I have a 10x10 covered enclosure for my 4 hens to sleep in. They free range during the day. I leave the coop open for them to go in to at night but in the summer they like to sleep on top of the coop inside the enclosure but now that its getting colder should I lock them in their coop at night? This will be their first winter they are about 9 months old.. I live in California so it doesn't get super cold only a few night here and there at are freezing.