Elucidating and Biomimicking the Coloration Mechanisms Responsible for the Vibrant Blue Hues of the Common Kingfisher

Abstract Structural plumage coloration has been well‐studied, yet the mechanisms responsible for non‐iridescent structural colors still need to be fully understood. In this study, quasi‐ordered keratin nanochannels within the back feathers of the common kingfisher are analyzed to determine the origin of their non‐iridescent blue hues. It is found that the reflectance intensity varies depending on the overall width of the keratin nanochannels, with different volume fractions of keratin leading to a peak shift and broadening. Based on these mechanisms, inverse photonic glass (IPG) structures are designed to mimic the kingfisher's colors. Using IPG samples with different Al ₂ O ₃ shell thicknesses, a broad band of non‐iridescent blue colors, including those hues observed in the natural feathers, is achieved. These findings not only elucidate the natural coloration mechanisms of kingfisher feathers but also present a method for mimicking their blue hues.