This will be our first winter with chickens (barred rock, black sex-link, and chantecler) We live in Ontario (near Ottawa) and during the winter it is typically around -20 C (or -4 F) - sometimes warmer, sometimes colder. We will have two heat lamps for between 24 and 30 birds in a coop that is roughly 8' 20'. This is the first winter with the space insulated we don't know what its temperature will be during the coldest days/nights. What is the coldest temperatures chickens can handle? Is there anything else we can do to keep them warm, especially at night when the temperature can really drop. Thanks!