page_title: House mouse
section_title: Life cycle and reproduction
hierarchical_section_title: House mouse / Life cycle and reproduction
caption_attribution_description: English: House mouse, 1 day old.
context_page_description: The house mouse is a small mammal of the order Rodentia, characteristically having a pointed snout, large rounded ears, and a long and hairy 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.
  The house mouse has been domesticated as the pet or fancy mouse, and as the laboratory mouse, which is one of the most important model organisms in biology and medicine. The complete mouse reference genome was sequenced in 2002.
context_section_description: Female house mice have an estrous cycle about four to six days long, with estrus itself lasting less than a day. If several females are held together under crowded conditions, they will often not have an estrus at all. If they are then exposed to male urine, they will come into estrus after 72 hours.
  Male house mice court females by emitting characteristic ultrasonic calls in the 30 kHz–110 kHz range. The calls are most frequent during courtship when the male is sniffing and following the female; however, the calls continue after mating has begun, at which time the calls are coincident with mounting behaviour. Males can be induced to emit these calls by female pheromones. The vocalizations appear to differ between individuals and have been compared to bird songs because of their complexity. While females have the capability to produce ultrasonic calls, they typically do not do so during mating behaviour.
  Following copulation, female mice will normally develop a copulation plug which prevents further copulation. The plug is not necessary for pregnancy initiation, as this will also occur without the plug. The presence or absence of the plug will not affect litter size either. This plug stays in place for some 24 hours. The gestation period is about 19–21 days, and they give birth to a litter of 3–14 young (average six to eight). One female can have 5 to 10 litters per year, so the mouse population can increase very quickly. Breeding occurs throughout the year. (However, animals living in the wild do not reproduce in the colder months, even though they do not hibernate.)
  The pups are born blind and without fur or ears. The ears are fully developed by the fourth day, fur begins to appear at about six days and the eyes open around 13 days after birth; the pups are weaned at around 21 days. Females reach sexual maturity at about six weeks of age and males at about eight weeks, but both can copulate as early as five weeks. If the infants live in high temperatured area from birth, they will become less-haired.
caption: A two-day-old mouse
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