>>...they could not lead recruits across water until Lindauer strung a rope with leaves across a pond, which the bees used to make a scent trail.

Most interesting what these stingless bees do.  I'd think the honey bees' dance communication (please don't reply with your contraty views on bee dances unless an R&R experiment supports it beyond the shadow of a doubt :), is more efficient and allows foragers more leaway in adjusting the flight path based on wind conditions, need to go around passing objects etc.  

>>He set a feeding station on a tower about 65 feet up. Stingless bees could bring recruits to it (88 bees in 30 minutes). Honey bees could not bring recruits to the top of the tower.

This is interesting as well.  I'd love to examine how bees in Manhattan communicate forage availability. 

>>The dance language only contains horizontal (2 dimensional)
information and so completely fails when the food source is not on or
near the ground.

I'd suggest bee dances work in 3D with a possible qualifier that the  vertical component works if the hive is positioned higher than the forage.  I assume here, since most city hives are on roof tops, downward vertical foraging is no problem because the bees can traverse the horizontal distance to flowers and then descend on them.  [But how do they find their way back up to the hive???? :)]

On the other hand, Lindauer suggests it might be a problem for a ground level hive to locate flowers in rooftop gardens... but who would let me place a bee hive at ground level in Manhattan for an experiment!! :)

>>They have no way of indicating a food source is far above the ground, so the recruits follow the direction to the base of the tower and look there.

Lindauer's case is somewhat unique in that it had a single tower in a flat (?) landscape.  We know bees don't starve in seemingly barren Manhattan or in certain mountain ranges.

Waldemar

******************************************************
* Full guidelines for BEE-L posting are at:          *
* http://www.honeybeeworld.com/bee-l/guidelines.htm  *
******************************************************