Taxonomy
Rattus norvegicus | Brown Rat | Francach
Distribution
Status
Conservation status
Least Concern
Legal status
Third Schedule listed species under Regulations 49 & 50 in the European Communities (Birds and Natural Habitats) Regulations 2011. (Note: Regulation 50 not yet enacted). Listed as a schedule 9 species under Articles 15 & 15A of the Wildlife Order (Northern Ireland) 1985 (Article 15A not yet enacted).
First reported in the wild
pre-1900
Invasiveness
Invasive species - risk of High Impact
Irish status
Established
Introduction pathways - 1
Transport Stowaway
Introduction pathways subclass - 1
Hitchhikers on ship/boat
Invasive score
24
NAPRA Ireland risk assessed
No
Species Biology
Identification
Larger, longer tailed and with a pointed muzzle and broader longer hind feet, compared to smaller rodent species (Quy & MacDonald, 2008). Distinguished from Rattus rattus by relatively smaller eyes and ears, with hair on the ears (Quy & MacDonald, 2008). Colour not diagnostic, black rats may be brown and brown rats may be black, however black rats in Ireland are thought to be restricted to Lambay Island.
Ecology
Considered an 'obligate pest', in that across most of their geographical range their survival is based on human agricultural production, with the level of damage varying according to the scale of the agricultural system being exploited (Alpin et al., 2003). Generally do not tend to survive well in natural ecosystems (Alpin et al., 2003), their effects on wildlife are largely confined to islands, particularly those with endemics not adapted to mammalian predators such as New Zealand (Jones et al., 2008; Towns et al., 2006). Negative impacts have been recorded for flightless invertebrates, ground-dwelling reptiles, land birds, and burrowing seabirds (Towns et al., 2006), while globally, ship rats have been associated with the decline in 60 indigenous vertebrate species (Towns et al., 2006) and rats in general with the decline of 75 seabird species globally (Jones et al., 2008).
Habitat
Constructed, industrial or other artificial habitats
Reproduction
Promiscuous mating system producing, on average, produce 5 litters of 9 pups annually (Quy & MacDonald, 2008).
Pathway and vector description
Introduced into Europe and then Ireland from China in the 18th century, displacing the ship or black rat (Rattus rattus) (Quy & MacDonald, 2008). While it is unlikely that an effective control of rats will be developed due to their behavioural plasticity (Quy & MacDonald, 2008), care should be taken to avoid spread to any off shore islands that may currently be rat free.
Mechanism of impact
Predation
Broad environment
Terrestrial
Habitat description
While highly adaptable and versatile suffer from competition in the wild and typically occur where food is augmented by human activities, though not an obligate commensal (Quy & MacDonald, 2008), they are commensal (found in association with humans) and do not tend to survive well in natural environments (Alpin et al., 2003).
Species group
Vertebrate
Native region
Temperate Asia
Similar species
Distribution
World distribution(GBIF)
Irish distribution
Established - Widespread & Common
Native distribution
Originally from the steppes of Central Asia (Quy & McDonald, 2008).
Temporal change
Date of first record category
Pre-1900
Fifty year date category
Unknown
Records submitted to Data Centre in 2024
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How can you help
Report any sightings to the National Biodiversity Data Centre.
Further information
Delivering Alien Invasive Species In Europe (DAISIE) project list this as one of the 100 Worst Invaders in Europe.
References
Publications
Aplin, K. P., Chesser, T., & Have, J. T. (2003). Evolutionary biology of the genus Rattus: profile of an archetypal rodent pest. In: Singleton GR, Hinds LA, Krebs CJ, Spratt DM (eds) Rats, mice and people: rodent biology and management. ACIAR, Canberra, pp 487–498.
Feng, A. Y., & Himsworth, C. G. (2014). The secret life of the city rat: a review of the ecology of urban Norway and black rats (Rattus norvegicus and Rattus rattus). Urban ecosystems, 17(1), 149-162.
Jones, H. P., Tershy, B. R., Zavaleta, E. S., Croll, D. A., Keitt, B. S., Finkelstein, M. E., & Howald, G. R. (2008). Severity of the effects of invasive rats on seabirds: a global review. Conservation Biology, 22(1), 16-26. Towns, D. R., Atkinson, I. A., & Daugherty, C. H. (2006). Have the harmful effects of introduced rats on islands been exaggerated?. Biological invasions, 8(4), 863-891.
Quy, R.J. & MacDonald, D.W. (2008). Genus Rattus Common rat - Rattus norvegicus In: Mammals of the British Isles : Handbook, 4th edition Harris, S. & Yalden, D.W. (eds) The Mammal Society, UK.
Relevant links
Global Invasive Species Database