Can New York City Ever Win Its War Against Rats?

What do rats do in heat waves? Or to put it differently, what is it that they don’t do?

As temperatures have continued to stifle all will, and the humidity level has been Bangkok-in-a-thunderstorm-percent high, I raised the question with Kathleen Corradi, New York City’s first dedicated rat czar. The specific target of her enmity is the improbably named Norway rat, the dominant species in the city. Having no known association to Scandinavia, the name presumably galling to anyone living in Oslo, it arrived in New York in the late 1700s on ships coming from Silk Road trade routes and has defied efforts to evict it ever since.

Fifteen months since she was appointed by Mayor Eric Adams to bring the rat population under control, Ms. Corradi has walked and biked around the city, observing the situation with lawmakers, tenant groups and so on, and has analyzed the various methods and technologies available for making rats less visible. A few months ago, rat contraception seemed to hold a lot of promise. Still, she seemed dubious that it could ever turn New York into Calgary, which, like the rest of Alberta Province, remains one of the very few places on earth that is essentially rat-free, all 256,000 square miles of it.

But if the prevailing scent of summer in New York — something close to eggs left in a moldy basement before the first Bloomberg administration — suggests rodent activity at its most willful and aggressive, it is also true that heat functions as birth control of a kind. Rats are mammals, Ms. Corradi pointed out, and they find oppressively warm weather as enervating as we do. “Anything that causes them stress is good for our work,” she said. “A stressed rat is reproducing less. A happy rat is reproducing at a rate that science says we cannot exterminate our way out of.”

It is fair to say that Mayor Adams has made his revulsion to rats, both happy and unhappy, a big part of his brand. His vow to defeat them is one reason that the city is restructuring its outdoor dining program in ways that might effectively end it. The matter of dining sheds will surely come up over the course of two days in September when the city will hold what it is calling its inaugural National Urban Rat Summit. The objective of this unlikely assembling of academics, civic leaders from around the country and people in the extermination business is to brainstorm ways to outwit creatures maniacally adept at getting their needs met.

There are an estimated three million rats in New York, but in the absence of a proper census, there is really no way to know how many. One way the city measures its progress in eliminating them is by keeping track of the number of relevant calls to 311. In May, the Department of Sanitation announced that new rules to reduce the time that garbage spent on the street and new secure container requirements for all businesses, in effect since March, left rat sightings down in 12 of the previous 13 months compared with the year before. In Hamilton Heights, the northern edge of West Harlem, where a residential containerization effort was in a pilot stage, rat complaints decreased by 55 percent.