Why are armadillos moving up north?

Armadillos are turning up in states like Kentucky and Illinois, far from their warm southern habitats. Why are they moving north?

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

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• 0:47Ira Flatow?

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• 1:06Flora Lichtman?

  Hey, it's Flora and you're listening to Science Friday. What does the presence or absence of certain species tell us about an ecosystem and how it's changing? That's a question wildlife biologists in Louisville, Kentucky are asking as the climate changes and a new animal moves in. I'll give you a hint. It's bumpy and armored and jumps five feet in the air when it's startled. Yes, the armadillo. It's been crawling up the southern U.S., making itself at home as far north as Kentucky, Indiana, and Illinois. Reporter Giselle Roden at Louisville Public Media has been reporting on this armadillo influx in Louisville and what it means for local ecosystems. Welcome, Giselle.

• 1:49Speaker 03

  Thank you, Flora, for having me.

• 1:51Flora Lichtman?

  Thank you for being here. Is there a name for this concept, this idea that animals can tell us something about the environment or an ecosystem?

• 2:00Speaker 03

  That's a great question, yes. So it's called signal species, and that means it's really an organism that can tell us about the changes that are occurring in our ecosystem.

• 2:09Flora Lichtman?

  What kind of changes, and could you give me a couple of examples?

• 2:12Speaker 03

  Yeah, of course. So signal species specifically can tell us about things that are rising in temperatures. Temperatures can usually indicate where these animals are going to end up. But a lot of the time, when the temperatures are rising, they move either farther north or farther south, depending on the temperatures that they need. There's also vegetation. Sometimes their habitats are being dismantled, so they have to move somewhere where they can find better habitat. So it seems like more of a natural expansion, even though some of the stuff that is happening isn't really necessarily their fault.

• 2:41Flora Lichtman?

  Right, it's like the ecosystem is changing, so their habitat is changing.

• 2:44Speaker 03

  Exactly.

• 2:46Flora Lichtman?

  Okay, so the signal species you focused on is the nine-banded armadillo.

• 2:51Speaker 03

  Yes.

• 2:52Flora Lichtman?

  Are they popping up in Louisville?

• 2:54Speaker 03

  They are. It's really interesting because they're starting to show up more and more. And I think as far as we know, right, that in 1986, in LaRue County, Kentucky, that was when they first noticed sightings of these nine-banded armadillos. But since then, they have reached 63 of Kentucky's 120 counties. It is absolutely incredible how fast these guys are moving.

• 3:17Flora Lichtman?

  And what's their historic range?

• 3:19Speaker 03

  They're typically found in the deep south, so we're talking in Texas, places like that, maybe New Mexico. They're also found in Mexico and South America, but since around 1970, the rising average temperatures in Kentucky, they're increasing by nearly three degrees. So they're coming up here more, and we've actually found them in Tennessee, Indiana, and Ohio. I'm a Southern Illinois native, and I've actually seen them in my hometown, too. So now that we're having milder winters, they feel more comfortable moving up there. Nobody brought an armadillo to Kentucky and just dropped it there. They're making their way on their own.

• 3:54Flora Lichtman?

  Giselle, thanks for joining us today.

• 3:56Speaker 03

  Yeah, no problem. Thank you, Flora.

• 3:58Flora Lichtman?

  Giselle Roden is a reporter at Louisville Public Media in Louisville, Kentucky. As armadillos make their way north, more and more of us will encounter them for the very first time. So we thought we would take this opportunity to acquaint you with the weird and wild world of armadillo biology, because these little nuggets have a lot of freaky adaptations that might make you want to jump five feet in the air. Here to take us down the armadillo hole is biogeographer and mammalian evolutionary biologist Anderson Feijao at the Field Museum in Chicago, Illinois. Welcome to Science Friday.

• 4:35Speaker 04

  Thank you, Flora. It's great, my pleasure to be here.

• 4:38Flora Lichtman?

  You're an armadillo expert. Would you agree that armadillos are strange creatures?

• 4:43Speaker 04

  I agree, and that is one thing I love about them, their uniqueness.

• 4:48Flora Lichtman?

