Mus musculus

Geographic Range

Mus musculus may have originally been distributed from the Mediterranean region to China, but it has now been spread throughout the world by humans and lives as a human commensal.

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
• palearctic palearctic
  • native native
• oriental oriental
  • introduced introduced
• ethiopian ethiopian
  • introduced introduced
• neotropical neotropical
  • introduced introduced
• australian australian
  • introduced introduced
• oceanic islands oceanic islands
  • introduced introduced

• Other Geographic Terms
• cosmopolitan cosmopolitan

Habitat

House mice generally live in close association with humans-- in houses, barns, granaries, etc. They also occupy cultivated fields, fencerows, and even wooded areas, but they seldom stray far from buildings. Some individuals spend the summer in fields and move into barns and houses with the onset of cool autumn weather. Because of their association with humans, house mice have been able inhabit inhospitable areas (such as tundra and desert) which they would not be able to occupy independently.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• scrub forest scrub forest

Physical Description

House mice are from 65 to 95 mm long from the tip of their nose to the end of their body, their tails are 60 to 105 mm long. Their fur ranges in color from light brown to black, and they generally have white or buffy bellys. They have long tails that have very little fur and have circular rows of scales (annulations). House mice tend to have longer tails and darker fur when living closely with humans. They range from 12 to 30 g in weight. Many domestic forms of mice have been developed that vary in color from white to black and with spots.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

House mice have a polygynous mating system. The recent discovery of ultrasonic songs produced by male mice, when exposed to female sex pheromones, suggests that this behavior may be involved in mate choice.

• Mating System
• polygynous polygynous

Mus musculus is characterized by tremendous reproductive potential. Breeding occurs throughout the year, although wild mice may have a reproductive season extending only from April to September. The estrous cycle is 4-6 days long, with estrus lasting less than a day. Females experience a postpartum estrus 12-18 hours after giving birth. Females generally have 5-10 litters per year if conditions are suitable, but as many as 14 have been reported. Gestation is 19-21 days but may be extended by several days if the female is lactating. Litters consist of 3-12 (generally 5 or 6) offspring, which are born naked and blind. They are fully furred after 10 days, open their eyes at 14 days, are weaned at 3 weeks, and reach sexual maturity at 5-7 weeks. Average life span is about 2 years in captivity, but individuals have lived for as long as 6 years. In the wild, most mice do not live beyond 12-18 months.

• Key Reproductive Features
• iteroparous iteroparous
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• viviparous viviparous

Young mice are cared for in their mother's nest until they reach 21 days old. Soon after this most young mice leave their mother's territory, though young females are more likely to stay nearby.

• Parental Investment
• altricial altricial
• pre-fertilization
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

If a house mouse is a pet, the average life span is about 2 years, but mutant and calorie-restricted captive individuals have lived for as long as 5 years. Wild-derived captive Mus musculus individuals have lived up to 4 years in captivity. In the wild, most mice do not live beyond 12-18 months.

Behavior

In the wild state, house mice generally dwell in cracks in rocks or walls or make underground burrows consisting of a complex network of tunnels, several chambers for nesting and storage, and three or four exits. When living with humans, house mice nest behind rafters, in woodpiles, storage areas, or any hidden spot near a source of food. They construct nests from rags, paper, or other soft substances and line them with finer shredded material. House mice are generally nocturnal, although some are active during the day in human dwellings. House mice are quick runners (up to 8 miles per hour), good climbers, jumpers, and also swim well. Despite this, they rarely travel more than 50 feet from their established homes.

Mus musculus is generally considered both territorial and colonial when living commensally with humans. Territoriality is not as pronounced in wild conditions, however. Dominant males set up a territory including a family group of several females and their young. Occasionally, subordinate males may occupy a territory or males may share territories. Females establish a loose hierarchy within the territories, but they are far less aggressive than males. Aggression within family groups is rare, but all the individuals in a territory will defend an area against outsiders. Young mice are generally made to disperse through adult aggression, although some (especially females) may remain in the vicinity of their parents.

• Key Behaviors
• cursorial
• terricolous
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• territorial territorial
• social social
• dominance hierarchies dominance hierarchies

Communication and Perception

House mice have excellent vision and hearing, a keen sense of smell, and use their whiskers to feel air movements and surface textures. House mice often squeak to each other in the nest. They use pheromones and other smells to communicate with each other about social dominance, family composition, and reproductive readiness. It was recently discovered that male mice produce complex, ultrasonic songs in response to female sex pheromones.

