Fig. 7. Reflectance spectra of the kingfisher crown. Data are for a vertically aligned feather, but the horizontal alignment spectra are the same. This feather had diffuse coloration, with a spectrally non-selective specular reflectance. Variation in reflectance across the spectrum was greatest with the surface perpendicular to the line of sight. (A) Spectra for illumination near co-axial with the line of sight, E=5°: (i) O=0°; (ii) O=8°; (iii) O=45°. (B) Spectra for oblique orientation, O=45°: (i) E=5°; (ii) E=90°. Spectrum i is the same as spectrum i in A. (C) The spectral location of the reflectance peak (_max) versus E. Values of O are given in degrees. (D) Reflectance under diffuse illumination. (i) O=0°; (ii) O=60°. At O=30°, the spectrum was intermediate between the two illustrated. O, surface orientation; E, illumination elevation.

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