I pulled a few of my Western Bluebird and jay photos to illustrate the following excerpt. This month’s Smithsonian Magazine has a short piece entitled Why So Blue? by Helen Fields, which explores the natural magic behind bluebird blue:
[Ornithologist Richard Prum] discovered that as a blue feather grows, something amazing happens. Inside each cell, stringy keratin molecules separate from water, like oil from vinegar. When the cell dies, the water dries away and is replaced by air, leaving a structure of keratin protein interspersed with air pockets, like a sponge or a box of spaghetti. When white light strikes a blue feather, the keratin pattern causes red and yellow wavelengths to cancel each other out, while blue wavelengths of light reinforce and amplify one another and reflect back to the beholder’s eye. The result: blue, an example of what scientists call a structural color (as opposed to a pigmented color) because it’s generated by light interacting with a feather’s 3-D arrangement. And different shapes and sizes of these air pockets and keratin make different shades of blue.
Why So Blue? by Helen Fields
The article goes on to speculate why the color blue is so prevalent in bird plumage, and how that blue might be perceived — aesthetically or otherwise — by other birds.