We have coop with attached run (tractor coop) that is very secure. It is up against a pen area that is also very secure (all sides enclosed). They line up next to eachother, and there is a small door they can go through to get back and forth (the doors lock together so there is no entry from outside the pen/run. Do you think it would be ok to leave their coop door open overnight so that they can get in and out on their own as early in the morning as they want to, or should I be locking it up every night. This morning at 6:30 a.m. it was 29 degrees - the coldest it has been in a long time. It's been in the 30's. I live in California, so it doesn't snow here, but it does rain and we do get some wind.