Mice

The HSUS/Janet Snyder

House mice emerge from beneath loose floorboards.

For an animal that usually weighs less than an ounce and eats about one-tenth of its weight in food each day, the house mouse (Mus musculus) has, throughout history, given humans a good deal of grief.

Mice are adapted to a diet consisting largely of seeds and grain. As a consequence, the agricultural revolution that swept through Europe and central Asia more than 10,000 years ago also swept mice right up to humanity’s front door. Our association became so intimate that today house mice (and their larger rodent cousins, Norway and roof rats) are described by the term "commensal," which literally means “sharing the table.”

Fast Facts

Status: Found throughout North America Appearance: Gray-brown fur with a naked tail as long or longer than body  Lifespan: About one year Reproduction: As many as 8 litters per year Food: Seeds, grain, nuts

House mice accompanied the first Europeans to the New World and have since become established almost continent-wide in North America. They are most common around human residences, farm sites, industrial areas and commercial complexes, although they can also survive in wooded areas.

Almost everyone has seen a house mouse at one time or another. They're small (2-3 inches long) with gray-brown fur, and possess a nearly naked tail that is as long or longer than its body. They are often confused with native mouse species such as white-footed and deer mice (Peromyscus spp.), or meadow voles (Microtus spp.).

Habitat

House mice prefer to live inside buildings, whether these be single-family homes, apartment complexes, granaries, barns or sheds. The entire area occupied by a mouse during his lifetime may be less than the size of an average room. Much of his life is spent in secure, comfortable niches between walls and behind cabinets and appliances.

The only sign of mouse occupancy may be the evidence of gnawed foods and droppings on floors, shelves, and counter tops.

Diet and Reproduction

House mice are omnivores and eat a variety of foods, preferring seeds, grains, and nuts. Unlike rats, mice can live without access to fresh water if the solid food they eat is somewhat moist. They breed year-round and can raise as many as eight litters annually, with an average of 4-7 young in each.

Females can begin reproducing at one to two months of age. Under the right conditions, mouse populations can grow almost explosively. This potential is partially counterbalanced by the tendency of mice to be short-lived. One year is about the longest any house mouse can expect to survive.