Unfortunately, rats love Chicago. In 2017, the city’s 311 service received 2.6 times more rodent complaints than New York City, according to data analyzed by real estate site RentHop. There is some good news though: the complaints were down in 2018. But not enough to knock Chicago from the top of the list.

The “abundance of garbage and buildings” in Chicago provide shelter and food, the study says. Other cities on the list offer that too, so we believe there’s another reason for our exceptional rat problem: Midwest rats are just hardier.

The common species in Chicago and other parts of the U.S. is known as the Norway rat. The city’s website warns: “They can crawl through holes the size of a quarter, tread water for three days, and fall unharmed from a five-story building.” Yikes.

In 2018, the city received 40,057 rodent complaints through CHI 311 which is about 20 percent less than the previous year. Overall, that’s good news.

However, looking at the beginning of 2019, there’s a 7 percent increase compared to the same time period last year. From January to July this year, the city had 21,991 rat complaints. In general, there tends to be more reports of rats from early spring to July. The numbers dip in winter, which makes sense because rats move less in cold temperatures.

This past winter was brutal with the polar vortex’s record low temperatures, and to answer your question, no the weather did not kill off a significant part of the population. The rats have adapted, the Chicago Reader explains.

The study also examines rat complaints by neighborhood, which can be seen on an interactive map, but it’s hard to say which areas truly have the most rats versus vigilant residents reporting problems to the city. Plus, the city launched a new website and mobile app for 311 which made it easier to make reports and could account for spikes in certain areas.