Perdido Key Beach Mouse

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Perdido Key Beach Mouse

Peromyscus polionotus trissyllepsis

ListedJune 6, 1985
DescriptionA small mouse.
HabitatSparsely vegetated, coastal dunes.
FoodSeeds and insects.
ReproductionGives birth to several generations each year of naked, helpless young, which are raised by the female.
ThreatsHabitat loss, predation by cats, competition with house mice.
RangeAlabama, Florida


The Perdido Key beach mouse, also known as the Florida beach mouse, has a small body, haired tail, relatively large ears, and protuberant eyes. Its head and body length is 2.7-3.3 in (6.8-8.4 cm), plus a tail of 1.7-2.5 in (4.3-5.1 cm). Its upper parts are colored grayish-fawn to wood-brown with a very pale yellow hue and an indistinct middorsal stripe. The white of the underparts reaches to the lower border of the eyes and ears, and the tail is white to pale grayish brown with no dorsal stripe.


The Perdido Key beach mouse probably feeds at night on grass seeds, roots, stems, and insects. It digs tunnel systems and living chambers within the root network of dune vegetation. It gives birth to several generations each year of naked, helpless young, which are raised by the female. Breeding may occur at any time of the year, but peaks during the fall and winter. The litter size ranges from two to seven. Beach mice are monogamous and remain in the same home range until the death of either mate. Their average lifespan is 180 days. Females reach sexual maturity at six weeks of age.


The Perdido Key beach mouse inhabits sparsely vegetated, but mature, coastal sand dunes. It prefers areas with varied topography, and high densities of crab burrows as escape cover.


The Perdido Key beach mouse only occurs on Perdido Key, an island in the northeastern Gulf of Mexico. It occurs on the western part of Perdido Key, including the Gulf State Park, in Baldwin County, Alabama, and on the eastern part of the key at the Gulf Islands National Seashore, Escambia County, Florida.


The greatest threat to the Perdido Key beach mouse has been the destruction of its natural habitat through various commercial and residential developments, as well as natural hurricanes. About 34% of Perdido Key has been developed and is no longer suitable habitat. The remaining natural habitat is fragmented and often degraded in quality by human activities, such as the use of off-road vehicles and pedestrian traffic. The total population of the Perdido Key beach mouse in the wild is no more than several hundred individuals. In addition, the introduced house mouse (Mus musculus ) appears to be competing with the Perdido Key beach mouse for food and cover. Human dwellings in the vicinity of beach mouse habitat serve as points of introduction for house mice. Predation by feral domestic cats (Felis catus ) associated with residential development may also occur.

Conservation and Recovery

The most necessary conservation measures in support of the Perdido Key beach mouse are the preservation of the remaining privately owned, mature sand-dune systems, and the protection and enhancement of publicly owned habitat at the Gulf State Park, Perdido Key State Preserve, and the Gulf Islands National Seashore. Necessary management actions include: the strict exclusion of off-road vehicles from sand-dune habitat; control of pedestrian access across the dunes by limiting transits to board-walks; and the planting of native dune vegetation to stabilize severely eroded areas. It is also necessary to control or eliminate feral cats and house mice in the critical habitat of the endangered beach mouse. Recovery efforts undertaken for the Perdido Key beach mouse include the release of captive-bred animals to reestablish a population on the Gulf Island National Seashore. A captive breeding colony has been established and housed at Auburn University, Alabama, to provide stock for use in re-introductions to restore the depleted wild populations.


U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345

U. S. Fish and Wildlife Service
6620 Southpoint Drive South, Suite 310
Jacksonville, Florida 32216-0958
Telephone: (904) 232-2580
Fax: (904) 232-2404


U. S. Fish and Wildlife Service. 1992. "U. S. Fish and Wildlife Service Division of Endangered Species, Species Accounts: Perdido Key Beach Mouse, Peromyscus polionotus trissyllepsis. " U. S. Fish and Wildlife Service Endangered Species Program. ( Date Accessed: July 6, 2000.

U. S. Fish and Wildlife Service. 1985. "Endangered and Threatened Wildlife and Plants: Determination of Endangered Status and Critical Habitat for Three Beach Mice." Federal Register 50 (109): 23872-23889.