Psittacofulvin pigments cause the bright-red, orange, and yellow colours of parrots. Colourful feathers with high levels of psittacofulvin resist feather-degrading Bacillus licheniformis better than white ones. ... Found on http://en.wikipedia.org/wiki/Psittacofulvin
1) Biological pigment 
Psittacofulvin pigments cause the bright-red, orange, and yellow colours of parrots. Colourful feathers with high levels of psittacofulvin resist feather-degrading Bacillus licheniformis better than white ones. ...