brown rat

The brown rat or Norway rat is the most common rat in the British Isles. It is thought to have originated in northern China. It has spread to all parts of the globe wherever humans are.

Rats are usually dark brown or dark grey and can reach 25cm (10 inches) long plus a tail of the same length. Males are larger than females. They often live underground and their holes are about 50mm (2 inches) in diameter. In gardens these will commonly be found in compost heaps under wood piles etc.

Common signs of an infestation are typically:

  • Chewing damage
  • Droppings
  • Tracks – well-worn tracks back to their breeding sites
Bird feeders attract rats
Rat infestation in bin bags

Rats are omnivorous but grain and cereals are the main source of food and they are often attracted to gardens by the availability of bird food and refuse sacks and bins.

Rats breed all year round and if conditions are good a female will have up to 5 litters of 6 or 7 young in a year.

Rats are known to carry diseases such as:

  • Weil’s disease
  • Viral hemorrhagic fever.

Unlike the black rat however, brown rats are not known to carry bubonic plague.

Rats are colour blind!


Treatment will usually require traps or poison to be placed in the areas where activity is detected. It is usually possible to reduce the chance of rat infestation by changing bird feeding habits and removing areas of cover and thick undergrowth.