Mechanisms of three-dimensional (3D) path integration in the desert ant Cataglyphis fortis - odometry and slope detection

Desert ants, Cataglyphis, navigate in their vast desert habitat by path integration. They continuously integrate directions steered as determined by their celestial compass and distances travelled gauged by as yet unknown mechanisms. Here we test the hypothesis that navigating ants measure distances travelled by using some kind of step integrator, or “step counter”. We manipulated the lengths of the legs, and hence the stride lengths, in freely walking ants. Animals with elongated (“stilts”) or shortened legs (“stumps”) take larger or shorter strides, respectively, and concomitantly misgauge travel distance. Travel distance is overestimated by experimental animals walking on stilts, and underestimated by animals walking on stumps.