8 : The Flight Guidance Mechanisms of Honey Bee Swarms
use these pheromones to help the followers find their way into their new home.
Streaker Bees?
A second way that the leaders could provide flight guidance is by means of visual signals. One way they might do so is
by repeatedly making high- speed flights through the swarm cloud. They could do this by shooting forward in the top of the swarm cloud until they reach its front and then by flying slowly to the rear of the swarm along its bottom or sides (Figure 2). Martin Lindauer, the German researcher who pioneered the study of house- hunting by swarms, reported seeing several hundred ‘streaker bees’ shooting through the tops of flying swarms and he speculated that they were signalling the flight direction (Lindauer, 1955). Lindauer’s observations have
recently been confirmed in a study that used harmonic radar tracking of the flight paths of individual leaders (scouts) during the take-off and first few minutes of flight of two swarms (Greggers, et al, 2013). Only one of two swarms observed in this study flew all the way to its
destination and in this swarm, just two leaders had their flight manoeuvres tracked, but both bees displayed the streaker-bee behaviour. High-speed flights were made in the direction of the swarm’s destination and these were separated by slower rearward flights and stationary loops. The slow-speed manoeuvres of the leaders moved them to the rear of the swarm cloud, hence to the right place to start another high- speed flight forward through the swarm. The results of this study support the streaker-bee hypothesis for swarm flight guidance.
Tracking Individuals Further support for the
streaker-bee hypothesis comes from a study in which the movements of thousands of individual bees in a swarm were tracked simultaneously, and measurements were made of each bee’s position, flight direction and flight speed (Schultz, et al, 2008). The goal was to get information on the movements of all the bees in a flying swarm to see if, as predicted by the streaker-bee hypothesis, the high-speed fliers in a swarm are, indeed, shooting
Figure 3. Kirk Visscher (left) and Tom Seeley (right) in 2006, watching a test swarm move into a bait hive on Appledore Island, in the State of Maine
toward the swarm’s new home. This study also aimed to check Lindauer’s report that streaker bees are seen mainly in the top of a flying swarm. This makes sense since this location would render these bees conspicuous – as dark objects against the bright sky – to all the rest of the bees in the swarm, but it still needed to be checked. The study began by having a swarm fly over a high-definition video camera. The camera was equipped with a wide- angle lens so that it could ‘see’ the full width of the airborne swarm. The camera also had an extremely high shutter speed – one ten-thousandth of a second – so that within each frame of the video recording each bee
appeared as a short, ellipsoidal blob rather than a long streak. To have the swarm fly directly over the camera, the recording was made on a treeless island six miles out in the Atlantic Ocean, where the only desirable home site was a bait hive positioned 250 metres from the swarm (Figure 3). The camera was positioned 15 metres from the swarm’s bivouac site along the swarm’s flight path to the bait hive.
The same swarm was forced to make two complete flights to the bait hive and each time (thankfully!) it flew squarely over the video camera.
3D Reconstruction With these two recordings of
Figure 2. Schematic view of the flight patterns of bees in a swarm flying to the right. Lindauer reported observing streaker bees mainly in the top of the swarm cloud
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April 2015 Vol 97 No 4
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