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Episode Transcript: Rat Race

LAURA PELLICER, HOST: Recently, while driving in Los Angeles, Monique surprised her girlfriend Emily with a question.



LABORDE: How do you feel about rats?

EMILY: Ah! Why would you do this to me? I hate rats. LABORDE: Did you know that Los Angeles is one of the most rat-infested cities in America?

EMILY: Really? I mean, I can't say that that surprises me. But I thought New York would top us.

LABORDE: They might, they might. Per square rat capita.

EMILY: Yeah, per square foot. I'm sure. I'm sure that New York has more rats than LA.


ROBIN: I live in New York City, which is surprising that it doesn't top the list of cities that has the most rats. But it does come in at number three, so we're still crushing it on that front. You see them on the subway platforms, you see them down in the subway tracks, like, they're disgusting.

PELLICER: That’s Robin. And the list she and Monique and Emily are talking about? That’s the annual ranking of America’s rattiest cities, published by pest control company Orkin. In 2020, L.A. and New York came in second and third. The city with the dubious distinction of first place, which has topped the list for six years running, is… Chicago.


ELIZABETH FRIEND, HOST: The fifty cities on the list span the continental United States; from Burlington, Vermont, to Portland, Oregon, to Houston, Raleigh, Atlanta, and West Palm Beach, Florida. Very different places with something disturbing in common: An outsized rat population.


PELLICER: This is CREEP, stories about creatures invading our space and changing the world around us. I’m Laura Pellicer.

FRIEND: And I’m Elizabeth Friend.

MIKE COVE: Rats have followed us across the entire globe. There are even rats in, you know, base camps and research stations in Antarctica.

FRIEND: That’s Mike Cove, the research curator of mammals at the North Carolina Museum of Natural Sciences.

COVE: I’m a conservation biologist at heart so the majority of my research goes towards studying the ecology of different species to better inform their management and ultimately their conservation.

FRIEND: Rats have been living alongside us for so long, we likely forget that they’re an invasive species. They’re an early example of how global trade and human travel provide pathways that transport enterprising creatures all over the world.

COVE: They basically just hitched rides on ships and all different kinds of transport vehicles all across the globe for many centuries, if not millennia.


PELLICER: The Norway rat showed up in England in the 18th century. Observers thought the rat was hitching a ride on ships carrying lumber from Norway — hence the name. But in truth, the rodent came from Asia long before that time, and likely traveled to Europe along with luxurious Asian imports.

Not long after, the not-so-Norwegian rats landed in North America. They’re also called brown rats, sewer rats, water rats, or wharf rats. And this rat began to muscle out many of its smaller cousins, like the black rat also called roof rat, another invasive that made the trek from Asia to Europe centuries before.

FRIEND: Roof rats are still among us, causing problems. They’re especially fond of warmer environments near saltwater, so they’re often found in port cities or coastal areas. But when you think of a large rodent skittering through metropolitan alleyways at night, it’s likely the Norway rat you’re picturing.

COVE: Someplace like a city is just a giant buffet for them, you know, being able to hop in the dumpsters, literally ride subways, to other sites, and, and just travel through all these networks of pipes and sewer lines under underneath the city, and really only coming up at night when a lot of people aren't around to even notice… Rats are super opportunistic, and can capitalize on any of our resources that we provide for them. And so they can get incredibly large.

PELLICER: Rats will eat just about anything that can possibly be considered food, and some things, like soap, leather, and dog poop, that most creatures WOULD NOT consider to be food.

They’re opportunistic eaters and they’re also predatory. Rats will hunt down other rodents, birds, eggs, reptiles, even fish if they can get them. And if food is really scarce, they’ll eat each other.

LABORDE: And what is it about the rat, that freaks you out. Like, as an animal.

EMILY: We're kind of like told that they carry all kinds of diseases and stuff that they only exist in spaces that are like, filthy, for the most part. But also they're just in, they, they're the invaders. They just like pop up out of nowhere. And they surprise you like a horror movie. They're just like somewhere they're not supposed to be and like ravaging your kitchen.

PELLICER: Pixar has done its part romanticizing a rat’s place in the kitchen. But for the real picture, ask Fredo. He’s a chef living in New Orleans, which is currently the 21st rattiest city in America, up six places from last year. Fredo’s worked in many restaurants and he’s meticulous when it comes to keeping a clean workspace. But he also knows no kitchen is truly safe when it comes to rats.

