Who Will Win The Rat Race?

26:21 minutes

a large brown rat sits in a discarded cardboard box atop trash bags
It’s a rat’s world and we’re just living in it. Credit: Shutterstock

Last fall, New York City’s Sanitation Commissioner Jessica Tisch stood in front of a microphone and announced her plan to deal with NYC’s most hated residents: rats. She went on to make a now-viral declaration: “I want to be clear, the rats are absolutely going to hate this announcement. But the rats don’t run this city: We do.” 

Soon after, NYC announced its search for a rat czar. Someone who is “highly motivated and somewhat bloodthirsty” with “the drive, determination, and killer instinct needed to fight the real enemy—New York City’s relentless rat population.”

This news—and the memes born from it—put rats in the forefront of city dwellers’ minds. And now, the newly appointed rat czar Kathleen Corradi’s reign has begun. But ridding cities of rats is no easy feat. It requires public participation, new policy, behavioral changes, and an all-hands-on-deck approach from several government departments. 

So what’s it going to take to rid cities of rats? And is it even possible? In this live call-in, Ira talks with Bethany Brookshire, science journalist and author of Pests: How Humans Create Animal Villains, and Dr. Bobby Corrigan, urban rodentologist and pest consultant. They discuss the history of humans’ relationships with rats, why these critters thrive in cities, and why we’ll need to learn how to live with them. 

To learn more about “Pests,” read an excerpt from Bethany’s book and listen to her conversation with Ira from earlier this year.

Further Reading

Segment Guests

Bethany Brookshire

Bethany Brookshire is a science journalist and author of Pests: How Humans Create Animal Villains. She’s from the D.C. area.

Bobby Corrigan

Bobby Corrigan is an urban rodentologist and pest consultant based in New York, New York.

Segment Transcript

IRA FLATOW: Are there any critters more resilient, scrappy, impressive, and hated than

MAN: Rats.

MAN: Rats! MAN: Rat! It’s a rat!

WOMAN: A rat? There’s a rat.

MAN: Why, you little rat. Ooh.

IRA FLATOW: That’s right. Hate them or not, rats are all around us. These resourceful rodents are really good at, not just surviving, but thriving almost anywhere we are. Right? And that makes getting rid of them really hard. Cities like New York are fed up, and the mayor’s office is ready to go to war.

WOMAN: The rats are absolutely going to hate this announcement, but the rats don’t run this city. We do.

IRA FLATOW: That’s what you think. But do we actually? Because rats have been around us for millennia, and it’s going to take a lot to get rid of them. But I’ll give you a hint– doing so starts with us.

We assembled our own Rat Pack to talk all things rats. Let me introduce them. Bethany Brookshire, science journalist and author of Pests– How Humans Create Animal Villains. Joining me from wamu in Washington, welcome back to Science Friday.

BETHANY BROOKSHIRE: Hi. Thanks for having me. Proud to be Rat Pack.

IRA FLATOW: And Dr. Bobby Corrigan, urban rodentologist and pest consultant, joining me right here in our New York studios. Welcome to Science Friday.

BOBBY CORRIGAN: Thank you, Ira. It’s great to be here.

IRA FLATOW: Nice to have you. Bobby, you’ve been studying rats for decades and have become a real legend in pest control I understand. As pesky as rats can be, what is it about them that you admire?

BOBBY CORRIGAN: You know, it’s an incredible mammal. And when you look at it, it started in Mongolia. Pretty much spread around the world. And so, what I admire about them is they’re able to get the job done.

No matter what we throw at them, they’re able to adapt to it. They’re not an animal that is going to complain, if you will, about having the same meal over and over again. And they make the most of taking advantage of all the nooks and crannies in all our cities.

IRA FLATOW: Well, if we’ve whetted your appetite, maybe a bad way to describe it, and you want to talk about rats, give us a call. Our number is 844-724-8255, 844-SCI-TALK, or you can tweet @scifri.

Now, since you’ve been doing this for so long, I’m sure you’ve seen some real adventures– had some real adventures– studying rats. What’s the wildest thing that’s happened to you?

