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When a Northern Saw-whet Owl spreads its wings, many birds can see something our human eyes can’t: the owl’s flight feathers glow with ultraviolet light. It’s invisible to humans without the help of a UV blacklight. While the glowing feathers on parrots might help them attract mates, the reason for the owls’ glowing feathers still isn’t clear. However, scientists realized that they could estimate an owl’s age based on the pattern of luminescent color on the wings, which changes predictably as birds grow and replace their feathers.
BirdNote®
Glowing Feathers
Written by Conor Gearin
This is BirdNote.
When a Northern Saw-whet Owl spreads its wings, many birds can see something our human eyes can’t: the owl’s flight feathers glow. It’s invisible to humans without the help of an ultraviolet blacklight, which reveals a bright magenta color.
[Northern Saw-whet Owl call]
Producing this other-worldy light is a trait called photoluminescence. While some bird feathers simply reflect UV light, photoluminescence involves special pigments or structures in the feathers that absorb UV and then release light of their own, often in a different color.
Some cases of luminous feathers have an apparent purpose. For example, parakeets called budgerigars have glowing feathers on their crowns and cheeks that may help them stand out to mates.
[Budgerigar calls]
Over 50 species of parrots, as well as some toucans, have similar gleaming ornaments. But for other birds, such as owls, we still don’t have a good idea for the reason behind the glow.
The luminous owl wings do have a specific use for biologists, though. Scientists realized that they could estimate an owl’s age based on the pattern of luminescent color on the wings, which changes predictably as birds grow and replace their feathers.
It’s a practical application of a beautiful mystery.
[Northern Saw-whet Owl call]
For BirdNote, I’m Ariana Remmel.
BirdNote is grateful to the many contributions of Dr. Gordon Orians, and for his ongoing support of the show.
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Senior Producer: Mark Bramhill
Producer: Sam Johnson
Managing Producer: Jazzi Johnson
Managing Producer: Ariana Remmel
Content Director: Jonese Franklin
Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Northern Saw-whet Owl ML125346 recorded by T. Sander, and Budgerigar ML 350861481 recorded by R. Singal.
BirdNote’s theme was composed and played by Nancy Rumbel and John Kessler.
© 2022 BirdNote July 2026 & August 2022 & September 2024
Narrator: Ariana Remmel
ID# feather-06-2022-07-12 feather-06
References:
https://www.researchgate.net/publication/232672438_Use_of_Ultraviolet_Light_as_an_Aid_in_Age_Classification_of_Owls
https://www.atlasobscura.com/articles/why-birds-glow-blacklight
Conor Gearin
Writer
Ariana Remmel
NarratorSights & Sounds
