How Common Are Rats?

Several studies indicate that there is roughly one rat for every person in the United States, and the ratio is similar in other nations. A study conducted in the United Kingdom in 1909 indicated a similar ratio, although the results of that study have been periodically challenged. Many of the 56 species of rats live in the wild and do not tend to thrive in areas inhabited by humans.

More facts about rats:

• New York is considered one of the more rat-infested locations in the United States, with rats thriving in sewers, subways and other areas of the city. Several studies indicate a one-rat-per-person ratio there, although there are some differences in certain sections of the city.


• In 1972, the U.S. Government adopted the one-rat-per-person ratio as the standard for evaluating rat populations in cities and other jurisdictions.


• A rat's litter can include as many as 12 offspring. Rats typically are born 21 to 23 days after the mating took place.

Frequently Asked Questions

How widespread are rat populations globally?

Rats are one of the most widespread and adaptable mammals on Earth. According to the Integrated Taxonomic Information System, there are over 60 species of rats worldwide. They thrive in a variety of environments, from rural to urban areas, and are particularly prolific in cities due to abundant food sources and shelter opportunities.

What is the estimated number of rats living in urban areas?

Urban rat populations can surpass human populations in some cities. For instance, in New York City, it's a common myth that there are as many rats as people, although scientific estimates suggest there may be closer to 2 million rats, a fraction of the human population, according to a study by Jonathan Auerbach published in Significance magazine.

Are rats found in all parts of the world?

Rats are found on every continent except Antarctica. The Norway rat and the roof rat have spread to all parts of the globe, primarily through human travel and trade. They are highly adaptable and can live in a wide range of climates, although they prefer temperate zones, as per the National Pest Management Association.

How do rat populations affect ecosystems?

Rats can have significant impacts on ecosystems. They are known to prey on native wildlife, including birds and their eggs, small mammals, and reptiles. This predation can lead to declines in native species, particularly on islands where ecosystems are more isolated. Rats also compete with native species for food and habitat, as noted by the U.S. Fish and Wildlife Service.

What diseases can rats transmit to humans?

Rats are vectors for numerous diseases that can affect humans, including leptospirosis, hantavirus, and the bubonic plague. The Centers for Disease Control and Prevention (CDC) warns that rats can spread diseases directly through bites and indirectly by carrying fleas and ticks that transmit infections to humans.

How can rat populations be managed or controlled?

Effective rat population management involves a combination of sanitation, exclusion, and population control measures. Sanitation reduces food and water sources, while exclusion involves sealing entry points to buildings. When necessary, population control can be achieved through traps and rodenticides, although these methods should be used responsibly to minimize risks to non-target species and the environment, as recommended by the Environmental Protection Agency (EPA).