I have read that a heater in your chicken coop is a bad idea for several reasons. I live in South Dakota where it can get down to -20 some days/nights. I have the girls in a metal shed, so there is plenty of ventilation but there is no insulation (it's cold in there!) It shields them from the wind and I have pine shavings on the ground but I worry that it's just too cold for them. They are a part of our family and I want them to be comfortable, definitely don't want to lose any this winter. I do have a smaller coop in the shed that they lay in but will not go into at night, I'd rather not make them go into it. Should I just not worry? They are just chickens and will be ok? Should I start putting them into the little shed at night? Any advice would be appreciated. I included a picture of our shed/coop.