How do field mice give birth? - briefly
Field mice have a gestation period of roughly 19–21 days, after which the female delivers a litter of 4–8 altricial pups in a shallow nest. The newborns are blind, hairless, and depend on maternal care for about three weeks.
How do field mice give birth? - in detail
Field mice reproduce by giving birth to relatively large litters after a short gestation period. The gestation lasts approximately 19 to 22 days, depending on species and environmental conditions. During pregnancy, the female builds a nest of soft material such as grass, leaves, and shredded fur, often in concealed locations like burrows, under dense vegetation, or within human structures.
Parturition occurs in the nest, where the mother delivers pups one by one. Newborns are altricial: hairless, blind, and incapable of thermoregulation. The average litter contains 4 to 8 offspring, though numbers as high as 12 have been recorded in optimal conditions. After delivery, the mother licks each pup to stimulate circulation and remove membranes, then positions them against her body to provide warmth.
Feeding begins within a few hours. The mother produces milk rich in protein and fat, sufficient for the rapid growth required during the first two weeks. Pups gain weight steadily, opening their eyes at about 10 days and developing fur by the second week. By the third week, they become more independent, exploring the nest and practicing locomotion.
Weaning occurs around 21 days, after which juveniles start consuming solid food while still receiving occasional nursing. The mother continues to guard the nest and may produce a second litter within the same breeding season, as field mice can breed multiple times per year. Seasonal variations affect reproductive timing: breeding peaks in spring and summer when food availability and temperatures are favorable.