BOBBY CORRIGAN: You know, Ira, it’s true, you do– they take you on an adventure. For me, I’ve been in sewers, for example, below old cities, crawling through those sewers. The other name for the Norway rat is the sewer rat. And so, I see that animal in sewers, I see them at the surface level, in all different kinds of basements, and ceilings, and so forth. But for me, when I think back, the most adventurous is chasing them through the sewer systems.

IRA FLATOW: Can you describe the– paint a picture for us.

BOBBY CORRIGAN: Well, most people can appreciate, a sewer is not a pretty place to hang out. You know? And you have a flashlight, you’re in dark, and it’s quite smelly, as you can imagine, and it’s wet below. And every once in a while, you’ll feel this furry thing scurry by. And so, it’s the definition of mysterious, yet at the same time frightening.

IRA FLATOW: How did you overcome that fear?

BOBBY CORRIGAN: It took a while. But I have to tell you, the first time down in a sewer, or the first time down in the basement, knowing there’s rats all around me, my heart was pounding. It was full speed ahead, and I didn’t know what to expect. But doing it more and more and more, as the years went by, for research and for experience, gradually I realized these rats are not going to attack me. They’ll scurry away. But if I leave them alone, they’re going to leave me alone.

IRA FLATOW: Bethany, you went on a field trip with Bobby when you were writing your book. What did the two of you do?

BETHANY BROOKSHIRE: Yeah, sadly he did not take me into the sewers. I want to go. Next time! No, he took me on a wonderful rat safari, where we got to hang out in a bunch of the parks in Manhattan and look at some of the rodent control efforts that they were trying out there. It was really amazing. Because once you start seeing signs of rats places, you cannot unsee them. And you realize they are everywhere.

IRA FLATOW: Well, you wrote a whole book that I loved about pests and our relationship with them. When did our relationship with rats start?

BETHANY BROOKSHIRE: I mean, our relationship with rats started actually before the brown rat really, which is the Norway rat, the sewer rat. It started probably, we think, with the black rat, which came out of India and started spreading around 8,000 years ago. Actually, the brown rat didn’t really kind of come into Europe, and certainly not to North America, until the 18th century, when we know that we started seeing large amounts of brown rats. And they kind of displaced the black rat in a lot of places.

So, for example, it’s probably only brown rats that live in New York. But brown and black rats both live in places like Los Angeles, where the weather is warmer. So there’s a couple of different species that you’ll see around. But probably in New York, you’re looking at Brown rats.

IRA FLATOW: This is Science Friday from WNYC Studios. We’re talking rats. So much to talk about here. Let me go to the first tweet that came in. Speaking of New York City– Visited New York City, and a cat-sized rat ran between his legs.” Bobby.

BOBBY CORRIGAN: Well, if it was cat-sized it probably was a cat that ran between his legs, you know? But everybody–

IRA FLATOW: Is that a myth?

BOBBY CORRIGAN: It is a myth. Everybody loves to say the rats in our alley are big as alley cats, and everyone holds out their hand like giant fish stories. But the average rat, even a large rat, is going to weigh perhaps 1 pound 6 ounces– somewhere in there. There’s no 2-pound rats, and there’s no rats that are going to get as big certainly as alley cats or anything like that.

It’s actually to their disadvantage to get much bigger. Because then they can’t dart away, and dart down small holes, and escape into the shadows. So we’re not going to have these super big rats.

IRA FLATOW: So why are rats so good at living in cities then?

BOBBY CORRIGAN: Well, the cities have billions of interstitial spaces and all kinds of basements below the streets. We have pipes of all different types– not just sewers. We have abandoned pipes that have been there for 200 years.

But they can get it done. They can live in ceilings, walls, bushes, in the earth in burrows. So they’re successful because they do it all is kind of the way it is.

IRA FLATOW: And we have a lot of food for them, don’t we?

BOBBY CORRIGAN: Yes, we do. Whenever you have a city with a lot of people, somewhere I read with the experts saying 20% to 25% of the people are very– they spill things. They drop things. They don’t use litter baskets correctly. So the rat has no shortage of opportunities for finding a tidbit to eat.

