Norway rats

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  • Colour Brown or dark grey
  • Size From 40 cm to 50 cm long, nose to tail
  • Also known as Brown rats, Common rats, Street rats, Sewer rats, Wharf rats.
  • Description Have coarse fur, protruding ears, and long tails. They have small eyes and ears, a blunt, slanted snout, and a stocky, heavy body.
Norway rat photo

General Facts

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.


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

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.

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


Why do I have Norway rats?

Norway rats live on every continent except Antarctica. They like to stay in damp environments at ground level or in burrows, but enter homes looking for warmth, food, and water.

These pests squeeze through gaps in walls and foundations, plumbing, attics, and sidings to nest in crawl spaces, basements, or around the perimeter of homes. They are also strong swimmers, and can enter through toilets and drain pipes too.

Rats will generally eat anything and are attracted to any food easily available. Norway rats tend to prefer foods high in fat content, like grease and meat.

How worried should I be about Norway rats?

Norway rats can transmit many diseases, like the bubonic plague, typhus, Weil’s disease, toxoplasmosis, and trichinosis, as well as contaminating food with their faeces, saliva, and urine and the parasites like mites and ticks that they carry with them.

These pests also cause structural damage, leaving unsightly holes in lawns, undermining building foundations, and gnawing through electrical wiring, causing power outages and electrical fires. They also leave teeth and rub marks on the walls.

As a business owner, rats can ruin your reputation, eliciting reactions of horror and disgust from customers, causing structural damage to your property, putting your employees at risk, and harming your ability to operate legally.

Norway rats can breed quickly, giving birth to litters of up to 12 offspring up to six times a year – so even with traps in place, an infestation can spiral out of control easily. To truly deal with a Norway rat infestation, professional pest control services are crucial.

How can I prevent Norway rats invading?

Check wiring for chew marks and gnawing, Check the walls for rubbing marks or holes, Look out for small, pellet-like droppings, Keep food preparation areas clean, Clean up spills and crumbs immediately, Remove food sources, including bird feeders, Clean and rotate dumpsters regularly, Make sure trash cans are covered tightly, Trim back vegetation from building exterior, Seal any cracks or holes with caulk or foam, Fix leaky soda or ice machines and HVAC units, Remove any standing water outside, Don’t leave doors open for a long time, Install weather strips around doors and windows

What is the difference between a Norway Rat vs Roof Rat?

Canadian homeowners who have problems with rats are likely dealing with one of two species, the Norway rat or the roof rat, also known as the black rat. These pests create similar damage, making identification hard for residents. Being able to spot a few key differences between the two species can aid in control and removal.


Norway rats are also called brown rats, and some people refer to roof rats as black rats. Despite these common names, colour is not a good way to identify a rodent. The fur of both species can vary from gray or brown to black.

Instead, consider the builds of Norway rats vs. roof rats. Norway rats are bigger and stockier, while roof rats are slender and athletic. The Norway variety is also larger in general, though they have smaller ears and eyes. In addition, the tail of a Norway rat is shorter than its body. Roof rats have tails longer than their bodies.


Roof rats are natural climbers, which means they usually enter attics and the upper levels of houses. On the other hand, the Norway rat prefers to stay low to the ground, appearing in basements and garages.


Even though the pests have the similar diet, Norway rat vs. roof rat feces look different. Norway rat scats are bigger and have an oval shape and blunt ends, while roof rat poop is smaller and pointed at the ends. Because these pests leave behind trails of waste wherever they go, droppings are often the first sign of rodents.

Other pests related to Norway rats

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