• Communication Channels
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• pheromones pheromones

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• ultrasound ultrasound
• chemical chemical

Food Habits

In the wild, house mice eat many kinds of plant matter, such as seeds, fleshy roots, leaves and stems. Insects ( beetle larvae , caterpillars , and cockroaches ) and meat (carrion) may be taken when available. In human habitation, Mus musculus consumes any human food that is accessible as well as glue, soap, and other household materials. Many mice store their food or live within a human food storage facility.

• Primary Diet
• omnivore omnivore

• Animal Foods
• carrion carrion
• insects
• terrestrial non-insect arthropods

• Plant Foods
• leaves
• roots and tubers
• wood, bark, or stems
• seeds, grains, and nuts
• fruit

• Foraging Behavior
• stores or caches food stores or caches food

Predation

House mice are eaten by a wide variety of small predators throughout the world, including cats , foxes , weasels , ferrets , mongooses , large lizards , snakes , hawks , falcons , and owls . House mice try to avoid predation by keeping out of the open and by being fast. They are also capable of reproducing very rapidly, which means that populations can recover quickly from predation.

Ecosystem Roles

Where house mice are abundant they can consume huge quantities of grains, making these foods unavailable to other (perhaps native) animals. House mice are also important prey items for many small predators.

Economic Importance for Humans: Positive

Domesticated forms and albinos have been developed which are commonly used as laboratory animals (especially in medicine and genetics), and as pets. Mus musculus also has a small role as an insect destroyer, but this is minimal.

• Positive Impacts
• pet trade pet trade
• research and education
• controls pest population

Economic Importance for Humans: Negative

House mice do not cause such serious health and economic problems as do Rattus norvegicus and Rattus rattus . Mice are agricultural pests in some areas, however, and they do consume and contaminate stored human food with their droppings. They also destroy woodwork, furniture, upholstery, and clothing. In addition, they contribute to the spread of diseases such as murine typhus, rickettsial pox, tularemia, food poisoning (Salmonella), and bubonic plague. Recent research has also shown that they carry a virus--the mouse mammary tumor virus (MMTV)--that may contribute to breast cancer in humans.

• Negative Impacts
• injures humans
  • carries human disease
• crop pest
• household pest

Conservation Status

Commensal populations of Mus musculus are generally stable and densities can be as high as 10 mice per square meter. In the wild, populations are less stable and densities may be less than 1 mouse per 100 square meters. Overall, populations are flourishing and are in fact aided by human construction of houses, barns, and other structures.

Other Comments

Mus musculus often refers to several fairly distinct kinds of mice. As many as seven separate species may be placed under Mus musculus , such as Mus domesticus , western European house mice, and Mus castaneus , southeastern Asian house mice. "Dancing" and "singing" mice are other names for house mice. The former refers to a genetic strain with inner ear defects, causing the mice to weave, turn in circles, and wobble when they walk. The latter refers to a pathological condition causing mice to twitter constantly with a "song" resembling that of a cricket.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

Allison Poor (editor), University of Michigan-Ann Arbor.

Liz Ballenger (author), University of Michigan-Ann Arbor.

References

Holy, T., Z. Guo. 2005. Ultrasonic songs of male mice. Public Library of Science, Biology , 3/12. Accessed November 02, 2005 at http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0030386 .

Indik, S., W. Günzburg, B. Salmons, F. Rouault. 2005. Mouse mammary tumor virus infects human cells. Cancer Research , 65 (15): 6651-6659.

Sage, R., W. Atchley, E. Capanna. 1993. House mice as models in systematic biology. Systematic Biology , 42(4): 523-561.

Stewart, T., R. Sage, A. Stewart, D. Cameron. 2000. Breast cancer incidence highest in the range of one species of house mouse, Mus domesticus. British Journal of Cancer , 82(2): 446-451.

Jackson, H.H.T. 1961. Mammals of Wisconsin. The University of Wisconsin Press, Madison, Wisconsin.

Kurta, A. 1995. Mammals of the Great Lakes Region. The University of Michigan Press, Ann Arbor, Michigan.

Nowak, R.M. and J.L Paradiso. 1983. Walker's Mammals of the World. 4th edition. John Hopkins University Press, Baltimore, Maryland.