Brown rat

Rattus norvegicus


Photo credit: ©GBNNSS
Rattus norvegicus
Common Names:
  • Brown rat, common rat, Norway rat

  • The brown rat is much larger than other rodent species found in Ireland. It can be distinguished from the black rat (Rattus rattus) by its larger size, smaller eyes, and hair on the ears. has brown fur on its back and grey fur on its belly. It is only one of two rat species in Ireland.

Origin and Distribution:
  • With a possible origin of North East China, this species has benefited greatly by allying itself closely to man.
  • This species is now present in most parts of the world.

  • This species is known to impact on native flora and fauna. The effects these animals have maybe greater on island habitats. It have been observed to attack and kill chicks, and adult birds, and take eggs from nest sites.
  • Globally, these two species of rats have lead to the decline, local extinction and/or total extinction of bird and other species through predation and competition. It has been recorded predating on at least 53 species.
  • Evidence of predation of predation of small birds on islands is difficult to obtain, therefore this number is likely to be much greater.
  • It has impacts on plant communities too. These impacts on isolated island ecosystems are extremely important and of concern to conservation managers and enthusiasts alike.
  • The species is omnivorous, and as well as animal species they are known to eat leaves, seeds, flowers, bark and stems of many species, some of which are endanger of extinction due to their isolation on island ecosystems and lack of adaptations to the new predator. It is known to prevent the regeneration of woodlands by damaging young saplings and adult trees.

How did it get here?
  • This species can stow away on freight containers and ships

Is it found in Northern Ireland?
  • Brown rats are widespread across Northern Ireland and are present on an unknown number of offshore islands. There is still the risk of spread to other unimpacted islands.
  • More distribution information can be seen here on the NBN Atlas NI

You can help by reporting any sightings: @ the Centre for Environmental Data & Recording (CEDaR) - Or via the iRecord App.

Methods for Prevention:
For further queries, you can contact the Invasive Non Native Species (INNS) Team in the Northern Ireland Environment Agency on 028 9056 9558 or Email:  
Invasive Species Northern Ireland

Invasive Species Northern Ireland