The Dances of Honeybees at Small Zenith Distances of the Sun

Abstract

ABSTRACT The dances of honeybees have been studied in Jamaica (18° 00′ N.), Trinidad (io° 38’ N.), and British Guiana (5° 11′ N.) when the sun was near the zenith. When the zenith distance of the sun was less than about io° the orientation of the observed dances deviated, often very widely, from the direction expected if the bees were indicating the angle between the sun azimuth and the food-source azimuth. But the dance angles did not show the wide scattering to be expected from a failure of perception of sun azimuth. They were frequently well orientated, and successive dances often progressively changed direction clockwise or anticlockwise. The dance angles plotted against time gave smooth curves symmetrical about noon, but of smaller maximum slope than the curves of changing sun azimuth. The direction of turning of the dances was often opposite to that expected from the direction of sun azimuth change. Various conceivable explanations are discussed. It is concluded that the dances can best be explained as the result of two control mechanisms : (i) A mechanism which uses all available information about the real sun azimuth and limits the possible dance angles to a certain range. This range becomes increasingly wide the nearer the sun approaches to the zenith. (ii) A mechanism which takes into account the dance directions (or sun positions) memorized for particular times of day, and between successive memorized positions turns the dances through an angle proportional to time. This mechanism is subject to the limits imposed by mechanism (i). This dual-control hypothesis would provide a general explanation of the orientation of honeybee dances. It could explain the orientation of dances at night and when the sky is completely covered with cloud. Evidence is presented that the acuity with which bees can perceive the position of the sun relative to the zenith is not less accurate than 2°–3°. This is a measure of the accuracy with which they can localize a visual stimulus relative to the direction of gravity. The mechanism proposed for orientating the dances would provide a possible means whereby bees might communicate the direction of a food-source by dances which do not indicate the angle between the azimuths of the food-source and the sun.