We occasionally see a bright spot amid the grays and browns in the coldest months of the year – a few purple berries left uneaten by the birds, for instance, or the occasional sighting of a cardinal. But mostly we’re left with muddy ground, dormant trees, and wildlife wrapped in their dullest colors to match their surroundings.
And then a blue jay jets into our yard and reminds us that another color of the rainbow hasn’t
|Blue jay (Paul Dacko)|
Except that blue jays aren’t really blue.
You read that right. The first time I heard about it – in my college ornithology class – I didn’t believe it either. Blue jays aren’t blue? How can that be? I can see their blue feathers with my own two eyes! And yet every scientific reference I’ve checked in the last 35 years – and I double-check every year or so, including this week – tells me it’s still true.
In the natural world, there are red feathers and white feathers and yellow feathers and black feathers. There are green feathers and brown feathers and even a few purple feathers and orange feathers. But there are no blue feathers. They don’t exist. Anywhere.
That means that blue jays aren’t blue, and neither are bluebirds. And if you think that an indigo bunting is actually indigo, you’d be wrong about that, too.
According to every ornithologist and scientist I’ve spoken to – and there have been many – blue feathers are a figment of our imagination. Or as one birder called it, “a pigment of our imagination.” What looks to our brains to be a blue feather is, in fact, a blue-looking color generated by white light interacting with the three-dimensional architecture of the feather. It’s what scientists call a structural color, rather than a pigment.
Most birds get their colored plumage from pigments in the foods they eat. That’s why many pink flamingos at zoos aren’t very pink – because they don’t get their natural diet of algae and crustaceans that results in their pink feathers. Blue pigments, like those in blueberries, are destroyed when digested by birds.
According to a Yale University ornithologist, blue feathers are created when the cells inside the growing feather dry up, leaving behind an architecture made of keratin molecules – the same material as our fingernails – containing air pockets like a sponge. When white light strikes it, the keratin structure somehow amplifies the blue wavelengths while canceling out the red and white wavelengths, making the feather look blue. Even though it isn’t.
Take it away from a white light source or mess with that architecture, and the feather won’t look blue any more.
Now that I’ve explained the bizarre science behind blue feathers, my advice is to ignore it and appreciate the beauty of those blue feathers – regardless of how they’re formed. We need those splashes of color to help us get through the bleak winter days, and I wouldn’t want to take anything away from your enjoyment of our local blue jays.
And if you can’t find a blue jay, point your eyes skyward on a cold clear day and take in the bright blue sky. As far as I know, it’s really blue. But don’t quote me on that.
This article first appeared in the Independent on January 9, 2021.