Landmark orientation in natural situations in the red wood antFormica lugubrisZett. (Hymenoptera Formicidae)

Abstract

Terrestrial landmark orientation was studied in Formica lugubris by investigating the effects of two natural phenomena on homing. First, the influence of a thick layer of snow on site recognition was studied in early spring, and second, the orientation of workers passively displaced by a stream at various distances from their nest was examined. The results show that ants associate the location of their nest with the position of the trees which have the highest apparent size above the horizon. Since for most parts of the foraging area this always involves the trees standing close to the nest, ants only need to follow this simple rule to readily go back to their nest. The significance of this orientation behavior for individual ants as well as for the organization of the foraging of the colony is discussed.