FREDO: It was days we could smell it but we just couldn't pinpoint it. I pulled out the refrigerator, I moved the reach-in coolers, moved the ovens around, you know, I just couldn't get it. And one day, I don't know what happened but we kind of got a whiff and noticed it might be coming from the roof. So before service started, I can't remember what day of the week it was but before service my boss gets the ladder and he goes up, climbs up he pushes the little panel over and whoosh there it is! The smell... we found it, we knew where it was in there so basically he had to get a garbage bag he had to get some gloves you know this thing was, thing was rancid, ain’t no telling how long it's been up there. But he gets it down and when he gets it down the rat was the size of a football no lie, how swollen it was.

FRIEND: Poison is a favorite method of dealing with rat infestations, but poison has a way of spreading beyond its intended target.

COVE: Baits and things can have really, really strong negative effects throughout the ecosystem. They can't be specific just to the invasive house rats, right. So all of our native rodents are going to be eating these and also get sick and die. And it also works its way up the food web.

PELLICER: Rats are cautious, unlikely to eat unfamiliar foods, making it hard to convince them to take the bait. Beyond that, it’s unlikely poison would be enough to make a dent in fast-growing rat populations. A single female rat can have half a dozen litters each year, each with up to twelve pups. And her babies will be ready to breed in about three to four months.

FRIEND: With their voracious appetites and remarkable rate of reproduction, these invasive rodents pose a serious threat to biodiversity. They’re estimated to have played a role in at least 75 extinctions of bird, reptile and mammal species worldwide.


COVE: Rats are probably not going anywhere. And I think the important issue to focus on for conservation and invasion biology, right now, is to manage rats, where we can and where it's most critical.

PELLICER: So, if we are stuck with rats in our cities and suburbs, what about places where it’s not too late to limit their spread? To find out, we’re heading south, all the way down to South Georgia.

FRIEND: But... maybe not the South Georgia you’re thinking of.

NAOMI CORDEIRO: It’s pitch black and stars are shining. I’m just getting Sammy loaded up into the car. C’mon.

FRIEND: Meet Naomi Cordeiro. She’s a bio-security dog handler working for the Falkland Islands and South Georgia Island.

CORDEIRO: (Door opens) Up up. Good lad.

FRIEND: They are very far south, not too distant from the Antarctic Circle. During winter, they can see just three hours of sunlight a day. 

CORDEIRO: …Get the boat.

FRIEND: The Falklands are a collection of more than 700 islands at the tip of South America, roughly 400 miles off the coast of Argentina. Fewer than 4,000 people live on the islands, which, all together, are about the size of the state of Connecticut.

South Georgia Island is even more remote. Located 800 miles southeast of the Falklands, the rocky island has no permanent human residents, but plenty of seals, penguins, and the world’s only sub-Antarctic songbird. 

Part of Naomi’s job is to patrol islands that have been cleared of invasive rats and mice to make sure they haven’t been re-infested.

CORDEIRO: We’re in a little inlet and it’s really rocky with steep sides and tussac right up the top and all the way down at the back in a kind of gully. There’s kelp in the water so it’s hard to get a little boat with a motor, but we managed it...

FRIEND: Today she’s visiting a couple of islands in the Falklands she hasn’t been able to check yet this year. But she can’t do this work alone. She relies on the keen judgment of her co-worker Sammy. Sammy is a golden, fluffy-tailed Shiba Inu dog, specially trained to alert his handler to the presence of rodent feces or live rodents. Rats and mice were first transported to these islands on whaling ships in the 1700s.

PELLICER: Humans also brought along a host of other invasive species, including cats, foxes, feral swine, and even reindeer, which — unlike the rats — really did come from Norway.

FRIEND: The rats were especially hard on the native birds, decimating their populations by eating the eggs and chicks of species like the Tussac bird, Cobb’s wren, and several types of burrowing petrels.

And, ever opportunistic, the rats were able to use one of the key features of the Falklands habitat to their benefit: The dense, clumping Tussac grass that covers some of the islands instead of trees.

CORDEIRO: …seeing some tussac birds, cobb’s wren which are a really good sign that this is a rodent-free island, which is what we expected.

FRIEND: In the past two decades, there’s been a push to eradicate rodents from some of the many islands they’ve invaded. It’s a painstaking effort that involves hand-seeding poisonous bait over a large area, or delivering it via helicopter in harsh sub-Antarctic conditions, then checking and rechecking for years after to make sure no rats have returned. On these windswept islands in the far South Atlantic, it can be cold, windy work.

CORDEIRO: So now on to our second island of the day, we just got dropped off on Bottom Island. Just as we were jumping onto the rocks and scrambling up towards the tussac, a little tussac bird came and sat on the bow, which was really lovely. And you know, it's a really nice sign that there's probably no rodents here. So we’ll give Sammy a good chance to have a sniff around. But there's other signs as well, the tussac birds, the cobb’s wren, that give us confidence that this isn't an island with rats on. Let’s see if we can get started. You ready? Find it.

