Tuning regimes in ant foraging dynamics depend on the existence of bistability

Characterizing how behaviour must be tuned to produce useful coordination is key to understanding the evolution and regulation of collective behaviour. While computational models can answer this for specific cases, recurring patterns in model dynamics suggest a more general means of classifying collective dynamics. Using ant foraging models as an example, we investigate mechanisms that produce symmetry-breaking transitions to bistability as a first basic classification. Collective transitions are functionally important: they lead to sudden changes in collective states, enhanced sensitivity to environmental inputs and hysteresis. We use bifurcation theory to argue that the point where discontinuous transitions merge at a continuous transition forms a codimension-2 bifurcation with universal properties, functionally equivalent to the critical point of a phase diagram. We show how analogous bistable transitions appear across ant foraging models with different mechanistic assumptions and explore biologically relevant effects near the transition. This framework clarifies the difficulty of tuning collective behaviour: locating a continuous transition typically requires tuning two parameters, while a discontinuous transition requires only one. Finally, we explore conditions that degrade or destroy bistability: heterogeneity blurs transitions, while recruitment without positive feedback produces no bistability.