Hi, I have 6 buff orpington hens. I know they are cold weather hardy, and they love to be outside of their coop in their run, only stay in coop to lay and roost. This is my first winter with them. I keep a deep layer of pine shavings in their coop now verses summer. They have sand in the outdoor run that has plastic around the sides now except for one area I can roll the plastic up and down when needed for weather purposes. I feel that with the cold New England weather I'd like more than just sand in the outdoor run, which by the way is covered also with a peaked steel roof. Which would be better to use for warmth and ease of cleaning hay or pine shavings. I plan to continually maintenace the coop and run throughout the winter.