I often wondered about the local DCA(s) as I live on a small peninsula which includes a very high middle section complete with sheer cliffs. It is a very compressed area, bee flight range-wise. Wherever they are they seem to work, helped by our high honey bee density here (lots of backyard beekeepers). In pursuit of good matings for our queens our local club has in recent years asked local beekeepers to do two things: ditch drone sacrifice as a mite control tool, and put a drone frame or shallow-frame-in-a-deep to encourage drone production in their best colony.

My fave bee book is "Mating Biology of Honey Bees" by Koeniger and Koeniger. They refer to findings that DCA's tend to occur where the height of the land disappears into the horizon. In areas lacking elevation, they write that drones do not congregate but diffuse across the landscape.

An excellent Gudrun Koeniger lecture to the UK National Honey Show is available on YouTube:
https://www.youtube.com/watch?v=cI26DLS2CyM&t=3s

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html