Rats in New York City are widespread, as they are in many densely populated areas. They are considered a cultural symbol of the city. For a long time, the number of rats in New York City was unknown, and a common urban legend declared there were up to five times as many rats as people. However, a 2023 study estimates that there are approximately 3 million rats in New York, which is close to a third of New York's human population. 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 1 inch (25 mm) wide, 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 hold their breath for 3 minutes. 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 Clostridioides difficile (C. diff), Salmonella, E. coli, and Leptospira. Bartonella bacteria cause cat scratch disease, trench fever, and Carrion disease. These bacteria may be spread through contact with rat saliva, urine or feces. Rats can carry disease-causing viruses such as sapoviruses, cardioviruses, kobuviruses, parechoviruses, rotaviruses, hepaciviruses, and Seoul virus. Rats may 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 hair, urine or feces.
Description
Species Rarely seen in daylight, rats have been reported in New York City since early colonial days. As recently as 1944, two distinct species were prevalent: the brown rat (Norway rat) and the black rat (ship rat, roof rat). Over the next few decades, the larger and more aggressive brown variety displaced the black rats, typically by attacking and killing them, but also by out-competing them for food and shelter. By 2014, the city's rat population was dominated by the brown rat. The brown rat is 16 to 20 inches (410 to 510 mm) long and weighs 1 to 2 pounds (450 to 910 g). It is brown or gray in color with a lighter-colored belly. It is nocturnal, and sleeps approximately 10 hours a day. The black rat is between 5 and 7 inches (130 and 180 mm) long (not including the tail) and weighs between 2.5 and 8 ounces (71 and 227 g). It is usually black to light brown in color with a lighter-colored belly.
Population
Rats are elusive by nature, and public health officials have not developed any reliable way to estimate their numbers. However, a 2014 study by Jonathan Auerbach, which was reported in the Royal Statistical Society's Significance magazine, estimated that there were closer to 2 million rats in the city. In 2023, another study by pest control company MMPC using Auerbach's methodology estimated that the rat population has since increased to nearly 3 million. This is close to a third of New York's human population. It conflicts with the often-repeated statistic that there are more rats than people in the five boroughs of New York City (8.5 million in 2023), with some estimates putting the number of rats far higher at as many as five rats per person (33.6 million). In 2014, the television channel Animal Planet named New York City the "Worst Rat City in the World". Compared to other cities within the United States, studies indicate New York is particularly well-suited for rats. This conclusion is based on characteristics such as human population patterns, public sanitation practices, climate, housing construction standards and other variables. Experts consider that the actual population of rats varies, depending on climate, sanitation practices, efforts to control the population, and season.
Genetics Studies have repeatedly failed to find restricted gene flow in Manhattan's rats due to the island's buildings. However Combs et al. (2018) presents a more geographically detailed analysis. They find that the island's buildings are restricting gene flow, especially in Midtown. Combs et al. found that there were genetically distinct clusters of rats north of 59th Street (in Upper Manhattan) and south of 14th Street (in Lower Manhattan), although both clusters were likely descended from rats imported from Britain.
Food and shelter Rats only require 1 ounce (28 g) of food and water a day to live. The rodents primarily find food and shelter at human habitations and therefore interact with humans in various ways. In particular, the city's rats adapt to practices and habits among New Yorkers for disposing of food waste. Curbside overnight garbage disposal from residences, stores, subway and restaurants, as well as littering, contribute to the sustenance of the city's rats. Rats nearly always use the same routes to their food sources. Rat infestations have increased as a result of budget reductions and more wasteful disposal of food. Rats burrow underground or create nests in suitable soft material, with a small group of rats in each nest. Brown rats in New York City prefer to live at ground level or basement level. They congregate in colonies of 30 to 50 rats. Rats live 100 feet (30 m) to 400 feet (120 m) from their food source.
Habits Unlike many mammals, the rat's skull is not plated together. This means it can change the shape of its head to squeeze through holes or gaps as small as a quarter (0.955 inches (24.3 mm)). They are able to leap 4 feet (1.2 m) laterally and can fall five floors without any injuries. An adult rat can tread water for three days. They typically travel tight, well-worn paths. Each litter has up to a dozen pups. Rats can mate at the age of two or three months and then produce a new litter every two months. The rats live for approximately one year, mostly due to predation rather than natural lifespan. They rarely travel more than 600 feet (180 m) from where they were born.
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