Palearctica

Palearctica, often spelled Palearctic in modern usage, is a biogeographic realm used to categorize the distribution of flora and fauna. The term Palearctic is the standard designation in contemporary biogeography, while Palearctica appears in some older or nonstandard sources.

Geographically, the Palearctic realm is the largest of the eight biogeographic realms. It covers Europe, the parts of Asia north of the Himalayas, and extends into North Africa west of the Sahara, as well as parts of the Middle East and the Arabian Peninsula. Its northern boundary runs along the Arctic coast, while the southern limit follows the Sahel and Sahara regions, with the eastern edge reaching into the Russian Far East. The realm is separated from the Nearctic to the north-west by the Bering Strait and from the Indomalayan realm by the Himalayas and Tibetan Plateau.

The Palearctic encompasses a wide range of climates and biomes, including tundra, boreal forests (taiga), temperate deciduous and mixed forests, steppes, deserts, and Mediterranean-type ecosystems. This environmental diversity supports a rich array of plant and animal life, from large mammals such as the brown bear, gray wolf, caribou/reindeer, and saiga, to predators like the snow leopard in Central Asia, and numerous bird and insect communities. Many species exhibit wide distributions across the realm, while others are regionally endemic.

In scientific usage, the Palearctic is a foundational element of zoogeographic classification and conservation planning. The term Palearctica is less common in current literature but may appear in some sources; modern references typically use Palearctic.