How perceived threat increases synchronization in collectively moving animal groups

Area of Science:

• Collective animal behavior
• Mathematical modeling of biological systems
• Fish behavior and ecology

Background:

• Collective motion in nature often involves identical individuals.
• Previous models simplified group dynamics by overlooking individual variations.
• Understanding how diverse individual characteristics influence group movement is crucial.

Purpose of the Study:

• To develop a model that incorporates individual-level characteristics into collective motion.
• To investigate the relationship between perceived threat and group synchronization.
• To empirically validate model predictions using fish behavior.

Main Methods:

• Developed a model using stochastic asynchronous updating of individual positions and orientations.
• Simulated group movement under varying updating frequencies, linked to threat levels.
• Conducted experiments with three-spined sticklebacks exposed to different threat levels.

Main Results:

• Model predicts higher updating frequency (perceived threat) leads to more synchronized group movement.
• Speed and nearest-neighbor distributions become more uniform with increased updating frequency.
• Experimental data from sticklebacks strongly support model predictions.

Conclusions:

• A single parameter, updating frequency, can explain fish collective behavior under different agitation states.
• The model provides a mechanism for environment-induced collective behavioral changes.
• Findings are explained by confusion and oddity effects influencing individual responses within the group.