Download . Brown Rat, Rattus norvegicus Overview Overview table Invasion

B r o w n R a t , Rattus norvegicus
Overview
.
Short description of Rattus norvegicus, B r o w n R a t
The large size and long, thin, almost hairless tail distinguish rats from other
grey-brown rodents. Confusion is possible with water vole, but these are smaller and
darker brown, with shorter ears, a furry tail and a blunter snout. The ship rat is slimmer
than the brown rat, with relatively longer ears and a tail that is longer than its body.
The brown rat's tail is shorter than the body length and has a paler underside.
Description of Rattus norvegicus, Brown Rat status in GB
Author's name:
The brown rat is very abundant in GB and almost ubiquitous in both urban and rural
environments. The GB pre-breeding population was estimated to be at least 6.8 million
animals in 1995.
John Marchant
Last updated:
H a b i t a t s u m m a r y : Rattus norvegicus, B r o w n R a t
March 12th, 2012
Brown rats are found in a very wide range of habitat types, typically in association with
humans.
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Overview table
Environment:
Terrestrial
Species
status:
Non-Native
Native range:
Middle Asia, China, Kazan-retto, Nansei-shoto,
Ogasawara-shoto, Russia Central, Russia East, Russia
North, Russia Northwest, Russia South
Functional
type:
Omnivore
Status in
England:
Non-Native
Status in
Scotland:
Non-Native
Status in
Wales:
Non-Native
Location of
first record:
first record is unknown (ancient)
Date of first
record:
1720
Invasion history: Rattus norvegicus, B r o w n R a t
Origin
The species is believed to have originated on the steppes of central Asia and to have
reached eastern Europe from the east in the early 1700s, possibly by natural dispersal.
First Record
The first brown rats in GB are reported to have arrived at English ports around
1728–29.
Pathway and Method
Brown rats can thrive on ships at sea and come ashore in ports or through shipwrecks.
Species Status
The brown rat is highly invasive and is regarded as a serious pest almost worldwide.
Ecology & Habitat: Rattus norvegicus, B r o w n R a t
Dispersal Mechanisms
Brown rats have spread around the world through their readiness to travel in ships.
They swim well and can disperse naturally to and from offshore islands.
Reproduction
The species breeds prolifically throughout the year. As many as 13 litters can be
raised in a year, each of up to nine young, and females mature sexually after just 8–12
weeks.
Known Predators/Herbivores
Young rats fall prey to a variety of avian and mammalian predators, including owls,
domestic cats and dogs, and foxes. Fully grown animals can escape predation through
their large size and aggressiveness.
Resistant Stages
None known.
Habitat Occupied in GB
Brown rats are typically commensal with man in a wide range of urban and agricultural
habitats. They are abundant in sewers, refuse tips, warehouses and storage barns,
along water courses, and in hedge-bottoms on farmland. Populations also occur
independently of humans in more natural habitats, such as saltmarshes.
Distribution: Rattus norvegicus, B r o w n R a t
Brown rats occur almost throughout GB, being absent only from exposed montane
areas and from some smaller offshore islands. The species has spread almost
worldwide, with the exception of some tropical and subtropical areas.
I m p a c t s : Rattus norvegicus, B r o w n R a t
Environmental Impact
The abundance and ubiquity of brown rats mean they have considerable impact on
ecosystems, for example as predator and prey, and as competitors for food, shelter
and nest sites. The arrival of brown rats displaced ship rats, which had occupied a
similar niche, from mainland GB. Their presence on islands can lead to extinction of
seabird colonies. Worldwide, rats have contributed to many extinctions or
near-extinctions of island endemic species.
Health and Social Impact
Brown rats can spread a number of diseases to humans through their bites and
droppings, including leptospirosis (Weil's disease), and their ticks can carry Lyme
disease. Weil's disease is a significant public health hazard to anyone entering fresh
water in rat-infested areas, the causative bacteria L
( eptospira) being able to infect
humans through broken skin. Inside buildings, rats can cause considerable nuisance
through fouling surfaces and water tanks, gnawing timbers and wiring, and through
their noise and aggression.
Economic Impact
Brown rats have major economic impacts. They consume and contaminate human
food, both as growing crops and in storage, and damage grain storage bags. In
buildings, they gnaw access holes in woodwork and pose electrical hazard by gnawing
into cables and insulation.
References & Links: Rattus norvegicus, B r o w n R a t
Identification
Harris, S. & Yalden, D.W. (2008) Mammals of the British Isles: Handbook. Fourth
edition. The Mammal Society, Southampton.
Biology, ecology, spread, vectors
Clark, M. & Summers, S. (1980) Seasonal population movements of brown rats and
house mice in Hertfordshire. Transactions of the Hertfordshire Natural History Society,
2 8, 17–19.
Hilton, A.C., Willis, R.J. & Hickie, S.J. (2002) Isolation of Salmonella from urban wild
brown rats (Rattus norvegicus) in the West Midlands, UK. International Journal of
Environmental Health Research, 1 2 , 163–168.
Management and impact
Abdelkrim, J., Pascal, M., Calmet, C. & Samadi, S. (2005) Importance of assessing
population genetic structure before eradication of invasive species: examples from
insular Norway rat populations. Conservation Biology, 1 9, 1509–1518.
Drummond, D.C. (1985) Developing and monitoring urban rodent control programmes.
Acta Zoologica Fennica, 1 7 3, 145–148.
Langton, S.D., Cowan, D.P. & Meyer, A.N. (2001) The occurrence of commensal rodents
in dwellings as revealed by the 1996 English house condition survey. Journal of
Applied Ecology, 3 8, 699–709.
Lorvelec, O. & Pascal, M. (2005) French alien mammal eradication attempts and their
consequences on the native fauna and flora. Biological Invasions, 7 , 135–140.
General
Harris, S. & Yalden, D.W. (2008) Mammals of the British Isles: Handbook. Fourth
edition. The Mammal Society, Southampton.
Lever, C. (2009) The Naturalized Animals of Britain and Ireland. New Holland
Publishers, London.
Twigg, G. (1975) The brown rat. David & Charles, Newton Abbot.