Rats in New York City

Rats in New York City are prevalent, as in many densely populated areas. For a long time, the exact number of rats in New York City was unknown, and a common urban legend was that there were up to four times as many rats as people. In 2014, however, scientists more accurately measured the entire city's rat population to be approximately only 25% of the number of humans; i.e., there were approximately 2 million rats to New York's 8.4 million people at the time of the study.

The city's rat population is dominated by the brown rat (also known as the Norway rat). The average adult body weight is 350 grams (12 oz) in males and about 250 grams (8.8 oz) in females. The adult rat can squeeze through holes or gaps the size of a quarter (0.955 inches (24.3 mm), jump a horizontal distance of up to 4 feet (1.2 m) (or vertically from a flat surface to 3 feet (0.91 m)), survive a fall from a height of almost 40 feet (12 m), and tread water for three days. Each litter has up to a dozen kittens. Rats can mate at the age of two or three months and produce a new litter every two months. They live about a year.

New York City rats carry pathogens that can cause diarrhea, vomiting, and fever in humans, especially in children. The pathogens they carry include bacteria such as Clostridium difficile (C. diff), Salmonella, E. coli, and Leptospira. Bartonella bacteria cause cat scratch disease, trench fever, and Carron disease. These bacteria may be spread through contact with rat feces, saliva, or urine. Rats can carry disease-causing viruses such as sapoviruses, cardioviruses, kobuviruses, parechoviruses, rotaviruses, hepaciviruses, and Seoul virus. Rats carry fleas that are vectors of diseases such as bubonic plague, typhus, and spotted fever. In addition, some people have an allergic reaction to the presence of rodent feces, hair, or urine.

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