Hi! My Plymouth Rock chicken began sitting in the earlier days of November. Her chicks just hatched and we have five Plymouth Rock-Cochin Bantam chicks. They are currently living in the coop, and I am concerned for them. Winter is approaching which means freezing temperatures. This is my first time raising chicks that were not purchased. Will their mother keep them warm enough, or do I need to figure something else out to keep them warm through the winter?