Meet Kathleen Corradi, New York City's New Rat Czar : Short Wave This week, New York City crowned Kathleen Corradi its first rat czar. The new position is part of a multipronged approach from city officials. Reporter and New Yorker Anil Oza called up rodentologists to understand — does their approach withstand the test of scientific research?

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New York City appointed a rat czar. Her job will be a tall ask

New York City appointed a rat czar. Her job will be a tall ask

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This week, New York City appointed the first rat czar, Kathleen Corradi, in the latest step in a years long battle against the city's rat population. Rodentologists say that an effective plan will take thinking outside of the usual pesticide box. Lindsay Elliott hide caption

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Lindsay Elliott

This week, New York City appointed the first rat czar, Kathleen Corradi, in the latest step in a years long battle against the city's rat population. Rodentologists say that an effective plan will take thinking outside of the usual pesticide box.

Lindsay Elliott

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New York City Mayor Eric Adams has been locked in a multiyear war with millions of his constituents.

"Everyone that knows me knows one thing: I hate rats," he said in an October 2022 press conference.

Eradicating rats has been a consistent talking point for Adams. Just this week he appointed his new right hand in the battle against rodents, Kathleen Corradi. Corradi has worked in the city's public school system for years. But experts say that Corradi's new job to "fight the real enemy — New York City's relentless rat population" will be a tall order. That's partly because research on urban rats is slim, and partly because that slim research points to a penchant for being elusive.

While rats have been a perennial problem in New York City, complaints have increased over the past two years. When restaurants shuttered their doors in the early pandemic, less food waste was available to rats. Many rats were forced to change their behavior or migrate to new areas, which led to fewer rat-related complaints.

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Then restaurants reopened. "When the restaurants reopened, we had a problem because the few rats had actually made that migration and were successful in finding new places. Guess what? They've placed their little flag in a new neighborhood and a new resource. Now once that flag is there, it stays," says Michael Parsons, an urban ecologist at Fordham University.

Know your enemy

Parsons says that the New York City plan doesn't follow the science. He's written a five step playbook to get rid of the city's rats. It all starts with the tried and true "know thy enemy."

"That really is about understanding the biology of our enemy," he says. Unlike the many studies that have been conducted on lab rats, less is known about their wild, urban counterparts.

What researchers do know about rats points to one key equation: garbage in = rats out. Part of the New York City government plan is to reduce the number of hours garbage sits on street curbs by making people put their garbage out later in the evening. However, this may not be effective at minimizing rat feasts. That's because brown and black rats – the types located in New York City – are biologically nocturnal.

"The majority of rats don't care because they're asleep. They're waiting for the picnic to happen in the evenings," Parsons says.

The importance of understanding rats in order to eradicate them is also why Parsons says he's concerned that Corradi is not a rodentologist. But, he says, she still deserves the chance to rise to the occasion.

Think outside the rat trap

Current rat eradication strategies focus on killing rats. But researchers say it's time to move from mitigating the symptoms of a problem — like an overabundance of rats — to tackling the root of the problem.

"We need to not just be thinking about 'How do we eradicate rats?'" says Kaylee Byers, a senior scientist at the Pacific Institute for Pathogens, Pandemics and Society. "We've been doing that for thousands of years — catch, kill, repeat — and it's not working." Instead, she suggests officials consider a more holistic approach, tackling how "rats intersect with other aspects of urban planning in the city — waste management, green spaces, transit, housing."

Part of launching a successful rat eradication campaign is investing in new research.

Byers notes there are no surveillance programs that track the movements of rats or how their populations fluctuate over time. "I would set up camera traps underground in the burrow system, so you could actually watch how urban rats interact with each other. Those interactions are really important to understanding how diseases are transmitted among rats," Byers says.

As part of her research, Kaylee Byers tracks the movements of local rats in Vancouver, Canada. After the rats are caught, samples are taken and then re-released to where they were caught. Lindsay Elliott hide caption

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Lindsay Elliott

On an even more fundamental level, Bobby Corrigan, a pioneer of the urban rodentology field, argues there needs to be research into the population biology of these rats. That would help officials uncover the full scope of rat dwellings within the city and how they interact.

"There's a whole city below the city — and then maybe an older city below that city. And so we have these rats that occupy all the spaces. They occupy ceilings in some of the most modern skyscrapers in any city around the world," he says. "When someone initiates a campaign to control the rats of a neighborhood, well, what does that mean? Are we controlling the surface rats? What about the subsurface rats?"

Inspiration — and more rats — half a world away

New York City isn't the only locale to take aim at its furry inhabitants. Rodents are a global problem. One particularly ambitious bid against the rats comes in the form of New Zealand government's Predator Free 2050 program. It aims to eradicate other invasive species, like possums and stoats, in addition to rats.

"You have to admire these animals. They are pests because they are just so good at doing what they do," says Dan Tompkins, the science director of Predator Free 2050. "They get everywhere and they can survive in most places."

The initiative has had some early success, in part, because of its ability to engage many people across communities – not just pest management professionals.

"We're trying a nationwide eradication, and so we quickly realized that to get this job done, you've got to have the engaged support of communities. So you can't follow the old model of going in and having a plan and dictating top down how it all happens," he says.

This also points to one potential drawback of creating a sole New York City rat czar: It spotlights the actions of a single person instead of collective action.

In the end, Corrigan says successfully reducing the number of rats in the city requires one more mental shift — toward rodent appreciation.

"We really underappreciated this mammal and ... we're paying a very high price for that," he says. "I'm surprised to some degree it's not worse, you know. But if you're a rat or a rodent or a mouse or something and say, look, we're doing what you're trying to do, we're trying to increase our species as fast as we can. That's what every mammal is trying to do."

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This episode was produced by Liz Metzger, edited by Rebecca Ramirez and fact-checked by Brit Hanson.