---
title: "What the sources say about the Brown Rat | AnimalTracks.wiki"
description: "55 claims from the Brown Rat profile, each beside the words of the source that backs it."
image: "https://animaltracks.wiki/images/animals/brown-rat-1.webp"
canonical: "https://animaltracks.wiki/animals/brown-rat/sources/"
---

# What the sources say about the Brown Rat (*Rattus norvegicus*)

> 55 claims from the Brown Rat profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Brown Rat](https://animaltracks.wiki/animals/brown-rat/)

## Rattus norvegicus. Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Rattus_norvegicus/

| The page says | The source says |
| :--- | :--- |
| Every continent except Antarctica, including sewers, basements, open fields and woodlands | Today, Norway rats (also known as brown rats) can be found on every continent of the world except Antarctica. (note: stats.habitat) |
| including sewers, basements, open fields and woodlands | They occupy a variety of habitats including garbage dumps, sewers, open fields and woodlands, basements, and nearly anywhere else that food and shelter might be found. (note: stats.habitat) |
| Omnivore, mostly discarded human food in cities | In metropolitan areas, they survive mainly on discarded human food (note: stats.diet) |
| Omnivore | Primary Diet omnivore (note: stats.diet) |
| Feels its way through total darkness with paws and whiskers, backed by a spectacular sense of smell | feel their way through total darkness with their paws and whiskers. However, these rats would not have such an advantage over all other foragers if it were not for their spectacular sense of smell (note: stats.superpower) |
| they can feel their way through total darkness with their paws and whiskers | feel their way through total darkness with their paws and whiskers |
| lives on every continent except Antarctica | can be found on every continent of the world except Antarctica |
| They weigh 140 to 500 g | weigh 140 to 500 g |
| average 399 mm from nose to tail | Average length 399 mm |
| males usually larger | Males are usually larger than females. |
| In cities, brown rats survive mainly on discarded human food | In metropolitan areas, they survive mainly on discarded human food |
| Some rats living near the sea have been observed catching fish with their paws | Some Norway rats living near the sea have been observed catching fish with their paws. |
| one wild rat's stomach in Germany held 4000 items, most of them plants | Examination of a wild R. norvegicus stomach in Germany revealed 4000 items, most of which were plants |
| Eats Almost Anything | they survive mainly on discarded human food, and anything else that can be eaten without negative consequences (note: heading) |

## AnAge entry for Rattus norvegicus. AnAge: The Animal Ageing and Longevity Database, Human Ageing Genomic Resources.

https://genomics.senescence.info/species/entry.php?species=Rattus_norvegicus

| The page says | The source says |
| :--- | :--- |
| wild rats rarely live more than a year | In the wild, rats experience a high mortality and rarely live more than 1 year |
| one large study found a captive maximum of 3.8 years | Arguably the most accurate data comes from one large study with thousands of animals in which maximum longevity was 3.8 years |
| AnAge says wild rats rarely live more than 1 year, though exceptional ones can live up to 3 years | rarely live more than 1 year, though in exceptional cases they can live up to 3 years (note: faq) |
| In captivity, a study of thousands of rats recorded a maximum of 3.8 years | one large study with thousands of animals in which maximum longevity was 3.8 years (note: faq 1) |
| weightKg: 0.3 | Adult weight 300 g (note: battleStats.weightKg, typical adult (#1117)) |

