The Norway Rat

The Norway Rat


The Norway Rat

The Norway Rat is the most common and widely distributed rat species in the United States, being found in all states. Often known as the house rat, brown rat or roof rat. The Norway Rat is the largest, strongest, and more aggressive species of rat. They are also more equipped for better adaption which allows for them to produce more young and survive in colder climates over other rat species.

With a bulky body, the Norway Rat can weigh up to 12-16 ounces. The fur on their body is very coarse and they range in colors of brown, reddish, and/or black with white under coatings. They have a blunt nose, small ears that can not cover their eyes if pulled down. The tail of The Norway Rat is scaly and naked and shorter than their entire body.

Where Will You Find a Norway Rat?

Very social, The Norway Rat lives in colonies in the ground. On farmlands, you may find that they inhabit barns or livestock buildings. In cities, rat nests are found in the ground where space is available. The Norway Rat may live and nest it’s entire life inside buildings or any type of city infrastructure like sewers, subways and utility chases.

Subdivisions also have great nesting places for The Norway Rat. They find residences such as food facilities, warehouses, stores and hotels to inhabit, as well as, surrounding forests and parks.

Indoors, The Norway Rat will usually occupy the lower floors, but in some cases, they may retreat up stairs and establish a nest in ceilings, walls or attics. They will nest in furniture within the same room occupied by humans. Outdoors you will find a nest alongside or beneath boulders, slabs, tree roots and along foundations.

What Do Norway Rats Feed On?

Generally, The Norway Rat as an adult, eats about 110 calories per day to maintain its health. That means they consume about one to 2.5 ounces of food daily. Most of the time, those that are nesting indoors find food items in household garbage that are sufficient enough for their health upkeep.

Outdoor rats feed on trash and litter and in cities, they feed on insects, especially cockroaches inside sewers. They also become predators to birds eggs, smaller reptiles, earthworms, crickets and caterpillars.

Unlike Mice, Rats can not survive for very long without a source of water if eating a dry diet. When the Rat has a moist diet, the need for water drops. Rats maintain their survival by gathering water from rain puddles, sinks, toilets, water tanks, sewers, and even from items with condensation.

Capabilities of The Norway Rat

Most rats are nocturnal. They begin to peak out around dusk or right before dawn. They may even adjust their schedules to peak out when their food source if more prevalent or the freshest. This does not mean that you may never see a rat during the daytime. Daytime rats are seen as a result of overcrowding, other sick or dying rats, or a recent disturbance in their nest area.

The Norway Rat is also known to be climbers. When climbing is necessary, they can scale the walls of your home or of buildings, climb stairs, pipes, wires and even concrete walls. They have the most impressive capabilities out of all the smaller mammals.

They may have poor vision, but in return are very sensitive to motion up to 50 feet away! Rats also have a great sense of taste that allows them to sniff out chemicals- thus the reason why peanut butter is often used to capture or trap rats. Rats hearing has a frequency range of up to 50kHz, which is more than a human can hear. They rely on odors to help them navigate to food sources and even help them find the opposite sex for mating. Odors also help a rat to reveal if an intruder is a stranger, and if they are a strong or weak individual.

Reproduction wise, The Norway Rat mates all year long with a gestation period of 22 days, having at least seven litters per year. The female can have a litter of up to 12 pups at a time. Like mice, the pups are born naked and blind. After about 25 days, the pups eyes are opened and they have been weaned. Rats learn their surroundings and pathways to food by imitating their mothers. In captivity, rats may live for three or more years. Wild rats may only live for five to 12 months.

Diseases Passed on From Rats

  • Typhoid
  • Weil’s Disease
  • Leptospirosis
  • Plague
  • Rat Bite Fever


Preventive Pest Control will create a Rodent Control Program that best fits the needs of your home or infestation. Mice trapping and exclusion is included within your general pest control contract with us here at Preventive. For all questions regarding or Rodent Control Program, call our office today! 615-850-4351

Tips to Winterize Your Home Against Pests

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Source: Truman's Scientific Guide To Pest Management Operations