(NEWSnet/AP) — Rudolph the red-nosed reindeer may have millions of carrots set out for him on Christmas Eve. But what about the rest of the year?

Finding food in a cold, barren landscape is challenging, but researchers at Dartmouth College in New Hampshire and University of St. Andrews in Scotland say reindeer eyes may have evolved to allow them to spot a preferred meal.

Reindeer are famous for pulling Santa’s sleigh, but it’s their vision that sets them apart, says Nathaniel Dominy, a Dartmouth anthropology professor and co-author of a recent study published in the journal i-Perception.

“They’ve been sort of obscure and unheralded in the annals of visual neuroscience, but they’re having their moment, because they have a really fascinating visual system,” he said.

For years, Scientists have known mirror-like tissue in reindeer eyes changes color from a greenish-gold in summer to vivid blue in winter. It’s a process believed to amplify low light of polar winter. But experts were puzzled by another fact: Unlike other mammals, reindeer can see light in the ultraviolet spectrum.

“Most animals that are active under daylight conditions want to avoid UV light. UV light is damaging,” Dominy said. “Snow reflects UV light, which is a problem, which is why humans get snow blindness.”

Some scientists believe reindeer vision evolved to protect the animals from predators. The new study points to another possibility: food.

Reindeer subsist largely on light-colored reindeer moss, which isn’t actually moss but a type of lichen that grows in northern latitudes.

Researchers traveled to Cairngorms, a mountain range in Scottish Highlands, which contains than 1,500 species of lichen and Britain’s only reindeer herd. Scientists found reindeer moss absorbs UV light, meaning the white lichen humans have trouble seeing against the snow stands out as dark patches to the animals.

“If you’re a reindeer, you can see it and you have an advantage because then you’re not wandering around the landscape. You can walk in a straight line and get to that food, and you conserve energy in the process,” Dominy said. “These animals are desperate for food, and if they can find lichen sufficiently, then they have an advantage.”

Dominy said the new information could have human implications. Pharmacological research on lichen shows it has antioxidant properties. Reindeer eyes sensing UV light suggests there might be a mechanism to protect them from damage, he said.

“Reindeer eyes are full of ascorbic acid, or vitamin C, and vitamin C is just terrific for repairing damaged cells,” he said.

Dominy is updating the advice he offered after writing a 2015 paper exploring why a reindeer’s red nose would be ideal for guiding Santa’s sleigh.

At that time, he recommended children leave cookies and other high-calorie food for Rudolph to replenish the body heat he loses through his nose. Now, Dominy says, focus on his eyes and save the milk and cookies for Santa.

“The best thing to give them to protect the health of their eyes would be something rich in vitamin C,” he said. “Orange juice, carrots, these would be perfect treats for reindeer on Christmas Eve.”

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