This is my second year keeping chickens. Last year I started with 4 and lost two to predators. I still have a Delaware named Babushka and a Saphire Gem named Bluebelle. I got four chicks 6 weeks ago--one Buff orpington and two California Whites. These chicks are growing and developing much faster than my first 4 chicks. They look pretty much fully feathered and they can fly. I have been keeping them in a 2.5 X 3" X 3" box with a small heater plate inside it. They no longer fit under it and seem to prefer not sleeping under it so I removed it. If I don't cover the box, they fly out into the house, and they are difficult to catch, so I am anxious to get them settled in the coop. I clipped their wings on one side to slow down their flying, but it hasn't worked. I think they could be introduced gradually to the other hens, but the nighttime temperatures are still in the 30s. Last night the temperature was 27, but that was colder than other nights. The hens have an upper roost area with a 4" long heater plate over their heads. There is a small wooden shed area inside the coop, and the opening to it could be screened so it could be used as a introduction cage. But, with the cold nighttime temperatures, I am not sure it's safe. I could put the little brooder heat plate in there with them, but it might not give off enough heat. The coop is fairly large, about 8' x 8' X 8'. I currently have it wrapped in heavy plastic to keep the cold wind and rain out. It has a solid wood back wall and the rest of the coop has wood walls that are 3' tall with double chicken wire on top, up to the metal roof.