Our coop is just an old shed that came with our house, so it's not insulated and it's rather breezy. It's maybe 6x8 or so. I'm wondering, as a winter settles in here in SD, how cold is too cold for the chickens? I have 7 total and a 10 slot nester deal, so they all have a spot to nest/sleep at night, though most like to roost on the 2x4. Will they gather together as it gets colder? I have a heat lamp out there I can plug in at night, but wondering what the best way to winterize would be. Any help/suggestions would be greatly appreciated!