There are two main species of house rats, the Norway rat (Gray) and the Roof rat (black to a brownish gray).
Norway rats average 8 to 12 pups per litter, while Roof rats average 4 to 8 pups per litter.
Pups are born in three weeks and the mother can become pregnant again within 1 to 2 days after giving birth.
An average sized deer mouse is 184mm (7.2 in) in total length.
The breeding season is from late March through October, and each female produces 2-4 litters.
After a gestation period of 21-37 days, a female gives birth to 3-11 (average 5 or 6) young.
A single household mouse can contaminate ten times more food than it eats.
Mice produce 6 to 10 litters of 5 to 10 pups per year. They begin breeding at two months of age.
Digs underground burrows where it stores food for the winter and females give birth to their young.
Litters consist of 4 to 6 young per litter and gestation lasts 20 to 23 days