1/13/17 @coldsunnyday The ducks aren’t actually green. They’re untrustworthy creatures, and they’re lying about what color they are. Don’t listen to them.
It’s an optical illusion called “structural color.” Their feathers are black. The fluffy side bits of the feathers (barbs) are also black. The little hooks that keep the barbs all lined up (barbules) are also black. There are microscopic little ridges (tubules) on the barbules that are also black. But the tubules are exactly the same size as a wavelength of green light, so instead of absorbing green light the way a black object should, they reflect it and the ducks look green.
If you put one of the ducks under a good enough microscope, you’d see that no individual part of it was actually green in any way.
Avian biology generally can’t produce blue or green pigments. Birds that look blue or green are lying about it. Don’t trust them.
Except for turacos. They’re actually green, and very pleased with themselves about it. Look at this guy, here’s a bird you can trust: