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

Abstract

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.