Experimental ethology of learning in desert ants: Becoming expert navigators

Foraging desert ants are repeatedly presented with the challenge of leaving the nest, searching the scorching desert landscape to find food, and then transporting it back home. To accomplish this task, foragers have a navigational toolbox, which relies on olfactory, idiothetic, visual and magnetic cues. Desert ants have been widely studied with regards to these abilities, including a heavy focus on learned visual cues, the most prominent being the terrestrial panorama. Nest cues are first acquired during pre-foraging learning walks. Once foragers leave the nest area, they also learn a number of cues to aid them when returning both back to the nest and to known food sites, using experience of previous trips to navigate on future trips. In this review, we describe the learning processes involved in accurate navigation in desert ants. We first focus on recent research on nest-site panorama learning during pre-foraging learning walks as well as panorama learning away from the nest during foraging. We also review learning cues beyond the terrestrial panorama, including tactile, magnetic, olfactory and vibrational cues. These studies provide a basis for future work to further explore how these navigators, despite their small brains, acquire, retain and use many cue sets present in their environments. We call for more experimental ethology focussed on learning processes, both by exploring run-by-run and step-by-step acquisition of information for navigation, as well as for other natural tasks in an animal's life.