I'm planning my "chicken tractor" of sorts. It's way too small for a heat lamp. I am wondering if there are ways to add just a bit of heat to a very small henhouse that doesn't require electrical wiring. Anything battery operated? A small heating pad? A hot water bottle? (I can't imagine that would be terribly effective on a below freezing night.) I'm in the mid-south, so it doesn't get below freezing for long periods, but I know there will be times when the hens might need just a bit more warmth. We could run a huge outdoor extension cord if absolutely necessary. I could bring them into the garage too, I suppose.