Birds-of-paradise are among the most resplendent creatures on Earth, with long, elaborate feathers in eye-popping shades of yellow, blue, and red. Naturalists have admired them for centuries. Yet it turns out they didn’t know the half of it.
As if those vibrant colors weren’t enough, a recent study found that the birds — native to Australia, Indonesia, and New Guinea — are also biofluorescent. Their skin and plumage absorb light at high-energy wavelengths, then re-emit it at low-energy wavelengths visible to other birds as a bright yellow-green. Basically, they harness the sun’s rays to make their already impressive displays even more dazzling.
Biofluorescence by itself isn’t big news; it shows up in plenty of animals, including humans (our teeth fluoresce under UV light). But almost always it either has no discernible function, or it’s used for camouflage.
This, says lead author Rene Martin, a biologist at the University of Nebraska-Lincoln, “is one of the few cases where we’re seeing biofluorescence is very likely being used as a signal. That’s where it tends to be rare.”
