The armadillo, a unique mammal known for its distinctive bony plates, is becoming an increasingly common sight in Missouri. These armored creatures are establishing a presence across the state, sparking curiosity about their journey and integration into local ecosystems. Their arrival signifies a notable shift in Missouri’s wildlife.
Armadillos’ Historical Range and Northward Journey
The nine-banded armadillo, the only armadillo species found in the United States, originated in Central and South America. Their ancestors, part of the Xenarthra group, migrated into North America about three million years ago via the Panamanian land bridge. An earlier lineage became extinct around 11,000 years ago, leaving no armadillos in the U.S. for millennia.
The modern northward expansion of the nine-banded armadillo into the United States began in the mid-1800s. These “little armored ones” crossed the Rio Grande from Mexico into Texas, establishing a foothold in the southern part of the country. From Texas, their population spread eastward across southern states, including Louisiana, Oklahoma, and Arkansas, driven by natural dispersal and human-aided movements. This expansion has been remarkably swift for a mammal.
Documenting Their Presence in Missouri
Armadillos first appeared in southern Missouri in the mid-1970s. Initially, sightings were rare, but their presence has steadily increased over the decades. By the 1980s, armadillos became a more familiar sight in southern Missouri.
Researchers at Missouri State University were among the first to study armadillos in the state. A 1996 survey indicated sightings as far north as the Missouri River. By 2014, studies confirmed their continued spread, with sightings in every county, though they remain more common in the southern half. While the Missouri River was once considered a northern boundary, armadillos have been sighted north of it, demonstrating their adaptability.
Environmental Factors Driving Their Spread
The northward expansion of armadillos, including into Missouri, is linked to several environmental factors. A primary influence is the changing climate, particularly milder winters. Armadillos possess little body fat and do not hibernate, making them vulnerable to prolonged severe cold where food becomes scarce or the ground freezes. Warmer winters in the Midwest have allowed them to survive and extend their range into previously too cold areas.
Habitat alteration has also played a role. The conversion of grasslands to brushy or forested areas, driven by human settlement and agricultural expansion, provides suitable new habitats and foraging grounds. Their ability to tolerate human-dominated landscapes, including parks and golf courses, aids their colonization of new regions. Additionally, their high reproductive rate, typically producing identical quadruplets, contributes to rapid population growth and dispersal.
Their Role in Missouri’s Ecosystem
Established in Missouri, armadillos occupy an ecological niche through their feeding and burrowing behaviors. Their diet primarily consists of insects and other invertebrates, which they locate using their keen sense of smell. They consume a variety of prey, including ants, beetles, flies, grubs, and earthworms, along with occasional fungi or fruits. This insectivorous diet positions them as predators of soil invertebrates.
Armadillos are prolific diggers, using strong claws to unearth food and create burrows. These burrows provide shelter and nesting sites. While their digging can sometimes disturb lawns and gardens, it also aerates the soil and benefits other species. Their abandoned dens are often utilized by other wildlife, such as snakes, skunks, and groundhogs, contributing to habitat availability.