The threat-evading actions of animal swarms without active defense abilities

Abstract

For hunting foods, migrating and breeding, some small animals tend towards flocking. Once encountering predators, these swarms usually present some special threat-evading behaviors and show incredible regularity in movement by coordinating with each other. In this paper, the actions of a small fish swarm evades a blacktip reef shark are taken as an example, we put forward the concept of predator threat-field and present a mathematical model to describe the threat-field intensity, demonstrate the decision-making process of preys escaping the predator’s threat by revising R-A model. The validity of the model is shown by simulations.