You are being held in a landing pattern...

This old bird house has been taken over by a colony of bumblees. I've never seen one of these before (I've always thought they were largely solitary insects) but apparently some species form colonies of around 400 for breeding purposes.  To put that in perspective, a honeybee colony/hive has around 50000 individuals in it.  

There was one bee who seemed to be on guard duty - it shuffled right out to allow another bee to exit, but it wouldn't let the two or three that were circling to enter. At one point, it climbed out and seemed to be fanning the colony within with its wings. 

They're essentially harmless if they're left alone, so I hope they will come back next year.