It's cold in Atlanta - are the bees warm? Only they know but supposedly they are clustered in a ball shaped group in the center of the brood box and are maintaining the cluster temperature at around 45 degrees at the outer edges and warmer in the center.

The bees are not keeping the entire hive warm, just their cluster. Occasionally when the days get above 55 I see them flying out of the hive.

The entrance reducer allows them to enter and leave through this small entrance. Here two bees are stepping all over each other as they leave.