The first winter I had chickens, I spent a bunch of time hanging plastic tarps inside the coop to keep the girls warm and free from draft. It was a major pain and it looked ugly. Imagine my surprise when I visited a lady with 50 hens who lived about 30 minutes from me. She didn’t even have a coop; just an enclosure to protect them from predators! It dawned on me that chickens are birds with feathers—like the ones who sleep outside in trees all winter long.
That said, we here in Southern California rarely deal with freezing temperatures (it was 52 degrees last night…mid December), and very cold weather does bring a set of challenges that need to be addressed. So….
There is no need to add heat to keep your coop warm because chickens can keep themselves warm (see below). But, you do want to make sure that your coop’s roof doesn’t leak and that there is an area where they can roost at night out of the wind (drafts are fine, wind is not—see below).
You may also want to cover part of your run during inclement weather. Some people also put wood or other items in the run for the chickens to stand on out of the snow.
In addition, let them have romping time when it is sunny. They so enjoy it!