Emergence of coordination in collective food transport by the ant Aphaenogaster cockerelli

Cooperative transport by ants is a leading example of self-organized behavior, meaning that it emerges from behavioral changes due to local cues, without a leader or global knowledge of the process. Compared to analogous phenomena like food source selection and exploitation, the mechanisms behind cooperative transport are still poorly understood. While most ant species are relatively unskilled at this behavior, a few have evolved impressive skills that are important to their ecological success. We designed a set of standardized field experiments to investigate cooperative transport in one of these species, the desert ant Aphaenogaster cockerelli. Workers were induced to recruit to a standardized food item and then transport it over a flat surface. We measured the speed of the transported object, the number of ants and their orientation. We also measured the deviation of the carried object from the most direct route to the nest, as well as the stabilization effect induced by an increased number of ants taking part in transport. These experiments will allow us to describe the mechanisms behind the onset of cooperation and the coordination of workers to reach a common goal: retrieving an object too large for a single ant. Besides its obvious biological interest, we expect insights on the leaderless coordination of ants to interest robotics engineers seeking to imitate this robust, decentralized behavior.