Norway Rat

 

 
This looks like your typical large rat, about 13"-18" long.  It is a native of Asia, but probably came to North America  from Europe.  It has an elongated snout, small eyes, moderately sized, nearly naked ears; and a nearly naked tail with scaly rings.  Upperparts are grayish brown with scattered black hairs, grading to pale gray or yellowish white on the underparts.  The feet are grayish or whitish.  The Norway rat is found throughout the U.S. and parts of Canada.  They tend to live near human habitation, making tunnels under the floor or simply living within the nooks and crannies of buildings.  They are active during all parts of the day, but mainly at night.  They are probably the most omnivorous of all mammals, feeding on both dead and living material.  You name it, they will probably eat it.  These are important pests of humans.