Fig. 9. Radial means of the two-dimensional Fourier power spectra of transmission electron micrographs of avian dermal collagen arrays: (A) Oxyura jamaicensis, light blue; (B) Tragopan temminckii, dark blue; (C) Tragopan temminckii, light blue; (D) Tragopan caboti, orange; (E) Coua reynaudii, dark blue; (F) Ramphastos toco, dark blue; (G) G. leucapsis, light blue; (H) Dyaphorophyia concreta, green and (I) Terpsiphone mutata, dark blue. The shaded zones show the range of spatial frequencies that are likely to produce coherent scattering of visible light wavelengths. G. leucapsis has a larger peak spatial frequency that falls outside the range of values likely to produce a visible colour by coherent scattering.