Herpetofaunal Surveys at Fort Matanzas National Monument


Atlantic beach and sand dunes - The open beach facing the Atlantic Ocean on the east side of Fort Matanzas National Monument is formed of fine white silica sand. Above the reach of the tide and waves, the dry sand is blown by the wind into dunes 15-20 feet (4.6-6 m) high, which form sand ridges parallel to the beach. Sea oats (Uniola paniculata), railroad vine (Ipomoea pes-caprae), beach morning glory (Ipomoea stolonifera), sandspur (Cenchrus spp.), and bitter panic grass (Panicum amarum) are pioneer vegetation found on the upper beach and anchoring the fore dunes against the wind. The loggerhead sea turtle, green turtle, and leatherback sea turtle come ashore during the summer months to nest above the tide on the upper beach or in the sand dunes. Kemp's ridley sea turtles nest primarily on Gulf of Mexico beaches in northern Mexico and southern Texas, but occasionally come ashore after being injured by shrimp nets. Six-lined racerunners, gopher tortoises, southern racers, and rough green snakes occasionally are found in the fore dunes. The center of the north end of Rattlesnake Island also contains open sand dunes, the result of sand that was pumped in years ago from dredge operations that maintain the depth of the Intracoastal Waterway.

dunes diagram

Dunes Meadows - Anastasia Island's fore dunes shelter the secondary dunes from much of the onshore wind, which allows additional plants to become established, including beach cordgrass (Spartina patens), purple muhly grass (Muhlenbergia capillaris), and pennywort (Hydrocotyle bonariensis). These plants stabilize the dunes and allow the lower flatter areas to function as a meadow by providing food for gopher tortoises, rabbits, beach mice and other herbivorous animals. These dunes meadows include the storm water overwash areas immediately east and west of the Highway A1A bridge over the Matanzas River Inlet. The plants that are probably most characteristic of the dunes meadow are the prickly pear cactuses (Opuntia spp.), whose thousands of spine bristling seedlings carpet the ground and stick to your shoes and puncture the skin of your lower legs. The fleshy pads of the older cactuses are eaten by gopher tortoises. Blanket flower (Gaillardia pulchella), broomsedge (Andropogon spp.), standing cypress (Ipomopsis rubra), beach sunflower (Helianthus debilis), and horsemint (Monarda punctata) provide abundant color in the dunes meadows. Dense clumps of greenbriar (Smilax auriculata) and saw palmetto (Serenoa repens) provide shelter to many animals, including six-lined racerunners, southern racers, and coachwhips. Dense thickets of scrub live oak (Quercus geminata), wax myrtle (Myrica cerifera), and hercules club (Zanthoxylum clava-herculis) make the dunes meadows a transition community between the dunes and the maritime forest further inland.

The northern end of Rattlesnake Island and its eastern shore consist of white silica sand dunes and storm water overwash areas. Sea oats (Uniola paniculata), and beach cordgrass (Spartina patens) has stabilized much of the dunes area and turned it into dunes meadow. Large patches of saw palmetto (Serenoa repens), southern red cedar (Juniperus salicicola), and cabbage palm (Sabal palmetto) have invaded much of the area. The dunes meadows on Rattlesnake Island are similar to those on Anastasia Island, except that many are blanketed with dog fennel (Eupatorium capillifolium), and they have fewer blanket flower (Gaillardia pulchella), standing cypress (Ipomopsis rubra), beach sunflower (Helianthus debilis), and other colorful flowering plants.

The most abundant reptiles in the dunes meadows are the six-lined racerunners and gopher tortoises. Eastern diamondback rattlesnakes, coachwhips, southern racers, yellow rat snakes, corn snakes, rough green snakes, and box turtles also are typical of this habitat.

Atlantic Maritime Forest - The leafy tops of the trees in the maritime forest touch and interlace to form a closed canopy that blocks out the sun. The only places where the full force of the sunlight reaches the ground is where the canopy is broken by dead trees, or by patches of open dunes, or roads. Wind and salt spray kills many of the tender new leaves on the trees near the beach. That slows growth and sculpts the canopy so that it sweeps up from a low edge on the beach side to a higher level inland. Along Highway A1A, the canopy is 15-20 ft (4.6-6 m) high, and further west (between the highway and the Matanzas River) the canopy reaches a height of 30 ft (9.1 m) in some places. Wind sculpted thickets in the dunes meadows are composed of scrub live oak (Quercus geminata), red bay (Persea borbonia), wax myrtle (Myrica cerifera), hercules club (Zanthoxylum clava-herculis) and southern red cedar (Juniperus salicicola). Clumps of silverling (Baccharis halimifolia) and recumbent saw palmetto (Serenoa repens) are common between the thickets.

The high canopy forest on the western side of Anastasia Island is live oak hammock. The dominant trees are live oak (Quercus virginiana), southern magnolia (Magnolia grandiflora), red bay (Persea borbonia), southern red cedar (Juniperus salicicola), and cabbage palm (Sabal palmetto). The understory trees and shrubs growing in the shade of the canopy are composed of erect saw palmetto (Serenoa repens), wax myrtle (Myrica cerifera), yaupon holly (Ilex vomitoria), hercules club (Zanthoxylum clava-herculis), American beautybush (Callicarpa americana), and wild grape (Vitis spp.). Stinging spurge (Cnidoscolus stimulosus), coontie (Zamia pumila), coralbean (Erythrina herbacea), and Boston fern (Nephrolepis exaltata) are common groundcover and resurrection fern (Polypodium polypodioides) clothes the trunks of the trees.

