Sunday, July 4, 2010

Beach Mice

In my very first blog entry where I introduced myself, I briefly talked about a field research position I held in Florida trapping, radio collaring, and tracking Santa Rosa beach mice during the summer of 2009.  
Beach Mouse being released from trap
There have been several people who have asked me what the results were of that research.  Recently Elliot Wilkinson, the post-doctorate student conducting the research, finished his report, titled “Habitat Restoration for Beach Mice: Landscape-level Population Studies and Dune Restoration.”  In it are the results of the data I helped him to collect. 

The research took place on Eglin Air Force Base on Santa Rosa island off the coast of Fort Walton Beach, Florida, which is on the Gulf Coast.  Sand dune habitat on the island has been heavily damaged by tropical storms and hurricanes.  The value of fragmented habitats depends on whether the mice can use them as nest and foraging sites, but little information about the use of these habitats is available.  Most of Santa Rosa island is made up of dune fragments bordered by open sand, small developing dunes with vegetation, and wetland habitat.  The beach mice must continuously cross open sand gaps between these vegetation patches while foraging for seeds and insects.  Factors, such as predation risk, are likely to affect animal movement.  The safe future of the Santa Rosa beach mouse depends on sand dune restoration efforts.  Planting of woody plant species will stabilize dunes during storms and encourage re-growth of beach mouse habitat following storms.

After we applied radio collars to a total of 65 mice, we tracked their movements using radio telemetry.
Radio collared Beach Mouse
Beach mice are nocturnal.  Therefore, we recorded the location of their nest before sunset every day.  After dark we would triangulate the location of each mouse three times, with at least an hour in between each time.  The points were transferred from the GPS’s onto satellite maps of the landscape.

The results show that during a full moon, fewer open sand gaps are crossed due to a higher risk of predation.  Overall, Santa Rosa beach mice use a range of habitats for foraging but prefer primary dunes (dunes near the gulf that survived storm overwash), secondary dunes (dunes further from gulf), and wetland margin habitat (dunes that have formed along the edge of a wetland) for nesting.  Beach mice may also forage in scrub dunes, which are located on the bay side of the island, but use them less often when compared to primary dunes. 
Primary dune habitat
However, scrub dunes play an important role in providing safe habitat for beach mice when storms and hurricanes destroy their preferred habitat.
Scrub dune habitat
It was estimated that 67% of the study site was suitable foraging habitat, but less than 21% was preferred habitat for nesting.  It is therefore suggested that conservation and recovery efforts for this delicate ecosystem be concentrated on habitats the beach mice prefer to nest in.  Beach mice are a very important part of the dune ecosystem because they are the main species that promote seed dispersal of the vegetation that makes sand dunes possible.  Ensuring the survival of the beach mouse is essential to the survival of this ecosystem.
Me (Sara Oliver) holding a Beach Mouse
What can you do to help beach mice?  If you live on a beach residence and have a pet cat, keep it indoors.  Don’t feed stray cats either if you live near the beach because that will encourage them to become permanent residents in beach mouse habitat.  Also, you can plant native dune plants such as bluestem, sea oats, evening primrose and ground cherry.  They add structure to the landscape while providing food for beach mice and encourage dune regeneration.  When you visit the beach, staying off the dunes will keep them stable.  The beach mice thank you!

Submitted by Sara Oliver, World Bird Sanctuary Naturalist

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