Birds like the Atlantic puffin see the world with vision that is different from ours. They have tetrachromatic vision. People see a mixture of three colors of light: red, blue and green light, according to ornithologist Jamie Dunning. According to CBC News, Dunning studies evolutionary history at the University of Nottingham and first discovered that the bill of a deceased Atlantic puffin glows under UV light. Dunning explained to CBC News that the puffin can see colors that humans can't comprehend due to our limited vision.
The scientist knew auklets, a bird in the same family, have bills that light up under UV light. He wondered if puffin bills light up as well. One day, after a hard time in the lab, he turned off the light and put a UV light to a puffin carcass. The lamella and the cere, the two yellow ridges found on the puffin's bill, glowed under the UV light. Dunning pointed out that it's genuine fluorescence.
"Fluorescence is a physical phenomenon during which a material is electronically excited by absorption of a quantum of electromagnetic radiation and subsequently emits light," Chemistry and Light reports.
Some quality of these two parts of the bill allowed the UV light to be absorbed then re-emitted as a bright glow. The only problem is that he isn't sure what quality made that happen. Plus, they aren't sure what purpose it might serve.
Since the bird was dead, it could be something that occurs during decomposition. That's one possibility. Yet, the researcher knows that puffins can see an entirely other dimension of hues than humans, so there may be more to it. It's unlikely that they see the bills as glowing, or that they use them as lamps in the darkness. For one thing, UV light isn't as available at night, so that might not make sense.
Still, though significantly lower amounts of UV light is available at night, according to Science Daily, the color spectrum is shifted toward UV-wavelengths at night. For example, Science Daily reported that bats see UV light emitted from flowers at night. Plus, caribou seem to be one of the few species of mammals that naturally perceive UV light visually, according to Anchorage Daily News. Most mammals lost the cones needed to see UV light through evolution. Most mammals are dichromats with two cones. Humans and other primates have three, as noted above. Caribou may use this extra vision to detect wolf urine during the dark arctic winter, researchers think.
Dunning suspects that it appears in a way to birds that must be attractive or have some use. He says that it seems like puffins must be able to see something extra in the yellow ridges that we can't. Otherwise, he sees no reason for it to even exist. The current research is focused on whether the quality exists in live puffins. They believe it does, yet, they have to know for sure.
To figure this out, they can't just shine UV light on live puffins in the darkness, as they don't want to hurt their eyes. Dunning made sunglasses to cover the eyes of live puffins. When puffins are caught for tagging, they can shine the UV light onto their bills to see if they glow when the birds are alive. We'll get to learn more about the findings of his team in a forthcoming publication from the University of New Brunswick.