Swarm Cohesion in Bats Emerges from Stable Temporal Loops
Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Swarming in echolocating bats presents a compelling example of decentralised coordination driven by acoustic sensing. Unlike visually guided animals, bats navigate and maintain cohesion in dense groups using self-generated sonar signals. I present a biologically grounded simulation framework in which agents operate asynchronously using a closed-loop control policy based on local echo delays. Building on the theory of biosonar responsivity and the deduction of temporal precision in bat echolocation, my model predicts a tight coupling between echo delay, call duration, and call rate, and demonstrates that local, echo-timed inter-actions suffice to generate stable, self-organised swarm behaviour. To test these predictions, I systematically varied initial velocity and responsivity coefficient ( k r ) across a simulation grid and analysed the resulting call dynamics and collision risks. An information propagation model was derived, estimating the effective spatiotemporal speed of behavioural updates across the swarm. I also developed a decay-based model of perturbation attenuation to quantify the spatial limit of influence for local disturbances. Together, these analyses reveal a trade-off between responsiveness and stability: lower k r yields faster information flow but higher collision risk in denser regions, while higher k r promotes stability but reduces reactivity. My results align closely with recent empirical findings and provide a generative explanation for swarm cohesion based on the temporal precision of echolocation. These insights offer a promising design framework for decentralised control in bioinspired robotic swarms, where stability, autonomy, and resilience emerge from local sensing and feedback, rather than explicit synchrony or global coordination.
Summary
The evening emergence of bats from caves-millions streaming into the sky in twisting, coordinated ribbons-has long fascinated observers. Despite the incredible density and speed of these flights, bats rarely collide and maintain fluid, cohesive movement. Unlike birds or fish, bats navigate using sound: they emit high-frequency calls and interpret returning echoes to sense their surroundings. But in a dense swarm filled with thousands of calling individuals, how do they avoid overwhelming acoustic interference?
I present a formal framework and agent-based simulation demonstrating that bats solve the challenge of acoustic interference through a simple yet powerful principle: each bat tracks the echo from its nearest neighbour and times its next call based on this echo delay—a fundamental feature of biosonar behaviour preserved across contexts. This echo-timed coordination forms a closed-loop feedback system, enabling continuous, real-time adjustments without requiring global synchrony or awareness. My simulations show that this local timing mechanism maintains swarm stability even under crowded conditions, with information propagating through the group like a wave—rapid enough to support timely corrections, yet naturally attenuated to prevent overreaction. These findings align closely with a growing body of empirical work and reflect a broader shift in understanding how echolocating animals mitigate acoustic interference in complex social environments.
This model not only explains how bats maintain safe spacing in flight, but also offers insights for designing autonomous robotic swarms that are decentralised, responsive, and robust.
