ABSTRACT
One of the chief features of rodents, which results in their pest status, is the ability to produce large populations in relatively short periods of time. On a cosmopolitan scale the commensal rodents Rattus and Mus are the most widespread and at the same time, given favorable circumstances, among the most productive. The ability of some pest species to produce larger litters more often when conditions are good is one of the main reasons why they are pests. Among the commensal rodents, Mus musculus provides a striking example of the adaptability of a species to capitalize on favorable conditions, as was seen in a study of the reproduction of the mouse in four different English habitats. Many rodents may, under certain conditions, assume pest status. In microtine rodents this is variable, and changes in the rate of sexual maturation of young voles and lemmings are a major driving force behind population cycles.