IRA FLATOW: Bethany, rats, as we have been saying, are easily one of the most hated critters out there. In your research, why are we so averse to them? If they don’t seem to be– they leave us alone, like Bobby says, if we leave them alone.

BETHANY BROOKSHIRE: Yeah. I mean, I ended up actually going down a big research rabbit hole around the science of disgust. Because people are often afraid of rats. They’re afraid of being bitten. But really, the major emotion you get is disgust, right?

And it’s because disgust is one of the basic emotions. We have basic emotions like joy, and anger, and disgust. And disgust is one of those emotions that specifically is about getting things that might make you sick away from you. Right?


BETHANY BROOKSHIRE: So think of the face that people make with disgust. Which, by the way, this face is universal– the [BLEGH] face. That face. Sometimes the sound is included.

IRA FLATOW: Look at your radio. Yeah.

BETHANY BROOKSHIRE: Yes. [LAUGHS] And that face is associated with trying to get something out of your mouth. So that sense of disgust doesn’t seem like– we’re not eating rats. Except there are some cultures where they do eat rats. But we don’t usually think of it.

But disgusting things are things that might cause sickness– so feces for example. And then you have rats that are in sewers with the feces.


BETHANY BROOKSHIRE: Pretty soon, disgust gets transmitted to the things that are associated with things that might make us sick.

IRA FLATOW: But Bobby, rats leave behind some of their droppings, right?

BOBBY CORRIGAN: They do. The research has shown the average adult rat can defecate into pellets 45 to 65 times every night. And it’s not true that they don’t have bladders. They do have bladders. It’s not true that they can’t control their urine. They certainly can control the urine. But they are defecating and urinating pretty regularly wherever they go.

IRA FLATOW: Wow. Wow. Bethany, you talked about some places where that rats may not be public enemy number one. Where might that be?

BETHANY BROOKSHIRE: Yeah, there are a couple of places around the world. One of my favorite examples is the Maori who live in Aotearoa, otherwise known as New Zealand. And they brought the Pacific rat, which they call kiore, to New Zealand when they actually came there. And it was part of their food package. And they still really regard the rat with a lot of respect.

IRA FLATOW: All right. We’re going to take a break. We have so many phone calls. We’re going to get to them 844-724-8255. Still some room for you to call, or you can tweet us @scifri. Stay with us. We’ll be right back.

This is Science Friday. I’m Ira Flatow. We’re talking rats with Bethany Brookshire, science journalist, author of Pests– How Humans Create Animal Villains. Dr. Bobby Corrigan, urban rodentologist and pest consultant– he’s here with me in our Studios. Our number 844-724-8255. You can also tweet us @scifri. Let’s go to the phones to Craig in Houston. Hi.

CRAIG: Hi there. How’s it going?

IRA FLATOW: Go ahead.

CRAIG: Hey. Yeah, I’m on my third generation of rats. They live about three or four years– pet rats. Also, in Cambodia rats have been trained to detect landmines. There are ways that rats can be helpful in society, and they’re friendly creatures.

I promise, you they are friendly. If given to their own druthers they potty train almost themselves and are very clean. They spend a lot of time grooming. In fact, that’s how they show dominance within a pack of rats is by aggressively grooming each other, which is wonderful to watch.


BOBBY CORRIGAN: Yeah, those are great comments. And it’s very true. It’s an animal we really have to admire for everything you just mentioned. It’d be great if they would stick to their own territories, for example. And as Bethany mentioned, unfortunately, when humans use food and we discard it and what have you, we draw them a little bit too close to us if they’re coming out from beneath a dirty dumpster with lots of germs and bacteria. And even though they’re great mammals, it’s probably, in a city environment, we don’t want to get too friendly with them and getting too close of a proximity with them.

IRA FLATOW: Thanks for calling. Bethany, when you did your research, did you find that people were defending rats?

BETHANY BROOKSHIRE: I mean, certainly there are people who have rats as pets. Actually, when I got my author photos taken, I got to pose with one of my friend’s rats. And she was lovely. Her name was Magrat. And she did not poop or pee on me at all the entire photo session, so A-plus to her.

