This is a scenario I see often, yet I am not sure if it's a good one or a bad one...

I have a TBH. There are several bees positioned backwards on the entrance landing. There heads are pointed in the hive and their tails pointed out. I have seen them with their tails up, but today they have their tails down and they are beating their wings rapidly. My entrance is about 1" deep and 12" wide. There is a cluster of bees fanning at 1/3 of the entrance.

Sorry no pictures - technologically challenged here.

Any ideas why this happens?

Much Thanks,
Tara