Distribution and Abundance of the Perdido Key Beach Mouse (Peromyscus polionotus trissyllepsis) in the Perdido Key Unit of Gulf Islands National Seashore in 2010

Gore, Jeffery; Greene, Daniel

The Perdido Key Beach Mouse (Peromyscus polionotus trissyllepsis) occurs only on Perdido Key in Florida and Alabama, and it has been threatened with extinction due primarily to habitat loss from land development and tropical storms. In recent years, Gulf Islands National Seashore (GINS) has supported the most stable population of Perdido Key beach mice and in some years GINS has supported the only population. To assess the current status of the Perdido Key beach mouse population in GINS, we set livetraps for mice in 19 trapping grids and checked them for 5 consecutive nights from 21-26 March 2010. In 2,280 trap nights, we captured 20 individual mice (40 total captures) at 9 of the 19 grids. More than 20 mice undoubtedly were present at GINS because our trapping grids covered only a portion of the available habitat and we did not capture mice at several locations where tracks were detected prior to trapping. Unfortunately, the number of mice captured was too small and nightly captures too variable to provide a precise estimate of the size of the total population on GINS. The distribution of mice did change since 2008. We did not catch mice at several back dune locations where they were captured most often in 2008; conversely, mice were trapped on the western portion of GINS where they were absent in 2008. We could not provide a useful estimate of population size, but more mice were captured in the central and western portions of GINS than at the eastern end or in the back dunes. However, because few mice were captured, the trapping results may not reflect real differences in mouse abundance between areas. Additional research on predators and vegetation might suggest conservation actions that could be taken to enhance the beach mouse population.