A couple of weeks back I was scrolling about the internet when this stunner slid across my screen.
And I thought, holy heck, you are the bluest bird that ever did live. And then I got thinking, well, what is the reddest bird that ever did live and the yellowest etc. So, for the next couple of weeks I’m going to bring you the most extremely coloured birds I could find, and we are starting with the Grandala (Grandala Coelicolor).
These jaw-droppingly blue birds are members of the Thrush family, ironically the same family Black Birds belong to. They live in the Himalayas, of all places. They roam about everywhere from high mountain passes, right down to the valleys where they form into flocks of thousands to feed on berries. Only the males have the eclectic-blue feathers, while the females are a bit on the dull side.
Now, as I have previously mentioned when we looked at the Blue Jay, there is almost no example of a blue pigment that exists in nature. Whhhhaaaaattttt? It’s true, blue is the rarest pigment in the natural world. So how do our plucky little friends, the Gandalas, pull off their blues?
Well, there are two ways to make colour. You can use a pigment: here a chemical absorbs every wavelength of light except for one specific colour which gets reflected and becomes the colour you see. Or, you can use structural colouration. This works on the nano-level and has to do with how the feather is physically structured. It basically interferes with light, reflecting and refracting the wavelengths. The other colours undergo destructive interference until you’re left with just one. In this case, blue. It’s similar (but different) to how the sky looks blue because the atmosphere scatters blue light more than the other wavelengths. If you’re interested, here’s a video that does a better job of explaining than me.
But this does explain why these Grandalas look so extremely and unnaturally blue: it’s a trick of physics, which makes the colour purer. But the same is true for every blue feather you have ever seen. Each bird has a slightly different way of pulling off the same illusion, but for my money Grandalas are the best at it.