I know a lot of people who respect rats. They’re used, for example, in laboratory research and biomedical research, and they have contributed amazingly to human health and to the health of other animals. So yeah, there’s a lot of respect. But I think when you’re encountering one coming out of a dumpster, it’s a different feeling.

IRA FLATOW: Well, yes. And it’s true. Seriously, we do owe a lot of our medications to rats who sacrifice their lives.

BOBBY CORRIGAN: It’s also worth mentioning that this business of disgust with these animals and also fear– I think if we go all the way back to imagining sleeping in a cave or a yurt or something like that, and in the middle of the night. You see something close to the ground that’s slinking by and dragging something behind it, almost that has a snake image. And it may even squeak and hiss at us as we’re getting close to it. It can be a very disturbing experience to go through that.

IRA FLATOW: Let’s go to the phones to Susie. Is it Higganum, Connecticut, Susie?

SUSIE: It is.

IRA FLATOW: Hi, go ahead.

SUSIE: Hi. So I have rats living under my house, and I tried trapping them. I got one adult and one baby that I relocated last summer. After that, all I got were squirrels, birds, and chipmunks. So I found this– I don’t want to kill them. I found an herbal birth control that I give to them every three days scattered on some food. But I’m seeing little ones now, so it’s not working 100%. And my friends all think that they’re going to chew up my wires and destroy my house. So I don’t know what to do at this point.

IRA FLATOW: Bobby, is that correct?

BOBBY CORRIGAN: Well, you make a very important point. And that is, chew up the wires. The word rodent actually translated means to gnaw. And so, a rodent is a gnawing mammal, and they do like to gnaw on wires. And it can cause fires and shortages. So it is important that you don’t allow any rodent– squirrels or rats– to live below your house for that exact reason as you mentioned.

The best advice would really be call in a good professional in your area, and they have the expertise to come in and live trap and remove those animals. If you do not want them killed, that can be done. You just state that service, and that can be done. That’s the best way to approach that.

IRA FLATOW: All right. There’s good advice for you, Susie. Good luck.

SUSIE: OK. Thank you.

IRA FLATOW: Yeah. I have I have discovered in my back yard that I have a lot of rodents as you mentioned. They chew on your barbecue wires.


IRA FLATOW: Because if you leave the grease inside, right?


IRA FLATOW: In your barbecue, they go after that. And then they say, hey, some wire here.

BOBBY CORRIGAN: Yeah. And sometimes wires also look like vegetative stems. So they’re– forget the pun, but they’re hardwired to be attracted to that shape. That linear long thing looks like a stem.

IRA FLATOW: When New York City published this job posting for its first rat czar, remember that few weeks ago, it went viral. It became a pop culture moment of its own. Bobby, did you think about applying at all for that job?

BOBBY CORRIGAN: No. You know, a czar, a governmental czar, is someone that’s great at organizing things, getting parties together, forming plans, and this kind of thing. But I’m a rat scientist, not an organizer or a planner and this kind of thing. But I think it’s great that the city of New York took that step to actually spot the importance of having a czar that’s going to get everybody organized.

IRA FLATOW: But the rat czar has no experience in pest control I understand.

BOBBY CORRIGAN: I’m not sure they would necessarily have to, although they’re going to go through a fast course in what it’s all about, and already have, and it’s biology. And so, their czar is trained in biology and so forth. I think they’re off to a running start.

IRA FLATOW: All right. Let’s go to David in Pittsburgh. Hi, David. Well, maybe– David, are you there?


IRA FLATOW: Hi. Go ahead.


IRA FLATOW: Hi there.

DAVID: Hi. I have not heard you mentioned that rats harbor fleas, which can be very dangerous carrying bubonic plague and things like that. I think rats were implicated in the Great Plague.

BOBBY CORRIGAN: Yes, it’s true. They carry ectoparasites– fleas, mites, and ticks, these kinds of animals. And so, from that aspect, it is important not to have them, again, close to us. Because it may not be the rat themselves that transmits a particular pathogen. It could be a flea. So, in general, the rat being close to humans beings is not a desirable situation.

