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Norway rat

The Norway rat (*Rattus norvegicus*), also called the brown rat, is a large, stocky rat that lives successfully alongside humans in cities, farms, sewers, and other disturbed habitats.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

The Norway rat (*Rattus norvegicus*), also called the brown rat, is a large, stocky rat that lives successfully alongside humans in cities, farms, sewers, and other disturbed habitats. Despite its common name, it is native to northern China and has spread worldwide through human activity. It is one of the most widespread rodent species and an important pest species in many regions.

Taxonomy and naming

The Norway rat is classified as *Rattus norvegicus* in the rodent family Muridae. Common names include brown rat, sewer rat, and wharf rat, reflecting its appearance and association with human environments.

Description

Norway rats are large, stocky rodents with coarse fur that is typically grey-brown to dark brown. They have a blunt snout, hairless tails usually shorter than the body, and a heavy body shape. They are generally larger and more robust than roof rats.

Range and habitat

The species is native to northern China and adjacent parts of Asia. Through human transport, it has spread across much of the world, especially in urban and agricultural areas. It commonly lives near people in burrows, sewers, cellars, wharves, and other sheltered places.

Behaviour and ecology

Norway rats are usually nocturnal, good swimmers, and strong burrowers. They are poor climbers compared with the black rat. They are highly adaptable omnivores and foragers, eating a wide range of foods such as grains, meats, fish, nuts, and fruits, which helps them survive in many environments.

Human importance

Norway rats are major urban and agricultural pests because they contaminate food, damage property through gnawing and burrowing, and can carry disease-causing organisms. Females can produce multiple litters per year, allowing populations to grow quickly. They are also used as laboratory animals and sometimes kept as pets. In Canada, they are established in urban, industrial, and agricultural settings and are monitored and controlled as invasive pests by public health and pest-management agencies.

Key facts

  • The Norway rat is a large, stocky rodent with coarse fur and a tail usually shorter than its body.
  • It is a highly adaptable omnivore and forager that thrives around human food and shelter.
  • The species is usually nocturnal, a strong digger, and a poor climber compared with the black rat.
  • Females can produce multiple litters per year, allowing populations to grow quickly.
  • It is widely regarded as an invasive pest and can damage structures through gnawing and burrowing.
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Canadian context

Norway rats are established in Canada and are common in urban, industrial, and agricultural settings. They are monitored and controlled as invasive pests by public health and pest-management agencies.

Frequently asked questions

What is the scientific name of the Norway rat?
The scientific name is *Rattus norvegicus*.
Why is it called the Norway rat if it is not from Norway?
The common name is misleading; the species is native to Asia, especially northern China, and spread through human transport.
What does a Norway rat look like?
It is a stocky rat with coarse brown or grey-brown fur, a blunt snout, and a hairless tail usually shorter than its body.
Where do Norway rats live?
They live in burrows and human-made structures such as sewers, cellars, wharves, and garbage areas, often close to people.
Are Norway rats considered pests?
Yes. They are widely treated as pests because they damage property, contaminate food, and may spread diseases.
What do Norway rats eat?
They are opportunistic omnivores and can eat a wide range of foods, including grains, meats, fish, nuts, and fruits.

References

  1. Smithsonian’s National Zoo & Conservation Biology Institute — https://nationalzoo.si.edu/animals/norway-rat
    Supports: Common names, native range in northern China, and general ecology
  2. Alaska Department of Fish and Game — https://www.adfg.alaska.gov/index.cfm?adfg=invasiveprofiles.norwayrat_characteristics
    Supports: Physical description, behaviour, reproduction, and habitat
  3. DLA / species account — https://www.dlia.org/atbidata/SpeciesPage.php?ftaxon=Muridae&gtaxon=Rattus&staxon=norvegicus&sstaxon=
    Supports: Non-native status in North America and broad human-associated distribution
  4. San Mateo County Mosquito and Vector Control District — https://www.scmvcd.org/norway-rat
    Supports: Common names, origin in Asia, adaptation to human environments, and use as laboratory animals or pets
  5. University of Illinois Extension — https://extension.illinois.edu/invasives/norway-rat
    Supports: Invasive pest status, origin in Asia, and damage/health impacts
  6. Texas Tech University — https://www.depts.ttu.edu/nsrl/mammals-of-texas-online-edition/Accounts_Introduced_Rodentia/Rattus_norvegicus.php
    Supports: Taxonomy and conservation status