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   Rattus norvegicus (mammal) français   
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         General Impact

    Norway rats are known to restrict the regeneration of many plant species by eating seeds and seedlings. They prey upon most animal species smaller than themselves such as reptiles, small birds, birds eggs and freshwater and intertidal species. Norway rats eat food crops and spoil human food stores by urinating and defecating in them. Additional economic damage is caused by rats chewing through power cables etc. and spreading diseases.

    Both R. norvegicus and Rattus rattus transmit the plague bacterium (Yersinia pestis) via fleas in certain areas of the world. There have been a series of recent outbreaks in Madagascar in recent years (Boiser et al. 2002).




         Location Specific Impacts:
    Intermares (Brazil) English 
    Threat to endangered species: Predation by the Rattus norvegicus on eggs and hatchlings of the endangered Hawksbill turtle (see Eretmochelys imbricata in IUCN Red List of Threatened Species) during the 2003/2004 and 2004/2005 nesting season was identified as a the main cause of poor nesting rates (losses of close to 3000 eggs and hatchlings were estimated) (Zeppelini et al. 2007).
    Anegada Is. (British Virgin Islands) English 
    Reduction in native biodiversity: On Anegada Is. rats will be having a detrimental impact on birds, lizards and frogs through competition for food and predation of eggs, young and adults (Veitch, 1998 in Varnham, 2006).

    Reduction in native biodiversity: On Anegada Is. rats will be having a detrimental impact on birds, lizards and frogs through competition for food and predation of eggs, young and adults (Veitch, 1998 in Varnham, 2006).

    Threat to endangered species: Rattus norvegicus may predate young 'Critically Endangered (CR)' Anegada Is. rock iguana (see Cyclura pinguis in IUCN Red List of Threatened Species) on Anegada Is., and also compete with them for food resources (Veitch, 1998 in Varnham, 2006).
    Langara Is. (Canada) English 
    Reduction in native biodiversity: Rattus norvegicus is implicated in the extirpation or decline of previously large seabird populations on Langara Island (Howald et al., 1999).
    Cayman Brac (Cayman Islands) English 
    Habitat alteration: Rattus norvegicus is also likely to be having impacts on regeneration of native flora due to seed consumption (Burton, 2003 in Varnham, 2006).

    Predation: Rattus norvegicus is a predator on native snakes and lizards, including hatchling rock iguanas, and nesting birds (Burton, 2003 in Varnham, 2006).
    Grand Cayman (Cayman Islands) English 
    Habitat alteration: Rattus norvegicus is also likely to be having impacts on regeneration of native flora due to seed consumption (Burton, 2003 in Varnham, 2006).

    Reduction in native biodiversity: Rattus norvegicus is a predator on native snakes and lizards, including hatchling rock iguanas, and nesting birds (Burton, 2003 in Varnham, 2006).
    Little Cayman (Cayman Islands) English 
    Habitat alteration: Rattus norvegicus is also likely to be having impacts on regeneration of native flora due to seed consumption (Burton, 2003 in Varnham, 2006)

    Predation: Rattus norvegicus is a predator on native snakes and lizards, including hatchling rock iguanas, and nesting birds (Burton, 2003 in Varnham, 2006).
    Falkland Islands (Malvinas) (sub-Antarctic) English 
    Habitat alteration: Brown rats may have some impacts on vegetation.

    Reduction in native biodiversity: The presence of rats on islands is negatively correlated with the presence of seven species of native passerines (Varnham, 2006).

    Threat to endangered species: Brown rats are likely to have destroyed whole poulations of 'Vulnerable (VU)' Cobb's wren (see Troglodytes cobbi in IUCN Red List of Threatened Species) and many other land and seabirds, especially burrowing petrels (BirdLife International 2006). Breeding of the Tussock bird (Cinclodes antarcticus antarcticus) has become restricted to cat- and rat-free islands. Reduction of small petrels including Antarctic prion (Pachyptila desolata) has occurred on rat-inhabited islands (In Atkinson, 1985 in Varnham, 2006).
    Amsterdam Is. (sub-Antarctic) (French Southern Territories) français  English 
    Reduction in native biodiversity: Rattus norvegicus and cats (Felis catus) contributed to the elimination of 10 or 12 of the 22 bird species that were originally present (Micol and Jouventin, 1995).
    Isle of Man English 
    Predation: There is concern that Rattus norvegicus could be taking eggs from ground nesting birds (Charter, 2004 in Varnham, 2006).
    Japan English 
    Predation: Rattus norvegicus preys on the apple snail (Pomacea canaliculata), an important pest of rice, in Japan (Yusa et al., 2000).
    Rodrigues Is. (Mauritius) English 
    Herbivory: Rattus norvegicus causes damage to the vegetation of Mascarene islands. Predation of fallen palm fruit and seedlings is a major problem.
    Rasa Is. (Mexico) English 
    Reduction in native biodiversity: Rats and mice may be responsible for the absence of nocturnal hole and crevice nesting birds on Rasa Island (Donlan et al., 2000).
    Rakino Is. (New Zealand) English 
    Predation: Rattus norvegicus was probably responsible for extirminating the grey-faced petrel from Rakino Island (ARC, 2002).
    Campbell Is./Motu Ihupuku (sub-Antarctic) (New Zealand) English 
    Predation: It is probable that Norway rats have caused catastrophic declines in the numbers of ground-nesting birds, but no particular case has been properly documented (SPREP, 2000).
    Whale (Moutohora) Is. (New Zealand) English 
    Predation: Rattus norvegicus preys on the eggs and chicks of the grey-faced petrel (Pterodroma macroptera gouldi) on Whale Island (Imber et al., 2000).
    Kayangel Is. (Palau) English 
    Disease transmission: Rattus norvegicus are known to affect community health in Palau by acting as disease vectors, exposing citizens to gastrointestinal illnesses and leptospirosis through water supplies

