Introduction
I live on a particularly ratty block in Prospect Heights, Brooklyn. As a result, I took special notice when the city announced that it had hired a rat czar on April 12, 2023. My own observations since the hiring indicated to me that not much had changed, and I wanted to see if I was right. My research question is: did the hiring of the rat czar in April 2023 have any impact on the amount of rodent complaints in New York?
To answer this question, I used the 311 data set. This data set is a collection of all the 311 complaints made online or by phone by New Yorkers, with each row being its own unique service request. I wanted to look at one year before the hiring of the rat czar, to get an idea of complaints pre-hiring, and one year post-hiring, to see if the rat czar was successful in her quest to mitigate the rat population. The rat czar was hired on April 12, 2023, however I chose to start my data set on the first of May, so that every month had a full month of data. After filtering by “created date”, I then filtered “complaint type” by “rodent” and downloaded the data set to get all rodent complaints from May 1, 2022 – May 1, 2024. While the term rodent can encompass many different animals, I found that in the descriptors category, rat and mouse were the only mentioned animals. Additionally, while the rat czar is publicly known for rats, the job does encompass all rodents and I wanted to see how her work may or may not have impacted different types of complaints related to rodents (Dubner).
Something that is important to note is that the hiring of the rat czar was highly publicized across many different media outlets. The mayor wants to make rat mitigation a key component of his administration, therefore this hiring was widely advertised (Mays). As a result, it’s possible that there might have been more of a bias towards complaints in the aftermath of the hiring. This is because so many people were aware of the hiring and might have been more likely to file a complaint since they knew that someone was working on the issue. Another important bias to note is that each entry in this data set exists because someone made a complaint. Some people might be fearful of making a complaint, for fear of retribution due to their legal status or for any number of reasons. Because of this, it’s also important to note that the number of rodent complaints might not always perfectly correlate with the actual number of rats.
Visualizations
This bar graph displays the total number of complaints by month from May 1, 2022 – May 1, 2024. Over time, there’s a clear trend where complaints peak in the summer and then go down in the winter. This makes sense since rats, like people, will spend less time outside in the winter and more time outside in the summer. The total number of complaints between the two years measured did go down by about ~800. This is a positive sign that the rat czar might be having some effect, especially since there might be a potential bias towards more complaints given how heavily publicized the rat czar was. However, overall, that decrease is fairly negligible since overall complaints hover in the 40k range.
This line graph displays the number of rodent complaints by a sampling of community boards from May 1, 2022 – May 1, 2024. I selected one board from each borough, either picking a board that had an interesting trend or was the most populous board in that borough. Most of the community boards follow the same trend of a higher volume of complaints over the summer and less over the winter. Brooklyn 1, however, has a much higher spike in the summer of 2023, after the rat czar started. This community board includes Williamsburg, which is a very dense area with a lot of restaurants and nightlife, probably then leading to more trash and therefore more rats and complaints.
According to the rat czar, controlling the amount of trash on the street is the best way to mitigate rat populations (Dubner). Trash containerization started as a pilot project in Manhattan Community Board 7 in September 2023 so I wanted to include this area (Lu). This program put large trash containers on the street so that garbage bags would no longer be left on the street and rats would no longer be able to get to it. For that community board we still see the same trend of higher complaints over the summer and less over the winter, however the summer peaks are dramatically lower in 2023 and there was a steep drop in the month after trash containerization began. This is a promising sign that trash containerization might be an effective strategy for rat mitigation.
This stacked bar graph shows the total number of rodent complaints from May 1, 2022 – May 1, 2024 divided by the location of the complaint. Most of the different location types take up a similar share of complaints from month to month. Residential buildings take up the greatest share of complaints, this makes sense since people are more likely to file a complaint if there are rats around their home. There are a couple of interesting things to note, however. The relative share for commercial buildings went down as well as the relative share for construction sites, which the rat czar cited as a priority area for keeping rats out of (Dubner). This is another indicator that targeted mitigation efforts might be impactful.
These two pie graphs show the share of types of rodent complaints, with one graph showing May 1, 2022 – May 1, 2023 and the other showing May 1, 2023 – May 1, 2024. The share of types of rodent complaints from year to year was fairly consistent, with the majority of complaints having to do with rat and mouse sightings and the rest having to do with signs of rodents or conditions attracting them. Rodent sightings as a main driver of complaints makes sense since seeing a rat would be more of a motivator to make a complaint.
Conclusion
This was a really interesting topic to look into. The number of rats in the city is an important public health and quality of life issue and it’s important to see if publicly funded programs are actually working for our benefit. I did a little bit of outside research, mainly a podcast episode with an interview of the rat czar, and I found that the rat czar also uses 311 data to measure the efficacy of rat mitigation programs (Dubner)! While this data set isn’t perfect, it was fun to learn that the rat czar and I are using the same data.
Based on the number of rodent complaints in the 311 data, overall the number of rats in the city has probably not gone down in most neighborhoods. That being said, there are some exciting new projects underway that show promising signs of being effective that will be implemented in the rest of the city soon. No matter how hard we try, we share this city with the rats and they will be here as long as we are.
Sources:
Dubner, Stephen J. “Can New York City Win Its War On Rats.” Freakonomics, Stitcher, 21 Feb. 2025,
Lu, Miranda. “West Harlem Trash Containerization Pilot Program Declared Successful, Citywide Rollout to Begin next Year.” Columbia Daily Spectator,
Columbia University, 24 Oct. 2023, Mays, Jeffery C. “She Has One Job: Get Rid of the Rats.” The New York Times, The New York Times, 12 Apr. 2023,
