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Biology
The Alabama beach mouse (ABM) is perhaps most truly representative of coastal dune habitat in Baldwin County, Alabama. This mouse is one of several subspecies of old field mice which live only in coastal sand dune areas. Living isolated from other beach mice for thousands of years has allowed each subspecies to develop its own slightly unique characteristics suited to its particular beach environment.
Other beach mouse species along the northern coast of the Gulf of Mexico include: Perdido Key beach mouse, Choctawhatchee beach mouse, Santa Rosa beach mouse, and St. Andrews beach mouse. They differ from the ABM and each other in coloration and body size.
The ABM was federally listed as endangered in 1985 because of impacts to its habitat.
Being nocturnal animals, they have large eyes and big ears to help them as they leave their burrows at dusk and remain active at night. They are much less active on moonlit nights though to avoid becoming a late night snack for predators.
Beach mice are small…about 4-5 inches long, including their tail, and weigh around 12.5 grams (less than the weight of three nickels). In the wild they may live 9 months to a year. Female beach mice usually bear around four pups per litter with a 23-day gestation period. A female beach mouse can breed again within 24 hours of giving birth.
Recent research indicates that beach mice are often monogamous and the family unit may utilize more than 10 burrows within their home range.
Live trapping studies have shown that the numbers of beach mice fluctuate greatly, as does the geographical area they occupy. These sometimes drastic changes to the status of ABM populations are thought to be related to the abundance of food and cover and other factors.
During times of high population numbers, ABM can be found in relatively large numbers in all suitable habitat from the primary-secondary dunes inland to adjacent escarpment and interior scrub oak dune areas.
During unfavorable habitat conditions, such as after tropical storms or during droughts, the ABM may be restricted to smaller areas within their habitat. Such conditions may cause the ABM to be either absent or at very low numbers because small isolated populations may be lost as a result of a number of chance variations in environmental conditions or population factors; protection of habitat and connections between patches is very important.
ABM feed primarily on seeds and insects. Some of these plants include sea oats, ground cherry, dune spurge, bluestem, evening primrose, beach pea, joint-weed, seashore elder, seaside pennywort and the various acorns found in the interior "scrub" habitat. Unlike the house mouse, beach mice are not known to live in buildings, cars, garages. Nor do they frequent garbage sites.
While population fluctuations are a normal part of beach mouse life, there are a number of threats which continue to challenge the persistence of ABM. These include both natural and man-made threats.
Feral and/or free-roaming cats are thought to be at least partly responsible for the loss of ABM on Ono Island and are considered to be a factor in the extinction of the pallid beach mouse on the Atlantic Coast of Florida.
Natural predators…like the coachwhip snake or owls...are more of a concern when beach mice are vulnerable, such as following storms or during periods of low populations.
Habitat
The Alabama beach mouse (ABM) makes its home in the dunes of coastal Alabama. The mouse relies on a mix of habitat types to survive.
Primary and secondary dunes provide sites for burrows, as well as food.
Scrub dunes lying further inland also provide food and cover for the ABM are are especially important when frontal dunes are damaged. These areas are critical when mouse populations grow and the frontal dunes are no longer able to support the entire population.
Higher elevation dunes-or escarpment-provide safe haven during and immediately following hurricanes and tropical storms when much of the traditional habitat is flooded by storm surge or heavy rains.
Corridors between areas allow mice to move about in search of food or burrow sites, and contribute to maintenance of genetic diversity needed for the species' long-term survival.
Habitat Elements
To survive, the species requires several elements from its habitat: food (areas for foraging); shelter (areas for burrowing); and cover (areas which provide cover from predators).
Food: The ABM depends on an assortment of foods throughout the year, including the seeds of dune plants, acorns from oak trees growing in the interior scrub, and insects. Some of the plants which are important to the mice are: sea oats, ground cherry, dune spurge, bluestem, evening primrose, beach pea, joint-weed, seashore elder, seaside pennywort and the various acorns.
Shelter: Beach mice make their homes in burrows dug into the sloping sides of sand dunes. The burrow contains 3 main parts: an entrance tunnel, which extends at an incline to a nest chamber usually 2 to 3 feet underground, and an escape tunnel that rises from the nest chamber to within an inch of the surface. Beach mice can quickly pop open this plug of sand and escape if threatened or disturbed. A beach mouse family will often use as many as 10 burrows within their home range. Sand contaminated with gravel or construction debris could pose a problem to ABM burrowing efforts.
Cover: The ABM is constantly in danger from native predators that roam the dunes…from snakes to birds to larger mammals. Often, these predators hunt at night, the very time when the mouse is most active. For protection, the ABM seeks out areas with enough vegetation to provide cover to hide from these predators, though not so much vegetation as to hinder its movement. Some common predators include natural predators: coach-whip snake, great horned owl-and those introduced by man, such as feral cats and red foxes.
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