Signs of a rat’s presence are droppings, gnawing marks, tracks, runways, and burrows.
Like mice, rats are nocturnal, have very poor eyesight, but have very strong senses of smell, taste, and hearing.
Compared to mice, rats are much larger, have coarser fur, and have proportionately larger heads and feet.
The most common rat species in the U.S. are the Norway rat and the roof rat. These two do not get along and will fight each other to the death. The larger Norway rat usually wins.
Norway rats tend to live in lower floors of buildings and roof rats will live on the upper floors, so they can both infest the same building at one time.