Reindeer, along with their wild counterparts known as caribou, are inhabitants of the Arctic and sub-Arctic regions throughout the Northern Hemisphere. They possess a circumpolar distribution, meaning they can be found across the northern latitudes of Europe, Asia, and North America. These large deer are adapted to survive in the harsh, cold environments of the tundra, taiga, and boreal forests. Their presence is a defining feature of the Arctic landscape.
Defining Caribou and Reindeer
Reindeer and caribou are not two different species, but rather a single species, Rangifer tarandus. Their different names are based primarily on geography and domestication. The term “caribou” is generally used to describe the wild populations native to North America, encompassing Alaska and Canada.
Conversely, the term “reindeer” typically refers to the populations found in Eurasia, which include both wild and semi-domesticated herds. In North America, the name “reindeer” is sometimes applied to domesticated animals introduced to the continent. The species’ range extends from the high Arctic islands down to the more temperate boreal forests.
Physical Adaptations for Arctic Survival
Survival in the extreme cold is possible due to several highly specific physical adaptations. One of the most important is the coat, which consists of a thick, double-layered covering of fur. The individual guard hairs are hollow, trapping air and creating effective insulation against frigid temperatures.
Their hooves are also highly specialized, being large and crescent-shaped. This broad surface area acts like a natural snowshoe, distributing the animal’s weight to prevent sinking into the soft snow or tundra. The sharp edges of the hooves are used for digging through snow to access forage.
The species also has a unique circulatory system in its legs and nose that helps conserve body heat. This counter-current heat exchange mechanism minimizes the temperature difference between the animal’s core and its extremities, reducing overall heat loss. The nasal passages are also highly vascularized, pre-warming frigid air before it reaches the lungs.
Seasonal Diet and Migration Patterns
The life of a reindeer or caribou is governed by a continuous search for food, which necessitates extensive seasonal migrations. In the summer, the diet is diverse, consisting of grasses, sedges, herbs, mushrooms, and the leaves of deciduous shrubs. This period of abundant plant growth allows them to build up fat reserves for the coming winter.
As winter approaches, the diet shifts dramatically, becoming almost exclusively reliant on lichens, particularly a type often called “reindeer moss.” These lichens are a high-energy food source that the animals can locate by smell, even when buried under deep layers of snow. The process of using their hooves to clear the snow and reach this food is known as cratering.
The need to find fresh feeding grounds and suitable calving locations drives the longest terrestrial migration of any land mammal, with some herds traveling up to 3,000 miles annually. These movements typically involve migrating north to the tundra for summer grazing and calving, then moving south to the sheltered boreal forests, or taiga, for the winter. The sheer size of these herds, which can sometimes number in the hundreds of thousands, makes seasonal movement a matter of survival for the entire population.