Caribou, also known as reindeer in Eurasia, are a species of deer found across the northern regions of the globe. Their range encompasses diverse landscapes, providing resources for their survival and reproduction throughout the year. Understanding their habitat is important for appreciating the resilience and challenges faced by these animals in their northern homes.
Where Caribou Live
Caribou exhibit a circumpolar distribution across the northern parts of North America, Europe, and Asia. This spread includes countries such as the United States (Alaska), Canada, Greenland, Scandinavia, and Russia. They inhabit a variety of cold-adapted biomes, primarily the treeless arctic tundra, mountainous tundra, and the northern boreal forests (taiga).
Caribou populations can be found as far north as 80 degrees north latitude, extending into the high Arctic islands, and as far south as 46 degrees north latitude in some woodland areas.
Caribou Subspecies and Their Habitats
Caribou (Rangifer tarandus) are categorized into distinct subspecies or ecotypes, each adapted to specific habitats.
Barren-ground Caribou
These caribou primarily inhabit the open tundra and migrate extensively between summer calving grounds in the north and winter feeding areas in the taiga. Herds often give birth in elevated, rocky areas of the open tundra, which helps in predator avoidance and insect relief. In winter, they seek areas with shallower snow and readily available lichens, sedges, and small shrubs.
Woodland Caribou
Woodland caribou are more sedentary, preferring dense, old-growth coniferous forests of the boreal region. They rely heavily on arboreal lichens that grow on trees, especially in winter when snowpack can be deep. These caribou require large, continuous tracts of undisturbed forest, often utilizing peatlands and muskegs, for foraging and calving.
Mountain Caribou
A specific ecotype of woodland caribou, mountain caribou are found in the steep, mountainous terrain of western North America, particularly in British Columbia and parts of the northwestern United States. They depend on arboreal lichens found in the mid-canopy of old-growth forests during winter, especially where snow depths can exceed five meters. They undertake altitudinal migrations, moving to higher elevations in summer and descending into old-growth forests in winter for food.
Peary Caribou
Peary caribou are the smallest North American subspecies, residing on the high Arctic islands of Canada. Their habitat is treeless Arctic tundra and polar desert environments with short growing seasons. They utilize exposed areas like hilltops and raised beach ridges in winter, where snow is thinner, to find sedges, willows, grasses, and herbs. These caribou often move between islands across sea ice, covering distances up to 150 km each way.
Eurasian Reindeer
Eurasian reindeer also display diverse habitat preferences. Tundra reindeer inhabit vast continental tundras and taiga, forming large migratory herds. Eurasian forest reindeer thrive in dense boreal forests, often living in smaller family groups. The Taimyr reindeer of central Siberia is an example of a large tundra population, adapted to extreme temperature fluctuations.
Why Caribou Move
Caribou undertake extensive movements, or migrations, driven by survival factors. A primary reason is to find adequate food sources, as vegetation availability changes seasonally. In summer, the Arctic tundra offers abundant grasses, sedges, flowering plants, and mushrooms. As winter approaches, these surface plants become scarce, prompting caribou to seek areas with more accessible lichens, which they can dig for under the snow.
Accessing suitable calving grounds is another motivator, particularly for pregnant females. These remote birthing areas, often in open coastal tundra or mountains, offer protection from predators like wolves, grizzly bears, and golden eagles. Females with calves avoid areas with high predation risk and human disturbances, even if it means less access to high-quality forage initially.
Caribou also move to escape harassment from biting insects, such as mosquitoes and black flies, which can be relentless in warmer months. By heading to higher elevations or more exposed coastal areas, they find relief from these “micro-predators.” Large aggregations also serve as a defense mechanism, making it harder for predators to single out individuals. The scale of these movements can be immense, with some herds migrating over 3,000 miles annually between their summer and winter ranges, making it one of the longest land migrations on Earth.
Protecting Caribou Range
Caribou ranges face pressures from various sources, leading to habitat fragmentation and degradation. Human development, including resource extraction (logging, mining, oil and gas exploration), creates linear features like roads and seismic lines. These disturbances destroy habitat and provide easier access for predators, like wolves, increasing predation risk. Hydroelectric development also leads to habitat loss through flooding and impedes caribou movement.
Climate change presents another threat, altering caribou habitat by influencing temperatures, precipitation patterns, and wildfire frequency. Warmer winters with less snow allow other ungulates, such as white-tailed deer, to expand their range into caribou territory, attracting more predators. Increased rain-on-snow events create ice layers that prevent caribou from accessing ground-dwelling lichens in winter, directly impacting their food supply. Forest fires, whether natural or human-caused, can destroy lichen-rich winter forage that takes decades or centuries to recover.
Conservation strategies aim to preserve and restore caribou habitat through a multi-faceted approach. Protecting large, undisturbed areas of mature and old-growth forests is a priority, often through protected areas and conservation zones. Land use planning manages industrial activities and minimizes their impact on caribou ranges, ensuring sufficient undisturbed habitat remains. This includes restoring linear features and implementing careful forest management practices. Community involvement and Indigenous knowledge are important components in developing effective, long-term conservation plans for caribou populations.