The other day I found a tall cliff near The Dalles, and stopped to look over a vertical field of tan dessicated grass, munching cows, and tiny drought-resistant pink flowers stretching down to the Big River.
As I was standing there, sweltering in the sun and leaning forward to peek over the precipice, a magpie flew to a utility pole below me and perched, shimmering with sunlight.
Until then I thought magpies, members of the allegedly very intelligent and corvid family which includes crows and ravens, were plain crisp black-and-white, like a caricature of good and evil. But this magpie’s back and tail glowed a vibrant, living green, like fantasy emeralds.
Because I’d never gotten between a magpie and the sun before, I hadn’t seen the effect of minute nanostructures in their feathers that reflect certain colors of sunlight, creating colorful shimmers of yellow-green, violet and navy blue. Look at a magpie from below, or with the sun behind it, and the colors disappear like a magic trick.
The colors are created by vertically layered melanin tubes on the surface of feather barbules. Barbules are the tiny hooks that grow on one side of the barbs, slender filaments that make up feathers’ broad surfaces. The barbules hold the barbs together, sort of like velcro.
Because these tiny structures in a magpie’s barbules are irregular, the iridescence is weak, so you must look from just the right angle to see it.
Six scientists in 2017 succeeded in making artificial structures shaped like those in a magpie feather, by wrapping a flexible thin film with line corrugations around an optical fiber. Air columns between the layers of film simulated melanin tubes in magpie feathers. The artificial magpie-bits showed magpie-like greenish hues. By altering the optical thickness of a single cortex layer (whatever that means), the scientists found they could create any color in the visible spectrum.
The spectrum visible to humans, that is. Perhaps magpies, able other birds to see in ultraviolet, might see their colors differently. Did my second magpie of the day, swooping to a higher wire, see compatriot below as green and gleaming? Or did they see colors my brain can’t even visualize? I don’t know if there’s any research on this. If so, I can’t find it.
Anyway, studies like this could help scientists invent their own iridescent stuff, in mimicry of magpies.
Why that’s important, I have no idea. Perhaps there’s a brilliant use, as it were, for human-made feather iridescence. Building artificial editions of those beautiful iridescent deep-green beetles I find in my garden, maybe? So that if the real ones eat too many lawn chemicals, and go extinct, we can still enjoy them?
Still, no generally-available product can yet match in splendor the unforgettable glimmer of a living bird.
And I rather hoped nothing ever would. In this world positively screaming with artificial dye, paint and colored light, I enjoy knowing that in the backwoods of my county lives this unique color we can’t steal and civilize quite yet: Magpie.
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