Most of the Fort Matanzas National Monument amphibians and reptiles occur in the maritime forest. Eastern diamondback rattlesnakes, southern racers, coachwhips, indigo snakes, and spadefoot toads are found in the wind and salt sculpted thickets. The moist shade beneath the live oak hammock is the home of spadefoot toads, southeastern five-lined skinks, ground skinks, green anoles, squirrel treefrogs, green treefrogs, barking treefrogs, rough green snakes, corn snakes, yellow rat snakes, indigo snakes, pinewoods snakes, ringneck snakes, coral snakes, and box turtles. Six-lined racerunners, gopher tortoises and glass lizards are found in the sunlit patches where the canopy is broken.

Permanent freshwater pond - Fewer species of amphibians and reptiles are found on coastal barrier islands like Anastasia Island and Rattlesnake Island than on the adjacent mainland. One of the primary reasons for the difference is the scarcity of freshwater on the islands. Amphibians and reptiles on the islands must be able to find what little moisture is available between rains and to survive until the next rain. Rain rapidly disappears into the sandy soils, where it forms a lens of freshwater that floats on top of the saltwater much deeper in the soil. That lens of freshwater is close to the surface in some low areas in the live oak hammock between Highway A1A and the Matanzas River. A number of swales have moist soil and one is sufficiently low to hold a permanent freshwater pond 3-4 ft. (91-122 cm) deep. The dominant vegetation around the pond is elderberry (Sambucus canadensis), saltmarsh mallow (Kosteletzkya virginica), and coastal plain willow (Salix caroliniana). The surface of the pond is covered with duckweed (Lemna spp).

The pond provides breeding habitat for leopard frogs, narrowmouth toads, squirrel treefrogs, green treefrogs, barking treefrogs, and Cuban treefrogs. The permanence of the pond makes it ideal habitat for slow maturing tadpoles. The pond also is habitat for green anoles, which abound on the shrubs around its margin.

Buildings - The Fort Matanzas National Monument Visitor Center, office building, and public restroom building are constructed of coquina rock. The residences are wood structures and the service buildings are concrete block and metal. Cracks and crevices in all of these buildings provide warm habitats for Indo-Pacific geckos, Mediterranean geckos, brown anoles, and Cuban treefrogs, that could not otherwise survive the cold winter temperatures. Squirrel treefrogs hide under the shingles of the roofs. Corn snakes forage for mice and lizards on these buildings. Green anoles and rough green snakes are found on the shrubs around the buildings, and greenhouse frogs abound in the leaf litter under the shrubs.

Matanzas River beaches - The shore of the Matanzas River between the Fort Matanzas National Monument Visitor Center and the mouth of the river are fine white silica sand similar to the Atlantic beach. Above the high tide level, the major beach vegetation is sea oats (Uniola paniculata), railroad vine (Ipomoea pes-caprae), and bitter panic grass (Panicum amarum). The only reptiles that regularly are found here are six-lined racerunners and gopher tortoises.

Salt marshes, tidal creeks and mangroves - A large salt marsh cuts a wide swatch across the northern section of Rattlesnake Island from the Matanzas River to the Intracoastal Waterway. A number of smaller salt marshes occupy the center of Rattlesnake Island. Tidal creeks meander north out of those smaller marshes to join larger creeks that drain the large marsh into the Matanzas River and Intracoastal Waterway. Another large salt marsh and tidal creek complex lies outside the north boundary of Fort Matanzas National Monument on Anastasia Island. A small strip of salt marsh runs south along the east side of the Matanzas River to the Fort Matanzas National Monument Visitor Center. Salt marshes are salt tolerant grasslands lying between the high and low tides. The tidal flow through the larger creeks fills them with sea water, but the upper reaches of the tidal creeks and pools in the smaller marshes are hypersaline from evaporation. Glasswort (Salicornia spp.), saltwort (Batis maritima), saltmarsh cordgrass (Spartina alterniflora), and black needlerush (Juncus roemerianus) are the dominant plants of the Fort Matanzas National Monument salt marsh. Small patches of black mangrove (Avicennia germinans) occur along the edge of the marsh. Most salt marsh animals are found on the surface, in the vegetation, or in the tidal creeks. There is little or no oxygen in the gummy mud of the salt marsh, which limits burrowing animals to the top few inches (cm) of soil.

Diamondback terrapins range through the saltwater habitats of Fort Matanzas National Monument, including the tidal creeks. Eastern glass lizards, corn snakes, pine woods snakes, and six-lined racerunners are found along the edges of the salt marsh.

Cedar, wax myrtle and cabbage palm forest - Protected from wind and salt spray by Anastasia Island lying between it and the Atlantic Ocean, the forest on Rattlesnake Island is not typical closed canopy maritime forest. The trunks of the trees are more erect and there is no salt and wind sculpting of the canopy. The only closed canopy forest on Rattlesnake Island is produced by dense groves of erect southern red cedar (Juniperus silicicola). The forest around the perimeter of the island is formed primarily of southern red cedar, wax myrtle (Myrica cerifera), and cabbage palm (Sabal palmetto). Coachwhips, southern racers, rough green snakes, yellow rat snakes, corn snakes, six-lined racerunners, ground skinks, and gopher tortoises are found there.

Slash pine and red bay woodland - Rattlesnake Island has numerous small groves of slash pine (Pinus elliottii). This is not typical pine flatwoods since the groves are too small, the fine white sand that makes up the soil is too dry, is not seasonally wet, and lacks the hardpan typical of pine flatwoods. The pine most often occurs with red bay (Persea borbonia). Squirrel treefrogs, greenhouse frogs, narrowmouth toads, spadefoot toads, southeastern five-lined skinks, ground skinks, green anoles, rough green snakes, corn snakes, yellow rat snakes, and indigo snakes occur in the slash pine and red bay woodland.

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