## Modlinska & Pisula (2020). The Norway rat, from an obnoxious pest to a laboratory pet. eLife.

https://doi.org/10.7554/elife.50651

| The page says | The source says |
| :--- | :--- |
| breeds all year | R. norvegicus can breed all year long (note: tagline) |
| quickly learns to shun the taste of food that once made it ill | Rats quickly develop strong aversion to the taste of substances which have caused illness (note: tagline) |
| Wild rats reach sexual maturity at about 11 weeks, stay pregnant for 21 to 24 days and give birth to litters of about 7 or 8 pups | Wild rats reach sexual maturity at about 11 weeks, remain pregnant for 21–24 days, and give birth to litters of about 7 or 8 pups. |
| They can breed all year and average 3 to 5 litters a year | R. norvegicus can breed all year long and has 3–5 litters per year on average. |
| The pups arrive almost naked, blind and totally dependent on their mother | the young are born almost naked, blind and totally dependent on the mother |
| start leaving the nest and eating solid food at about 14 days | The young start leaving the nest and ingest solid foods at about 14 days after birth. |
| Wild Norway rats have relatively poor eyesight and are sensitive to sharp light | Wild Norway rats have relatively poor eyesight and are sensitive to sharp light |
| Their main sensory input is touch from the facial whiskers, plus a particularly well-developed sense of smell | the main sensory input is touch from the facial whiskers (or vibrissae) and a particularly well-developed sense of smell |
| They hear from about 0.25 to 80 kHz, which enables them to communicate with ultrasound | They can detect sounds between about 0.25–80 KHz ( Heffner et al., 1994 ), which enables them to communicate with ultrasound |
| calls humans cannot hear without special equipment | These vocalizations are inaudible to humans without the use of specialized equipment. |
| Rats develop preferences for particular foods by sniffing at the mouth and fur of an individual who has finished eating | Rats develop preferences for particular foods by sniffing at the mouth and fur of an individual who has finished eating |
| They also have no sweat glands. They regulate body temperature through behavior, such as hiding in burrows, and the sparsely haired tail plays a part | Rats have no sweat glands and regulate their body temperature through behavior, for example, by hiding in burrows. The sparsely haired tail also plays a part in thermoregulation |
| the Norway rat most likely originated in Asia | Despite its name, the Norway rat most likely originated in Asia. |
| reached North America between 1750 and 1775 | The Norway rat reached North America between 1750 and 1775 |
| After an unfamiliar food, they markedly reduce what they eat | They also markedly reduce their food intake after they are introduced to an unfamiliar food. |
| they develop an aversion to foods that cause adverse effects within up to 6 hours | Rats develop an aversion to foods that cause adverse effects within up to 6 hours |
| That often limits the effectiveness of traditional pest control | which often limits the effectiveness of traditional pest control procedures |
| Like the black rat, the Norway rat often lives close to humans and may carry various pathogens and parasites | Like the black rat, the Norway rat often lives in the immediate vicinity of humans, including in cities ( Aplin et al., 2011 ), and can pose a serious threat to human health because it may carry various pathogens and parasites |
| People once believed it reached England from Norway on ships in the 18th century | it was believed to have immigrated to England from Norway aboard ships in the 18 th century (note: faq) |
| reached Europe from there via Russia | the species originally arrived in European countries from Asia via Russia (note: faq) |
| Their hearing spans about 0.25 to 80 kHz, and they use ultrasound to communicate | They can detect sounds between about 0.25–80 KHz ( Heffner et al., 1994 ), which enables them to communicate with ultrasound (note: faq) |
| it most likely originated in Asia | the Norway rat most likely originated in Asia (note: faq 2) |
| a rat has no sweat glands | Rats have no sweat glands (note: faq 4) |
| It controls its temperature with behavior instead, for example by sheltering in a burrow, and its thinly haired tail helps with thermoregulation too | regulate their body temperature through behavior, for example, by hiding in burrows. The sparsely haired tail also plays a part in thermoregulation (note: faq 4) |
| Sniff test | Rats develop preferences for particular foods by sniffing at the mouth and fur of an individual who has finished eating (note: heading/lead-in label only) |
| Wired for Whiskers and Scent | the main sensory input is touch from the facial whiskers (or vibrissae) and a particularly well-developed sense of smell (note: heading) |
| A person needs specialized equipment to pick up those calls | These vocalizations are inaudible to humans without the use of specialized equipment. (note: faq 3) |
| Yet rats are cautious about new things | Rats are highly inquisitive and eager to explore new environments but exhibit neophobia (i.e., caution towards new objects; Pisula, 2009 ) |
| Built to Multiply | R. norvegicus can breed all year long and has 3–5 litters per year on average. (note: heading) |
| Eats Almost Anything, Wary of New Food | They also markedly reduce their food intake after they are introduced to an unfamiliar food. (note: heading) |
| Rats develop preferences for particular foods by sniffing at the mouth and fur of a rat that has just eaten | Rats develop preferences for particular foods by sniffing at the mouth and fur of an individual who has finished eating (note: vibe.reason) |
| their sense of smell is particularly well developed | the main sensory input is touch from the facial whiskers (or vibrissae) and a particularly well-developed sense of smell (note: vibe.reason) |

## Hulme-Beaman, Orton & Cucchi (2021). The origins of the domesticate brown rat (Rattus norvegicus) and its pathways to domestication. Animal Frontiers.

https://doi.org/10.1093/af/vfab020

| The page says | The source says |
| :--- | :--- |
| Its indigenous range is often cited as northern China, Mongolia and/or south-eastern Siberia | The indigenous distribution of the brown rat is often cited as the northern regions of China, Mongolia, and/or south-eastern Siberia |
| most likely transported globally on ships, apparently sometime in the 1700s | the brown rat was later transported globally, most likely on ships ( Puckett et al., 2020 ). This appears to have occurred sometime in the 1700s |
| An Asian Rat That Went Global | From its native distribution in East Asia, the brown rat was later transported globally (note: heading) |

## Biancolini & Johnson (2026). Rattus norvegicus. The IUCN Red List of Threatened Species 2026: e.T19353A286459858.

https://doi.org/10.2305/iucn.uk.2026-1.rlts.t19353a286459858.en

| The page says | The source says |
| :--- | :--- |
| Least Concern | IUCN Red List category: Least Concern (LC). (note: stats.conservationStatus) |