Reindeer are herbivores uniquely adapted to survive in the harsh, cold environments of the Arctic tundra and boreal forests. Their diet is distinct and vital for their survival, allowing them to thrive.
Core Dietary Staples
Reindeer primarily consume plant matter, with their year-round diet heavily influenced by the availability of specific vegetation. A fundamental component of their diet is lichen, particularly “reindeer moss” (Cladonia rangiferina), which is not a true moss but a symbiotic organism of fungus and algae. Lichens are rich in carbohydrates, providing a crucial energy source that can constitute 40% to 90% of a reindeer’s winter diet. This high carbohydrate content is essential for maintaining energy levels during the colder months.
Beyond lichens, reindeer also consume various mosses and grasses. These plant types are available even in harsh climates, often found growing on rocks or beneath thin layers of snow. Their digestive system enables them to break down tough plant material that other animals might find indigestible. Their ability to utilize these staple foods allows them to persist in their challenging habitats.
Seasonal Variations in Diet
A reindeer’s diet undergoes significant changes throughout the year, reflecting the dramatic seasonal shifts in their environment. During the short Arctic summer, when vegetation is abundant, reindeer shift to a more protein-rich diet. They graze on a variety of available plants such as grasses, sedges, herbs, forbs, leaves, and shoots from shrubs and trees like willow and birch. This summer diet, which can contain up to 15% crude protein, helps them build up essential fat reserves for winter months.
As summer transitions to autumn, reindeer often supplement their diet with fungi, including mushrooms. This period is crucial for accumulating body reserves, as their appetite and food intake decrease during winter. In contrast, the winter diet becomes heavily reliant on the carbohydrate-rich lichens, as most other vegetation is either covered by deep snow or dormant.
Foraging Strategies and Nutritional Requirements
Reindeer have developed specific strategies to locate and consume food, especially during periods of snow cover. They possess an excellent sense of smell, allowing them to detect lichens and other vegetation buried beneath the snow. Once located, they use their broad, sharp hooves to dig craters, called “kiekerös,” in the snow to access their food source. This “cratering” behavior is a key adaptation for winter foraging, though they also prefer snow-free patches when available to conserve energy.
Reindeer are ruminants, meaning they have a multi-chambered stomach that hosts specialized microorganisms capable of breaking down complex carbohydrates found in lichens and other tough plants. In winter, when protein intake from lichens is low, reindeer can recycle urea, a waste product, to provide nitrogen for their rumen microbes, which then produce microbial protein. Reindeer also require minerals such as calcium, phosphorus, and trace elements for overall health and particularly for antler growth. While lichens are generally low in minerals, reindeer may seek out specific plants or mineral licks to fulfill these needs, contributing to the rapid development of their antlers.