Peromyscus polionotus
oldfield mouse

Peromyscus polionotus occurs in the southeastern United States. Populations in the continental United States have been found scattered throughout parts of Mississippi, Tennessee, North Carolina, South Carolina, and south to Florida (Whitaker and Hamilton, 1998; Wilson and Ruff, 1999). This species of deer mouse also inhabits coastal islands off the southeastern sea board (Nowak 1999). (Nowak, 1999; Whitaker Jr. and Hamilton Jr., 1998; Wilson and Ruff, 1999)

Oldfield mice inhabit diverse environments. These mice typically occupy early successional habitats such as abandoned fields, beach dunes, and scrub habitats (Wilson and Ruff, 1999). They dig underground nest cavities which lie 0.3 to 0.9 meters below the surface. There is a leading and an escaping tunnel. A mound of soil or sand marks the entrance of the leading tunnel. (Wilson and Ruff, 1999)

Adult females are slightly larger than adult males (Wilson and Ruff 1999). Total length ranges from 110 to 150 millimeters with the average tail length ranging from 40 to 60 millimeters. Weight varies between 10 and 15 grams (Wilson and Ruff 1999). Peromyscus polionotus has several distinguishing characteristics. This species is smaller in size and has a smaller skull compared to other species in th genus Peromyscus. The white and brown colored tail, with a white underside, are two identifiable characteristics (Whitaker and Hamilton, 1998). (Whitaker Jr. and Hamilton Jr., 1998; Wilson and Ruff, 1999)

Distinct local color variation is found among the subspecies. For example, individuals inhabiting the beach tend to have less pigmented hair than individuals of an inland population (Wilson and Ruff 1999). This pale coloration may help beach populations blend into the sandy environment, thus avoiding predation. (Wilson and Ruff, 1999)

Oldfield mice probably live for no longer than about 18 months in the wild. (Wilson and Ruff, 1999)

Oldfield mice are primarily nocturnal. Highest levels of activity have been recorded on moonless or cloudy evenings. These mice are also hoarders and excellent diggers. Stashes of seeds have been found underground in their burrowed nests. Oldfield mice construct and use extensive burrows. They are most likely restricted to sandy and loamy soils throughout their range because of their reliance on tunneling. (Wilson and Ruff, 1999)

Home Range

Oldfield mice probably occupy the same general area throughout their lives and may defend small territories. (Wilson and Ruff, 1999)

Like other Peromyscus species, oldfield mice have keen vision, hearing, and tactile sensation. They use chemical cues extensively in communication.

Oldfield mice are granivorous, feeding on the seeds of grasses and herbs. They store food in underground caches (Wilson and Ruff, 1999). They will also consume arthropods, insect parts have been found in nests (Gentry and Smith, 1968). (Gentry and Smith, 1968; Wilson and Ruff, 1999)

Oldfield mice are preyed upon by many small predators, such as raptors, owls, snakes, weasels, foxes, and cats (Whitaker and Hamilton, 1998). They escape predation by seeking refuge in their burrows and by being active primarily at night. (Whitaker Jr. and Hamilton Jr., 1998)

Oldfield mice are an important prey base for small predators in the areas in which they live. They may also play an important role in influencing seed survivorship of the plant communities in which they occur. The following parasites have been found in individuals living in Florida: nematodes- six species, trematodes- one species, acanthocephalans- one species, and fleas- two species (Whitaker and Hamilton 1998). (Whitaker Jr. and Hamilton Jr., 1998)

It has been reported that Peromyscus polionotus can be a pest when it digs up the seeds of local gardeners for consumption (Whitaker and Hamilton 1998). (Whitaker Jr. and Hamilton Jr., 1998)

Oldfield mice are excellent models for genetic research and have been used extensively to study variation in pigment controlling genes.

Several subspecies of P. polionotus are on conservation lists. The status varies by subspecies. For example, on the IUCN list, some subspecies are listed as extinct while others are listed as endangered, critically endangered, or lower risk. Beach development and water recreation are just two causes for this mouse being in danger of extinction (Wilson and Ruff, 1999). A third probable danger to P. polionotus is climatic. For example, the coast along the Gulf of Mexico has been subject to hurricanes and other violent weather in the past. Swilling et. al (1998) have recorded populations of Peromyscus polionotus to be severely reduced several months after Hurricane Opal hit the Alabama coast. (Swilling Jr, Wooten, and Holler, 1998; Wilson and Ruff, 1999)

Subspecies of oldfield mice considered endangered are: Peromyscus polionotus allophrys, Peromyscus polionotus ammobates, Peromyscus polionotus peninsularis, Peromyscus polionotus phasma, and Peromyscus polionotus trissyllepsis, all of which occur in Florida and Alabama. Peromyscus polionotus niveiventris are considered threatened, they occur in Florida. Additional subspecies recognized by the IUCN are Peromyscus polionotus leucocephalus, near threatened in Florida, and Peromyscus polionotus decoloratus, extinct from Florida.

Fossil evidence in the geological record dates this mouse back to the late Pleistocene epoch (Wilson and Ruff 1999). (Wilson and Ruff, 1999)