Oldfield mouse

This article is about the North American species Peromyscus polionotus, known as the "oldfield mouse". See Thomasomys for the South American genus also known as "oldfield mice".

The oldfield mouse or beach mouse (Peromyscus polionotus) is a nocturnal species of rodent in the family Cricetidae. It is found in the southeastern United States on sandy beaches, in corn and cotton fields, and in hedge rows and open timber tracts. Coloration varies with geographic location: inland populations are generally fawn-colored while coastal populations are lighter or white. The mouse eats seeds, fruits, and occasionally insects, and lives and raises its three to four young in a simple burrow. Weaning occurs at 20–25 days, and females may mate at 30 days of age. Predators are those that prey on small mammals. One individual lived in captivity for about five years. The mouse is of least concern to conservationists because it is abundant and widespread, and no major threats exist for the species as a whole, but several subspecies with small distributions are endangered or even extinct.