This rat (Rattus norvegicus) can be found close to human habitation throughout the world. It is considered a serious pest to farmers, spoiling what it does not eat with its urine and droppings. Poisoning and trapping seem to have only a temporary effect as the rat can produce six to eight litters a year. Its reputation is not enhanced by its penchant for living in rubbish dumps and sewers and its tendency to spread diseases. A modern-day Pied Piper of Hamelin would earn a fortune.
Brown rats form large social groups with a large dominant male guarding his harem against other suitors. Females will defend the group aggressively. Rats sleep for up to 13 hours a day becoming more active at night. They must ensure their diet contains liquid, as they cannot survive for long without water.