This region includes the north American continent up to the middle of Mexico. Climate is temperate with an arctic edge. There are grasslands in the middle of the continent. Western part is arid with mountains and coniferous forests.
Mammals. There are 24 families of land mammals.
Endemic mammals include rodents, pocket mice (Heteromyidae), pocket gophers (Geomyidae) and mountain beavers (Aplodontidae). Pronghorns and Sewellel (Antilocapridae) are endemic artiodactyls.
Palaearctic elements include beavers, moles (Talpidae), pikas and jumping mice.
Neotropical species that have crossed over to North America are marsupials such as opossum (Didelphis virginiana), shrew opossum (Lestoros inca); 9-banded armadillo (Dasypus) and tree porcupine.
There are some mammals of wide ranging distribution, namely, shrews, rabbits, squirrels, mice, cats, bats, bears, deers and bovids.
Birds. There are 49 families of birds in this region out of which 39 are widely distributed.
Exclusive birds are: red cardinals, humming birds, tanagers and wild turkeys (Meleagrididae). Golden plover migrates from Europe.
Reptiles. There are turtles, non-poisonous garter snakes, rattle snakes, geckos, horned lizards, limbless lizard (Ophisaurus), horned toad (Phrynosoma) and Alligator mississipiensis. Gila monster (Heloderma) is exclusive to this region.
Amphibia. Urodeles include salamanders, hellbender (Cryptobranchus), neotenic larva called axolotl, eel-like siren, the Congo eel (Amphiuma) and tiger salamanders, Ambystoma tigrinum. Newts include Smooth newt, great crested newt, banded newt, alpine newt, Bosca’s newt. There are dusky salamanders, red-backed salamander and Jordan’s salamander.
Anurans include American Bell toad, Liopelma, North American bull frog and Leopard frog found in grassy meadows. Rana cascadae and Bufo boreas inhabits Cascade Mountains of Oregon, USA. The desert spade-foot toad is adapted to the arid climate of northwestern America. Other toad species are: Oak toad, southwestern toad and the giant toad which is 20 cm long.
Fishes. There are many carps (Cyprinidae) and perches. Holostei are endemic that include only two surviving ganoid fishes, one species of bowfin (Amia calva) found in American lakes and 7 species of garpike (Lepidosteus) found in American rivers. These fishes possess sharp teeth to seize and gulp prey with extraordinary swiftness. Paddlefish (Polyodon) occurs in Mississippi river of America and represents Chondrostei. Another species of paddlefish occurs in China. These fishes have paddle-like snout that carries sensory organs for locating prey by detecting its electrical fields. Ameiurid catfishes, moon-eyes (Hiodontidae) and bass family with genera Morone and Upiblema are also endemic.
The fauna of Nearctic Region is rich in reptiles and is a complex of tropical and temperate animals.
SUBREGIONS OF NEARCTIC
Californian. Narrow strip between Sierra Nevada and Cascade Range. From Vancouver to British Columbia.
Fauna includes 86 families of vertebrates that include vampire and free-tailed bats.
Rocky Mountains. This includes dry mountainous region east of California.
Fauna contains 107 families of terrestrial vertebrates. There are pronghorns (Antilocapra), mountain goat (Haplocerus), American bison, prairie dogs (Cynomus) and Heloderma.
Alleghany. This includes eastern region of USA.
The fauna includes opossum, starnosed mole, vampire bats, turkeys and mud eel (Siren).
Canadian. This sub region includes Canada, Greenland and Alaska.
The fauna is poor and resembles palaearctic region. There are reindeer, sheep, bisons, lemmings, polar beer, elk and arctic fox.