    Economic/Livelihoods: Rattus norvegicus are causing economic losses by damaging crops including papaya and corn.

    Threat to endangered species: Ground birds such as the Micronesian megapode (see Megapodius laperouse in the IUCN Red List of Threatened Species) are particularly vulnerable to introduced predators such as rats and cats.
    Azores (Portugal) English 
    Disease transmission: Rattus norvegicus plays a significant role as a maintenance host of leptospirosis in the Azores.

    Predation: Rats are a major factor in determining the distribution of Puffinus spp.in the Azores (Pitta Groz et al., 2002).
    Reunion (La Reunion) English 
    Herbivory: Rattus norvegicus causes damage to the vegetation of Mascarene islands. Predation of fallen palm fruit and seedlings is a major problem.
    Saint Helena English 
    Reduction in native biodiversity: Rattus norvegicus are highly omnivorous, eating plants, invertebrates and young birds (Ashmole and Ashmole, 2000 in Varnham, 2006). They may predate on 'Critically Endangered (CR)' endemic wirebird's (see Charadrius sanctaehelenae in IUCN Red List of Threatened Species) chicks and eggs (McCulloch and Norris, undated in Varnham, 2006).
    Fregate Is. (Seychelles) English 
    Human nuisance: Rattus norvegicus were a nuisance to the plantation and hotel on Fregate Island (Millet and Shah, 2001).

    Reduction in native biodiversity: Rattus norvegicus impacted on the avifauna and invertebrates of Fregate Island (Millet and Shah, 2001).
    Sth. Georgia and Sth. Sandwich Iss (sub-Antarctic) English 
    Predation: Rattus norvegicus take eggs and young of most burrow-nesting small petrels, and also eat penguin chicks (McIntosh and Walton, 2000 in Varnham, 2006). Other sources suggest they are only likely to predate weak or dead penguin chicks (Poncet, 2003 in Varnham, 2006).

    Reduction in native biodiversity: Rattus norvegicus are known to eat native plants (esp. Paradiochloa flabellata, a tussock grass), as well as invertebrates and carrion (Leader-Williams, 1985 in Varnham, 2006).

    Threat to endangered species: Breeding of the 'Near Threatened (NT) Antarctic pipits (see Anthus antarcticus in IUCN Red List of Threatened Species) and South Georgia pintails (Anas georgica georgica) has reportedly become restricted to rat-free habitats (in 8). However, other more recent sources say that although rats may have reduced pintail numbers and affected breeding success they have not eliminated them, and pintails are found all over South Georgia (Poncet, 2003 in Varnham, 2006).
    United Kingdom (UK) English 
    Disease transmission: Rattus norvegicus present a zoonotic disease risk in the UK.

    Human nuisance: Rattus norvegicus causes damage to stored food and structures in the UK.
    Canna Is. (United Kingdom (UK)) English 
    Reduction in native biodiversity: Norway rats threaten the seabird populations of Canna Island, as well as the native woodmouse.
    Lundy Is. (United Kingdom (UK)) English 
    Reduction in native biodiversity: Rattus rattus and R. norvegicus threatened breeding seabirds on Lundy Island, such as the manx shearwater and puffins (Appleton et al., 2002).
    Hawaii (United States (USA)) English 
    Predation: Rattus norvegicus in Hawaii are thought to be responsible for suppressing seed regeneration of endemic plants, reducing populations of native snails, and significantly limiting breeding success of many native birds (Pitt, 2004).



ISSG Landcare Research NBII IUCN University of Auckland