COS 47-7 - Distribution and habitat use of the gopher tortoise (Gopherus polyphemus) in a declining southeast Florida conservation area

Tuesday, August 9, 2011: 3:40 PM
18A, Austin Convention Center
Joshua P. Scholl1, Leonardo Calle2, Evelyn M. Frazier2 and Tobin Hindle3, (1)Dpt. of Ecology and Evolutionary Biology University of Arizona, University of Arizona, Tucson,, AZ, (2)Biological Sciences, Florida Atlantic University, Boca Raton, FL, (3)Geosciences, Florida Atlantic University, Boca Raton, FL
Background/Question/Methods

Gopher tortoises have been declining throughout their range over the last few decades due mostly to anthropization, which often leads to the creation of island habitats. This confines populations and eliminates natural management by wildfires resulting in degraded island habitats. To maximize conservation efforts in rapidly developing regions it is critically important to investigate not only the natural ecology of native species, but specifically how they are affected in confined and degraded habitats. We studied a gopher tortoise population to determine its status, distribution, and habitat use in a confined, degraded ecosystem on the Florida Atlantic University campus in Boca Raton, Florida. We conducted complete burrow surveys using belt transects, directly captured tortoises, and performed vegetation and soil analyses through aerial photos and United States Geological Survey data, respectively. The status of the population was assessed directly based on carapace length measurements and indirectly through ratios of active to abandoned burrow categories.

Results/Conclusions

Tortoise burrows were densely clustered in areas of low vegetation and completely avoided areas with closed canopies, which comprised about 15% of the habitat. Soil types did not appear to have any significant correlation to burrow distribution. We found a high ratio of active to abandoned burrows, which could indicate an active and healthy population; however, demographic data compiled from captured tortoises revealed a lack of juveniles, suggesting an unsustainable population. We concluded that superficial burrow surveys may provide misleading results on the status of gopher tortoise populations in confined, degraded habitats and more direct population assessment methods such as tortoise captures or burrow measurements need to be used.

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