Rats are some of the most common and formidable pests in the world — damaging and contaminating food, structures and human health. Although people don't usually see the actual rats, signs of their presence are relatively easy to identify. Two primary species of rats inhabit North American homes: the roof rat and the Norway rat.
Norway rats, sometimes called brown or sewer rats, are identifiable by their stocky, gray-brown bodies. Their tails are shorter than their body length and their ears and eyes are small relative to their body. Norway rats are larger than most other rat species. They burrow in gardens and fields, as well as beneath building foundations, trash or woodpiles. Norway rats line their nests with fibrous materials, such as shredded paper and cloth. These rats tend to inhabit the lower levels of buildings.
Roof rats, sometimes called black rats, are superb climbers that tend to nest above ground. In the wild, roof rats inhabit shrubs, trees and dense vegetation. In domestic environments, they seek out secure, elevated places such as attics, walls, sheetrock ceilings and cabinets. They may enter homes through trees close to windows or eaves. As opposed to the Norway rat, roof rats tend to limit their geographical range to warmer climates often along the coast.
Rats are generally larger than mice. While young rats can sometimes be mistaken for mice, they can be distinguished by their disproportionately long feet and oversized head. Both rodents are capable of chewing through hard, wooden surfaces, but rat teeth marks are much larger than those of mice.