Homeward navigation in Pogonomyrmex occidentalis harvester ants

The purpose of this study was to determine the relative importance of known sources of navigational information for invertebrates in Pogonomyrmex occidentalis ants. The relative importance of polarized light patterns, landmarks, and panoramic cues on the ability of Pogonomyrmex ants to orient homeward during foraging were analyzed.  When a worker ant was displaced from its original location to a new spot around the nest, it initially walked in the direction its nest would have been, had the ant not been moved. During trials in which the ants were not displaced, ants were able to walk in the direction of the nest after being baited, picked up, and returned to their original location. Neither a polarizing filter nor changing landmarks affected orientation. However, when a wall was placed behind the nest while an ant was navigating homeward, it became disoriented, walked in random directions, and took more time to find its nest. This result suggests that the Pogonomyrmex rely on visual guidance based on panoramic cues above other navigation methods.

Keywords: Foraging, orientation, landmarks, polarized light, panoramic cues