Why do caribou graze on lichen in the winter?

Tundra Food Sources

In the arctic tundra, lichen is a primary food source for caribou during the winter. This non-vascular plant thrives in areas with low temperatures and high humidity, allowing it to grow year-round. Caribou can survive on a diet of up to 90% lichen during the winter months, due to its high caloric content. A single caribou can consume up to 10 pounds of lichen per day, which is essential for maintaining its body weight during the lean winter period.

Caribou Adaptations

Caribou have several adaptations that enable them to thrive in the harsh tundra environment. Their thick coats provide insulation against the cold, and their hooves are specially designed to grip the snow and ice. Additionally, caribou have a unique digestive system that allows them to break down the cellulose in lichen, making it a viable food source. In the winter, caribou may travel up to 20 miles per day in search of lichen and other food sources, often following established migration routes.

Winter Survival Strategies

Caribou employ various strategies to survive the harsh winter conditions. They tend to congregate in areas with abundant lichen and other food sources, such as river valleys and coastal plains. In areas with permafrost, caribou may dig into the snow to create sheltered areas, protecting themselves from wind and extreme cold. These strategies, combined with their specialized digestive system and adaptations, enable caribou to thrive in one of the harshest environments on Earth.