Peromyscus Polionotus Trissyllepsis

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Monday, 09 August 2004

PERDIDO KEY BEACH MOUSE Peromyscus polionotus trissyllepsis FAMILY: Muridae STATUS: Endangered, Federal Register, June 6, 1985 DESCRIPTION: The Perdido Key beach mouse has a small body, haired tail, relatively large ears, and protuberant eyes. Its head and body length is 2.7 to 3.3 inches; the tail length is 1.7 to 2.5 inches. The 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. This species is a nocturnal herbivore. Beach mice feed primarily on the seeds of sea oats (Panicum repens) and beach grass (Panicum amarums). When these seeds are scarce, especially in the late winter or early spring, beach mice may consume invertebrates (Ehrhart in Layne, 1978) or fruiting bodies of sea rocket (Cakile) sp. (U.S. Fish and Wildlife Service, 1987). REPRODUCTION AND DEVELOPMENT: Based on studies of other subspecies of P. polionotus, it can be inferred that reproduction may occur throughout the year, but peak during November, December, and January. Beach mice litters may range from two to seven, and the young may reach sexual maturity by 6 weeks of age. Results of a laboratory study (Blair 1968) show that female beach mice are capable of producing litters every 26 days, and they may produce 8O or more young in their lifetimes. Studies of other closely-related beach mouse species indicate that beach mouse life spans may be short, ranging from less than 5 months in the wild to over 3 years (Blair 1948). RANGE AND POPULATION LEVEL: The Perdido Key beach mouse currently survives on the western part of Perdido Key including the Gulf State Park, Baldwin County, Alabama and on the eastern part of the key at the Gulf Islands National Seashore, Escambia County, Florida. The mouse has been reestablished on the Gulf Island National Seashore. The species is presumed to have once inhabited the entire key. The Perdido Key State Preserve is located in the central part of Perdido Key. Beach mouse habitat exists in the Preserve, although it is less than optimum in terms of average dune height. Trapping at Gulf State Park in 1990 yielded approximately 48 mice in designated critical habitat. The estimated population varied between 48 and 167 animals between November 1988 and May 1991 (Holler, unpublished data). Three trapping surveys at Gulf Islands National Seashore in 1991 resulted in a population estimate range of 85 to 118 mice (Holler and Moyers, 1991). Trapping at Gulf Islands National Seashore is an ongoing project initiated in 1989 to monitor the Perdido Key beach mouse population during and after a major beach renourishment program. A captive breeding colony has been established and housed at Auburn University, Alabama to provide beach mice where reintroduction is necessary to restore the wild populations, due to the potential of loss due to a catastrophic event (Holler, pers. comm.). HABITAT: The habitat is restricted to the mature coastal barrier sand dunes along the Gulf. The depth of the habitat extending inland may vary depending on the configuration of the sand dune system and the vegetation present. There are commonly several rows of dunes paralleling the shoreline and within these rows there are generally three types of microhabitat. The frontal dunes are sparsely vegetated with widely scattered coarse grasses including sea oats (Uniola paniculata), bunch grass (Andropogon maritimus), and beach grass (Panicum amarum and P. repens), and with seaside rosemary (Ceratiola ericoides), beach morning glory (Ipomoea stolonifera), and railroad vine (I. pes-caprae). Frontal dune grasses also appear as a lesser component on the higher rear dunes. The interdunal areas contain sedges (Cyperus sp.), rushes (Juncus scirpoides), and salt-grass (Distichlis spicata). The dunes farther inland from the Gulf support growths of slash pine (Pinus elliotti), sand pine (P. clausa), scrubby shrubs and oaks, including yaupon (Ilex vomitoria), marsh elder (Iva sp.), scrub oak (Quercus myrtifolia), and sand-live oak (Q. virginiana var. maritima). The beach mice dig burrows mainly on the lee side of the primary dunes and in other secondary and interior dunes where the vegetation provides suitable cover. The mice may also use ghost crab (Ocypoda quadratus) burrows. CRITICAL HABITAT: Alabama. An area of land, water, and airspace in Baldwin County with the following components (Tallahassee Meridian): that portion of the Perdido Key unit of the Gulf State Park south of State Road 182 in T9S R33W Sec. 2-3, Florida. Areas of land, water, and airspace in Escambia County with the following components (Tallahassee Meridian): (1) that portion of the Perdido Key State Preserve south of State Road 292 in T3S R31W Sec. 25-26 and Sec. 28-34, and in T3S R32W E 1/2 Sec. 36, and W 1/2 Sec. 36 south of the entrance road, parking lot, and Johnson Beach recreational facilities at the Gulf Islands National Seashore. Within these areas the major constituent elements that are known to require special management considerations and protection are dunes and interdunal areas, and associated grasses and shrubs that provide food and cover. REASONS FOR CURRENT STATUS: Tropical storms and loss of habitat are considered to be primary factors in the mouse's decline. It is estimated that approximately 34 percent of the island has been developed and is no longer suitable habitat. Commercial and residential development, especially if the latter is high density multiple housing, isolates small