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Mammals are vertebrates of the taxonomic class Mammalia including animals such as American marsupials (order Didelphimorphia), Insectivores (order Soricomorpha), Bats (order Chiroptera), Edentates (order Cingulata), Lagomorphs (order Lagomorpha), Rodents (order Rodentia), Carnivores (order Carnivora), and Artiodactyls (order Artiodactyla). Thought of as warm-blooded, mammals are endotherms, meaning they are able to regulate their own body temperature independently of the temperature of their surroundings. Mammal characteristics include skin covered with hairs, females with mammary glands that secrete milk to feed young, and a reproduction strategy of internal fertilization and bearing relatively mature live offspring. In Alabama, Kentucky, Mississippi, and Tennessee, mammals are represented by numerous taxonomic families within the taxonomic orders below:

	American marsupials (Order Didelphimorphia) The American opossum is the only marsupial found in the SAIN region.
	Artiodactyls (order Artiodactyla) This order includes hoofed mammals such as deer, elk, bison, and pigs.
	Bats (order Chiroptera) Bats are the only mammals capable of true flight. There are two families of bats in the SAIN region.
	Carnivores (order Carnivora) Carnivores include predatory mammals such as wolves. There are five families within this order in the SAIN region.
	Edentates (order Cingulata) This order includes armadillos. Armadillos are steadily increasing their range northward from the Southern U.S.
	Insectivores (order Soricomorpha) This order includes moles and shrews, mammals that primarily consume small invertebrates such as insects.
	Lagomorphs (order Lagomorpha) This order is represented by the taxonomic family Leporidae, which includes rabbits, hares, cottontail, and jackrabbits.
	Rodents (order Rodentia) Rodents include mammals such as squirrels, mice, and beaver. There are eight rodent families in the SAIN region.

Ecological Importance of Mammals
Mammals play several important roles in ecosystem. By excavating burrows and tunnels, burrowing mammals create habitat for other animals. Burrowing activities can also improve soil structure and aeration, which benefits plants. As consumers, mammals help disperse plants seeds and regulate populations of the organisms they consume. Demonstrating this, mammals such as bats consume large quantities of insects while other predatory mammals such as foxes consume smaller mammals such as rodents. As prey items, smaller mammals are consumed by a variety of larger predators. Not all mammals contribute to a functioning ecosystem, however. Introduced mammals such as the wild boar have significant negative impacts on regional ecosystems.

Mammals in Alabama, Kentucky, Mississippi, and Tennessee
Mammal populations in Alabama, Kentucky, Mississippi, and Tennessee include both naturally occurring species and non-native exotic species. Some mammal species are endemic, found nowhere else in the world. Mammal species in the SAIN region number as follows: in Alabama, there are 75 species including 6 exotic species; in Mississippi, there are 79 species including 6 exotic species; in Tennessee, there are 85 species including 6 exotic species; in Kentucky, there are 63 species including 5 exotic species [source: NatureServe Explorer Database]. For additional Web resources about mammals in Alabama, Mississippi, Kentucky, and Tennessee, refer to the NBII catalog query for mammals on our Mammal Web Resources page listed on the navigation menu at left.