Norway Rat

Norway Rat

Detailed information about Norway Rats, the only rat species on the island of Newfoundland, is found below.

Print or download a brochure that outlines how to prevent rats by removing food sources and potential shelters, and how to rat proof your property including proper yard and lawn maintenance to make it inhospitable for rodents.

If you have rats it doesn't mean your property is dirty, it means there is shelter and an open food source for them.

Rats are attracted to small spaces because they feel protected in them. If a space is small enough for rodents to access, but not for their predators such as cats and dogs, rats will make a home there.

Rats can make homes in anything that provides shelter including sheds and garages, wood or rock piles, under enclosed patios and stairwells, and in unwanted items such as old water tanks, appliances, building materials and tires.

In brief, the key points for rat prevention, rat proofing, and eliminating rats are (more detailed information below):

How to prevent rats:

Remove food sources

  • Do not store garbage outside; place it at the curb no earlier than 6 a.m. on your garbage collection day
  • Remove bird feeders or attach catch basins so bird feed does not fall on the ground
  • Do not store pet food, bird feed and lawn seed outside
  • Compost properly - do not add fish or meat to backyard compost bins

Remove potential shelters

  • Tall grass, weeds and vegetation next to buildings and fences should be removed
  • Lumber, rocks, garbage, building materials, and other unwanted or unused materials should be removed
  • Do not enclose the base of patios and raised stairwells, not even with lattice
  • Items that must be stored outside should be at least 46 cm (18 inches) off the ground and 30 cm (12 inches) from walls and fences.

Rat Proof your property:
Make it impossible for rats to get into any structure

  • Use screens in drains and tightly seal where utilities enter buildings
  • Install a metal kicking plate or heavy weather stripping beneath doors, including garage doors
  • If building a patio or shed on a grade, bury sheet metal 30 cm (12 inches below the grade and skirting

Eliminate rats:
Rat eradication is best done by a professional pest control operator. Look up 'Pest Control Services' in the Yellow Pages or online.

Norway RatDetailed Contents
Introduction
Biology
Physical Abilities
Behaviour
Preventive Control Measures
Precautions & Legal Implications
Community Control Program

Introduction
The Norway rat (Rattus norvegicus), also known as the sewer rat, harbour rat, wharf rat or common rat, is the only species occurring in Newfoundland. It is not native to North America, but is believed to have been introduced by early settlers when their rat infested ships first visited our eastern shores. The Norway rat quickly spread and became a serious pest.
 
Wild rats are recognized as the most destructive vertebrate animal in the world, both in terms of economic losses they cause and their effects on human health.
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Biology
Knowledge of the biology, physical abilities and behaviour of the rat can help you in establishing a successful control program.

The adult Norway rat weighs an average of 450 g (1 lb). Body length various from 190 to 255 mm (7.6 to 10 inches). The tail is round, almost hairless and shorter than the body, averaging approximately 180 mm (7 inches) in length. The life-span of a wild Norway rat may extend from nine to 14 months.

In general, Norway rats have large litters of eight to 12 young. Under ideal conditions Norway rats can produce six to seven litters in a single year. Born in a nest about 21 to 23 days after conception, young rats are naked and their eyes are closed. Females may mate again within a day or so of littering.

At about three months of age the young are reproductively mature. The females come into 'heat' every four to five days and remain receptive to males for a day or two.


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Physical Abilities

Balance
Rats have an excellent sense of balance and, like a cat, a falling rat always lands on its feet. A Norway rat can drop as much as 15 meters (50 feet) without being killed or seriously injured.
Swimming
Norway rats are good swimmers. They are able to swim up through floor drains and toilet bowl traps. They may swim as far as 0.8 km (½ mi), dive through water plumbing traps, and travel in sewer lines, even against substantial water currents.
Climbing
The Norway rat can climb quite well when necessary. When rat proofing a structure, it would be wise to consider that rats can:
 
  • Climb both horizontal and vertical wires
  • Climb the inside of vertical pipes that are 4 to 10 cm (1.5 - 4 inches) in diameter
  • Climb the outside of vertical pipes that are up to 7.5 cm (3 inches) in diameter
  • Climb brick or other rough exterior walls which offer footholds
Burrowing and Gnawing
 
  • Burrow vertically 1.25 meters (4 feet).
  • Gnaw through a wide variety of materials especially if a small hole is present, including; lead pipe, brick, cinder block, aluminum sheeting, plastics and glass.
  • Gain entrance through any opening that is larger than 1¼ cm (½ inch) square.
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Behaviour
Feeding Habits
Rats are omnivorous, meaning they eat nearly any type of food although each colony or group of rats has its own preferences. The Norway rat is an avid consumer of man’s garbage. Rats are a nocturnal animal which means they are most active at night.
Social Behaviour
Rats can be very aggressive with other rats, especially when they become numerous. Dominant males exclude other males from the burrow which may be occupied by several females. This is one major cause of rat migration. Again, migration will occur when all suitable habitat is occupied or if available food is not sufficient to sustain the present population.
Reaction to Strange Objects
Rats will often avoid strange objects, and other changes in their environment for three or more days. The rat will recognize a trap or poison bait only as a new object to be avoided; something which may be hazardous. A change in location of a familiar object may cause avoidance, or a noticeable drop in feeding. In environments where strange objects appear regularly, such as at dumps or in busy warehouses, rats may show little evidence of shyness.
 
