Desert ants (Melophorus bagoti) learn from experience to improve waste dumping

Abstract

The Central Australian red honey-pot ant Melophorus bagoti maintains non-cryptic ground-nesting colonies in the semi-desert habitat. An intriguing aspect of their behaviour is the management of waste, unwanted food, dead nestmates, and some other wastes, typically deposited at distances > 5 m from the nest entrance. In a largely observational study, we found a difference in the waste disposal tactics between naive and experienced ants. Naive individuals, lacking prior exposure to the outdoor environment around the nest, exhibit a less efficient dumping process, characterized by much scanning and meandering during waste disposal. In contrast, experienced ants dump waste with straighter paths and a notable absence of scanning behaviour. Furthermore, experienced dumpers deposit waste at a greater distance from the nest compared to their naive counterparts. These differences suggest that in red honey ants, learning supports waste disposal, with dumping being refined through experience. At the focal nest, curiously, no naive dumper took any learning walks before their first dumping trip, seeming to ‘learn on the job’ of their first trip away from the nest.

Nest excavators’ learning walks in the Australian desert ant Melophorus bagoti

“…In M. bagoti, it remains uncertain whether those desert ants engaged in daily nest excavation activities require learning walks for this task and to what extent they generalize views during this process. We did not expect excavating ants to do any learning walks because our companion study conducted earlier on dumpers (Deeti et al 2024 preprint), which travel greater distances than excavators, showed that dumpers at one nest did not do any learning walks, and because the distance travelled by excavators is small, not more than 15 cm. To foreshadow, however-a point that will be obvious in the next paragraph and the methods-we were wrong.…”