The Armored ArmadilloIf you live in the southern or south-central U. S. (or further north, lately), you may have encountered the plodding Nine-banded Armadillo in your yard, along roadsides or in almost any kind of dry, open habitat. This species, along with close relatives like the the Six-banded Armadillo of South America, are members of a small group of mammals (the Edentata) that lack teeth and retain epidermal scales in addition to hair. Armadillos are remarkable in how close they allow humans to approach them. In fact, simply grabbing one is often possible (but hardly recommended). They leave an impression of being from an ancient, almost dinosaurian line of mammals adapted to survive by being inconspicuous, omnivorous and of course, armored. In the U. S., they are rather recent visitors from Mexico. In the mid-19th century they were seen only in far southern Texas. Although appearing sluggish, the armadillo is regarded as a pioneer species which probes the edges of its range, seeking to expand into new habitat. Such wandering animals are at high risk of mortality and of not finding mates, yet represent the chief natural means of range expansion. In the U.S., however, because of their apparent docility and small size, armadillos also are sometimes relocated intentionally by humans.
By the early 20th century, the critters had expanded their range across much of southern and central Texas, including a westward extension along the Pecos River nearly to the border with New Mexico. Eastward extension into
Louisiana and into western and southern Mississippi and parts of Alabama came later. Meanwhile, 3 purposeful introductions of armadillos were made in Florida in the 1920s and 1930s, facilitating their rather rapid colonization by 1972 of all of the state except the Everglades and the Panhandle Region. Southern Arkansas, Oklahoma and Georgia soon followed. The current range extends to Kansas, Missouri and most of South Carolina. Outliers beyond that range may or may not represent real range extension. Global warming would favor range expansion in response to decreasing number of freeze-days even though it seems unlikely to explain the initial expansion out of Mexico. See S. R. Humphrey (BioScience vol. 24, pages 457-462, 1974) for further discussion of range extension and climatic effects.
Undoubtedly the armadillo’s least attractive feature is its vulnerability to leprosy or Hansen’s Disease. In fact, this dreaded bacterial disease which destroys the liver and kidney if not treated early, infects only armadillos and humans, no other species! Once thought of as a problem restricted to the tropical regions, 150 to 250 human cases occur annually in the U.S and over 200,000 in developing nations. In the U. S., about a third of the cases are traceable to contact with infected armadillos. Many cases are found in Louisiana and Texas where armadillos are hunted, skinned and eaten but just handling the animal might risk getting the disease ! Leprosy thus has joined the growing list of diseases like West Nile Virus that have spread from animals to humans.
In armadillos leprosy is apparently much more recent than in humans. The disease is believed to have been unknown in any species of the New World prior to the trans-Atlantic voyages of Columbus and other explorers, but has a long history in humans of the Old World. Evidence suggests that crusaders and other travelers carried it to Europe from western Asia around 1000 C.E. Fortunately the disease has declined in Europe since the 16th century.