The tundra biome is a unique and challenging environment characterized by extremely cold temperatures, a short growing season, and permafrost. This permanently frozen layer of subsoil prevents deep root growth. Tundra regions are primarily found in the Northern Hemisphere, encircling the Arctic, and at high elevations on mountains globally (alpine tundra). These areas receive low precipitation yet remain wet due to slow evaporation rates in the cold.
Survival Strategies
Animals in the tundra possess specialized adaptations to endure harsh conditions. Many species have thick fur or feathers, often with a dense undercoat, for insulation. Larger mammals may have blubber, serving as both an insulator and an energy reserve.
Compact body shapes, shorter limbs, ears, and tails help minimize heat loss. Behavioral adaptations also play a role. Some animals hibernate, entering a dormant state where metabolism and body temperature decrease. Others burrow into snow or ground, using the snowpack as insulation.
Many bird species migrate to warmer climates for winter. They return to the tundra for breeding during the brief summer.
Mammals of the Tundra
The tundra is home to several iconic mammal species. Caribou (reindeer in Eurasia) are large herbivores known for extensive migrations. They have specialized hooves for navigating snow and a thick double coat. Musk oxen are prominent herbivores with thick, shaggy coats and a dense undercoat called qiviut, warmer than sheep’s wool. When threatened, musk oxen form a defensive circle, protecting their young.
Arctic foxes are small predators with thick, often white, fur for camouflage. Their compact bodies and fur-lined feet help conserve heat. They are opportunistic omnivores, feeding on small mammals, birds, eggs, and carrion.
Polar bears, found primarily in coastal and sea ice tundra, are large predators with blubber and dense, oily fur that insulates them even in frigid water. Lemmings, small rodents, are a foundational prey species, with population booms influencing their predators. Arctic hares have thick fur and large, hairy feet that act as natural snowshoes.
Birds, Fish, and Invertebrates
The tundra supports a variety of other animal life, including numerous bird species. Many birds are migratory, traveling to the tundra during summer to breed and feed on abundant insects and vegetation. Examples include shorebirds, waterfowl, and the snow goose.
Resident birds, such as the snowy owl and ptarmigan, remain year-round. The snowy owl is a prominent predator, relying heavily on lemmings. Ptarmigan have feathered feet for warmth and camouflage that changes with seasons.
Tundra lakes and rivers support cold-adapted fish. The Arctic char is a notable example, thriving in very cold waters due to antifreeze proteins in its blood. During the brief summer, the tundra experiences a surge in invertebrate populations. Mosquitoes and flies are numerous, forming a significant food source for migratory birds. Other insects like bumblebees, beetles, and spiders also inhabit the tundra, often spending larval stages frozen or burrowed to survive winter.
Conservation of Tundra Wildlife
Tundra ecosystems and their wildlife face increasing threats. Climate change is a significant concern, causing permafrost to thaw, which can destroy habitats and release greenhouse gases. Rising temperatures also lead to changes in plant life, with shrubs and trees potentially encroaching on traditional tundra vegetation, altering food sources and habitat.
Resource extraction, including oil, gas, and mining, disrupts habitat through roads, pipelines, and drilling sites. This infrastructure can interfere with animal migration routes and pollute the environment. Pollution, including industrial air pollutants and chemicals, can accumulate, impacting delicate food webs. Human encroachment and overhunting also contribute to pressures on tundra wildlife.