The brown rat, also referred to as common rat, street rat, sewer rat, Hanover rat, Norway rat, Norwegian rat, or wharf rat (Rattus norvegicus) is one of the best known and most common rats.
One of the largest muroids, it is a brown or grey rodent with a body up to 25 cm (10 in) long, and a similar tail length; the male weighs on average 350 g (12 oz) and the female 250 g (9 oz). Thought to have originated in northern China, this rodent has now spread to all continents except Antarctica, and is the dominant rat in Europe and much of North America—making it by at least this particular definition the most successful mammal on the planet after humans. With rare exceptions, the brown rat lives wherever humans live, particularly in urban areas.
Norway Rats. Norway rats are omnivorous eat a wide variety of foods but mostly prefer cereal grains, meats, fish, nuts, and some fruits. When searching for food and water, Norway rats usually travel an area of about 100 to 150 feet in diameter; seldom do they travel any further than 300 feet from their burrows or nests. The average female Norway rat has four to six litters per year and may successfully wean 20 or more offspring annually.
Norway rats typically nest in underground burrows from which they enter buildings in search of food. They tend to remain in hiding during the day.
The Norway rat reaches sexual maturity in two to five months and can breed any month of the year. Litters may number from four to 22. Females can have three to 12 litters per year. Adults generally live up to one year in the wild.
SIGNS OF NORWAY RAT INFESTATION:
Outdoor burrows surrounding the building may be an indication of Norway rat nesting. Other signs of Norway rats are their gnaw marks on food and objects such as utility lines. Rub marks or grease stains caused by rats running along an edge also can indicate activity. In general, the darker the stain, the greater the activity. Perhaps one of the most well-known signs is their droppings.
Similar to other rodents, brown rats may carry a number of pathogens, which can result in disease, including Weil's disease, rat bite fever, cryptosporidiosis, viral hemorrhagic fever, Q fever and hantavirus pulmonary syndrome.
This species can also serve as a reservoir for Toxoplasma gondii, the parasite that causes toxoplasmosis, though the disease usually spreads from rats to humans when domestic cats feed on infected brown rats.