When foraging, the Norway rat generally travels on the ground, but it is also a good swimmer, jumper and climber. They follow the same routes when they make their rounds foraging each night. Home ranges are generally only 50 m in diameter, although rats have been known to travel 2-3 miles a night to forage in farmers fields at harvest time. Rats are most frequently found living together in large groups in which a large male is dominant, maintaining preferential access to food, water, and resting sites. This male continuously guards a harem of females and aggressively prevents other males from mating.
Females actively defend group resources against strangers and often nest together.
Nests are built out of leaves, paper, rags, twigs, or anything useful the rat can find. If a suitable cavity or crevice is not available for nesting, rats make burrows in the ground and trails on the surface, particularly under the cover of old boards and the like. Even though rats are nocturnal, some rats can often be found foraging during the daytime in areas of high population. Habitat Chiefly found in areas around human settlement, Norway rats occur wherever there is an abundance of food and shelter, from the subways and crowded tenements of metropolitan districts, to the corn and grain fields of farm country, to the salt marshes of the Atlantic Coast where edible flotsam is washed up on the beaches. Negative Many consider this rat to be the greatest mammal pest of all time.