UNITED NEWS INTERNATIONAL (UNI) — Puffins are not the showiest birds in the animal kingdom but there is more to them than meets the — human — eye.

Their bright and colorful beaks glow under UV light.

Bird expert Jamie Dunning made the discovery earlier this year.

CBC News reports he had wondered whether puffins had glowing beaks like other seabirds in the same family called auklets.

So one day while studying a puffin carcass in the lab, Dunning switched on a UV light.

The two yellow ridges on the puffin’s beak lit up like a neon sign.

Dunning found the same was true with living puffins. He protected their eyes using special sunglasses.

Dunning said their beaks fluoresce. This means they’re absorbing UV light and re-emitting it.  

He thinks the glowing beaks are used to attract mates.

Humans can’t see the effect during the day but birds have tetrachromatic vision, which means they can see an entire dimension of colors we can’t.