SPECIES ACCOUNTS

SOUTHEASTERN BEACH MOUSE

Peromyscus polionotus niveiventris

ANASTASIA ISLAND BEACH MOUSE

Peromyscus polionotus phasma

FAMILY: Cricetidae

STATUS: Anastasia Island beach mouse is Endangered. Southeastern beach mouse is Threatened. (Federal Register, May 12, 1989)

DESCRIPTION: The Anastasia Island beach mouse and the Southeastern beach mouse are two of six existing coastal subspecies of the oldfield mouse (Peromyscus polionotus). The oldfield mouse is a wide-ranging species in the Southeast. One of the largest species of beach mice (averaging 138.5 millimeters in length and 53 millimeters in tail length), the Anastasia Island beach mouse is much paler than most inland races of the oldfield mouse. This beach mouse has a light buff-colored back, pure white underparts, and indistinct, white markings on its nose and face (Howell, unpublished. ms., circa 194O). The Southeastern beach mouse is the largest beach mouse; it averages 139 millimeters in total length and 52 millimeters in tail length. Although it is darker and more buffy than the Anastasia Island beach mouse, it is still lighter than most inland subspecies of the oldfield mouse.

RANGE AND POPULATION LEVEL: The historic range of the threatened Southeastern beach mouse was north Florida's Mosquito (Ponce) Inlet in Volusia County to south Florida's Hollywood Beach in Broward County. Now, the Southeastern beach mouse has apparently been eliminated from the southern section of its habitat at Jupiter Island, Palm Beach, Lake Worth, Hillsboro Inlet, and Hollywood Beach. Beach mice also may be gone from the East Peninsula. Humphrey (1987) sighted only a few small, fragmented populations between Sebastian Inlet to Hutchinson Island. The healthiest populations appear to occur on public lands: Cape Canaveral National Seashore; Merritt Island National Wildlife Refuge; Cape Kennedy Air Force Station; the southern half of Sebestian Inlet State Recreation Area, and Pepper Park.

Apparently once ranging from north Florida's St. John's River to south Florida's Anastasia Island, the endangered Anastasia Island beach mouse may remain only on Anastasia Island. Some suitable habitat still exists in the north between Ponte Vedra Beach and South Ponte Vedra Beach in St. John's County (Guana River Wildlife Management Area), but no mice have been found there. Much of Anastasia Island has undergone residential development, and viable mice populations may be restricted to the State Recreation Area and Fort Matanzas National Monument.

HABITAT: Both species inhabit sand dunes which are vegetated by sea oats and dune panic grass. The scrub adjoining these dunes is populated by oaks and sand pine or palmetto. A study conducted on Merrit Island indicated that the Southeastern beach mice may prefer open sand habitat with clumps of palmetto and sea grapes, or dense scrub habitat dominated by palmetto, sea grape, and wax myrtle; over seaward habitat with sea oats (Extine and Stout 1987). Little specific information exists about these species' burrowing habits, although they are presumed to be similar to those of beach mice on the Gulf Coast. Sometimes beach mice use the former burrows of ghost crabs, but usually they dig their own. Burrow entrances are generally found on the sloping side of a dune at the base of a clump of grass (Ehrhart in Layne 1978). The burrows are used for nesting and food storage as well as a refuge.

BIOLOGICAL INFORMATION: Breeding activities may be similar to those of beach mice on the Gulf Coast. The breeding season for beach mice appears to start in November and end in early January (Blair 1951). The female, which may reach reproductive maturity at 6 weeks of age, produces two to seven beach mice per litter. A female beach mouse can usually produce liters at 2O-day intervals, but mortality is high. Most of the progeny will not survive over 4 months. Predictably, beach mice feed on sea oats and beach grasses. The sea oats must be blown to the ground for the mice to eat. During the spring and early summer when seeds are scarce, beach mice may eat invertebrates (Ehrhart in Layne 1978).

REASONS FOR CURRENT STATUS: Both of these species are primarily threatened by beach and residential development which has eliminated suitable habitat. Predators such as raccoons, skunks, snakes, great-blue herons, dogs, and cats pursue the species (Myers 1983). Competitors, such as house mice, are also threats. The control of free-ranging housecats has been identified as important to the species' survival.

MANAGEMENT AND PROTECTION: Most of the remaining habitat for both species is on public land, and management efforts have centered around the control of house mice. Facilities for the public have been located inland of the dune grassland. This includes campgrounds, park concessions, refuse dumpsters, or anywhere else where house mice could survive. The Florida Game and Fresh Water Fish Commission is conducting a study of populations, habitat requirements, and conservation needs for the Anastasia Island beach mouse (Mike Bentzien, U.S. Fish and Wildlife Service, Personal Communication).

REFERENCES:

Blair, W.F. 1951. Population Structure, Social behavior and Environmental Relations in a Natural Population of the Beach Mouse (Peromyscus polionotus leucocephalus). Contrib. Lab. Vert. Biol., Univ. Michigan 48:1-47.

Bowen, W.W. 1968. Variation and Evolution of Gulf Coast Populations of Beach Mice (Peromyscus polionotus), Bull. Florida State Mus. Biol. Sci. 12:1-91

Department of the Interior. Fish and Wildlife Service. Endangered and Threatened Wildlife and Plants: Endangered Status for the Anastasia Island Beach Mouse and Threatened Status for the Southeastern Beach Mouse. Federal Register. Vol. 54. No. 91. May 12, 1989. pp. 2O598 to 2O6O2.

Extine, D.D. and L.J. Stout. 1987. Dispersion and Habitat Occupancy of the Beach Mouse (Peromyscus polionotus niveiventris). Mammal 68:297-3O4

Hall, E.R. 1981. The Mammals of North America. John Wiley and Sons, New York. 1175 pp.

Humphrey, S.R. and D.B. Barbour. 1981. Status and Habitat of Three Subspecies of Peromyscus polionotus in Florida. J. Mammal. 62:84O-844.

Humphrey, S.R. 1987. Status Survey of Seven Florida mammals. Florida Cooperative Fish and Wildlife Research Unit Tech. Report. No. 25. Gainesville, Florida. 39 pp.

Layne, J.N. (ed.). 1978. Rare and Endangered Biota of Florida, Volume 1, Mammals. Univ. Presses of Florida, Gainesville, pp. 18-19.

Myers, J.M. 1983. Status, Microhabitat, and Management Recommendations for Peromyscus polionotus on Gulf Coast beaches. Rept. to U.S. Fish and Wildlife Service. Atlanta, Georgia. 29 pp.

Osgood, W.H. 19O9. Revision of the Mice of the American genus Peromyscus. North American Fauna 28:65 pp.

For more information please contact:

U.S. Fish and Wildlife Service
31OO University Boulevard South Suite 12O
Jacksonville, Florida 32216

Telephone: 9O4/791-258O