An average litter of field mice is three to five babies, but may be as high as 13. Gestation takes about 3 weeks, and the female is ready to breed again immediately after birth.
As long as there is available food, breeding will continue. A single breeding pair can produce about 500 mice in about 5 months under ideal conditions. In the wild, their average life span is only a few months.
Baby field mice are blind, deaf and bald at birth but mature within about 3 weeks. Females are sexually mature at 4 to 6 weeks. Along with their natural habitat of the fields, they can be found in human habitation including homes and barns.