Fox Sparrow perched on a bare branch, facing slightly left. Rich rufous-brown upperparts with bold white breast heavily marked with dark chestnut chevron-shaped streaks and spots. Olive-brown crown, pale lower mandible with yellow base, russet tail. Soft gray-green bokeh background with bare twigs. Durham, NC. February 2026.
A Fox Sparrow's breast chevrons are (likely) a reaction-diffusion pattern; melanin pulses during feather growth, unfurling into V-shapes as the barb ridges spiral out of the follicle. Same math Turing described in 1952.
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