Ordering dynamics in collectively swimming Surf Scoters

Area of Science:

• Collective animal behavior
• Biophysics of animal groups
• Animal locomotion

Background:

• Collective motion in animal groups often exhibits high individual alignment, leading to polarized movement.
• Understanding reorganization dynamics after order loss reveals underlying individual interaction rules and their collective effects.

Purpose of the Study:

• To analyze Surf Scoter swimming trajectories during order-disorder transitions to understand collective motion dynamics.
• To identify interaction rules that optimize polarization efficiency while maintaining group cohesion and preventing collisions.

Main Methods:

• Analysis of Surf Scoter (Melanitta perspicillata) trajectories during transitions between ordered and disordered states.
• Utilizing a validated zone-based model framework to simulate and optimize individual interaction rules.

Main Results:

• Individual speed is positively correlated with group polarization; slower speeds correlate with lower alignment.
• Optimized polarization efficiency, under cohesion and collision-avoidance constraints, requires alignment-dominated propulsion and strong repulsion relative to attraction.
• The interaction parameter strengths derived from optimizing polarization match those previously found by best-fitting polarized Surf Scoter movement data.

Conclusions:

• The interaction rules governing Surf Scoter flocks are robust across varying group structures and responsive to perturbations.
• Efficient repolarization and flexibility in response to disorder suggest adaptive advantages for these specific interaction rules in collective animal behavior.