Reindeer's blue eyes act as night goggles to help them find food in the winter

Animals' eyes change color as the colder months approach to improve UV visibility, helping them detect lichens essential to survival.

Scientists have determined that Rudolph does not rely on his famous red nose to guide other reindeer, thanks to their unique night vision. The study discovered why reindeer are the only mammals whose eyes change color according to the season, changing from golden orange in summer to blue in winter. This adaptation helps them see better in snowy conditions and allows their eyes to emit ultraviolet light.

The study, led by Professor Nathaniel Dominy of Dartmouth College and Dr Catherine Hobaiter and Professor Julie Harris of the University of St Andrews, found that the color change helps reindeer absorb twice as much UV radiation as reflected from the sun. from the snow This enhanced vision allows them to see clearly in the dark and find food such as lichens. Hobaiter explained that it is difficult for the human eye to see lichens in white snow, but species essential to reindeer stand out as dark spots in the reflective snow landscape. Reindeer eat mainly Cladonia rangiferina, commonly known as "boa moss" a species of lichen that is essential for their survival. The purpose of the research was to find out if reindeer's night vision is specially adapted to search for this lichen.

Scotland, with its diverse lichen population, provided an ideal research environment. Working in the Cairngorms Mountains, the team photographed different types of lichens under UV light and found that different species absorb or reflect light differently. Boa moss absorbs light particularly strongly.

Professor Dominy emphasized that for reindeer in the white landscape, a direct route to food is crucial for energy conservation in a desert environment where food is scarce. The study sheds light on the reindeer's remarkable adaptations and shows how their unique vision plays a crucial role in their survival strategies.