EFFECTS OF HORIZON LANDMARKS ON HOMING SUCCESS IN HONEY-BEES

A hypothesis is proposed and field data presented indicating that in long-distance navigation, honey bee foragers use horizon landmarks to determine the direction of their home site. Metal tags were recaptured from marked foragers released at various distances and directions from their nests located in mountainous or flat terrain. The proportion of tagged foragers returning to their nests decreased as distances of the release points from the natal colony increased. However, the fraction of returns versus distance differed according to site horizon features. Twice as many foragers returned to their home nests located in mountainous terrain as compared to returns in flat terrain. Maximum distances from which honey bee foragers found their nests were about 5 km in flat terrain with no skyline features and about 9 km in a mountainous region. The data support the hypothesis that orientation cues relied on by foragers for distance navigation include deformations in the landscape horizon when available. A searching flight pattern is used when no such key physiographic features are conspicuous in the region.