Temps are dropping into the low 20's, possibly teens, tonight. Our coop has two screened windows, about 1ftx1ft. It is also ventilated at the top as the roof is not directly sitting on the support walls...raised slightly. Does this sound drafty? Should I plastic the windows? We only have ten chickens (10 months) and they all huddle together on the top roost as opposed to spreading out to the other roost, and one is setting in the nesting boxes; point being that there's plenty of airflow since they're not stuffed in tightly. Should I be worried about them?