Hi Andrea
 
The natural bee hives you are asking about would most likely be tree
cavities.  Bees in this part of the world don't build nests on exposed
limbs.  Two nature centers I've been associated with in the past had developed
simulated Bee Trees.  The concept used a hollow tree trunk, sealed and
moved indoors.  A long opening was cut in the tree and it was fitted with a
long plexiglass window. Inside the hollow trunk, a slotted frame was
attached to hold the standard hive frames. In this way, the colony could be
inspected for disease and frames of honey or brood could be added as needed.
The effect of seeing the bees in the tree trunk fascinated visitors.
 
If you would like to discuss this design further, please contact me at my
direct email address.  Happy to be of assistance
 
Regards
Gordy
 
**********************************************
Gordon Allen-Wardell
Extension Apiculturist
Department of Entomology
University of Maryland
College Park, MD  20742-5575
301 405 3953
email [log in to unmask]