Obstacle and predator avoidance by a flock

TL;DR

This paper presents a continuum model of flocking behavior to analyze how animal groups respond to obstacles and predators, revealing density disturbances similar to Mach cones influenced by wave propagation.

Contribution

It introduces a novel continuum model for flock dynamics and analytically predicts flock responses to threats, validated through numerical simulations.

Findings

Flock responses form Mach cone-like density disturbances.

Predicted Mach wedge angles and disturbance features match simulations.

Model parameters have minimal impact on disturbance configurations.

Abstract

The modeling and investigation of the dynamics and configurations of animal groups is a subject of growing attention. In this paper, we present a continuum model of flocking and use it to investigate the reaction of a flock to an obstacle or an attacking predator. We show that the flock response is in the form of density disturbances that resemble Mach cones whose configuration is determined by the anisotropic propagation of waves through the flock. We analytically and numerically test relations that predict the Mach wedge angles, disturbance heights, and wake widths. We find that these expressions are insensitive to many of the parameters of the model.