Panorama similarity and navigational knowledge in the nocturnal bull ant Myrmecia midas

Nocturnal ants forage and navigate during periods of reduced light, making detection of visual cues difficult, yet they are skilled visual navigators. These foragers retain visual panoramic memories both around the nest and along known routes for later use, to return to previously visited food sites or to the nest. Here, we explore the navigational knowledge of the nocturnal bull ant Myrmecia midas by investigating differences in nestward homing after displacement of three forager groups based on similarities in the panoramas between the release site and previously visited locations. Foragers that travel straight to the foraging tree or to trees close to the nest show reduced navigational success in orienting and returning from displacements compared with individuals that forage further from the nest site. By analysing the cues present in the panorama, we show that multiple metrics of forager navigational performance correspond with the degree of similarity between the release site panorama and panoramas of previously visited sites. In highly cluttered environments, where panoramas change rapidly over short distances, the views acquired near the nest are useful only over a small area and memories acquired along foraging routes become critical.