THE NORWAY RAT Identification and Biology

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The first step to rodent control is to properly identify and learn as much as you can about the type of rodent you're dealing with. In pest control, as with sports, knowing what your offense has up its sleeve will better prepare you in planning your defensive strategy.

The Norway Rat: Physical Appearance & Identification

Norway Rats may be identified by the following physical features:

  • The Norway Rat's adult head and body length is about 7 to 9 inces (18-25 cm); tail length is 6 to 8 in (15-21 cm);
  • The Norway rat has coarse, shaggy fur that is dark brownish to black in color, with a paler colored underside.
  • The Norway rat has a blunt nose, small close-set ears that will not cover the eyes when pulled down, and small eyes.
  • The tail of the Norway rat is scaly, sparsely haired, and shorter than the head and body combined.
  • The Norway Rat is slightly larger than the Roof Rat. When distinguishing the two, pull the tail back over the body. That tail of the Roof Rat will reach the nose, while the tail of the Norway Rat will only reach to the ears.

Other Identification Helps:

  • Droppings- Norway Rat droppings are 1/4 to 1/2 inch in length, capsule shaped, with blunt ends. They are usually a shiny black, but may vary according to diet. Rat droppings are three times as large as mouse droppings.
  • Tracks- Norway rats and Roof Rats leave a hind foot track of about 3/4-1 inch. A mouse's tracks will be much shorter. Rats will also drag their tails, leaving a mark between their feet tracks.
  • Gnawing holes- Gnawing holes from rats are about 2 inches or more in diameter and will have rough edges. They prefer gnawing on wood but may also damage electrical wiring.

The Norway Rat: Habitat & Food Sources

Norway Rats live in colonies and prefer to live right alongside people, where they can easily leech off of our food sources. Norway rats usually construct nests of shredded paper, cloth, or other fibrous material in below-ground burrows or at ground level around the lower levels of buildings, beneath concrete slabs, around streams, ponds, and garbage dumps, or wherever else food, shelter, and water are readily available. The Norway Rat will eat almost anything, but prefers fresh and wholesome foods such as grains, meats and fish, nuts, and some fruits. Norway Rats typically need 1/2 to 1 ounce of water daily when feeding on dry foods, and less when moist food sources are available.

The Norway Rat: Behavior & Biology

Norway Rats are primarily nocturnal, meaning that they sleep during the day and become active (seeking food and water) after dusk. If you see a rodents during the day, this is typically an indicator of especially large populations, a disturbed nest, or lack of food sources.

Norway Rats birth litters of about 6 to 12 young after a gestation period of 21 to 23 days, and may mate again
within a day after a litter is born. The average female Norway Rat gives birth to 4 to 6 litters per year. Newborn rats may reach reproductive maturity and start the cycle again within 2 to 3 months. As you can see, these little critters multiply rapidly, and that's why it is important to get them under control as soon as you become aware of a problem.

Products for Control of Norway Rats:

See our list of Products for the Control of Norway Rats

Read more about How To Get Rid of Norway Rats

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