Effects of different coping strategies in foragers dealing with predators and non-predators: a spatial agent-based modelling account

• ABM examines how group-living foragers respond to predator threats and false alarms. • We tested two subconscious behavioural mechanisms–experience gain and fear updating, • using clear assumptions and the detection-recognition-action chain. • Simple sensory and emotional adaptations can enhance group survival, • without requiring higher cognition or explicit communication among individuals. Group living benefits foraging individuals by improving their survival through passive risk dilution by sheer numbers and increasingly active processes, ranging from cue transmission to alarm calling. Focusing on the lower end of this range: an involuntary visual cue can be given by a fleeing action, leading to cue transmission within a group. Our model is a bottom-up model of foragers as agents embodied in a simple environment, with only assumptions about basic living competences, valid for a wide range of species, leading to conclusions about benefits of group living without calling on higher cognition. We use an agent-based, spatially explicit C ++-model to investigate the effect of predator disturbances, to which always fleeing is the appropriate reaction. To make the environment more realistic and to include not only predators, we added harmless passers-by that cause false, unnecessary, fleeing. We set out to investigate whether adaptive behaviour could improve outcomes: We investigated whether two common subconscious behaviours can mitigate the detrimental effects of false fleeing. The first is “experience gain”, a sensory change; the second is “fear updating,” an emotional change. To implement these behaviours we needed to: 1) model the anti-predator behaviour chain of “detection, recognition, and response” for which we added a recognition phase, 2) handle the combined probabilities of the detection and recognition sigmoids, and 3) define the initial settings for the three fear levels we added: one each for predator and passer-by and one for the environment, needed for the response in case of detection without recognition. These modelling decisions are shown to be very important. Situations with new predators or newly released groups can be mapped to these initial settings, distinguishing whether the forager group encounters a familiar predator type or a novel one, for instance, giving insight into what is most important for forager groups.