So this is going to sound dumb I'm sure. I opened my coop door. It's about a foot tall and a foot wide. In the winter when it's freezing cold...do I just leave it open all day? Letting the air into the coop? They only have access to food and water when it's open. Also. Yesterday was our first freezing day and snow...my birds stay in the coop all day. I assume they are coming down to eat since they are still living. Is this normal? Do they just hang out in the coop all day when it's cold??