Norway Rat
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Roof Rat
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NORWAY RAT
Rattus norvegicus
Norway Rat Characteristics:
- Originally native to northern China, but spread to Europe in the early 1700’s and North America by 1770
- Currently found on all continents except Antarctica
- Found in a variety of habitats including garbage dumps, sewers, open fields and woodlands, basements, and nearly anywhere else that food and shelter is readily available
- Total length averages about 15.71 inches
- Average mass is 400g but may vary
- Possesses coarse fur that is brownish in colour with occasional black or white hairs intermixed
- Ears and tail do not have hairs
- Excellent swimmers
- Length of the tail is shorter than the length of the body (distinguishing feature from Roof Rat)
Norway Rat Reproduction:
- May breed up to 7 times per year
- 2-4 offspring per litter (Average = 8)
- Gestation is 22-24 days
- Young are weaned in 3-4 weeks and sexually mature in 3-4 months
- (Social / Co-operative breeders) Usually breeds in large groups and many litters from different females may occupy the same nest with communal care provided for young (males are not active in parenting process)
- Adults are capable of reproduction for about 2 years
Norway Rat Signs of Infestation
- Primarily nocturnal but may be active at various times depending on population and food availability
- Creates complex burrow networks and shows capability of learning through navigation through these structures
- Territories can be 50 m in diameter, but Norway rats will travel further to secure food
- Feeds on a wide range of foods including plants and insects, but prefers meats if available
- May cause considerable damage to property, destroy crops, pollute human food storage and damage both interiors and exteriors of structures
- May kill poultry, domestic livestock, and game birds
- Responsible for the spread of the bubonic plague by hosting harbour fleas and lice which are direct carriers
- Outdoors, they will nest in burrows with multiple entrances usually along foundations of buildings
- Indoors, they will nest primarily on lower levels of structures but may also be found in attics and other void areas
- Nesting material consists of any soft materials chewed into small pieces
- Grease marks or rub marks from oils and dirt on fur may be visible signs of rodent runways
Norway Rat Control Techniques
Several control methods are available, but a professional inspection is highly recommended to determine the most effective control strategy. Some helpful suggestions when dealing with Norway rats include:
- Exclusion by sealing openings in walls using materials such as sheet metal, galvanized hardware cloth, steel, concrete, steel wool, copper wool etc…
- Ensure doors remain closed at all times when not in use and proper thresholds are in place to prevent possible pest entry
- Eliminate water, garbage and debris available around structure and property
- Keep grass, weeds and bushes trimmed short to reduce coverage around building perimeter
- Trim all tree branches and shrubs that make contact with the structure
- Store food items in rodent proof containers to reduce odour attractiveness
- Several mechanical trapping devices and baiting techniques are available and can be very effective if performed correctly
- Rats may exhibit a behaviour called ‘neophobia’ or fear of the new, therefore new objects in their environment may be avoided making control difficult
- Rats may exhibit a behaviour called ‘bait shyness’ where if something tastes bad or induces illness they may not return to feed on it again
References:
Benett, Gary W., et.al.. Truman’s Scientific Guide to Pest Control Operations. Duluth: Advanstar Communications, 1988. Pp. 310-314.
Myers, P. and D. Armitage. 2004. "Rattus norvegicus" (On-line), Animal Diversity Web. Accessed November 16, 2009 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Rattus_norvegicus.html.
Please click here to contact a Focus Pest Control professional to inquire about further treatments for this pest species.
ROOF RAT
Rattus rattus
Roof Rat General Characteristics:
- Otherwise known as ‘ship rat’, ‘black rat’ or ‘house rat’
- Found on all continents worldwide
- Predominant in costal areas due to spread of species through transport ships
- Very good climber that chooses elevated areas to dwell
- Omnivorous feeding habits, but primarily vegetarian diet consisting of fruits, grains and cereals
- Total length from 6.3 – 8.66 inches
- Mass averages about 200g
- Males are larger than females
- Rarely swims, unlike the Norway rat
- Usually black in colour with lighter coloured belly
- Ears are relatively large in comparison to body
- Tail is usually longer than the body and distinguishes this species from the Norway rat
Roof Rat Reproduction:
- Breeds throughout the year, but less in colder weather (Fall and Summer are preferred)
- 6-12 young per litter
- Gestation period is 21 – 29 days
- Young are weaned in 3 – 4 weeks
- Young reach maturity in 3 – 5 months
- Dominant male will breed most prolifically with multiple females
- Males do not care for young
- Can live up to one year in the wild and up to 4 years in captivity
Roof Rat Signs of Infestation:
- Primarily nocturnal but may be active at various times depending on population and food availability
- Predominant in costal areas due to spread through human shipping but does not like to swim
- Prefers high areas for habitation such as tops of structures and treetops in forested areas, but will inhabit ground areas in certain conditions
- Has been found up to 250m above sea level
- Territories rarely extend over 100 square meters
- Consumes about 15g of food per day and 15ml of water
- Responsible for the spread of the bubonic plague by hosting harbour fleas and lice which are direct carriers
- Nesting material usually consists of sticks and leaves
- Grease marks or rub marks from oils and dirt on fur may be visible signs of rodent runways
- May cause considerable damage to property, destroy crops, pollute human food storage and damage both interiors and exteriors of structures
Roof Rat Control Techniques:
Several control methods are available, but a professional inspection is highly recommended to determine the most effective control strategy. Some helpful suggestions when dealing with Norway rats include:
- Exclusion by sealing openings in walls using materials such as sheet metal, galvanized hardware cloth, steel, concrete, steel wool, copper wool etc…
- Ensure doors remain closed at all times when not in use and proper thresholds are in place to prevent possible pest entry
- Eliminate water, garbage and debris available around structure and property
- Keep grass, weeds and bushes trimmed short to reduce coverage around building perimeter
- Trim all tree branches and shrubs that make contact with the structure
- Store food items in rodent proof containers to reduce odour attractiveness
- Several mechanical trapping devices and baiting techniques are available and can be very effective if performed correctly
- Rats may exhibit a behaviour called ‘neophobia’ or fear of the new, therefore new objects in their environment may be avoided making control difficult
- Rats may exhibit a behaviour called ‘bait shyness’ where if something tastes bad or induces illness they may not return to feed on it again
Please click here to contact a Focus Pest Control professional to inquire about further treatments for this pest species.
References:
Benett, Gary W., et.al.. Truman’s Scientific Guide to Pest Control Operations. Duluth: Advanstar Communications, 1988. Pp. 314-315.
Gillespie, H. and P. Myers. 2004. "Rattus rattus" (On-line), Animal Diversity Web. Accessed November 18, 2009 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Rattus_rattus.html.
Disclaimer:
The Focus Pest Control ‘Pest Library’ is an educational resource written largely to educate the general public about common pests in Ontario. The Focus ‘Pest Library’ does not include all species in Ontario, nor does it include the most recent scientific data about species we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While Focus Pest Control staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.
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