Norway Rat (Rattus norvegicus)


Class: Mammalia
Order: Rodentia
Family:    Muridae
Size:    Length: 10 to 18 inches (25 to 46 cm)
Weight: Up to 1 pound (450 g)
Diet: Almost anything, including grain, garbage, wax, soap and other animals
Distribution: Worldwide
Young:  2 to 14 young, up to 12 time per year
Animal Predators:  Snakes, owls, hawks, skunks, weasels, minks, dogs and cats
IUCN Status: No special status
Terms: Group: Mischief  Male: Buck  Female: Doe  Young: Pinkie
Lifespan: Average 2 to 3 years



·        Norway rats are among the most prolific of all mammals.

·        The Norway rat is also known as the “barn,” “brown,” “sewer,” “water” or “wharf” rat.

·        Laboratory and domestic rats are domesticated albino strains of the Norway rat.

·        During the last millennium, rat-borne diseases killed more people than all the wars and revolutions put together.

·        Norway rats are one of the most destructive creatures known to man in terms of the economic losses, destruction of property and loss of human lives due to disease that they cause.

·        A rat’s temperature is regulated through its tail, and it sweats through the pads of its feet.

·        The oils in cedar and pine are toxic to rats.



Norway rats are one of the most common rats in the world, along with the slightly smaller black rat. Norway rats have coarse grey-brown fur above, and pale grey fur on their undersides. Their long, scaly tail is nearly hairless. 



Despite their name, Norway rats did not originate in Norway, but in northern China. They spread to Europe in the mid-1500s, and were brought to North America in 1775 aboard ships coming from England, which were carrying grain. Black rats were introduced to North America in the 16th century, and although both types of rats may inhabit the same area, Norway rats are more adaptable and live in a wider range of habitats. Norway rats dig tunnels underground with chambers, where they sleep during the day. 


Feeding Habits

Although rats eat more grain than anything else, they will feed on almost anything, including any kind of garbage, wax and soap, and they contaminate the feeding area by leaving their droppings behind. They can often be seen frequenting garbage dumps or compost heaps, where they are attracted by the smell of rotting food. They often form groups of 60 or more to prey on other animals such as chickens, lambs and piglets. Rats have a hierarchy, and dominant rats may not allow lower ranking rats access to food during nocturnal forays, so these individuals often venture out during daylight. 



Norway rats can begin breeding at the age of two to three months and produce seven to 12 litters per year. There may be two to 14 young in one litter, but the average is seven or eight. They breed all year around, and the female undergoes a three-week pregnancy. Once her litter is born, she often mates again, right away.  The young rats are born helpless, with closed eyes and no fur, but they mature quickly. Their eyes open in two weeks and they are completely weaned by one month. By about three months of age, they are able to reproduce.  



They are extremely aggressive and fearless animals. They can be found anywhere where humans are found, from cities to farms to beach communities, and unlike the black rat, they are excellent swimmers with no fear of water. 



Rats carry any number of diseases that can be transmitted to humans, including bubonic plague and typhus, making them one of the most dreaded animals, but despite efforts to eliminate them, their numbers keep increasing because of their large, frequent litters. The worldwide population of the Norway rat has increased as human populations and settlements have grown. The population of the Norway rat is currently between 150 and 175 million rats in the United States alone. In the province of Alberta, Alberta Agriculture runs a Norway rat control program that has essentially kept the province free of rats since 1950.