Most Unwanted: Ship rat
Rattus rattus
Habitat: Terrestrial
Threat: Threatens protected species
Status: Established
The black rat is not as widespread in Ireland as the brown rat. In fact the only known self sustaining population is on Lambay island off the coast of Dublin. Here this species has been protected from the Brown rat which out competes the black rat.
This species has been nominated as among 100 of the "World's Worst" invaders
What is it?
The black rat is much smaller than the Norway rat and can be distinguished by its ears which are larger and hairless.
Impact
Both species of rats present in Ireland are known to impact on native flora and fauna. The effects these animals have maybe greater on island habitats. These species 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. The black rat has been described to attack and kill at least 39 bird species, while the brown rat 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. Arthropods, snails, amphibians and reptiles are generally not as well studied as bird species, and few data is available on the impacts of rats on these organisms, but again there is little doubt that the number of impacted species is very large.
Invasive rats have impacts on plant communities too. These impacts on isolated island ecosystems are extremely important and of concern to conservation managers and enthusiasts alike. Rats are 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. Rats are also known to prevent the regeneration of woodlands by damaging young saplings and adult trees.
Where is it from?
This species of rat is native to India but now has a global distribution.
Where are they in Ireland?
The only known established and self sustaining population of black rats is on Lambay Island off the coast of Dublin. Occasionally this species does appear around ports because of its association with shipping.
How did it get here?
This species can stow away on freight containers and ships.
How are they spreading in Ireland
Self propelled. They are a highly mobile species and can swim.
Stow away on both large and small vessels.
What you can do
Prevent further spread to offshore islands by keeping boats free of rats.
Use rat guards where appropriate.
Report all sightings.
