To survive the dark and snowy Arctic winters, reindeer have evolved unique visual systems. Their eyes change color to adjust to the huge swings in sunlight between Arctic summer and winter, but may do even more to help them forage. A study published December 15 in the journal i-Perception found that their eyes may have evolved to see light in the ultraviolet spectrum to help them find their favorite food in their desolate home.
[Related: Jackrabbit’s color-changing fur may prepare them for climate change.]
Reindeer primarily eat Cladonia rangiferina (C. rangiferina), which is appropriately nicknamed reindeer moss. This plant is not a moss, but a species of algae-fungus called lichen. It forms a thick and crunchy blanket on the ground across the Earth’s northern latitudes and helps play an important role in the ecosystem as a food source.
In the study, the team worked in the Cairngorms mountains in the Scottish Highlands, home to Britain’s only reindeer herd. Reindeer were locally hunted to extinction, but began to be reintroduced from Scandinavia in 1952. The Cairngorms are home to more than 1,500 species of lichen, but the reindeer here only rely on C. rangiferina during the winter months
“A peculiar trait of reindeer is their reliance on this one type of lichen,” study co-author and Dartmouth College anthropologist and evolutionary biologist Nathaniel Dominy said in a statement. “It’s unusual for any animal to subsist so heavily on lichens, let alone such a large mammal.”
When up against snow, the white lichen is invisible to the human eye.. However, co-authors Catherine Hobaiter and Julie Harris from the University of St. Andrews found that C. rangiferina and some other lichen species that supplement the reindeer diet absorb ultraviolet (UV) light. The team used spectral data from the lichen and light filters that were made to mimic reindeer vision and found that the plants may look like dark patches against a…
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