We have five Ameraucana hens and five guinea fowl (three females and two males). Our coop is 8’x6’ (8’ high). There is an attached, fully enclosed pen, that is also 8’x6’. They typically free range all day, save for days like this, where it is -14C. The pen is wrapped in plastic (not airtight), so they can venture in between the coop and pen, on colder days. On days where it is really cold, like today (and days in January where it can get to -30C), is it okay to leave them in the coop, with the small door to the pen closed (in order to keep it “warmer” in the coop)? I realize chickens are supposed to have one square foot per chicken; will my small flock be okay in the closed coop for periods of time, in the bitter cold? There is plenty of roosting space, nest boxes that extend out of the coop... Thank you in advance for your insight.