The Secret of Blue Jays: The Complexity of Color

We all know how color works. Different pigments reflect different frequencies of light, meaning the color our eyes see is essentially the "reject" light. However, blue pigment is rare in nature, and difficult to craft even in this modern age. So how does the blue jay do it? New research has revealed that the bird doesn't rely on pigmentation alone, exposing a unique way to express color.

That's at least according to a study recently published in the journal Physical Review E, which details how blue jay feathers boast a unique structure that allows them to reflect blue light, while the stark red of cardinals relies on pigmentation alone.

Past research had revealed that blue jay feathers express their stunning blue in the same way that the sky pulls it off - air molecules can scatter light in a unique way that creates blue. In the case of the feathers,  they boast tiny air pockets that help facilitate this scattering.

The new research builds upon this discovery, revealing that the plumage of some birds will rely on a marriage between this intriguing feather mechanic and simple pigmentation to reflect complex colors.

"We thought, maybe the birds know something we don't," researcher Vinothan Manoharan, at Harvard University,  explained to New Scientist.

He and his colleagues wanted to investigate if every color can be crafted in this unique way, potentially offering a new way to make colored e-reader displays that don't glare in the sun.

The team studied nanometer-scale plastic beads - inverse versions of the feather air pocket structures. Their ultimate goal was to make red using this mechanic alone, as red is a primary base to many other colors. However, again and again they kept making different hues of purple instead.

This is likely because light scatters multiple times within these structures, enhancing other colors to the point that red is washed out.

This, the researchers write, could explain why the cardinal does not boast the feather mechanic, and likewise why most beetles (who often use a reflective mechanic similar to the beads) do not appear red.

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