A trick of nature: Blue jays aren't really blue

[sl8]

Last edited Tue Sep 27, 2022, 02:53 PM - Edit history (1)

https://www.reconnectwithnature.org/news-events/the-buzz/nature-curiosity-why-are-blue-jays-blue

A trick of nature: Blue jays aren't really blue

1/25/2019



(Photo courtesy of Paul Dacko)

The bright blue hue of a blue jay can be an eye-catching sight set against the dreary, drab backdrop of winter. In actuality, though, blue jays aren't really blue. Instead, the blue appearance is a trick of science, an optical illusion of sorts.

Whereas a cardinal, for example, gets its red plumage from red pigment, blue jays don't have any blue pigment. In fact, blue pigment is rare in nature. Instead, the pigment in a blue jay's feathers — melanin — is brown, but we perceive it as blue because of a phenomenon called light scattering, according to the Cornell Lab of Ornithology. https://www.allaboutbirds.org/guide/Blue_Jay/overview

Light scattering is similar to the effects of a prism. A blue jay's wings contain tiny pockets made of air and keratin, the same protein that makes up our hair and fingernails. When light hits these pockets in the blue jay's feathers, all of the colors of the wavelength except blue are absorbed. The blue wavelength is refracted, which is what allows us to see the feathers as blue in color, according to the Cornell Lab(Opens in a new window).

This optical illusion is not unique to blue jays. This same trick of the eye gives all blue-colored birds, including indigo buntings and bluebirds, their brightly colored appearance; none have any blue pigment.

[...]

[Walleye]

1. Interesting, I have noticed the little green heron actually looks purple when it's backlit

[jmbar2]

2. Interesting tidbit

I feed a family of bluejays on my porch every day. I will never see them the same again!

[Solly Mack]

3. I knew this but it has never changed my thinking on how pretty and blue they are...

[mike_c]

4. they're still blue

Jay feathers are an example of Tyndall blue, whereby blue wavelength light is scattered (reflected) by the microscopic feather structure. Blue pigments also reflect blue wavelengths, so pigments and Tyndall light scattering are simply two different mechanisms for producing blue coloration. The blue color only disappears when you interfere with light scattering, e.g. by grinding up the feathers sufficiently to disrupt the micro-structure that reflects blue wavelengths. While the feathers are whole, they are just as blue as any other object that reflects blue light. This happens in other animals too, especially insects.

[sl8]

5. Yes, they should have just said that they have no blue pigment. nt

[LudwigPastorius]

6. They are still the Crips of the Air.

They like to gang up on other birds...including mobbing a perfectly innocent owl or two.

[True Dough]

7. Okay, Brown Jays,

Let's play ball!

[Earth-shine]

8. Have you heard the news ... I got the blues ...

thought it was pigment ... but it was only a figment.

[zanana1]

9. Another illusion shattered.