  Their uniqueness, okay. So let's start with the basics. The species we see here in America, we often call the nine-banded armadillo. Kind of introduce me to the family tree and where it falls.

• 5:00Speaker 04

  Sure, so currently we have 25 species, and the nine-banded is part of one family that include other, now, eight species.

• 5:11Flora Lichtman?

  So it's not just one, the nine-banded armadillo is not just one species?

• 5:16Speaker 04

  Correct, so that was actually a very recent change. In America, we only have one, and the now scientific name is the Mexican long-nosed armadillo.

• 5:26Flora Lichtman?

  The Mexican long-nosed armadillo, okay. So that's what I, how I should address this armadillo if I meet it. What do they eat? What habitats do they like best?

• 5:36Speaker 04

  Yeah, so this species is actually very successful in survive and colonize and thrive in multiple habitats. So the whole group you can find in, in the Amazon, in dry forests of South America. You can find them in like wetlands, even in mountain areas. So it's a very successful group. And the species here in North America actually show a very, very interesting adaptation to survive in these more temperate, colder weather, which is not calm at all for armadillos.

• 6:12Flora Lichtman?

  What's the adaptation?

• 6:14Speaker 04

  So that's one thing actually I did during my PhD, to understand how the armadillos are increasing their distribution. And one thing that people not often are aware is that armadillos in West has actually new addition to the North America fauna. It was first recorded in the U.S. in 1850s, and since then has been expanding the distribution. So one thing that I was very curious was basically try to understand, do they do the same thing that you hear in the U.S. compared to the native range in South and Central America? So we did a bunch of comparison and realized that North America armadillos, they have

• 6:59Speaker 04

  a broader diet. And so while the native range, they rely strongly more on insects. And this is probably one adaptation for them, and I help explain how they were able to colonize and keep expanding north and north.

• 7:16Flora Lichtman?

  Hmm, that's interesting. So they went from straight insectivores to omnivores?

• 7:19Speaker 04

  Yeah.

• 7:20Flora Lichtman?

  And that's led them, allowed them to expand?

• 7:22Speaker 04

  Yeah, exactly.

• 7:23Flora Lichtman?

  So these armadillos that are moving north, do we think about them as invasive species? How do you think about them?

• 7:31Speaker 04

  Yeah, so it's a very typical invasive behavior. The first like colonization era was in Texas in the 1850s, but then they were able to colonize and expand, but for many years, they were only restricted to the South U.S., which had a more similar environment and weather than what they're used to.

• 7:54Flora Lichtman?

  How far could they go? I mean, could we expect to see them in Maine sometime?

• 7:58Speaker 04

  Yeah, so there has been the past three decades, several estimation of what will be the maximum they could reach in North America. And every time, they are beating these odds. I would not be surprised if in 50 years from now, they are reaching like the border of Canada as things are going. But this is a, because I'm giving the hell of credit here, because they are surprising us a lot, and I think they deserve that credit.

• 8:26Flora Lichtman?

  Let's get to why they're unique, as you said at the top. What's your top armadillo fun fact?

• 8:31Speaker 04

  Yes, certainly is the carapace, which is standout for anyone who ever saw an armadillo.

• 8:37Flora Lichtman?

  Their armor.

• 8:38Speaker 04

  Their armor, exactly. And it is something that actually I'm very interested to understand how and what drove the carapace evolution. So one project that we are developing now is to test how resistant is the carapace across different species of armadillos and relate that to the different bite force of predators.

• 9:00Flora Lichtman?

  Can predators bite through it?

• 9:03Speaker 04

  Yeah, I had one experience 10 years ago, I was in the field, tried to find armadillos, and I just was able to witness a domestic dog run after an armadillo and totally break the carapace.

• 9:17Flora Lichtman?

  Wow.

• 9:18Speaker 04

  So that was the point in time that I was, huh. So maybe it's not that anti-predator behavior as we usually think of.

• 9:29Flora Lichtman?

  Oh, that's interesting. Okay, we have to talk about the fact that they give birth to four identical quadruplets. I mean, I think that's my favorite fun fact about armadillos. Why? What is up with that?

