Mammals · Rodentia · Muridae

Brown Rat

Rattus norvegicus

Least Concern

The species is abundant and widely distributed; it faces no significant short-term risk. See full glossary

The brown rat, known in Spanish as rata gris, rata parda, rata marrón, rata noruega, rata china, guarén or rata de alcantarilla, is a species of myomorph rodent of the family Muridae. It is one of the best known and commonest rats; it is tied to human activity and thanks to that it has colonised the whole world from its origins in China, becoming a pest in some areas. It gave rise to the albino rats and other varieties used by people as laboratory or pet animals. No subspecies are recognised.

Weight

150 g – 500 g

Size

20 cm – 28 cm

Lifespan

2 years

Diet

Omnivore

Combines animal and plant food depending on availability.

Activity

Nocturnal

Active mainly at night.

Social structure

Colony

Lives in large concentrations, often for breeding reasons.

Sighting difficulty

Easy

FreshwaterGrasslandIslandsOmnivore Nocturnal Colonial Freshwater Grassland Islands Mammal

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Fun facts

inteligenciaLaboratory studies have shown behaviour associated with empathy: it frees trapped companions even with no reward for doing so.
The laboratory rat is this same species: it was domesticated from wild animals in the nineteenth century and is today one of the most important model organisms in biomedicine.
It is neophobic: it distrusts any new food in its territory and tries it first in the smallest amount, a behaviour that makes many fast-acting poisons fail.

Life cycle & biology

Skeleton type: Vertebrate - internal bony skeleton (mammal)
Habitat & environment: Sewers, cellars, ports, landfills, riverbanks and farmland across practically the whole world
Sexual maturity: 3 months
Gestation / incubation: 21 days
Litter / clutch size: 9.9 (average)

Sources consulted: https://es.wikipedia.org/wiki/Rattus_norvegicus