It finally warmed up enough to check my hives today . I found 1 hive were sadly the hive had honey but were dead bees in bottom . So I guess even thou I thought had left good enough ventilation condensation built up and got them . Another hive again had honey stores but had no signs of dead bees . But in the bottom could tell a mouse had chewed threw and made a nest . Is that what caused them to leave . We did have a real bad cold spell lowest with wind chill was -30 zero . I am not a newbie beekeeper , been doing it about 6 years but of course I am far from being a veteran beekeeper .