Bird 42 – Blue Jay

Today’s Bird of the Week is brought to you by the colour blue. Blue: the rarest colour in nature.

This may seem a bit counter intuitive as we have the sky, which takes up a good 50% of our visual field. But of course, the sky is blue because of the way light scatters in the atmosphere, not because there is something inherently ‘blue’ up there. And the same is true for nearly everything in nature: organically produced blue pigment just doesn’t exist. As a test, try to spot something blue just out and about and you won’t come up with much. Unless of course it’s a bird:

Introducing the Blue Jay (Cyancoitta cristata), cute little passerine bird from the US.

And it’s pretty blue, on a scale of 1 to Blue, it’s a good 8.5. On top of which, they’re also especially handsome.

They’re quite boisterous and bold birds. People can tame them fairly easily as well.

But what about them blue fathers? Well, unlike feathers that are red, yellow, brown, black or white, there is no pigment that makes them blue. Rather inside the feather itself there is a crystalline structure containing kertine and air bubbles that trap and cancel out the wavelengths of other light, while scattering blue, which gives the feathers a blue appearances.

If you look at the feathers with the light coming from the wrong angle they appear brown revealing that there is no pigment in them. How about that!

But the same is true for every blue that appears in animals, from the blue eyes in people, to all blue feathered birds, insects, frogs, you name it. They all use a trick of physics to make a blue instead of a pigment. But there is one exception – The Olivewing Butterfly.

This is one of the only known terrestrial animal that cracked the code and produces blue with a pigment. They live in Mexico. But this is Bird of the Week, not Butterfly of the Week, so don’t worry too much about that flutterby. The important take home message is Blue Jays, and their light-bending feathers. Physics!

10/09/2018