The head and body of the Norway rat range from 7 1/2 to 9 1/2 inches in length. The scaly tail is 6 to 8 inches in length. Their fur is shaggy brown with some black hairs. They have small eyes and ears.
These rats are nocturnal and quite cautious, usually not straying more than 100 – 150 feet from their nest. They can enter a structure through an opening as small as a 1/2 inch. Indoors, they prefer to nest on the lower levels, such as a basement. Outdoors, they burrow in soil, under sidewalks, near streams and rivers, piles of garbage, etc.
Foods of choice are meat, fish, and cereals. The will chew through almost anything to get to food or water.
Adults usually live between 6 to 12 months. Generally producing 3 – 6 litters, with an average of 7 – 8 young per litter.