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Brown Rat

Brown rat or Norway Rat

Brown rats are, in many ways, the most common and successful species of rodent. They live on every continent except Antartica, and in all climates except the northern most parts of Russia, north-eastern Canada, Greenland, and select islands. They are also known as the “Norway rat”, “common rat”, “street rat”, “sewer rat”, or “wharf rat”. Its scientific name is rattus norvegicus (Norwegian rat) is cause for some misunderstandings as the species did not originate from Norway. Brown rats have followed humans to nearly every major city and town, bringing disease and pestilence along as they search for food and shelter.


Why should I be concerned?

Brown rats are able to carry a number of pathogens. Some of the most well known of which are the bubonic plague, typhus, Weil’s disease, toxoplasmosis, and trichinosis. The can also damage and contaminate food as with their waste as well as the parasites which they carry. Rats can cause electrical fires by chewing through wiring and insulation and causing a short circuit, a habit which may be responsible for as much as 50% of farm fires. They prefer damp environments and will enlarge gaps in the walls and foundations, plumbing, attics, siding.

Habitat and Behaviour

A day in the life of a brown rat

Brown rats typically burrow underground, near another structure which can provide overhead shelter. Like most rats, they are nocturnal and will remain hidden during the day if at all possible. If you see one during the daytime it may be a sign of a large infestation.

The brown rat is a true omnivore and will consume almost anything, but cereals form a substantial part of its diet.


  • Measures 40 to 50 centimetres in length from, nose to tail
  • Weighs between 350 to 500 grams
  • Fur is normally brown or dark grey
  • The tail is longer than the rest of the body, dark and scaly in appearance
  • Snout is slanted, ears and eyes are small, and the body is stout

Tips for prevention and control

These tips may help you keep brown rats out of your home:

  • Store food, water, and garbage in containers with tight-fitting lids
  • Clean up spilt seeds under bird feeders, or remove the feeders at the first sign of rats
  • Seal any holes around doors, windows and roofs
  • Trim or prune all trees so that they do not overhang or contact your building

Test Your Knowledge of Brown Rats


  1. True or false: brown rats do not transmit disease to humans.
  2. Brown rats can cause electrical fires by chewing through wiring and insulation. This is responsible for what percentage of farm fires?
    1. 10 percent
    2. 25 perfect
    3. 50 percent
  3. Brown rats can be found in which of the following locations:
    1. Walls
    2. Foundations
    3. Plumbing
    4. Attics
    5. All of the above
  4. True or false: one sign of brown rats are greasy rub marks on walls caused by activity at night.


  1. False. Brown rats can carry a number of pathogens, such as the bubonic plaque.
  2. C. Brown rats love to gnaw through electrical insulation to keep their teeth sharp. This is a huge concern for homeowners because it can cause electrical outages or fires.
  3. E. Brown rats prefer dark, damp environments and will enlarge gaps in the walls and foundations, plumbing, attics, or siding.
  4. True. In general, the darker the stain, the greater the activity. 

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