Rat Control

The Norway Rat

The most common species of rat in the Prairies is the Norway rat (Rattus norvegicus). It is also known as the brown, common or sewer rat. The rat is one of the most destructive vertebrate in the world. Damages caused by rats are disease transmission, physical damage, and contaminated foodstuffs.





Rat Control Responsibilities

The Norway rat is declared, in Saskatchewan, a pest under The Pest Control Act. The responsibility to control rats resides on every person that owns land or buildings. It also resides on the person who occupies land and buildings.


Disease Transmission

Rats have a high potential to transmit disease because of the places they are likely to breed. Rats do occasionally bite and those bites should be treated properly by cleaning the area and disinfecting it. A tetanus shot is also recommended. Rats are not considered a threat when it comes to hantavirus or rabies because they have not been found infected with the virus.

Diseases can be transmitted directly by contaminated food and feeds from their urine and feces. They can also be indirectly transmitted by rat fleas or mites.


Physical Damage

Rats cause extensive damage by gnawing and tunneling. Damage can be done to buildings and structures including granaries and food storage buildings. Damage can also be done to wall and ceiling insulation, pipes, hoses, and electrical wiring.


Losses due to Contaminated Foodstuffs

One fifth of the world's field crops are consumed and contaminated each year due to rats. Rats eat about 10 per cent of their weight every day. They contaminate five to 10 times the food it eats with its urine and feces.


History and Identification of the Norway Rat

The Norway rat is not native to North America. It is believed that they were introduced by early settlers when ships docked on the eastern shores. The rats slowly moved West and in 1950 the first recorded rat colony was discovered on the Saskatchewan/Alberta border.
 
Norway rats are born approximately 21 to 23 days after conception. The size and number of litters depends greatly on the conditions of their habitat. Under ideal conditions, they can have 12 to 18 young per litter and can reproduce up to 12 times per year. Young rats typically cannot be trapped until one month of age. At three months, the young are independent of their mother and are reproductively mature.

An adult Norway rat averages 450 grams (1 pound). Their body length varies greatly from 18 to 25 centimeters (seven to 10 inches). The tails of rats are the most distinguishable feature. It is round and tapers near the end. The tail can be 15 to 22.5 centimeters (six to nine inches) in length. Their nose is blunt; ears are short and thick with fine hairs. The fur is reddish, grayish brown, or sometimes completely black. The fur underneath is grayish in color.

Norway rats nests and burrows under buildings such as granaries, livestock shelters, and under bale stacks. Nests are typically shallow and run horizontally with multiple exit holes. They have the ability to climb both horizontally and vertically. They can climb vertically inside pipes that are four to 10 centimeters (1.5 to four inches) and outside of vertical pipes up to 7.5 centimeters (three inches). They can crawl horizontally on any type of material from pipe to electrical wires. Rats can also jump as high as one meter (36 inches) as well at 1.2 meters (48 inches) horizontally. Norway rats are great swimmers. They have the ability to swim as far as 0.8 km (half mile). Rats are rarely seen since they are nocturnal. If rats are seen during the day it is a sure sign of an overpopulated rat colony.


Recognizing an Infestation of Rats

There are major signs that can be watched or when it comes to rat infestations.  Rats prefer to live in shallow burrows under foundations or feed bins.  Burrows do not have loose dirt around them like other animal burrows.  The entrances are typically four to eight centimeters (1.5 to three inches) in diameter.  Burrows are located approximately 100 feet from a food and water supply.  Old burrows should be closed once the infestation has been controlled to prevent migrating rats from re-establishing.

Since rats primarily use touch as a way to get around, an infestation can be detected by the well-beaten trails between their nests and their food sources.  Smudge marks along walls and beams is also an indication that rats are present.  This is due to the fact that Rats have very oily skin.

Rat droppings are an obvious sign of infestation.  They are capsule shaped with blunt ends and are usually 20 mm (3/4 inch) in length and six mm (1/4 inch) in diameter.  They are typically found along walls or in areas not clearly visible.  A single rat can produce up to 25,000 droppings a year.  If multiple sizes are found, there is a good chance that the rat population is actively breeding.

Rats must gnaw on objects in order to wear their teeth down.  They will chew anything from wood to concrete.  Teeth marks are anywhere from two to four mm (1/16 – 1/8 inch) wide.

If rats are seen during daylight, it is a sure sign of an infestation.  Rats are typically nocturnal in nature.  Meaning they are active from dusk to dawn and are rarely seen during in the daylight.  If an area has a serious infestation, rats that are less dominant will be seen during the day.  During the evenings, they will have to fight for food and water therefore making it easier for less dominant ones to feed in daylight.


Rat Control Measures

Rat baits can be found in many different kinds.  The R.M. of Corman Park carries Contrac, Oatmeal (Warfarin), Ratak, Ramex, and Rat X (Bar Bait).  A good practice is to place more than one type in each location.  This is the most effective way, as some poisons may not work as well in certain locations.  Bait stations may need to be spaced as little as seven to 10 meters (20 – 30 feet) in some situations.  Caution should be taken when using poisons to avoid harming other animals.  Bait can be placed in bait stations so other animals such as dogs and cats are unable to gain access to them.  Bait stations should be clearly labeled as Rat Poison and have the poison symbol visible.

Rat traps can be used in spaces where it proves to be effective.  This may be spaces indoors such as garages, sheds, and homes.  There is a lot more work involved if you choose to use traps.  They must be checked often and reset as needed.  There are pros to using traps.  There are no harmful poisons and rats can be removed from the traps and discarded to avoid odour problems.

More information can be obtained from the R.M.'s Pest Control Officer by calling (306) 242-9303.