Tundra (animal life)

From March to September, the tundra, which covers between one-tenth and one-fifth of the Earth’s surface, is warmed by sunshine. During this period the sun is visible for days, or even weeks. However, for the rest of the year, much of the tundra experiences little sunlight and temperatures range from –40 to –50 degrees Fahrenheit during these dark months.

There are two distinct kinds of tundra: the Arctic tundra, which follows the coniferous forest belt and covers the northernmost landmass of Europe, Asia, North America, Greenland, and Iceland; and alpine tundra, found on mountain slopes above the tree line in temperate areas.

Permafrost is a consistent feature of the Arctic tundra, as well as of the poorly developed tundra of the Antarctic. The summer thaw in the Arctic tundra extends to a depth of six to twelve inches, with most plant root depth and burrowing of animals limited to this thawable area. The tundra permafrost retards drainage, thereby causing boggy, saturated lowlands during the summer thaw. Alpine tundra is drier because of drainage.

Year-Round Inhabitants

Some hardy animals have learned to cope with the cold and maintain permanent residence in the tundra. Musk oxen, bulky animals with shaggy protective coats of hair, live along the shores of the Arctic Ocean and in other desolate areas of the tundra. These herbivores search for frozen twigs or grass beneath the snow and do not seek shelter even in the coldest weather. Also capable of enduring the cold winter is the arctic fox, whose thick fur coat turns white in winter and provides camouflage from his enemies. Foxes range over the alpine tundra in winter and feed on arctic hares, birds, and lemmings—small rodents that dig beneath the snow. Lemmings remain active all winter, living under the snow and feeding upon grass and roots. Frequently, they reproduce under the snow.

Ptarmigans spend winters on the tundra, having feathers on their feet to aid in traveling in the snow. Living in the driest areas of the tundra, they eat berries and tender leaves in the summer and rely on frozen vegetation during the winter. Their feathers turn white in winter, helping camouflage them from their fiercest enemy, the snowy owl. The owl, a bird of prey, moves southward into the forest in winter when the food supply becomes scarce in the tundra. Owls feed upon lemmings, small birds, insects, and arctic hares that are twice their size.

Some alpine mammals, such as marmots and ground squirrels, hibernate in the winter, eating large amounts of vegetation in summer and early fall before hibernation begins. Other small animals, including rabbits, forage as they can for winter feeding.

Migratory Inhabitants

As summer approaches and the days slowly grow longer and warmer, the frozen tundra begins to sprout grass, leaves, and wildflowers. The plants which have adapted to the tundra’s short growing season and shallow topsoil above the permafrost are unusually small and provide food for animals. Huge herds of caribou migrate north from the forest to roam across the tundra, feasting on tender, young vegetation. The tundra wolf, or arctic wolf, a strong, fast animal endowed with exceptional hearing, vision, sense of smell, and endurance, follows the caribou into the tundra. Living and hunting in family groups or packs, the wolves feed off young, sick, and old members of the caribou herd.

After hibernating in the forest for the winter, grizzly bears move north to enjoy the berries and plants of the summer. These blond-colored bears also eat fish, lemmings, and carrion (remains left over by other animals). Polar bears, who prefer to eat meat, live near the Arctic Ocean to enjoy seals, walruses, and fish. Occasionally, they move inland and devour berries, carrion, and other tundra animals.

Many birds also move north from the warm southern areas to feed, nest, and raise their young. Swans, ducks, and geese converge on the ponds, while gulls and terns occupy the tundra’s beaches, and falcons and eagles soar at great heights above the tundra seeking their prey. In summer, on the tundra, birds hatch as food becomes plentiful. As new vegetation is abundant and fish are plentiful in ponds and lakes, there are large numbers of insects on the tundra. Butterflies, moths, and bees abound, and flies and mosquitoes swarm after the caribou herds, providing food for the birds and fish.

Alpine animals, such as mountain sheep, ibex, wildcats, and many birds, who are not equipped for year-round alpine life, migrate south into more temperate forest environments in winter, returning to higher regions in the summer.

Changing temperatures have led to new species venturing into the tundra in search of food opportunities. Opportunist borreal animals, such as red foxes, moose, and snowshoe hares have begun competing with long-term tundra residents for the limited food sources. As a result, some year-round residents, such as snowy owls, are moving deeper into the tundra to try to find less competitive hunting grounds.

Principal Terms

Coniferous Forest: great northern forests, mostly evergreen, that end where the tundra begins

Herbivores: plant-eating animals

Lichens: organisms formed by algae and fungi that are a source of food for tundra animals

Migratory Animals: animals that move from one place to another for feeding or breeding

Permafrost: a permanently frozen layer below the earth’s surface

Temperate Region: a mild climatic area between the Tropic of Cancer and the Arctic Circle

Bibliography

Guynup, Sharon. "The New Arctic: Amid Record Heat, Ecosystems Morph and Wildlife Struggle." Mongabay, 14 Feb. 2024. news.mongabay.com/2024/02/the-new-arctic-amid-record-heat-ecosystems-morph-and-wildlife-struggle/. Accessed 22 Sept. 2024.

Johnson, Rebecca L. A Walk in the Tundra. Carolrhoda Books, 2000.

Sayre, April Pulley. Tundra. Twenty-First Century Books, 1995. Exploring Earth’s Biomes Series.

Shepherd, Donna W. Tundra. Franklin Watts, 1997.

“The Tundra Biome: Facts, Pictures & Information; A Land of Frozen Beauty.” Active Wild, 10 Aug. 2020, www.activewild.com/tundra-biome. Accessed 22 Sept. 2024.

Walker, Tom. Caribou: Wanderer of the Tundra. Graphic Arts Center, 2000.

Zwinger, Ann H., and Beatrice E. Willard. Land above the Trees: A Guide to American Alpine Tundra. Johnson Books, 1996.