Review Article

Path integration as the basic navigation mechanism of the desert ant Cataglyphis fortis (Forel, 1902) (Hymenoptera: Formicidae)

Ronacher, B.

Abstract: This review describes recent progress in the analysis of the fascinating navigation abilities of desert ants. On their foraging excursions, ants of the genus Cataglyphis cover distances up to hundred thousand body lengths. Having found aprey item they return to their inconspicuous nests with high precision, using path integration as their major navigationaid. This account focuses on the question of how these ants measure their travelling distances, information that is an essential constituent of path integration. Recently it has been shown that Cataglyphis uses a stride integrator to measurewalking distances. Remarkably, the ants' path integration module works precisely even when the animals forage in undulating terrain, e.g., when climbing over walls or hills. This indicates that the ants are able to measure the inclination ofascents or descents, and do integrate this information into their distance estimates. Navigation by means of path integration is error prone due to its susceptibility to accumulate errors. Cataglyphis and other desert ant species use landmarks– if present – as additional navigational aid. Many studies were devoted to the interactions between the path integrationsystem and landmarks. There are no indications that by combining vector and landmark information ants would acquirea representation of their environs in the sense of a "cognitive map". A lesson that we may learn from the small-brainnavigator Cataglyphis is how complex, "high-level" behaviour is achieved by the interaction of rather simple, "lowlevel" subroutines.