Good News New York: Humans Outnumber Rats In The City 4 To 1

November 5, 2014 | Prachi Gupta

There are some New York urban legends that we know are preposterous — like the carnivorous alligators dwelling in the sewers or the ghost ship that haunts the Hudson River — but the most persistent and believable of all rumors is that rats outnumber humans in the city. Well, rest assured New Yorkers, because Jonathan Auerbach, a statistics doctoral student at Columbia University, has found that this isn’t the case.

LiveScience reports that the rat population is actually around two million, only one quarter of New York’s eight million residents. And two million is a generous estimate. Here’s how Auerbach gets to that number:

The researcher looked at rat sightings on New York’s 842,000 property lots, during the first half of 2010 and then during the first half of 2011. The percentage of “recaptured” lots (or lots that had rat sightings in both 2010 and 2011) helped Auerbach determine that 40,500 (or 4.75 percent) of all New York’s lots were rat infested. Assuming a typical rat colony has 40 to 50 members, he estimated the total rat population in the city is 2 million. But even that number might be an overestimation, Auerbach said.

It’s an overestimation because Auerbach is assuming that every infested lot belongs to a separate colony of rats, when in reality it is possible that a single colony can occupy several lots. “This overestimation allows us to be confident that there are not 8 million rats in NYC,” he said.

This is good news and all, but let’s be real: If you had 2 million rat-sized horses versus one horse-sized rat, I think all New Yorkers would choose to battle the horse-sized rat. And that’s because two million of these creatures still feels like too many.

(Photo: Ludovic Bertron)