As temperatures rise in New York City, so does rat activity and the chances that New Yorkers will see them.
City officials have touted declines in rat sightings in recent years after previous Mayor Eric Adams launched an aggressive anti-rat campaign, including a trash containerization program and the appointment of a “rat czar.”
But estimates suggest there are millions of rats across the five boroughs. And warmer weather can make them more visible, according to Caroline Bragdon, who leads neighborhood interventions for pest control at the city’s Department of Health and Mental Hygiene.
“As all New Yorkers move outside and spend more time outdoors, of course, there’s also a higher likelihood that they’re going to see and observe rats,” she said.
Experts said several factors drive the seasonal increase in sightings: rats’ breeding cycles, less cautious behavior among juvenile rats and more people spending time outside.
Rats can breed year round under the right conditions. But colder winters can slow reproduction, particularly for rats living outdoors, according to rodentologist Bobby Corrigan.
“They’re going to shut down the reproduction because it’s too dangerous to try to have a family of pups [baby rats] and pups will be exposed to the super cold like we had this winter,” Corrigan said. “Winters reduce the rat population for outdoor rats.”
Corrigan, who has also worked with the city as a consultant on rodent control, said peak breeding periods typically occur in the spring and fall.
Human behavior also plays a role in rat activity.
“People start sitting out more in the springtime and having picnics, and people being people, some people are not exactly tidy with their outdoor activities,” Corrigan said. “Rats benefit from anything that we spill or leave behind or [when we] forget to empty a garbage can, those typical scenarios that living in a city brings.”
Bragdon said rats are primarily outdoor burrowers, but they can enter buildings — as New Yorkers are well aware. She recommends frequent inspections, sealing gaps around doors and vents, and keeping food and trash securely contained.
“You will definitely know if you have rats in your apartment, your building or your block,” she said. “We do want New Yorkers to recognize the signs of rat activity, and the telltale signs are rat droppings, rat burrows, gnaw marks, runways. You may see rub marks.”
New Yorkers can also check the city’s rat map to see reported activity in their neighborhoods.