Mice and rats have much in common. They breed quickly, have poor eyesight, and tend to be active at night. They also are adept at squeezing through tiny openings, and can easily chew their way through wood, aluminum, plastic and even cinder block.
Additionally, while house mice (Mus musculus) will make their homes almost anywhere, Norway rats (Rattus norvegicus) prefer burrows and spaces in the lower levels of a building. Rattus rattus, meanwhile, lives up to its common name of roof rat by opting for spaces in the upper parts of a structure. Patience and a trusty flashlight are required as you go on your hunt.
Signs of rodent presence include tracks, gnawing damage, burrows, runways, urine stains and grease marks. Droppings are key to identifying these intruders. Mouse droppings are about 1/4-inch long and rod-shaped. Roof rat droppings also are rod-shaped, but around 1/2 inch in length. The droppings of Norway rats are capsule-shaped, and average about 3/4 of an inch.
However, if the infestation is far along, you’ll also notice the distinct odor of rodents. You can’t miss it.