Mice

Average house mouse (which is more common) is 5 to 8 inches total length and can weigh about 1 ounce or 36 grams. The house mice in ideal conditions can produce offspring from 2 to 13 mice after a gestation period of 18 to 21 days.

Interesting to note that the house mouse is the most intensely investigated animal of all mammals besides humans. With newer and established mouse populations a female can produce 6 to 10 litters spaced between 30 to 50 days accounting for possibly 42 to 60 offspring in a year. The only thing that affects this would be temperature, food supply, and competition. The same as rats, the ideal condition for mice to thrive is an indoor structure like home or factory.