Norway Rats (Rattus Norvegicus)

The Norway rat, one of the most common rats seen in, and around homes in northern California

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

Norway Rat Description & Facts

  • Large & robust
  • Weight: 7 to 18 oz.
  • Blunt Muzzle
  • Small eyes & ears
  • Poor eyesight
  • The tail 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 gain entry into 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.

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 prior to sunrise.

It prefers to travel along walls and between objects in order 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 new food sources for a time. 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.  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 a 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 very small opening or gap and can 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.

If you would like us to care for it, no worries we have you covered!  We Specialize in Rodent Control.

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