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The sightings, however, became too frequent in some places to discount the possibility that the armadillos were actually the ones responsible for their being there. They’d been seen with increasing regularity in southern Kansas and even into southeastern Nebraska. By the mid-1990s, they’d spread over much of Missouri below the Missouri River; by 2006, they were digging up gardens in Ladue, an affluent suburb of St. Louis. They were sprouting up in greater numbers in Tennessee and western Kentucky — fishermen captured one swimming the Tennessee River just below Kentucky Dam in 2008. In the past decade, they’ve become established in southern Illinois and southwestern Indiana, and they’ve colonized most of South Carolina as well as some counties in North Carolina too. If current weather and migration trends continue, it won’t be long before they reach the nation’s capital.
Dr. Joyce Hofmann, a retired research scientist and mammalogist with the Illinois Natural History Survey, started collecting records of sightings in 2003 in the Land of Lincoln, prompted by a study that documented the animal’s already-dramatic expansion in neighboring Missouri. To get into Illinois, armadillos would have to cross either the Ohio or Mississippi rivers, but that wouldn’t be a problem.
“Armadillos have been known to hitchhike on barges; they’ve been found in train boxcars and even in trucks. And you have people who move them around intentionally, think it’s a joke,” Hofmann says. “I’d like to think at least some of them can actually cross the Mississippi on a bridge or maybe by swimming from island to island — they can swim, they just can’t go very long distances.”
Armadillos, researchers say, can hold their breath for up to six minutes and cross a small body of water underwater, gripping the bottom with their sharp claws. Alternatively, they can swallow air, inflating their stomachs and intestines, and float across. They may not be expert swimmers, but they seem to get around.
But why some armadillos are compelled to migrate and others stay put is unclear. Dr. W. James Loughry and Dr. Colleen M. McDonough, married armadillo experts on the faculty of Georgia’s Valdosta State University, have tracked some population groups, such as the residents of Mississippi’s Yazoo National Wildlife Refuge, for several years. One of the things they’ve found is that armadillos are remarkably asocial — they don’t interact with each other much, spending up to 20 hours asleep in their burrows and up to 90 percent of their waking hours focused on finding food. But they say they’ve clearly noted two sorts of armadillos: some who tend to stick around an area, year after year, and some who just pass through. “We don’t know what determines the difference between staying and going,” Loughry says.
Because the armadillo has a low body temperature, doesn’t hibernate and sleeps in fairly shallow burrows, scientists once assumed that their range was limited by cold weather. But the animals disproved that theory.
“They keep seeming to surpass that threshold,” Loughry says. “It’s kind of miraculous to me — they seem to be able to handle colder temperatures than people expected.”
This idea that there may be pioneering armadillos and homebody armadillos resonates with Dr. Frank Knight, a biologist at the University of the Ozarks. He and his wife, Amanda Withnell, have raised baby armadillos for two decades, since they moved to the Clarksville area in northwest Arkansas. Each winter, the couple, joined by students and Puddy, their 7-year-old Catahoula leopard dog, jump in their pickup, head for the levee and go looking for armadillos, hoping to capture pregnant females.