The brown rat (Rattus norvegicus), also known as the common rat, street rat, sewer rat, wharf rat, Hanover rat, Norway rat, Norwegian rat and Parisian rat, is a widespread species of common rat.
One of the largest muroids, it is a brown or grey rodent with a head and body length of up to 28 cm (11 in) long, and a tail slightly shorter than that.
It weighs between 140g and 500g (5 and 17+3⁄4 oz). Thought to have originated in northern China and neighbouring areas, this rodent has now spread to all continents except Antarctica and is the dominant rat in Europe and much of North America.
With rare exceptions, the brown rat lives wherever humans live, particularly in urban areas.
The house mouse (Mus musculus) is a small mammal of the order Rodentia, characteristically having a pointed snout, large, rounded ears, and a long and almost hairless tail.
It is one of the most abundant species of the genus Mus. Although a wild animal, the house mouse has benefited significantly from associating with human habitation to the point that truly wild populations are significantly less common than the semi-tame populations near human activity.