I keep my hives on stands, 18 inches off the ground. This year all of my hives went to screened bottom boards.
About a week ago while looking at one of my hives I saw some bees flying from under the hive. So down on all fours I went to have a look. To one side a cluster of bees the size of a grapefruit, was/is hanging from the screen. At first I thought they were starting a beard, but the temperature hasn't been high, and the hive has swarmed already. There is plenty of room in the hive also.
I was thinking that the bees were trying to keep some queen cells warm that were close to the bottom, but the new queen emerged some time last week.
Maybe someone can help me on this one.