IRA FLATOW: Bethany, managing trash it seems to be is key here. Because–


IRA FLATOW: –we leave it out. I mean, aren’t we as guilty as– we can’t blame a rat wants something to eat. Right? Get something to eat.

BETHANY BROOKSHIRE: I mean, if you’re going to leave Thai food sitting on the corner like that, of course. Who wouldn’t? Yes, I think the rat czar, as Bobby said, the big issue is going to be managing people. And a lot of that people management is managing the sanitation in New York City– trying to get rid of those piles of black trash bags that pile up on the corners every single night.

IRA FLATOW: Let’s go to Cecily in Cambridge. Hi, Cecily. Welcome to Science Friday.

CECILy: Oh, hi. Thanks for having me on. I just wanted to talk about the fact that it’s critically important to consider the impact of rat control on raptors, on Hawks, and eagles, and owls, and other wildlife. They’re the natural predators. They’re the natural pest control. And they’re being poisoned at a really frightening rate.

Where I live in Cambridge, Massachusetts, you see poison. It’s out of control. You see black bins in every yard. I’ve counted 100 bins placed along an avenue when a town is doing utility work. And what happens is the poison accumulates in the tissue of the rats, and a weakened dying rat is an easy prey.

So birdwatchers and park-goers here saw, for example, a family of great horned owls that raised and fledged two owlettes, and then the whole family was poisoned– found having bled out. These are anticoagulants, so they bleed internally. You bleed to death.

An eagle was recently found just a couple of weeks ago who people had been watching– she was getting ready to nest. She was found on the ground, rushed to rehab, impossible to save her. 90% of red-tailed hawks who are brought in to the tough veterinary clinic here have these SGARs, these anti-coagulant rat poisons in their bodies. So this has to stop.

IRA FLATOW: OK. Bobby, you–

BOBBY CORRIGAN: Yes, it’s a great comment. It’s a very important comment. In fact, I think it’s an ecological imperative that this is addressed. Right now, the Environmental Protection Agency is studying the issue in detail as to look further as to what intense restrictions are going to have to be implemented against these Second Generation Anticoagulant Rodenticides, SGAR as you mentioned.

So this is fully queued up right now, and there’s a lot of attention on it. It’s too bad it took so long quite frankly. But for sure, changes have to be made in the use of these rodenticides. For sure.

IRA FLATOW: Well, what is the best way then?

BOBBY CORRIGAN: Well, honestly, the best way, Ira, is what’s called integrated pest management. And that means, as Bethany stresses in her book, and others, is you don’t feed rats. These are mammals. If there’s no food, there’s no rats. And if you reward rats by them coming to your property, just because one of your garbage cans is sloppy, they know that reward. They come back to that same spot over and over and over again. So the best place is sanitation is rat control literally.

IRA FLATOW: Bethany, do you agree?

BETHANY BROOKSHIRE: Yes, absolutely. And I also wanted to note that the second generation anticoagulant rodenticides that she was talking about have already been banned. In California there’s currently a ban, and they just got permanently banned in British Columbia in Canada.


BETHANY BROOKSHIRE: So that’s absolutely ongoing.

IRA FLATOW: Let’s go to Stanley in New York. Hi, Stanley.


IRA FLATOW: Go ahead.

STANLEY: Well, in Istanbul there are no rats. There are millions of cats. Same in Tel Aviv. Tel Aviv, there’s lots of cats. There’s no rats. There’s no mice.

I live in Manhattan. OK? Mostly in the Chelsea village area. I’m on the Upper West Side right now for another month or so. I noticed the rats here are larger than the ones downtown. But I believe the only thing that really takes care of rats is cats, owls, hawks.

I know New York City at one time had an owl program, doing hunting for rats in Central Park. I know in Washington Square Park, the Parks Department no longer puts out poison. They find the holes. They put dry ice in the holes of the rats. It sucks out all the oxygen, and the rats die below in the ground.

And if you have an apartment, there’s three apartments on a floor, the apartment on the right and the left have cats, there’ll be mice in the center apartment.

IRA FLATOW: All right. All right. Let me get a comment. Bobby. Let me just say that this is Science Friday from WNYC Studios.

