Why Reindeer Eyes Change Color!

Why do reindeer’s eyes change color with the seasons? In this video, Alex Dainis explains why reindeer eyes change color from orange-gold in the summer to blue in the winter. This change allows them to see more UV light in the winter time, which might seem counterintuitive because of their bright, snowy habitat. However, the reindeers’ food source is a light colored lichen that absorbs UV light, making it appear darker than the snow to their eyes! This is an example of evolution selecting for favorable traits, since reindeer with color-changing eyes are more likely to find food, and therefore would pass their genes on to future generations.