Mus musculus

Its close association with people has helped it spread widely, but it also lives outside buildings.

A pointed muzzle, rounded ears, long whiskers and a long tail give the house mouse its characteristic outline.

Wild coat colours range from light brown to black, with paler or differently coloured fur on the underside.

House mice reproduce sexually and develop before birth as placental mammals.

Laboratory reference estimates put gestation at about 19–21 days, while emphasizing that strain and environmental conditions affect reproductive values.

Mothers give birth to litters, whose size varies with genetics, conditions and maternal age rather than following one fixed number.

Newborn pups have little visible hair and closed eyes and ears.

Fur and sensory function develop after birth, and pups begin trying solid food while nursing can still continue.

This makes weaning a transition from milk to independent feeding, not an instantaneous change on one universal birthday.

Breeding can continue through the year in sheltered commensal populations, whereas reproduction in free-living populations is often seasonal.

House mice eat plant material and can also take insects and other animal food.

Human food stores provide another resource, but mice also occupy grasslands, dunes and agricultural habitats.

Their foraging decisions respond to environmental cues rather than simply to the presence of food.

In a New Zealand field experiment, fewer seeds were removed from illuminated stations than from dark stations.

This supports a role for light in where the tested mice chose to forage, without showing that artificial light eliminates their need to feed.

House mice can damage crops and food supplies, and introduced populations can harm native organisms on islands.

They are also important in research on mammalian genetics and physiology.

A study of 460 wild house mice from 12 southern-UK sites found marked differences in immune state among populations.

Age and body condition helped explain variation, showing why laboratory findings alone cannot describe every mouse living in a changing environment.

Genome research now extends beyond the early C57BL/6J reference: a 2025 study reconstructed chromosome-scale genomes for C57BL/6J and CAST/EiJ and resolved previously missing chromosome ends and centromeric regions.

The differences between these strain genomes are part of mouse biological diversity, not errors that can be removed by treating one strain as the entire species.

The 2025 assemblies were derived from an embryonic stem-cell line originating from a male CAST/EiJ × C57BL/6J F1 embryo.

Parental short reads were used to assign long reads to their parental haplotypes before assembly.

The paper lists BioProject PRJEB47108 and assembly identifiers GCA_964188535 and GCA_964188545, without an accession-version suffix in that Data availability statement.

Farnworth and colleagues counted seeds removed because they could not determine whether every missing seed had been eaten or cached.

Their captive comparison used adult male C57BL/6 mice, whereas the field arm studied free-living mice at Maungatautari.

Those sampling contexts should remain separate even when both show avoidance of illuminated feeding patches.

The southern-UK immune study was cross-sectional and sampled M. musculus domesticus, including commensal animals in farm buildings.

The authors explicitly note that the temporal stability of population differences requires longitudinal study.

An association between condition, age and immune measurements therefore does not by itself establish a universal causal rule for all mice.