if they have their feathers, put them in the coop and hang a light down low in one corner. A light with a ( don't know what you call it) metal collar type or lamp shade, around the bulb to direct the heat downward. They can snuggle there at night and get warm if they need to, and still have room to roam and they are out of the horse. I usually put chicks in the coop first thing anyway. I just hang several lights down low about 8 to 10 inches off of the floor. They radiate enough heat that the little fellows can cuddle and get warm..with only a few like you have one light is sufficient.