Bobby Corrigan
Appearances
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Rodents like to hug walls so they feel safe and secure. So that's a very clear sign. And if you came here between 10 and 2 tonight, chances are good you might see a rat running along there.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
I want to be humane to this animal because I respect it. But if you put a rat on my airplane when I'm flying over the seas to Paris, I want that rat dead in any way possible.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
My wife, when we go out to eat, before we step into a new restaurant, she'll say, is it safe? These days, I wish I didn't know what I know.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
This is classic right here. Someone just came recently. They sat down to have their little snack. Human beings, I don't know, what I've read is 20% to 25% of us as a species, we do that behavior. That 25% is all the rats need. Probably it's triple what they need. The rats that live here will come out and say, well, how much was left in that wrapper? And the answer is enough for them tonight.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
We can't have this behavior, but we can't get away from it. No matter what posters you put up, please don't litter. Please do your trash right. Human beings, some don't care. Leave me alone.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
So this is a very smart thing for a city to do, is what we see here with this new bank of containerization that instead of leaving bags on the curb, they get put into a bank. The key thing is to make sure that if a car hits this or dents it or breaks it, that's going to be expensive, right? So everything's going to have its pluses and minuses.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Long-term sustainability, this is going to save hundreds of millions of dollars for a city. This is the most environmentally smart thing you could do, the most humane thing you could do. If the rats want to move on to some other place, go for it.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
You know, birth control on paper sounds pretty darn smart, right?
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Everyone thinks there's a rat world below our feet. And to some degree, that's true. But rats have a very specific subterranean environment they need.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
I have eaten a rat, but I'm going to tell you. That I cheated.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
And the way I cheated is I have a friend who works in a laboratory studying drugs and pharmaceuticals, and they use it on rats. So I just said, can you bring me a rat? So I ate a laboratory rat, but it's the same species. It's the same muscle tissue. It's the same everything. So technically, did I eat rat? Yes. Did I eat Norway rat? Yes.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
But did I eat wild Norway rat off the streets that may have come out of a sewer? I would be very dumb to do that. It's full of internal worms, viral, you know, it's disgusting. I would know you'd be dumb to do such a thing.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Yes. But here's the thing, all mammal muscle tissue, right? It's not that different.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
I guess I've always been a nature nerd. I was the kid that was in the backyard frying the ants with the magnifying glass while my brother played football. And so I've always followed that path of creepy crawlers and animals that were mysterious but cool and things we didn't know much about.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
I would put it at about 50-50 that we're going to see at least a couple of rats.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Rats love parks because the Norway rat is actually from Mongolia. And in Mongolia, their life was to burrow into the soil of the fields of Mongolia. So their brain says, get into the earth, right? Geotropic positive, get towards the earth. Squirrels are geotropic negative, climb trees away from the earth. So it's a situation where parks, if the soil is healthy, which it has to be for a park,
Freakonomics Radio
623. Can New York City Win Its War on Rats?
to keep the plants growing, the rats get down, they'll dig a hole, you'll see a hole probably, we'll find one here shortly.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Rodents are really great examples of work hard and you'll be successful, right? So these animals, they're constantly digging in soil, constantly constructing burrows, constantly seeking food, you know, they get it done. And so when people say it's so hard to get rid of rats, it's like, that's right, because you're up against a hardworking, intelligent, small rodent that we don't appreciate enough.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
I'm constantly thinking, you know, we could actually do things like rats a little bit more, as crazy as it sounds, and our species, Homo sapiens, would be better for it.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
When this city goes quiet, that's rat time. It's like when they're inside buildings and they're in the walls, how do they time their time to come out? When the plumbing stops. So when people get ready for bed and they brush their teeth and they use the showers and then all of that stops in the building, that's their time. When it starts up again in the morning, it's back to bed.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Animal behaviorists will say, you know, when we do study rat colonies, we're studying ourselves. It's very true. When you put rats under stress, they get aggressive. We get aggressive under stress. What causes people to, you know, be happy, be sad, be anxious? All of those things play out in the rats as well.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
You know, it's kind of crazy. I came from a poor family. I had no money to go to college, so I answered an ad in a newspaper for an exterminator in New York City. And the new guy gets the good job, right? So they put me in the sewers to hang rat poison. I was frightened to death, to be honest with you.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
So when I got into grad school and I signed on to studying rats as my species, I moved into barns that were full of rats. This was in Indiana. And farmers would tell me, you know, we're always fighting rats. So I asked if I could just move into their barn. I would camp literally on the floor inside these rat-infested barns. And over time...
