Nests are constructed in burrows, or in protected spots in human made structures or woodpiles. Human habitation and surrounding riparian habitats. Optimal habitat includes refuse piles, debris or vegetation for cover, and accessible free water. None usually, although some may move indoors in the fall in cold climates, returning to the outdoors in spring. Loose colonies are formed that are patrolled by aggressive males.
Several females reside in the territory of the male, hence the loose colonial organization.
Breeds year-round, with peaks in early spring and late summer. Gestation period is 19-21 days. Females breed at 8 wk. Competitors include introduced Norway and black rats and many rodents. House mice are subordinant to harvest mice and meadow voles.