Visible and UV Coloration in Birds: Mie Scattering as the Basis of Color in Many Bird Feathers

摘要

Many diurnal birds see UV light, and the plumage colors of birds include UV patterns. UV-reflecting black feathers contain a sponge-like structure similar to that found in many violet, blue, and green feathers. The origin of colors depending on this structure is not yet fully understood. The colors were often ascribed to Rayleigh scattering, but their reflection characteristics are not in agreement with the known rules of Rayleigh scattering. In this work, Mie theory was used to calculate theoretical scattering spectra for spongy structures of feathers as investigated by electron microscopy. Additionally, optical reflection and transmission properties of spongy structures were measured microspectrometrically at thin sections of spongy structures. The results of the measurements are in agreement with Mie theory.