Tennessee-- On the rear bumper of his Ford Ranger pickup truck, biologist Erich Eichler proudly displays a sticker that states "I Brake for Armadillos."
"What most people don't realize is I brake for armadillos after they are already road kill," laughed Eichler, a recent graduate of the University of Tennessee Chattanooga. "I went to high school in Florida where there are tons of armadillos and when we moved up to Tennessee I did not expect to see them anymore. I kept noticing them dead along the interstate while commuting between my home in Sewanee and UTC. I started keeping track of where we spotted the dead armadillos."
Eichler's curiosity led him to team up with his UTC biology professor, Dr. Tim Gaudin, to track the armadillo invasion. The pair recently published a research article that indicates armadillos are spreading faster than originally predicted into East Tennessee.
"Armadillos were already in western parts of the state near Memphis along the river. They have been in Georgia and Alabama for years. We've been spotting them in East Tennessee since 2007, but usually in the summers during mating season. There was no way to tell if they were just males roaming into the area or actual new populations here," said Gaudin.
Any doubt was eliminated by video proof of an armadillo emerging from its burrow near Sewanee in February.
"Park Ranger Jason Reynolds caught video footage of an armadillo this winter. I was really excited because this was the first lead we had on a real active burrow," said Eichler. "Now we've located several burrows and are thinking about setting up webcams to try to get more video of them."
Eichler and Gaudin said they were surprised to find the armadillos setting up shop in the higher elevations on the Plateau.
"Armadillos like to be along rivers and they thrive in warm weather. It is unexpected that the first place they would occur in Tennessee is on top of the Plateau. The elevation near Sewanee is almost 2,000 feet and the temperature is usually five to ten degrees colder than down in the valley. What I think this bodes for the future is armadillos will live almost everywhere in Tennessee, except for maybe the highest elevations in Smokies," said Gaudin. "We have some unverified reports that they are already in places near Sweetwater."
"What is surprising is how quickly they have moved into the area. The rate at which they've moved in was much faster than originally predicted," said Eichler. "They are not very bright animals and tend to collect on the side of the highway as road kill like opossums."
The old comedian Jerry Clower used to jokingly refer to armadillos as "possum on the half-shell." In truth, the creatures are not related to the opossum or anything else in North America.
"They originated in South America and Central America. They are unique and pretty much their own thing. The closest relatives they have are anteaters and sloths," said Gaudin. "Armadillos are the only mammals with a shell. The shell is actually made out of plates of bone that form a kind of mosaic. These plates are then covered by a scale that's made out of the same stuff as your fingernails. It's flexible. You might think about it more like an old style leather football helmet rather than like a turtle shell."
Gaudin said the armor serves mostly as a protection against vegetation rather than predators.
"Coyotes and bobcats can bite through the shell. Hawks can eat armadillos when they are young. The armor lets armadillos run through brush and thorns where predators might not want to go after them," said Gaudin. "The armadillos primarily eat beetles, grubs, and ants. They dig holes in people's yards and gardens to get to underground insects. People find that a little irritating."
The species of armadillo in North America does not bite people, but Gaudin warns people to use caution before bending over to shoo the shelled scavengers away.
"They are not the brightest animals and they are not threatened by humans, so you can usually approach them and they might be oblivious. The one thing you need to be cautious about is they have a startle reflex where it jumps. So if you were to reach down and brush it along the top of its shell it will jump straight up as hard as it can, about three and a half to four feet in the air," said Gaudin. "It will jump up hard enough to break your nose and knock loose your teeth. Then when they land they take off and run away."
There's also some concern because armadillos can carry an ancient disease.
"They are the only other mammals known to contract leprosy. So far the only cases are mostly in Louisiana and lower Mississippi. Armadillos become very valuable for leprosy research because we really do not know a lot about the disease. We don't know if it can be transmitted to humans from armadillos, but it is probably a good idea if you've handled armadillos to wash your hands really well."
While armadillos continue to expand their range due to natural proliferation with few predators, Gaudin and Eichler say another contributing factor to the speed of their spread is warmer weather.
"We believe it is the increased temperatures due to climate change that has them spreading as quickly as they are," said Eichler.
"The world is going to change and one of the consequences of making it warmer is you'll have armadillos digging up your back yard," said Gaudin. "If they're not there now, in the next couple of years you can expect them to arrive. I'd say you can safely expect to see them in Knoxville within the next five years."
Gaudin and Eichler want the public's help to photographically track the armadillo invasion.
"We would like to know about it if your viewers find them alive or dead. Send me a picture if you see one on the side of the road and include when and where the photo was taken. Maybe that will give us some clue as to why they are spreading and any patterns. We haven't been able to document that very carefully in the past so we're hoping to get a better handle on that."