BOBBY CORRIGAN: So all those comments, all those techniques that were just mentioned, they have a place. And that is the trick about the rat. You need a multipronged approach to doing rats in cities.

And once you have a city, for example, though, it’s very difficult, in a city, to introduce lots of predators that are going to have space to prey upon the rats. The rats can duck below cars. They duck down a sewer. They can duck down into a wall void. So it’s not as easy as getting hawks, and owls, and cats, and dogs, and this kind of thing. Although, here and, they’re all going to contribute. But the once they’re in the cities, the best thing we can do is eliminate the food.

IRA FLATOW: And where do rats live in the country.

BOBBY CORRIGAN: In the country–

IRA FLATOW: They dig rat holes? There’s a word, rat hole, right?

BOBBY CORRIGAN: That’s right. Burrows.

IRA FLATOW: Burrows.

BOBBY CORRIGAN: Right. And as Bethany mentioned, the brown rat, the rat we have in most of our cities, they are burrowing species. Where they came from, they were burrowing into the ground. They construct an underground burrow of six feet long. Nest is in the middle. They prefer to borrow in good soil. That’s their natural home–

IRA FLATOW: But they– we talked– I’m sorry.

BOBBY CORRIGAN: But they’ll take anything. They’ll adapt. Like the hollow trees they’ll do. They’ll do ceilings. That’s part of their success. They will take whatever they can get.

IRA FLATOW: Bethany, I think it’s interesting that New York City has had a rat problem forever. But this is the first czar the city has ever hired. Why now? What’s going on?

BETHANY BROOKSHIRE: Honestly, I think some of it is that now the rats are being visible to people who are richer or of higher economic status. Because people have been dealing with the effects of rats, especially people who are living unhoused, especially people who are living in public housing forever– forever. There are reports that you can find of babies being bitten by rats at home while they’re napping. And this was, I think, in 2018. There was a report on homeless shelters in 2015 that described them as overrun with rats. But I think it’s only when people who aren’t living on public assistance start complaining that we get these problems.

IRA FLATOW: Has COVID people, staying home– Bobby, has COVID had any effect on the rats coming out or being visible?

BOBBY CORRIGAN: COVID, especially during this shutdown, had tremendous impact on the rats. I was out doing surveys, for example, and when all the restaurants closed down and there were no bags of food, the rats pretty quickly learned where is the gravy train. And so, what we started noticing, the rats were leaving the areas where the food used to be abundant and spreading out towards residential areas where people were at home and putting out their garbage. And I suspect– although I have no empirical numbers to share, but I suspect– millions of rats died as a result of the pandemic just from their own stress of fighting over the little tidbits of food that were left behind when everybody evacuated the city.

IRA FLATOW: Yeah. There was that iconic picture in New York of the rat with the piece of pizza going down.


IRA FLATOW: But they are very smart, aren’t they?

BOBBY CORRIGAN: They are. And there’s a lot of good research to show how intelligent they are. And I have evidence with my wild cams. We’re showing them picking up sticks to set off rat traps, then setting off the trap, and getting the bait after it’s set off.

IRA FLATOW: Tool maker. Tool users.

BOBBY CORRIGAN: There are tool users. Good publications, refereed publications on rats using tools. We’ve taught them to drive little tiny cars. At Richmond University in Virginia, they did experiments where you put them in a little tiny car. They have to push the gas pedal, turn the steering wheel to get to the food.

IRA FLATOW: Bethany, last word?

BETHANY BROOKSHIRE: Yeah, I think we really need to appreciate rats for being the incredibly adaptable, wonderful little critters that they are and then realize that a lot of the control issue is us.

IRA FLATOW: There you go.


IRA FLATOW: It’s us. Thank you both for taking time to be with us today. Bobby Corrigan, urban rodentologist and pest consultant here in New York. Bethany Brookshire, science journalist and author of Pests– How Humans Create Animal Villains. Thank you both.

BOBBY CORRIGAN: Thank you, Ira.


IRA FLATOW: And if you’d like to read an excerpt from Bethany’s book go to sciencefriday.com/pests.

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