(Rattus norvegicus norvegicus)
The total length of this species is 316-460 mm, and the weight is 195-485 grams. The color reddish-brown to black on the back, and they have a pale to white belly. The tail is bicolored, and scaly. This species is nocturnal, and a burrower. It is colonial. It is associated with populated areas, and lives in buildings, sewers, fields, streambanks and marshes. It burrows into or under rubble, rocks, and logs. They are wary and suspicious, difficult to catch in live traps. The burrow system has several exits and occasionally up to a dozen will live in one burrow system. This species is exotic. They breed all year round producing several litters of around seven young. Predators include dogs, cats, hawks, owls, mink, weasels, fox, coyotes, skunks and snakes. The life span is approximately 3 years. It is often used as a laboratory animal. They are the cause of great economic loss in agricultural areas and are also vectors for diseases such as bubonic plague, tularemia, murine typhus and many others. Because of their aggressive behavior, they have in many cases displaced the black rat.
This species is most common in association with man although in some cases feral populations exist away from human habitation.. They are found wherever food and shelter exist. They are able to build a nest in almost any location.
This species will eat anything. It eats up to 1/3 of its body weight in food every 24 hours.