PELLICER: When Sammy smells a rodent he’s trained to send a signal. A whiff of urine or fur is enough to make him sit and point his jet-black nose in the direction of the scent. When he finds a live rodent, he gets excited, wagging his curly tail.

CORDEIRO: Back on the boat after searching Bottom Island, there were no rats to find which is great news. We saw plenty of tussac birds. No cobb’s wren, unfortunately. So Sammy’s done a really good job today. He’s very tired. He didn't didn't find anything. But um, he still gets a little reward when we get back to the boat, or back to the car, just for having done his job. It's not his fault we didn't find anything. So he's just given himself a little clean. Licking his paws. And the sun's come out now, which is really nice. We're just going to cruise back into Stanley and then Sammy can go and have a little nap.

FRIEND: I caught up with Naomi afterwards via Zoom at her house in Stanley, on the main island of East Falkland.

CORDEIRO: So we’re just back home after our search today. We’ll give Sammy some biscuits and then we’ll just relax for a little bit. Sammy usually has a crazy half hour after he’s been working, so that’s still to come. FRIEND: She lives there with her husband, a cat, a dog, and of course, her co-worker Sammy.

CORDEIRO: He's quite an unusual, particular little creature. He's kind of cat like, he's a bit aloof, you know, he doesn't really sort of come to you for a cuddle unless he really, really wants one or if he really, really likes you.


FRIEND: In addition to checking islands for evidence of rats and mice, a big part of Naomi and Sammy’s work is checking cargo ships, cruise ships, fishing ships, the ferry that goes between the Falkland Islands, and anything headed to South Georgia.

CORDEIRO: We sort of try and search as much as the vessels we can. We kind of focus on areas like the provisions around the galley, waste storage areas, and then any areas where mooring lines come from the dock onto the vessel around that area. So if a rat or mouse had climbed up the ropes, and then got onto the vessel, you think, well, where could it have stowed away? So we check all those little nooks and crannies around there.

FRIEND: Naomi and Sammy go out on a small boat to meet cargo and cruise ships at sea, before they reach the Falklands and well before any crew members, tourists, or rats can disembark. If they do find evidence of rodents, government inspectors are called in to decide if the problem warrants sending the ships away to keep them from landing on rodent-free areas.

CORDEIRO: Most of the time, if there's rats on the boat, they can't go. If there's any doubt, you know it's not worth the risk. So they won't be allowed out.

FRIEND: In the Falklands, some islands are currently infested, there are some where the rodents have been eradicated, and a few they never got to in the first place. It’s a balancing act to keep the problem from spreading, one made harder by the amazing adaptability of rats.

CORDEIRO: They're really good swimmers. Yeah, and that's one of the problems with doing the eradications around the Falklands is a lot of the islands are within the swimming distance of rats, and they were just recolonized after eradication. And they can swim far, I think, I think it's over a kilometer. It's really far. It's incredible.

FRIEND: According to biosecurity researchers in the U.K, a half mile swim is no problem for a Norway rat. Even a two and half mile swim can’t be ruled out. And, if need be, they can tread water for up to three days. At 900-plus miles to the southeast, rats aren’t swimming to South Georgia Island, but the stakes there are even higher.

Though there are no permanent human settlements on the remote island, there’s still plenty of boat traffic from fishing ships, scientific researchers and tourists who hope to glimpse seals, giant albatrosses, and some of the largest penguin colonies on the planet.

CORDEIRO: The idea of doing the inspections in the Falklands is that they're, you know, there's still hundreds of miles away from South Georgia.

FRIEND: The multi-million dollar effort to clear rats and mice from South Georgia was the largest rodent eradication project ever undertaken in the world. It took seven years to clear 420 square miles. The project wrapped up in 2018, and as Naomi points out, the timing was critical.

CORDEIRO: It's a bit of a sad story, there was a really good opportunity to do it because the rats were in certain areas that were separated by glaciers. And as the glaciers retreated, the rats would make their way into new areas. So if they did it when they did it, just before 2018, then that’d be less work than doing it when they had got across the whole island. This was the time to do it, before they could get further with the melting ice.

FRIEND: By monitoring vessels heading to South Georgia, Naomi and Sammy are a crucial line of defense for this protected wildlife haven. No one wants to risk undoing years of eradication efforts, so no ship on the way to South Georgia is allowed to leave the Falklands unless it’s clear that there are zero rodents on board. When Naomi and Sammy come aboard to screen a vessel, there’s a lot riding on their teamwork.