Freakonomics Radio
623. Can New York City Win Its War on Rats?
It's a whole crazy experience that you get to realize just how amazing these mammals are. I have to say, looking back, it was some of the most exciting years of my life. I say that with all seriousness.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
I use the term long rodent. We all know what long COVID means. Well, long rodent is, you know, once the colonies have become comfortable and had many, many families, they're laying down all kinds of pheromones with their bodies. They'll call any new rats into that area. They also have memories of their own neighborhoods, just like we do.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
So those neighborhoods, once they become really infested, there's a reason for that. The rats have found this works for us. And that's going to continue and be passed on to generation after generation.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Poisons, they're called rodenticides, meaning to kill rodents, are a primary tool that everybody uses to try to kill any rats that they see around their property. But Corrigan says this obvious choice is often the wrong choice. You would want to start first with not attracting the rats with food or clutter in the first place.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Poisons are probably the last resort that should be approached when it comes to rat control. It's an environmental thing.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
When I read that, I said, well, I am worried about this owl because I know the owls of the parks, they are preying upon rats and mice out in the parks and may be feeding on these poisons.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
And that's because the rats nearby got below the sidewalk, tunneled into this area, dug out the soil so they could have a burrow in this area. And now there's nothing supporting these heavy concrete pieces. It's expensive to put in a new curb.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Traps, if they're... applied by someone who's experienced, and it really does take experience. The rat's a very wily mammal, and it's very smart. It's not as simple as going to the hardware store, buying a rat trap, putting it out with a glob of peanut butter, and saying, that's it.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
So traps can be useful when done by experienced people, but we have to acknowledge that many of them are simply inhumane, especially glue traps. You know, if you ever sit and watch a rat or a mouse struggling on glue, it's not a pretty sight whatsoever.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
So it has great optics. You know, we don't have to use those bad poisons and the traps that are inhumane. So why not just, quote, give them the pill? But you have to get the birth control materials to large groups of mammals. And in cities, we have what's called open populations of rats.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
That means you can have colonies living in sewers, rats living in parks, rats living in basements, rats living in subways. How do you get the birth control to all these colonies? Are you bailing out the ocean with a teaspoon, I guess is the best way to put it.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
We haven't addressed this issue in 300 years. We've looked at these rats as just kill them, just put out poison, just trap them. No science has gone into this, but the compass is finally pointing in the right direction.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Just five feet away, we have the proverbial catch basin that the stormwater drains down. And sometimes you'll see rats come right out of these sewers. Their home is in the sewer in the middle of the street.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Within our first couple of weeks of being in the position of rat czar, we met for coffee. And Kathy said, what if we bring in all the scientists from around the U.S. and even maybe around the world to talk about this issue? And from there, it took off.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
We can leave these sensors in place. They're going to work 24-7, 365. No benefits are needed. You know, we're not going to pay them overtime, none of that. But they're giving us data.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
Okay, so we're outside in New York City looking at what we call active rodent signs, or ARS.
Freakonomics Radio
623. Can New York City Win Its War on Rats?
I want to show you something much more interesting. You'll notice along this building perimeter, if you let your eyes just continue along, you will see the gray concrete that's light. But next to the building, you'll see this dark charcoal stain that's linear. Right. The stain goes around, hugs the building. That is from rats. That's what's called a sebum stain.