I'm wondering if I didn't design the box correctly. I have five 10 week old Welsummers that will all spend the night in the nest box. I can't believe how stuffed-in they are. The box is built to hang outside of the coop so it doesn't take away from inside space. It is 12" x14" by 12" high. The bottom of it is 14" off the coop floor. It has a 2" lip may of plywood to keep the wood chips and eggs from falling out. I build it according to some info I got that suggested that size for med/large chickens. The coop itself is 6' by 4' and 4' high. There is 6' of 2x4 roost in the coop that they use, just not at night. Could 10 week old birds get too cold at night (It hasn't gone below about 50 F so far)? The rafter area of the roof is open for ventilation. I haven't been covering them, since I didn't think it was that cold yet. So, would anyone have a good idea of what might be causing this?