Brown Rat – Rattus norvegicus


A widespread pest, highly adaptable, a great opportunist and will live anywhere, wherever food and shelter are available. If you live in a town, you are probably never more than 15 metres from a rat. Twenty percent of the world’s food supply is either destroyed or eaten by rats.

Brown rats arrived in the UK 1730 from the Baltic, having originated in China and soon displaced the Black Rat by eating their young. They multiply at an alarming rate and live in large colonies. If left unchecked these colonies could number hundreds, despite a very high mortality rate.

Brown rats are mainly nocturnal and are good swimmers. They will run away from danger, but may attack in groups if cornered. Packs of rats have been known to attack rabbits, large birds or even fish. Rats identify each other by smell and will also fight off rival packs or their members. Their main predators are cats, owls and weasels and of course man.

Origin: Introduced.

Size: Usually 21 cm plus 18 cm tail, but vary between 32 and 58 cm including tail.

Description: Fine, soft fur and scaly, fleshy tail. Has a repulsive smell.
Habitat: Inhabits open countryside and towns, barns, warehouses, canal banks and sewers, anywhere there is a plentiful food source, typically alongside man.

Young: Litters of 1 – 20 every 6 weeks, all the year. Females breed at 3 months. Gestation is 21 days.

Nest: In chambers within their burrows lined with dry grass or other available materials.

Diet: Omnivorous. Can survive on almost any food, but prefers a cereal diet with some animal matter. Food is not stored but is taken to a safe place to be eaten.

Population: Estimated to be about 10 million.