Adults with combined head and body length 6-8 inches and the tail length is between 7-10 inches. The fur is soft and smooth; color is between brown with black intermixed to gray to black above with underside white, gray, or black. The muzzle pointed, eyes and ears are large, and they are almost naked. The tail will be scaly, uniformly dark, longer than head and body combined. Once established indoors, roof rats tend to follow the same route or pathway between their nest and food sources. Runways along vertical surfaces will usually include dark rub or swing marks on the vertical surface where their fur makes contact. Their runways will be free of debris, outdoors, the grass will be worn away to the bare soil.