Last night was my chickens' first outdoors. They are three months old and it's it got down to the single digits last night. I was soooo worried (they'd only experienced comfy indoor temps), and woke up and went out every couple hours to check on them. I built a really well insulated strawbale structure, but even so it got down to about 20 in there - and they all did just fine. Grumpy, but alive. I made sure they ate a whole bunch before turning them in; the one that didn't seemed to be a lot colder this morning. I'm wondering, though... I was hoping that my coop would stay warmer than it did. it's only about 5X5X6 and with 7 chickens in it I thought that I could maintain temps above freezing. No? Should I put plastic over the glass window? Build up the floor more? It's basically just sitting on the ground with a bunch of dry dirt shoveled in (the dirt here is clay-rich and GREAT at absorbing chicken poop). Any tips? Are there any battery-powered heating devices that I could use if temps dip really low? I dont like the idea of running an extension cord through straw in the mouse-filled woods thanks!