We recently bought 9 chicks of different ages. 1 black Orpington and 4 Bresse (all about 1 week) and then 4 chocolate orpingtons who are considerably older. I'm not sure exactly how old but they have lost more than 50% of their fluff and have feathered wings, back, and some have tails starting. They look like teenagers of the chick variety. I don't really like having these two age groups together and the chocolates have been spending all day out in the garden with no trouble. The big chicks come inside and sleep over with the fluffy babies at night still. When can they spend the night outside w/o a heat lamp?