In this investigation, the natural 2D photonic crystals (PhCs) within peacock feathers are applied to incorporate US nanocrystallites. Peacock feathers are activated by ethylenediaminetetraacetic/dimethylformamide suspension to increase the reactive sites on the keratin component, on which US nanoparticles (nano-CdS) are in situ formed in succession and serve as the "seeds" to direct further incorporation during the following solvothermal procedure. Thus, homogeneous nano-CdS are loaded both on the feathers' surface layer and inside the 2D PhCs. The obtained nano-CdS/peacock feathers hybrids are novel photonic crystals whose photonic stop bands are markedly different from that of the natural PhCs within original peacock feathers, as observed by the reflection spectra.