Best time to see: all year

Key facts

A serious pest, destroying food and property and carrying diseases

Adaptable and fecund, but prefers damp areas including sewers

Widespread across Europe except around the Mediterranean, where it is replaced by the black rat

Recognition

Usually dark brown fur with a greasy appearance, and with a long, scaly tail

Length up to 50cm including tail; weight up to 600g

Eats almost anything, sampling new foods and waiting a day or so to find out if it's harmful

Lifecycle

Nests in grass, paper or similar material, in a hole or burrow

Produces up to 5 litters a year, usually of 7–8 young, and at any time of the year