How to find delicious white treats in the snow?Ask the reindeer

Zhang Aisha, host:

So there are many myths about reindeer, at least one or more of which are true. They live in remote areas in the north where there is a lot of snow. And, you know, if your favorite food is white, living in that winter wonderland can be a challenge. But it turns out that reindeer have special vision. Scientists now know that reindeer have special vision, but recently they’ve discovered more evidence as to why.

Nate Dominy: When I learned that reindeer had a very unusual visual system, I thought, this must be an adaptation for finding food.

MARY LOUISE KELLY, HOST:

That’s Nate Dominy, professor of anthropology at Dartmouth College. He studies how animals find and eat food. Reindeer eyes can detect ultraviolet light, which can be harmful to human eyes, he said.

DOMINY: One idea is that the reason caribou have this special vision system is to see their predators – mostly wolves. So for us humans, it is difficult to see white wolves on the snow. But for reindeer, the situation may be completely different, because snow reflects UV rays, while wolves (the hair on their bodies) absorb UV rays. So to the reindeer, the wolf looks much darker than it does to us.

KELLY: Their special vision is also useful for finding food. You see, reindeer are large animals. They require a lot of energy. But surprisingly, their diet consists mainly of organisms called lichens, also known as reindeer moss, which gives them their white color.

DOMINY: Lichens are amazing living things. This is a symbiotic relationship between algae and fungi.

Zhang: In a study published in the journal i-Perception, Domini and his colleagues focused on specific lichens that reindeer eat to see how their interactions with light affect how reindeer see lichens. Like wolves, lichens absorb UV rays while snow reflects them, Dominy said. So, for reindeer on the prowl in search of food, the lichen stands out against the white snow.

DOMINY: If you were a reindeer and you could scan the distance and you could see a patch of edible lichen in the distance, then you wouldn’t have to wander around. You can move in a straight line, saving energy, to reach a food resource and eat it.

Zhang: Robert Fosbury is a retired astrophysicist who now studies the relationship between light and life. He had a chance to learn about the new research, which is how he described what the reindeer were seeing on the tundra.

Robert Fosbury: They were actually able to see different colors of lichens, which I think might have helped them select food sources.

KELLY: This study provides more evidence of how reindeer developed supervision, but there’s still more to know about their eyes. Meanwhile, Nate Dominy says that if you and your kids want to help keep their special eyes healthy, vitamin C may come into play.

DOMINY: When you want to give the reindeer that come to your house a snack, orange juice might be a good treat, or carrots might be a good treat too.

Zhang: Eat cookies for Santa Claus and drink orange juice for his reindeer.

(Soundbite of piano feature “Rudolph the Red-Nosed Reindeer”)

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