The great thing is that chickens come with down coats and many breeds tolerate cold much better than they do heat. My first winter with chickens was last year and the main problem I had was not enough ventillation - a few combs got frostbitten and had to be treated due to humidity in the coop. So, as strange as it may sound, make sure you have plenty of ventillation high up during the winter - no drafts right on the roosts or where the chickens are, but plenty of air flow high up to draw out the humidity and keep things dry. Other than that, as long as the birds have a sheltered area, they should be fine. Our winters here can have lows in the single and negative digits and we have stretches where the highs never reach freezing. Other BYCers have it much worse! And yet the chickens do just fine as long as they have a draft-free shelter and plenty of ventillation.
