Hi everyone, slight problem with our chickens. We've had them about 9 months now and they have been going into their coop every night since the beginning on their own. Now that the days are shorter and the cold weather is here, about half the flock will stay outside in the freezing cold. They would rather freeze in a snow storm than go back inside. Any ideas what the problem might be? The coop is very cosey, kept warm, food and water, everything they need. Any help greatly appreciated. Thanks!