FRIEND: Rats have a long history with humans, and they are widely reviled. But Mike Cove, from the North Carolina Museum of Natural Sciences, reminded me there are other ways to think about them.

I wonder if there are ways in which rats are useful to humans? I'll say I came up with two and that was like, species for study in the lab, and some make good pets. That's about it. That's as far as I got.

COVE: Probably, the vast majority of all of our medical breakthroughs, as a society have come from research on two species, right, the house mouse, Mus musculus, and the brown rat, Rattus norvegicus. Rats are super smart, right? They are actually incredibly smart. And that's also a big component of why they're so successful, as well. And so they do actually make good pets. You can train rats to do all types of things. They are really a unique and cool species.

The other thing that we don't typically think about in kind of our Western culture is that rats actually make good food. You know, rodents are a delicacy in many parts of the world. Rats and rodents in general, are actually quite tasty. But they're most tasty when they're eating their natural diets, right? They’re eating seeds, and plants and fruits, maybe some insects and things like that. So the old saying, ‘you are what you eat,’ you know, we're not going to want to eat New York City sewer rats. Right? But if we ate those rats in their natural habitat, with what they were consuming, in terms of, you know, natural seeds and fruits, the meat actually would be tasty because it carries over kind of that nuttiness from their natural diets.

PELLICER: It’s possible that one day, artisanal, hand-fed, organic rat could be a sought-after menu item in the U.S. But not pizza rat — we’ll leave that one to “live its best life” in the New York subways.


FRIEND: Let’s take a step back and think about biological invasions more broadly. One framework for considering how communities can deal with an invasive species is to look at four ways we might respond, depending on how well established the species has become.

The first level of response is prevention. The goal here is monitoring known threats and entry points to keep invasive species out of your area, like what Naomi and Sammy are doing to keep rodents off South Georgia Island.

PELLICER: If an invasive species does show up, the next level of response is early detection and eradication — essentially to get rid of the species before it gets a foothold. For species that have already gained that foothold, we can try to limit their spread through containment.

FRIEND: Finally, if a species is so widespread that it can't be contained, we have to focus on protecting key resources from further harm. For much of the United States, and in fact, much of the world, we fall squarely in that last category when it comes to rats. We can only hope to mitigate the damage rats do to humans, plants, animals, and the wider environment.

PELLICER: But for some key places, mostly remote or isolated spots like islands, there’s this opportunity to erase past damage and protect sensitive plants and animals. From palm-covered atolls in the Pacific to what used to be known as ‘Rat Island’ in Alaska, there are efforts underway to reclaim these places from the plague of rats and rebuild their native ecosystems.

FRIEND: As long as humans keep moving around the world, we'll keep bringing other creatures with us, some of which will go on to cause problems in their new habitats. Prevention is hard work, and it’s not always easy to convince people to mobilize against a threat that hasn’t shown up yet. But once invasive species take root, all the other steps to deal with them become even more complex, expensive, and hard to achieve.

COVE: I think that it's very easy for us to kind of, you know, keep our heads down and continue with the status quo, and not accept that, you know, something is becoming a problem until it's really in our faces. And I think in a lot of instances, that is why we’re in the position we’re in with many of the invasive species that we have, you know, here in the U.S. for example.

FRIEND: Mike Cove understands that if Naomi and Sammy were to stop their daily work the situation could get out of hand — fast. Layer in the pressures of a warming planet, and unchecked invasives become even more of a threat to the ecosystem. As he and other experts contemplate the future — he’s got a prime example in mind as a stark warning for what could happen here in the U.S.

COVE: The Burmese pythons in the Everglades continue to expand their invasion front, right. And, you know, the scary thing about that is, if you look at the models and projections with climate change, but also contemporary climate data Burmese pythons have the potential to colonize the entire southeastern United States.

PELLICER: CREEP is a production of North Carolina Public Radio, WUNC in partnership with the North Carolina Museum of Natural Sciences. Learn more about all the invasive species we've been talking about at

We’d love it if you wrote us a review and shared CREEP with a friend who’s curious about the world around us. There’s also an easy way to support this podcast: visit and make a donation in any amount. Your support can mean more deep dives into mysterious creatures.

FRIEND: Many thanks to science communicator Eleanor Spicer Rice for helping to review and provide scientific feedback for this episode. Thanks also to Monique LaBorde, Robin Gelfenbein and Katie Fernelius who brought us the voices from some of America’s rattiest cities.

Charlie Shelton-Ormond is our producer, Amanda Magnus is our editor, Jenni Lawson is our audio engineer, and Lindsay Foster Thomas is our executive producer. Our theme music is by Quilla.

I’m Elizabeth Friend.

PELLICER: And I’m Laura Pellicer.