GabySanta Claus doesn’t need to worry about his trusty reindeer getting lost in the vast Arctic wilderness or failing to see where they need to go. These animals possess a unique form of night vision. As the cold sets in, Arctic reindeer change the color of their eyes from golden to a deep blue. This adaptation allows them to perceive ultraviolet light, making it easier for them to locate lichen—a vital food source for their survival. This remarkable aspect of reindeer vision was revealed by a team of American and Scottish scientists. The research was led by Professor Nathaniel Dominy, an anthropologist from Dartmouth College (USA), along with Dr. Katherine Hobaiter and Professor Julie Harris from the School of Psychology and Neuroscience at the University of St Andrews (UK).
What the Researchers Discovered
The scientists uncovered why reindeer are the only mammals that change their eye color with the seasons: from a golden-orange hue in summer to a dark blue during the winter months. The team noted that while this color change helps the animals distinguish ultraviolet light and find their primary food source—reindeer moss—it also raises additional questions. Since the sunlight reflected off the snow causes reindeer to receive twice as much ultraviolet light, it complicates their foraging efforts. “To our eyes, as well as the eyes of most mammals, pale lichen on white snow is incredibly difficult to spot. But for reindeer, the lichen they feed on appears as dark patches against the snowy landscape,” explained Dr. Katherine Hobaiter.
It is known that reindeer feed on a specific type of lichen called reindeer moss (Cladonia rangiferina), which is often referred to as “reindeer moss.” This species, crucial for the survival of reindeer, is not actually a moss at all. It grows in northern latitudes as spongy shrubs.
According to the scientist, there are over 13,000 species of lichen in the world. One of the most fascinating features of Scotland is that there is a region where more than 1,500 different species of lichen thrive: the Highlands. In the eastern part of this area, within the Cairngorms mountain range, lies the national park of the same name, home to numerous reindeer. During their research, the team photographed lichen shrubs in the Cairngorms under ultraviolet light and discovered that different species absorb or reflect light in various ways. As for reindeer moss, it absorbs light to an extreme degree, as reported by The Guardian.
According to Nathaniel Dominy, reindeer do not want to waste energy wandering through these cold expanses in search of food. “If they can see lichen from a distance, it gives them a significant advantage, as they conserve precious calories when food is scarce,” the professor added.
