as it being too cold we have had hens with hatches in November and even December. Mom will make sure the babies stay warm and, as has already been said, you can use a heatlight.
