Why are peacock feathers colored?

In 1634, Sir Theodore de Mayerne, physician to Charles I, observed that the 'eyes' on the wings of the peacock butterfly "shine curiously like stars, and do cast about them sparks of the colour of the Rainbow; by these marks is it so known that it would be needless to describe the rest of the body though painted with a variety of colours."

In general, the diversity of bird feathers colors can be explained by mere two factors: pigments on one side and simple structures in the feathers which interfere with the incident light. Pigment particles are embedded into the newly grown feathers during the molting season. They absorb light of certain wavelength or disperse the reflected light and thus contribute to the color of the plumage.

Each feather consists of thousands of flat branches. When like shines on the feather, we see thousands of glimmering colored spots, each caused by minuscule bowl-shaped indentations. Stronger magnification reveals microscopic lamellae (thin platelike layers) at the bottom of the indentations (see photo below). Just like in butterfly wings, the regular pattern of the lamellas leads to interference phenomena and thus to iridescent colors. This principle is also responsible for varied colors of pheasants, birds of paradise and humming birds.
View at different angles.The color of a peacock feather is caused by its complex structure. The coloring changes with the angle of incident light - a characteristic feature of the structure-caused colors due to microlamellas.
Is it really just interference?
Yes. For example, the white color of this white peacock is due to the missing black melanine pigment. The usual rich colors of the peacock are seen because black pigment which absorbs most of the incident light, allowing us to see only the interferece colors. In this peacock, the interference is still happening, but the effect is entirely washed out by the abundance of white light. In this peacock, you can see that the "eyes" of the tail feathers are clear, not colored.


Tatum Tot said...

Very interesting. The albino peacock is gorgeous.

tropicalstorm30 said...

I need to know if they only re-place feathers yearly or do they automatically re-place when removed?

Andrei said...

Most smaller birds take around 2-3 months for their molt to be complete, larger birds can take up to a year but usually take around 6-8 months to complete their molts. It really can tend to vary from bird to bird based on their physical, mental and emotional situations.