Nearctic realm facts for kids

The Nearctic realm

The Nearctic realm is one of the Earth's eight main land areas, defined by the types of plants and animals that live there. Think of it as a huge natural region with its own unique wildlife.

This realm covers most of North America. This includes places like Greenland, Central Florida, and the high lands of Mexico. However, some parts of North America are not in the Nearctic realm. These include most of coastal and southern Mexico, southern Florida, and the Caribbean islands. These areas are part of the Neotropical realm, which also includes all of South America.

Major Natural Regions

The World Wildlife Fund (WWF) divides the Nearctic into four big natural areas called bioregions. These are groups of smaller natural areas that share similar plants and animals, especially at higher levels like families or genera.

Canadian Shield Region

This huge region stretches across the northern part of North America. It goes all the way from the Aleutian Islands to Newfoundland. Here, you'll find very cold arctic tundra and vast boreal forests. These forests are mostly made up of cone-bearing trees like pines and spruces.

Eastern North America Region

This area includes the forests and grasslands of the eastern and central parts of the United States and southeastern Canada. You'll find temperate broadleaf and mixed forests here, with trees that lose their leaves in autumn. The Great Plains also have wide-open grasslands. The southeastern United States, including central Florida, has temperate coniferous forests with evergreen trees.

Western North America Region

The Western North America region is known for its tall temperate coniferous forests. These forests grow along the coast and in the mountains of southern Alaska, western Canada, and the western United States. This area stretches from the Pacific Coast to the Rocky Mountains. You'll also find cold-winter deserts and xeric shrublands and temperate grasslands in the drier parts of the Western United States.

Northern Mexico and Southwestern North America Region

This region covers parts of Northern Mexico and the southwestern United States. It has deserts that can be mild or cold in winter. There are also warm forests of pine and oak trees. Areas with a Mediterranean climate, like parts of Baja California peninsula, are also found here. This region even has one special subtropical dry broadleaf forest, the Sonoran–Sinaloan transition subtropical dry forest.

Earth's Ancient History

Even though North and South America are connected by the Isthmus of Panama today, they were separated for about 180 million years! During this long time, their plants and animals grew and changed in very different ways.

Long, long ago, there was one giant supercontinent called Pangaea. About 180 million years ago, Pangaea split into two big pieces. North America stayed connected to Eurasia (Europe and Asia) as part of a northern supercontinent called Laurasia. South America, on the other hand, was part of the southern supercontinent called Gondwana. Later, North America also separated from Eurasia.

Since then, North America has been connected by land bridges to both Asia and South America. These land bridges allowed plants and animals to move between the continents. A famous example is the Great American Interchange, when many species moved between North and South America.

A land bridge across the Bering Strait (between Asia and North America) also allowed many plants and animals to cross. This is why the Nearctic realm shares many species with the Palearctic realm (Europe and Asia). Sometimes, these two realms are even grouped together as the Holarctic realm.

At the end of the last ice ages (the Pleistocene epoch), many very large animals, called megafauna, disappeared from North America. These included horses, camels, tapirs, mammoths, mastodons, giant ground sloths, sabre-tooth cats (like Smilodon), and short-faced bears. This event is known as the Quaternary extinction event.

Plants and Animals of the Nearctic

Animals and Plants That Started Here

Some amazing mammals first appeared in the Nearctic realm. These include:

• The first known primate, Purgatorius, which lived here a very long time ago.
• The Canidae family, which includes dogs, wolves, foxes, and coyotes.
• The Camelidae family, which includes camels and their South American relatives like the llama. Camels used to live in the Nearctic but are now extinct here.
• The Equidae family, which includes horses and donkeys. Wild horses are now only found in the Nearctic as feral (once domesticated) animals.
• The Tapiridae family, which includes tapirs. Tapirs are now extinct in the Nearctic.
• The Antilocapridae family, whose only living member is the pronghorn.
• A group of bears called Tremarctinae (short-faced bears). This group included the giant short-faced bear (Arctodus simus). The only living member of this group is the spectacled bear of South America.

Unique Nearctic Species

Some animals and plants are found only in the Nearctic realm. This means they are endemic to this region.

• One bird family, the wrentits, lives only in the Nearctic.
• Two mammal families are unique to the Nearctic: the pronghorns (Antilocapridae) and the mountain beaver (Aplodontiidae).
• Other groups, like divers (Gaviidae), grouse (Tetraoninae), auks (Alcidae), and waxwings (Bombycillidae), are found only in the larger Holarctic realm (Nearctic plus Palearctic).
• Certain beetle families, like Pleocomidae and Diphyllostomatidae, are also unique to the Nearctic.
• Plant families found only or mostly in the Nearctic include the Crossosomataceae, Simmondsiaceae, and Limnanthaceae.

Nearctic Terrestrial Ecoregions

See also

In Spanish: Neártico para niños

• List of ecoregions in Canada (WWF)
• List of ecoregions in Mexico (WWF)
• List of ecoregions in the United States (WWF)