Norway Rats (Rattus Norvegicus)

Norway Rats (Rattus Norvegicus)

The Norway rat is also known as the Brown rat, Gray rat, Sewer rat, Barn rat, Wharf rat, and Water rat. Additionally, because of its large size, it is referred to as the Super Rat or King Rat. The Norway rat originated in Central Asia.

Norway Rat Description & Facts

The Norway rat is a large rodent, usually brownish-gray, with lighter bellies and dark fur on their tails. Here are some more details about the Norway rat:

  • Large & robust
  • Weight: 7 to 18 oz.
  • Blunt Muzzle
  • Small eyes & ears
  • Poor eyesight
  • Scaly tail that is shorter than the body
  • Average total length: 16 inches (head to tail)
  • Good climber, jumper, and swimmer
  • Excellent sense of smell, taste, touch, and hearing
  • Typical color: Gray, grayish brown, blackish, reddish-brown
  • Fecal dropping size: 3/4 inch with blunt ends (up to 25,000 in a year)

Norway Rat Habits, Life Cycle & Facts

The Norway rat is very adaptable to many environmental conditions. They live in colonies with an alpha or dominant male. It will nest in hard-to-reach places such as underground burrows, crawlspaces, basements, and sewers. However, the preferred nesting site is in underground burrows.

It can enter a building through a hole the size of a quarter or a half-inch gap. Additionally, they are capable of chewing through most structural materials.

The Norway rat is a good climber but prefers to travel over flat surfaces. With a running start, it can long jump a distance of about 3 feet, and from a standing position, it can jump vertically about 2 feet. It can fall from heights of 50 feet without being injured.

When Are Norway Rats Most Active?

Contrary to popular belief, rats are not truly nocturnal. However, rats are more active when there is less danger, which is usually at night. Their peak activity is shortly after dark and again before sunrise.

It prefers to travel between walls and objects to protect itself from predators. They can move around very quickly in their well-known environment by what is called kinesthesis, meaning muscle memory. Even when frightened, kinesthesis allows them to race back to their home base or the cover of darkness at high speeds, even around objects, with an automatic sense of what is there. They are very cautious (neophobic) and may avoid new objects and food sources for a while. This makes control efforts challenging at times.


The Norway rat’s diet includes grains, nuts, seeds, fruits, insects, snails, meats, and pet food. However, Norway rats are also opportunistic omnivores, meaning they can consume many different types of foods, which usually includes human food. They need about 0.5 to 1 ounce of food and about 1 to 2 ounces of water daily.


The Norway rat generally lives for 6 months to 1 year. Females reach sexual maturity at 2 to 3 months of age and, after mating, can give birth in 21 to 23 days. The average litter size is 6 to 12 pups, and the average number of litters in a year is 3 to 6, but these numbers can be much higher. Depending on conditions, they can live for several months and up to 1 year.

Rat Pest Control

Fighting off a Norway Rat infestation takes a professional in many cases. Due to the rapid increase in the rat population, with up to 1,800 rats originating from a single mating pair in 1 year, the rat problem needs to be taken very seriously. Rats carry diseases and cause a serious risk to the health of people and pets.

Rats can enter a home through a small opening or gap and breed, hide, and multiply better than most mammals. Look for rat droppings in garages, attics, basements, behind and under rubbish piles and appliances. If found, you might try a store-bought rat poison, but chances are very good that a professional will be needed to correct and prevent a re-infestation.

Call Barrier For Professional Rat Control

If you’re looking for professional rodent control services, call Barrier! Our team has years of experience in servicing homes in the Sacramento area and is always ready to help. Get started with your free quote on any service today.


Frequently Asked Questions

How do I get rid of Norway rats in my yard?

Check for holes and cracks around the perimeter of your home that could serve as potential entry points. If you discover any, seal them up with materials like steel wool or caulk. Also, keep garbage cans tightly closed and stored away from your house. You can also set traps and baits around your property, which are best placed near walls or appliances.

How long do Norway rats live?

The Norway rat generally lives for 6 months to 1 year.

How may Norway rats live together?

Norway rats are social animals and typically live in large colonies with one dominant male. A single colony can contain dozens to hundreds of Norway rats living together, depending on the size of the available space and food sources.

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