How Do Rats Reproduce?

By Lisa Miller

Rats are well-known for their reproductive proliferation. A single female and her descendants can produce 2,000 offspring in a single year if breeding is unchecked and predation is low. Since rats can live for up to three years and they mature very quickly, a single pair of amorous rats can cause an exponential infestation.

The Mating Process

Mating in mature rats occurs throughout the year between seven and 15 times annually depending on species. When a female becomes receptive, she will mate with a large group of males within a short time span, up to 500 times within a six-hour period. Once a female becomes pregnant, gestation will last between 22 and 24 days.

Litter Sizes and Maturation

The litter size for rats varies depending on species, but is generally between two and 14, with an average litter size of about 10. Rats are weaned and leave the nest at approximately 3 to 4 weeks of age. Male rats reach sexual maturity at three months, females at four months.