What Causes the Angle-Insensitive Colors in Bird Feathers and Butterfly Wings?

[Alfred Cann]

I have long been puzzled by the colors of bird feathers and butterflies. They are mostly attributed to interference in microscopic structures, not dyes, yet do not display the typical change of color with viewing angle of interference colors. Why? There are a few exceptions; some butterfly spots and humming birds are iridescent; I am not concerned about those.

 

[Dale]

Summary:: Colors of bird feathers and butterfly wings

They are mostly attributed to interference in microscopic structures, not dyes, yet do not display the typical change of color with viewing angle of interference colors. Why?

I think this is far too simplistic. Chickens and ducks have both pigments and iridescence in their feathers. It isn’t an either-or phenomenon; both are present in the same animal and even on the same feather.

 

[DaveC426913]

[The colours] do not display the typical change of color with viewing angle of interference colors. Why?

This appears to be the core of the question.
Can you expound on what you're asking here?

 

[DaveE]

There are different ways of generating interference. Diffraction gratings are quite angle sensitive, thin films (fabry-perot) less so.

 

[A.T.]

yet do not display the typical change of color with viewing angle of interference colors. Why?

See this video at 4:39:

 

[Alfred Cann]

1. Most bird and butterfly colors appear quite angle-insensitive, not even Fabry-Perot. Is the literature wrong that I have read, that attributes these colors to interference?

 

[A.T.]

1. Most bird and butterfly colors appear quite angle-insensitive, not even Fabry-Perot. Is the literature wrong that I have read, that attributes these colors to interference?

Colors through interference don't have to be angle-insensitive. See post #5.