Buried bounty: Caribou survival depends on lichen and snow

Sadie Harley

scientific editor

Meet our editorial team
Behind our editorial process

Andrew Zinin

lead editor

Meet our editorial team
Behind our editorial process
Editors' notes

This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:

fact-checked

trusted source

proofread

The GIST
Add as preferred source

A study by researchers at the SUNY College of Environmental Science and Forestry indicates that if lichen continues to decline across the Arctic, caribou populations could struggle to survive the winter.

In the study, "Winter survival shaped by forage abundance and snow depth for a long‐distance migratory ungulate," ESF Ph.D. candidate Chloe Beaupré and her advisor, Dr. Elie Gurarie, examined the relationship between winter forage, snow conditions, and caribou survival. The paper is published in the journal Polar Biology.

Caribou are one of the few animals that can eat and digest lichen (also called "reindeer moss"). In winter, when other foods are scarce, caribou rely almost entirely on this resource. To understand how essential lichen is for caribou survival, researchers analyzed tracking data from the Western Arctic Herd.

Their analysis revealed that caribou living in areas with abundant lichen were up to nine times more likely to survive the winter than those in regions with sparse lichen. However, snow depth significantly affected access to this critical food.

"Caribou dig through snow in a behavior known as 'cratering', but once snow exceeds about 50 centimeters, even high-lichen areas become inaccessible," said Beaupré. "When snow is too deep for caribou to reach lichen, the survival advantage disappears."

Using GPS telemetry data from 1,067 caribou winters between 2009 and 2024, the study found that higher lichen cover significantly improves survival, but only when snow conditions allow access.

"As Arctic conditions continue to change, both lichen availability and snow depth will play a critical role in determining whether caribou can survive the winter," said Beaupré.

Beaupré and Gurarie collaborated with the National Park Service, University of Alaska Fairbanks, and University of Maryland on the study.

More information

Chloe Beaupré et al, Winter survival shaped by forage abundance and snow depth for a long-distance migratory ungulate, Polar Biology (2025). DOI: 10.1007/s00300-025-03439-w

Key concepts

animal behavioranimal trackingherbivoresmigration (organisms)plant and animal tagginglong-term ecological monitoringtundra ecosystemsartiodactylsdeer

Provided by SUNY College of Environmental Science and Forestry