Angle-dependent iridescent plumage

A mallard drake turns its iridescent green head toward a glancing light from high right, the head feathers shifting from emerald to deep violet across the curve while its matte brown chest stays unchanged. No letters, words, signs or logos anywhere in the image. A real photograph in natural-history bird photography, with reference-supported iridescent feather regions changing hue and brightness across their different orientations while adjacent matte regions keep their source colour. A fine-detail full-frame sensor look, natural telephoto 200mm perspective, shallow depth of field and crisp feather microtexture reveal localized structural colour. One small directional light from high right glances across the feather groups, making aligned surfaces glow and off-axis surfaces shade into their documented darker hues. Restrained natural colour keeps the angle-dependent sheen localized.