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INVENTORY OF AMPHIBIANS AND REPTILES
OF
THOMAS STONE NATIONAL HISTORIC SITE
Technical Report NPS/NERCHAL/NRTR-2008/111
Joseph C. Mitchell, Ph. D.
Department of Biology
University of Richmond
Richmond, VA 23173
March 2008
U.S. Department of the Interior
National Park Service
Northeast Region
Philadelphia, Pennsylvania
__________________________
Executive Summary
This inventory
was conducted at Thomas Stone National Historic Site (THST) in 2002 and
2003, to (1) document 90% of the amphibians (frogs, salamanders) and reptiles
(turtles, lizards, snakes) of THST, (2) describe their associated habitats,
and (3) provide park staff with conservation and management recommendations.
Survey methods included visual encounter surveys, audio surveys, and road
surveys; dipnets, minnow traps, and turtle traps.
Twelve species
of frogs, nine salamander species, five turtle species, five lizard species,
and 17 snake species were expected to occur at THST based on known distribution
patterns in published literature. The proportion of species documented
during this inventory was 67% for frogs, 56% for salamanders, 40% for
turtles, 40% for lizards, and 24% for snakes. Total success was 62% of
expected species for amphibians, and 30% for reptiles. These success levels
are below what one would expect given the sampling effort. However, limitations
caused by the drought conditions that prevailed during the study, the
small size of the park, and the history of intense land use at THST contributed
to the low species richness observed.
Five habitat types used by amphibians and reptiles at THST were described during this inventory, which included grassland, mixed hardwoods, impoundments, vernal pools, and stream. All habitats surveyed support multiple species, and most species use both aquatic and terrestrial habitat types. Habitats that support relatively unique assemblages include hardwood forests and vernal pools. The combination of habitat types used by amphibians and reptiles at THST should be viewed as a matrix of habitats imbedded within the landscape rather than as a series of separate habitat types and should be protected as such.
Although this
study documented less than 90% of the expected number of species for several
groups, there are opportunities to register additional species. This can
be accomplished in one oftwo ways by park staff: routine accumulation
of digital photographs of road-kills or live amphibians and reptiles encountered
with appropriate documentation appended to the digital image, and the
use of natural history (animal) sighting cards filled out by knowledgeable
visitors. Verification of new species records should be confirmed by a
herpetologist.
Recommendations for THST resource management include: (1) Additional species
inventory should be conducted for salamanders and snakes. Further work
to document snake species at THST should include the use of coverboards
as part of the sampling plan. (2) Areas of the park where there tend to
be high concentrations of Box Turtles should be evaluated before opening
them to recreational activities. (3) The public should not be allowed
to release any animals that have been in captivity, and park management
should educate park visitors on this issue. (4) Specific habitats at THST,
including hardwood forests and vernal pools should be monitored on a regular
basis for the occurrence and persistence of amphibians and reptiles. (5)
Educational< materials should be developed on ecology, flora and fauna,
and interactions with human history at THST. (6) Park raccoon populations
should be monitored, and population control measures implemented to protect
all amphibians and reptiles, especially turtles and their nests. (7) A
comprehensive natural resource management plan to conserve amphibians
and reptiles at THST should be developed. (8) Long-term habitat management
at THST should be viewed within the context of the landscape matrix in
and around the park.
_________________________________
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