Multimodal Influences on Learning Walks in Desert Ants (Cataglyphis fortis)

Ants are excellent navigators taking into account multimodal sensory information as they move through the world. To be able to accurately localise the nest at the end of a foraging journey, visual cues, wind direction and also olfactory cues need to be learnt. Learning walks are performed at the start of an ants foraging career or when the appearance of the nest surrounding has changed. We investigated here whether the structure of such learning walks in the desert ant Cataglyphis fortis takes into account wind direction in conjunction with the learning of new visual information. Ants learnt to travel back and forth between their nest and a feeder, and we then introduced a black cylinder near their nest to induce learning walks in regular foragers. By doing this across days with different prevailing wind directions, we were able to probe how ants balance the influence of different sensory modalities. We found that (i) the ants outwards headings are influenced by the direction of the wind with their routes deflected in such a way that they will arrive downwind of their nest when homing, (ii) a novel object along the route induces learning walks in experienced ants and (iii) the structure of learning walks is shaped by the wind direction rather than the position of the visual cue.