Egocentric and geocentric navigation during extremely long foraging paths of desert ants

Desert ants, Cataglyphis fortis, navigate individually in the salt pans of Tunisia by means of path integration. However, as path integration is error-prone, the ants in addition use visual and olfactory cues to pinpoint their nest entrance. It has been shown that the accuracy of the path integrator as well as the ants' confidence in that egocentric navigational tool decreases with increasing foraging distance. Here, we show that despite the accumulating errors, even after far-reaching foraging runs path integration provides the ants with surprisingly accurate information regarding the nest position. However, in addition, the ants take into account distant visual cues that are most probably provided by the patterns along the horizon line behind the nest entrance.