areas of beach mouse habitat thereby fragmenting populations and upsetting gene flow. Such barriers also prevent recolonization of an area should a population segment be extirpated. Tropical storms periodically devastate Gulf Coast sand dune communities, dramatically altering or destroying habitat, and either drowning beach mice or forcing them to concentrate on high scrub dunes where they are exposed to predators. The Gulf State Park area was severely flooded by Hurricane Frederick on September 13, 1979. Washovers completely destroyed mouse habitat on all dunes less than 11.5 feet high, leaving only the dune ridges in excess of this height as habitat. At the eastern end of the Key in Gulf Islands National Seashore, 80 percent of the area was overwashed during the hurricane, but has since recovered. Other threats include feral house cats, which may prey on beach mice, and house mice (Mus musculus) which may possibly compete with beach mice for food and cover. MANAGEMENT AND PROTECTION EFFORTS: The most effective conservation measures would be the preservation of the remaining privately-owned mature sand dune systems, and the protection and enhancement of the publicly-owned sand dune systems at the Gulf State Park, Perdido Key State Preserve, and the Gulf Islands National Seashore. On the publicly-owned lands, strict exclusion of off-read vehicles from the sand dunes would allow ecological succession to reestablish good beach mouse habitat. Strict control of pedestrian access across the dunes, by limiting pedestrians to elevated boardwalks, would also serve to protect the fragile dune vegetation. The planting of native dune vegetation would enhance ecological succession in severely eroded areas. Healthy mature sand dunes have a better chance of withstanding the impacts of tropical storms, thus protecting beach mouse habitat, than do eroded dunes. Both Alabama and Florida have statutes which generally protect sea oats against picking, but these laws provide no protection against loss from land conversion activities. Associated with residential and commercial development are feral house cats, which may prey upon beach mice, and house mice which may compete with beach mice for food. The control of feral house cats and house mice would be desirable and could be achieved through an aggressive public education program. The installation of animal-proof refuse containers and efficient refuse disposal systems might attract fewer potential mouse predators. Perdido Key is located between the Perdido Pass Entrance Channel and the Pensacola Bay Channel. Both of these channels are maintained by the U.S. Army Corps of Engineers. With the careful dredging of accreted sands and placement of spoil, beach mouse habitat should not be adversely affected by the routine maintenance operations. Since the Gulf coast is regularly subjected to tropical storms, a prudent conservation measure is to insure that populations of beach mice become established on the public lands from which the mice have been extirpated in recent years, specifically the Perdido Key State Preserve and the Gulf Islands National Seashore. Captive breeding of beach mice with subsequent release of offspring in the wild is a possible means of reintroduction. Another measure might be the translocation of some beach mice from the Gulf State Park to other suitable sites on Perdido Key. REFERENCES: Bowen, W.W. 1968. Variation and evolution of Gulf Coast populations of beach mice, Peromyscus polionotus. Bull. Alabama Mus. Nat. Hist., no. 2, pp. 88-92. Blair, W.F. 1948. Population Density, Life Span, and Mortality Rates of Small Mammals in the Blue-grass Meadow and Blue-grass Field Associations of Southern Michigan. Amer. Midl. Nat., 4O:395-419 Ehrhart, L.M. 1978. Choctawhatchee Beach Mouse. In Layne, J.N. (ed.) Rare and Endangered Biota of Florida Volume 1, Mammals. Univ. Presses of Florida, Gainesville, pp. 18-19. Holler, N. R., D.W. Mason, R.M. Dawson, T. Simmons, and M.C. Wooten. 1989. Reestablishment of the Perdido Key Beach Mouse (Peromyscus polionotus trissyllepsis) on Gulf Islands National Seashore. Conserv. Biol. 3:397-404. Holliman, D.C. 1983. Status and habitat of Alabama Gulf Coast beach mice (Peromyscus polionotus ammobates and P. p. trissyllepsis). Northeast Gulf Science 6(2):121-129. Humphrey, S.r., and D.B. Babour. 1981. Status and Habitat of Three Subspecies of Peromyscus polionotus in Florida. J. Mamm. 62:840-844. Linzey, D.W. 1978. Perdido Bay Beach Mouse. In Layne, J.N. (ed.). Rare and Endangered Biota of Florida. Volume 1, Mammals. University Presses of Florida, Gainesville. pp. 19-20. Meyers, J.M. 1983. Status, Microhabitat, and Management Recommendations for Peromyscus polionotus on Gulf Coast Beaches. Rept. to U.S. Fish and Wildl. Serv., Atlanta. 29 pp. 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 5O(1O9): 23872-23889. **U.S. Fish and Wildlife Service. 1987. Recovery Plan For The Alabama Beach Mouse (Peromyscus polionotus ammobates), Perdido Key Beach Mouse (P. p. trissyllepsis), and Choctawhatchee Beach Mouse (P. p.. allophrys). U.S. Fish and Wildlife Service, Atlanta, Georgia. 45 pp. For more information please contact: U.S. Fish and Wildlife Service 6578 Dogwood View Parkway Suite A Jackson, Mississippi 39213 Telephone: 6O1/965-49OO U.S. Fish and Wildlife Service 31OO University Boulevard, South Suite 12O Jacksonville, Florida 32216 Telephone: 9O4/791-258O

Last Updated ( Thursday, 08 February 2007 )

 

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