• 9:42Speaker 04

  Yeah, so that is something scientists still don't know, honestly, and is, but have been heavily studied.

• 9:51Flora Lichtman?

  And they always do, right? Like every time they give birth, it's four identical twins.

• 9:55Speaker 04

  Every time they give birth, it's four identical twins, yeah. Genetically identical, so they have been actually been used as a model to understand how humans give birth to twins. But then one curious factor about that is within their family, there are variation on the number of offsprings. So some species of the long-nosed group can give up to 12 identical twins.

• 10:19Flora Lichtman?

  12 twins?

• 10:21Speaker 04

  Yeah, it's amazing factor, and, and we still try to figure out what led to that evolution.

• 10:29Flora Lichtman?

  That's really fascinating. Okay, another armadillo signature feature is their whoop.

• 10:39Flora Lichtman?

  Is that music to your ears when you hear that? I see you smiling.

• 10:42Speaker 04

  Yeah, yeah, that is a great recording. I should put that as my alarm clock.

• 10:47Flora Lichtman?

  What's that about? When do they make it and what's it about?

• 10:52Speaker 04

  So again, it's not always species. There is one specifically species that's called the hairy armadillo, screaming hairy armadillo, that does the sound. And it's basically a defense mechanism and behavior feature they have. So if you hold them, for example, they'll start to screaming. It's basically to scare the predator, which will be like surprised with that noise and might let them go in and they might have the chance to run away.

• 11:20Flora Lichtman?

  What about the five-foot jump?

• 11:23Speaker 04

  Yes, that is another strategy to avoid predation.

• 11:27Flora Lichtman?

  But do they, biomechanically, how do they do that? Because they're very, they're small, so five feet is really high for their body size.

• 11:34Speaker 04

  Yes, yeah, it is. So as a burrower, they have a very strong limbs. So they do have very strong muscles and when threatened, they will do this jump high and then move out of the predator, which is also one of the reasons they are so commonly found by the roads. What happened is they are, if they're moving on the hood at night and suddenly there is a car approaching, they will try to evade and then jump out, but sometimes they jump towards the road. And that's what caused a lot of road killing then.

• 12:11Flora Lichtman?

  We know they carry leprosy. Does that mean I shouldn't try to pick one up if I see one?

• 12:16Speaker 04

  Yeah, so definitely you should not try to pick armadillo and wildlife because leprosy is other disease they can carry, especially if they're hurt, like in the road, if they're bleeding. So you expose yourselves to possible disease.

• 12:35Flora Lichtman?

  Have you had a very memorable armadillo encounter you want to leave us with?

• 12:38Speaker 04

  Yes, absolutely. So my preferred armadillo species is a tree-banded armadillo. It's the only armadillo that can roll into a bowl. So I have been working in Brazil for over 20 years and in areas they are supposed to be there, but I never saw them in the wild. A colleague of mine found what I call the paradise of the tree-banded armadillo. So in that area specifically, you can find a tree-banded armadillo quite easily. So in one of my vacations, I did a road trip just to visit this area. And then I finally was able to meet the tree-banded armadillo.

• 13:21Flora Lichtman?

  What was it like to see it face to face?

• 13:23Speaker 04

  No, I was excited. I was looking, I was feeling like a kid just got a new toy. I was taking photos all the time and the local folks in the area was very like, what, what is he doing? Why he's so excited about a species that for them is very common? So they couldn't understand why I was so excited because it's one of the most common species in their area. Now then, I was able to explain to them that I drove 12 hours just to go to that place and they were super curious but excited at the same time.

• 13:57Flora Lichtman?

  Anderson Feijao is the Assistant Curator of Mammals at the Field Museum in Chicago, Illinois. Anderson, thank you for joining me.

• 14:03Speaker 04

  Thank you, Flora. It was a pleasure talking about armadillos.

• 14:07Flora Lichtman?

  The pleasure was all mine.

• 14:17Flora Lichtman?

  This episode was produced by Iman Moyn and Kathleen Davis. Do you have something to tell us? Leave us a voicemail. 8774-SYFRI is our number. Until next time, I'm Flora Lichtman.