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Researchers have long marveled over the dance of the honeybee. In fact, close observation has even enabled them to read the insect's waggle performance. Yet despite years of study, new insight into the creature's unusual form of communication continues to come to light. According to findings published today in the journal Nature, honeybee dances do not convey absolute distances to the food source. Rather they impart the direction of the food and the distance the bee thinks it has traveled, based on the amount of scenery it has passed by.
To explore how foraging honeybees gauge distance, Harald E. Esch of the University of Notre Dame and his colleagues trained bees to forage from a feeder placed at varying distances beyond the far end of an eight-meter-long tunnel. Next the team studied how the bees back at the hive interpreted the performances given by the returning foragers. The recruits took off in the correct direction but overshot the mark. Flying through the tunnel, it seems, tricked the first group of foragers into thinking that they had traveled farther to the feeder than they actually had¿a false impression that they passed along to the recruits.
Instead of calculating absolute distances when mapping the path to nectar, the researchers conclude, honeybees measure distance using what is known as optic flow¿the amount of image motion that appears to occur as the position of the observer changes. Thus the dancer conveys only the direction of the food source and the total amount of image motion that should occur en route. In the case of the experimental bees, "their visually driven odometer misreads distance because the close tunnel walls increase optic flow," Esch and his colleagues explain in their report. "There must be a high selection pressure to ensure that a dance signals the direction of the food source as precisely as possible," the team asserts. "As long as the recruit flies in the same direction as the dancer, she will translate that image motion signalled by the dancer into the correct flight distance and find the goal."
