I’ve lost one button and two coturnix
Get a thermometer in there, make sure the flock is as warm as you think. It's possible the Coturnix could be under-feathered for the temperatures you mentioned at 3-4 months, but ruling out disease would also be prudent—do you still have one of the bodies you could send in for necropsy?
Ok I will put a thermometer in there but in all reality I think I’m just going to move them inside to my basement tomorrow. My basement stays 50-60 degrees year around. I do not have the bodies but I do know that there is nobody around me to do a necropsy except if I did one myself. I lost a duck in the spring and called around then.