Investigating the role of individual ant behaviours on the collective movement of bidirectional ant trails*

Avoiding traffic jams in crowded environments is a significant challenge for collective motion across scales, from migrating herds to cellular cargo transport. Experimental work has shown that Argentine ants have the ability to avoid typical traffic jamming patterns at high densities and instead maintain a constant bidirectional flow between their nest and a food source (Poissonnier et al, eLife 8:e48945, 2019). No large-scale spatiotemporal organisation such as lane formation or oscillatory flow is seen, suggesting that there is another dynamic mechanism allowing the ants to navigate in crowds without jamming.

We use detailed experimental analyses of extant data combined with agent based modelling to explore individual ant trajectories and properties that make up the collective colony movement. By quantifying spatiotemporal patterns of density, interaction rates and  ant speeds, we probe the role of the type of interactions and their rates on the group as a whole as it engages in crowded traffic. This leads us to propose feedback models by which individual ants respond to their local environment over time that capture the observed efficient movement in bidirectional crowds.