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arXiv · 2605.14127

Localized inhomogeneity and position-dependent stability of migratory bird formations

Hui Jiang·Nariya Uchida
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Abstract

We investigate how localized inhomogeneity affects the geometry and stability of migratory bird formations. We use a lifting-line model with a horseshoe-vortex representation to describe the longitudinal dynamics of aerodynamic interactions. As a reference case, we first analyze homogeneous formations and show that their steady states exhibit a U-shaped geometry with hierarchical streamwise spacing, in which adjacent birds become progressively closer toward the leader. We then introduce localized inhomogeneity by modifying the wingspan of a single bird, with its physical properties determined by scaling relations. We determine the range of wingspan variation that preserves a stable formation. The stability range depends strongly on the position of the modified bird, being narrower near the outer wing and broader near the leader. These findings provide a minimal dynamical framework for understanding how local aerodynamic interactions and localized individual differences affect collective flight structures.

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Hui Jiang, Nariya Uchida. 2026-06-06. Localized inhomogeneity and position-dependent stability of migratory bird formations. https://arxiv.org/abs/2605.14127

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