I am new to the forum (although I have been browsing--read: stalking knowledgeable chicken owners-- for months now) and have never posted before, but I am definitely in need of a bit of guidance here as the weather gets colder. I live in Northern NJ where the weather in winter frequently gets into the teens and sometimes single digits at night (20s is probably the average night temp in winter). I only have two birds, and the set-up I have for them is somewhat unusual. They live most of the time in a large chain-link dog kennel/run, inside of which is a rabbit hutch converted into a coop. The part that they roost in is basically a 2.5 foot by 3 foot box made of hardware cloth that attaches to the solid part of the rabbit hutch (the hutch is sort of like a room they go through before they enter the area they roost in at night and has deep shavings on the floor). They can come and go from the hutch/coop into the kennel as they wish, since the kennel is predator proof. For the winter, I have covered most of the sides of the kennel with 6 mil plastic-- I covered both long sides (leaving a slight gap at the top for ventilation) and half of one of the short sides, and left one entire short side open for ventilation. For the small roosting "box," I have used thick styrofoam insulation about half way up three sides (making sure they can't eat the styrofoam!), with the rest of these three sides covered in plexiglass. The side where the box attaches to the hutch remains just hardware cloth. I have a tarp over the whole thing for a little extra draft control. The top of the box is covered loosely in shingles and the bottom has deep hay. My question is primarily about ventilation: The box is pretty small, and I have only two birds. I did leave the one side open hardware cloth, but it is covered with a regular plastic tarp...Will the tarp allow adequate ventilation? I did cut a hole in the tarp right about at roof level (hole is probably about 3 inches by 3 inches), slightly above where the roost is. This ventilation stuff combined with the cold has me worried!! Thanks for any advice!