There is renewed interest in inventory and monitoring projects, due in part to mandates to evaluate the effects of surrounding development and climate change on the biotic communities of public lands. We inventoried an understudied area, Wormsloe State Historic Site, near Savannah, GA. We directly observed or trapped 21 herpetofaunal (i.e., amphibian and reptile) species. Chao estimates predicted that <1 additional amphibian species and 3–4 additional reptile species might occur with further trapping. Most species had low abundance: <10 individuals for 75% of species. Species richness on Wormsloe was about ⅓ that recorded on the adjacent mainland (<1 km distance). Some species not detected required specific habitats lacking at Wormsloe. Other undetected species may have been extirpated by past land-uses. Also, the changing landscape context, caused by development of surrounding areas, has likely diminished both landscape connectivity and available freshwater, shortening the hydroperiod of breeding ponds. Of import to breeding amphibians, each of the depressions on Wormsloe has a drainage ditch connecting it to salt-water tides but the water-control structures preventing tidal flux are no longer in place. Resources management can improve amphibian breeding habitat simply by eliminating tidal influxes along drainage ditches. Maintaining existing populations of common species should be a priority for all public lands.