The southeastern beach mouse (Peromyscus polionotus niveiventris) is one of sixteen subspecies of oldfield mouse historically found along the Atlantic Coast of Florida, from Ponce Inlet in Volusia County south to Hollywood Beach in Broward County. Due to the extensive and continuing urbanization of the coast, this species is classifed as threatened, as the undisturbed natural habitat necessary to support the animal has steadily diminished, with the greatest concentration still found around Cape Canaveral and the Kennedy Space Center.

Southeastern beach mice are the largest of the seven recognized subspecies of beach mice. They have pale, buffy coloration (similar to that of wet beach sand) from the back of their head to their tail. Their underparts are white, with white hairs extending up on their flanks, high on their jaw to within a few millimeters of their eyes. Their tail is also buffy above and white below. Young mice are more grayish in coloration than adults, but otherwise they are similar in appearance.

Nocturnal by nature and usually most active on stormy or moonless nights, the southeastern beach mouse inhabits sand dunes behind sea oats, dune panic grass and the adjacent coastal strand. Like most small mammals, their numbers often undergo considerable seasonal and annual fluctuations. Population is lowest in summer and highest in winter and spring, and current estimates put their average total at less than 5,000.

Beach mice usually dig their own burrows (as many as twenty in their home range), but may also use burrows of other mice and those of ghost crabs for temporary cover. Beach grasses and sea oats are the most utilized food plants, although invertebrates are also eaten. Potential predators include raccoons, skunks, snakes, hawks, owls, and great blue herons. In human-altered areas, dogs and house cats are potential predators and the house mouse (Mus musculus) may also be a competitor. Hurricanes and other natural weather patterns also pose a threat to survival, but predation is their primary cause of mortality.


Sources:
http://bioscience.ksc.nasa.gov/oldeco/threat/bchmouse.html
http://southeast.fws.gov/vbpdfs/species/mammals/sbmo.pdf

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