How honeybees share directions
AWhen a honeybee forager discovers a rich patch of flowers, she returns to the hive and performs a short routine on the surface of the honeycomb. In the 1940s the Austrian zoologist Karl von Frisch showed that this routine, now called the waggle dance, tells other bees where the food is. His work on animal communication was recognised in 1973 with a Nobel Prize, which he shared with two other researchers of animal behaviour.
BThe dance takes place in almost complete darkness, on a vertical sheet of comb. The forager runs forward in a straight line while shaking her abdomen from side to side, then circles back to her starting point, alternately to the right and to the left, and repeats the run many times. Bees that follow closely sense the movements mainly through touch and through the vibrations and air currents the dancer creates.
CThe direction of the straight run carries the direction of the food. Inside the hive, straight up the comb stands for the direction of the sun. If the run points 40 degrees to the right of vertical, the food lies 40 degrees to the right of the sun as seen from the hive entrance. Because the sun moves across the sky during the day, a dancer gradually adjusts the angle of her run, even if she has not been outside for some time.
DDistance is signalled by the duration of the waggle run: the longer the run, the further away the food. The exact relationship differs between colonies, but roughly one second of waggling corresponds to about one kilometre of flight. When the flowers are very close to the hive, bees perform a shorter, less precise version that was once described as a separate “round dance”.
EThe dance is not the whole message. Followers also pick up the scent of the flowers that clings to the dancer's body, and she may share samples of nectar with them. Recruits therefore leave the hive with information about both location and odour, and use the smell to recognise the right flowers when they arrive. Interestingly, experiments suggest that the dance helps a colony most when good food sources are scarce and widely scattered; where flowers are everywhere, bees find them almost as well by searching alone.