I'm looking at getting some birds (full grown) from some folks who free range their chickens, but heat their coop. My coop is not heated. My girls are acclimated to it, but I'm thinking it would make theirs sick if I switched them straight to an unheated coop. The raw temp tonight is -1, by the way. Is there a way to transition them?? Mabey run a heat lamp and then decrease the amount of heat by moving it higher in the coop little by little? I don't want to make anyone sick (mine or theirs), so if I have to wait till spring, so be it. What think you?