Puffin beaks are fluorescent and we had no idea

A scientist in England has made an enlightening discovery about Atlantic puffins — under a UV light, their bills glow like a freshly cracked glow stick.

"It was sort of discovered by accident," said Jamie Dunning, the ornithologist who first saw the beaks light up.

Dunning normally works with twites, another type of bird, but he had been wondering if puffins had Day-Glo beaks for a while, since crested auklets — seabirds in the same family — also have light-up bills.

So one January day, while having a "troubling" time in the lab, he threw off the lights and shone a UV light on a puffin carcass.

"What happened was quite impressive, really," he said.

The two yellow ridges on the puffin's bill — called the lamella and the cere — lit up like a firefly.

And it's real fluorescence, Dunning emphasizes: something about those parts of the puffin bill is allowing that UV light to be absorbed and re-emitted as a bright glowing light.

It's just not clear yet what that something is, he said.

Colours in the 4th dimension

Unlike humans, birds have always known about the extra colours in the puffin bill. That's because they can see a whole other dimension of hues, said Dunning.

Humans see colours that are a mix of red, blue and green light, he notes, while birds have a fourth colour in the mix — a property called tetrachromatic vision.

"They can see colours that we can't comprehend," Dunning said.

Birds probably don't see those ridges all lit up like we do, said Dunning.

"It's hard to say what it would look like [to them], we can't comprehend that colour space.

"But almost certainly it's attractive to the birds. They must be able to see it — that's the only reason it would exist."

Definitely not headlights

The fact some birds have this quality and some birds don't indicates the fluorescence certainly has some use for the puffins, Dunning said, but he's not sure what that use might be.

"The bill of a puffin is forged by generations, hundreds and thousands of years, of sexual selection. There's a lot going on there. That's why it's so colourful and pretty."

But the radiant colour is almost certainly not being used as a headlight, he said.

He said whatever's making the beak glow is reacting with the UV light waves, and those light waves aren't around in the dark.

Glow sticks and sunglasses?

So far, the fluorescence has only been seen in dead puffins in Dunning's lab.

That means he has to test out the UV light on some live puffins to ensure the beak brightening isn't happening because of decomposition.

So he's had sunglasses made.

For the puffins.

"This felt like the obvious thing to do," he said.

Researchers will be able to place the glasses on the birds when they're caught for tagging and then shine the UV light at them to see if their beaks light up.

"We've actually had some printed in the shape of Aviators, just for the fun of it," he said.

He'll be publishing a paper about puffin fluorescence with colleagues at the University of New Brunswick, and expects more research will follow.