Re: Drone Congregation Areas
I haven't seen one myself, but have heard them described. Apparently, once established, they are historically persistant and geographically definable. At an ABF Conference I saw pictures of one in Texas, if I remember correctly. It was found years ago and monitered for years and is still used by bees.
They aren't so high up to be unobservable by eye, if you are lucky.
Michael Bush probably has something about this on his website. Otherwise you may need to broaden your search.
Mark Berninghausen "To float, upheld, as salt water would hold you, once you dared." Denise Levertov, poet