Mice Rats and Relatives: Muridae

Rats, mice, and relatives are active during the day, at night, or both night and day (depending on the species). For their size, they can be very aggressive to predators and even to other members of their species. The rodents can be vocal, with various communicative sounds such as chattering, screaming, and whistling. They set up territories and defend them vigorously. Murids are sometimes found alone, but often are social, and are found traveling and sleeping together. They use nests for shelter and to raise their young. Some species breed throughout the year but others only during certain seasons. Murid rodents generally have high reproduction rates (lots of offspring) and large populations. Litters (groups of young born at the same time from the same mother) have one to seventeen offspring. Young are born blind and naked, although they develop fast, are weaned (stop drinking their mother's milk) quickly, and are able to reproduce within weeks or months.