The roof rat is dark brown to black in color and measures 13 to 18 inches in length including tail. They weigh 5-9 ounces, are slender, and their ears are large and nearly hairless. Their droppings are long and cylindrical.
Roof rats nest outside in trees, woodpiles and debris, and in dense vegetation. Inside, roof rats prefer to nest in the upper levels of a building in the attic and ceiling.
Roof rats are omnivorous, but tend to more vegetarian preferences. Typical food is fresh fruit, plant material, nuts and seeds, vegetables and even tree bark.
Rats can spread disease. Sometimes they transmit disease directly by contaminating food with their urine or feces or by biting people. Indirectly, they transmit by infecting as when fleas bite a disease-infected rat, then a person or other animal.
Rat burrows can cause structural damage by undermining the foundations of buildings, roads and walkways, can cause damage by gnawing, damaging plastic and lead pipes, door frames, upholstery, and electric wires, and can cause damage through the destruction and contamination of stored foods.
The house mouse is a small, slender rodent that has a slightly pointed nose; small, black, somewhat protruding eyes; large, scantily haired ears, and a nearly hairless tail with obvious scale rings. The adult mouse weighs about 2/5 to 4/5 ounces. They are generally grayish-brown with a gray or buff belly. Similar mice include the white-footed mice and jumping mice( which have a white belly), and harvest mice (which have grooved upper incisor teeth.) Native to central Asia, this species arrived in North America along with settlers from Europe and other points of origin. A very adaptable species, the house mouse often lives in close association with humans and therefore is termed one of the "commensal" rodents along with Norway and roof rats. Following their arrival on colonists’ ships, house mice spread across North America and now are found in every state including coastal areas of Alaska, and in the southern parts of Canada.
The Norway rat is a stocky burrowing rodent, unintentionally introduced to North America by settlers who arrived on ships from Europe. First introduced into the United States about 1775, this rat has now spread throughout the contiguous 48 states. The Norway rat is found generally at lower elevations but may be found wherever humans live. Also called the brown rat, house rat, barn rat, sewer rat, gray rat, or wharf rat, it is a slightly larger animal than the roof rat. The nose is blunt, the ears are small, close set and do not reach the eyes when pulled down. The tail is scaly, semi-naked and shorter than the head and body combined. When distinguishing the Norway rat from the Roof rat, pull the tail back over the body. The tail of the Roof rat will reach the nose. The tail of the Norway rat will not reach beyond the ears. Adult Norway rats weigh an average of about 1 pound. Their fur is coarse and usually is brownish or reddish-gray above, and whitish-gray on the belly. Blackish individuals occur in some locations.