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Preventive Control Measures
There are four steps which are usually required in any rat control program:
 
  • Remove food sources
  • Remove potential shelters
  • Rat proofing
  • Eliminate rats
The first three steps are considered 'preventative' control measures, while the fourth step is directly reducing the rat population through 'active' control measures, such as poisons, trapping and so on.

Each step is essential and must be examined carefully. If not, the control program will ultimately break down and the investment will be wasted.

The 'bottom line' to long-term rodent control is the fact that rodents must have adequate food and shelter to live and thrive. Thus, whenever there is an abundance of rats (or mice), there is usually also an abundance of food and shelter available to the rats. The removal or reduction of these factors alone via sanitation practices will have a tremendous impact on reducing rodent populations, even without the use of any rodenticides or traps.

 
Remove Food Sources
Around residences, it is important homeowners conduct proper waste management, storage practices and feeding of pets and wildlife.
 
  • Garbage should be properly contained and removed regularly.
  • Bird feeders should be removed or designed to eliminate rat access by attaching a catch pan to prevent spillage on the ground.
  • Pet owners should feed dogs and cats only what they will eat and then remove the food and any spillage.
  • Store pet, wildlife food and lawn seed in an area not accessible to rats or in rodent-proof containers.
Remove Potential Shelters
Rats must have shelter and nesting sites in order to survive and multiply. Rats move undetected along runways which are sheltered by tall grass, shrubs or rubbish. They nest in well protected, undisturbed places; under wood piles, under improperly maintained compost bins, under patios & sheds and in unwanted items such as old furniture, appliances and vehicles.
 
  • Grass, weeds and other undesirable vegetation adjacent to buildings and  fences should be removed.
  • If the area around building is landscaped, it should be properly maintained.
  • Lumber, rocks piles, rubbish, old equipment, construction materials, etc., should all be eliminated if possible.
  • Items which must be kept should be stored at least 46 cm (18 inches) off the ground and 30 cm (12 inches) away from walls and fences.
Rat Proofing
The most successful and permanent form of rat control is to 'build them out', that is, make it impossible for rats to gain entrance into any area or structure where they are not wanted. All places where 'food' is stored, processed, prepared, or fed to pets or wildlife should be rat-proofed. If rats can be denied access to hiding places and food they can not survive.
Drains and conduits:
 
  • Use 12 mm (½ inch) screens with 6 mm (¼ inch) holes in drains. Keep them in good repair, tightly seal all areas where utilities enter buildings.

Foundations:

  • Construct concrete floors and foundations of high quality materials.
  • In the case of patios and sheds built on grade, use sheet metal buried 30 cm (12 inches) below grade to skirt the structure.
  • Always use screens in open doors, windows and crawl space vents.
The spaces beneath doors, especially garage doors, should be checked and reduced using a metal kicking plate or heavy weather stripping.

Norway rats can be deterred from climbing vertical pipes by applying a 30 cm (12 inch) band of glossy paint around the pipe or conduit.

Eliminate Rats
As the Norway rat has such an enormous reproductive capacity, controlling the spread of this species means eradication, followed by year-round inspections to ensure the problem is corrected.

In a community-wide rodent control program, poisoning rats is an essential part of the plan. Timing of the poisoning effort is of utmost importance. Rat poisoning methods are applied most effectively before sanitation and cleaning programs are begun to prevent out migration of rats to other areas. Also early in the spring where burrows are easily recognized and prior to initial breeding of mature rats.

Forms of eradication:

  • Traps
  • Glue boards
  • Rodenticides
  • Fumigation
  • Ultra sonic devices
Whichever method of eradication is used, it is best conducted by a professional Pest Control Operator. Look for 'Pest Control Services' in the Yellow Pages or online.
 
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Precautions and Legal Implications

 
  • All rodenticides are potentially dangerous enough to cause death to animals other than rodents, so be sure to place them where they are inaccessible to children, pets, livestock and wildlife.
  • Read and follow the rodenticide label instructions.
  • Dispose of dead rats immediately and avoid handling rats with bare hands.
  • When baiting outdoors, put all bait deep into burrows or in covered rodent bait stations. If placed directly into burrows, baits must be contained in their original packets unopened. This will prevent spoilage caused by moisture and insects, as well as making it recognizable as a poison. The burrow should then be covered to prevent access by children or non-target animals.
  • When baits are placed indoors, use covered bait stations where possible. It is legal to use open bait trays indoors only when they are protected under equipment, furniture or some other fixed structure which limits access to humans or animals.
Note: We strongly advise against baiting indoors as there is always a chance of rodents dying in the walls and creating a foul odour.

Also, no matter what form of eradication method is used, it has to be placed where the rat will come into contact with it, ie. adjacent to a wall, behind objects.

To obtain information on provincial legislation as it relates to rodenticides contact:

Department of Environment & Lands
Pollution Prevention Division
Pesticides Control Section
Phone: (709) 729-3395

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Community Control Program
There is no government organized rodent control program in St. John’s or in the province of Newfoundland and Labrador. The responsibility for rat control lies with the owner and/or the occupant of the  land, dwelling or business.

If you suspect there is a rodent problem on City owned land, please call Access St. John's at 311 or (709) 576-CITY (2489) to arrange for an inspection.

For additional help, contact information or to submit a request visit Access 311.
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