FLOCK2: A MODEL FOR ORIENTATION-BASED SOCIAL FLOCKING

	2024. Hoetzlein, R. Flock2: A model for orientation-based social flocking Journal of Theoretical Biology, vol 593, 7 Oct 2024, 111880
	2024. Hoetzlein, R. arXiv Pre-print. April 27, 2024.
	Source code. https://github.com/ramakarl/flock2

Highlights

• A new computational model for bird murmurations shows emergent orientation waves.
• Bird flight is controlled by an aerodynamic model of flight actuated strictly with heading targets.
• Energy and frequency analysis leads to a deeper understanding of model-based flocking.
• Collision experiments demonstrate how high speed flocking birds may avoid interpenetrating flocks.

Abstract

The aerial flocking of birds, or murmurations, has fascinated observers while presenting many challenges to behavioral study and simulation. We examine how the periphery of murmurations remain well bounded and cohesive. We also investigate agitation waves, which occur when a flock is disturbed, developing a plausible model for how they might emerge spontaneously. To understand these behaviors a new model is presented for orientation-based social flocking. Previous methods model inter-bird dynamics by considering the neighborhood around each bird, and introducing forces for avoidance, alignment, and cohesion as three dimensional vectors that alter acceleration. Our method introduces orientation-based social flocking that treats social influences from neighbors more realistically as a desire to turn, indirectly controlling the heading in an aerodynamic model. While our model can be applied to any flocking social bird we simulate flocks of starlings, Sturnus vulgaris, and demonstrate the possibility of orientation waves in the absence of predators. Our model exhibits spherical and ovoidal flock shapes matching observation. Comparisons of our model to Reynolds’ on energy consumption and frequency analysis demonstrates more realistic motions, significantly less energy use in turning, and a plausible mechanism for emergent orientation waves.