Inventory and Monitoring Activities: Savannah and Harris Neck National Wildlife Refuges (Savannah Coastal Refuges complex)

Harris Neck:

       Harris Neck NWR (HNNWR) is located ca. 46 km south of Savannah and 31 km north of Darien, in McIntosh Co., Georgia (Fig. 1). The refuge comprises 1,255 hectares of mostly coastal deciduous and oak woodlands, grasslands, former cropland, and some pine (Fig. 2C) and is surrounded by salt marshes and tidal creeks, limiting amphibian colonization. Harris Neck has a long history of human occupation (Amerindian, with plantations prior to the Civil War, a series of many small farms in the late 1800's-early 1900's, an airfield, a military base during World War II [Harris Neck Air Base], and under the ownership and management of several county, state, and federal government agencies after the war; see Sullivan, 1997) which certainly affected herpetofaunal species richness and distribution as a result of extensive habitat modification. Harris Neck became a National Wildlife Refuge in 1962, and is managed primarily for waterfowl and wading birds, including the wood stork. Nearly all the wetlands at Harris Neck are either man-made impoundments, modified former tidal creeks, or ditches and borrow pits.

       HNNWR supports 13 amphibians (11 species of frogs and one species of salamander) and at least 17 species of reptiles (one crocodilian, five lizards, seven snakes, and four freshwater turtles).  It is likely that additional reptile species, particularly snakes, occur on the refuge. Historical information on the herpetofauna of HNNWR is apparently nonexistent, as we have been unable to locate any museum specimens from the refuge. SEARMI research began at Harris Neck in April 2004.

Savannah NWR

       Savannah National Wildlife Refuge (SNWR) (Fig. 1) comprises 11,320 hectares in Georgia and South Carolina immediately upstream along the Savannah River from the city of Savannah (Fig. 2D). As with Harris Neck, it is part of the Savannah Coastal Refuges Complex. The refuge has an extensive history of human occupation and use, from Amerindian through the plantation era, when the bottomlands and freshwater tidal marshes were extensively diked and modified for rice production (constructed from the mid to late 1700's). Designated in 1927, the refuge is primarily managed for waterfowl, and water levels within the former rice fields (1,364 hectares) are carefully controlled. The refuge occasionally clears vegetation from the impounded areas, resulting in a variety of marsh habitats of different depths, vegetation structure, and species composition.

       The northern part of the refuge (upstream from the freshwater tidal marshes) consists mostly of extensive islands of bottomland hardwoods (cypress, gum, maple) that may or may not be periodically flooded. These islands contain creeks and an extensive number of woodland pools and channels which hold water for varying amounts of time. There is only one large pond on the refuge (Kingfisher Pond, =DT2, an old borrow pit) not associated with the bottomlands. River bluffs and upland terraces on the refuge are few, as the refuge boundary often terminates at the base of the river bluff. However, some uplands and slope are present along Dodge Tram Road on the north side of the river, and more extensive upland and swamp habitats are found on the south side of the river east of O'Leary (as marked on the USGS 7.5' Port Wentworth topographical map). This area, the Solomon Tract, and is one of the most recent additions to SVNWR. This is also the location for sampling in connection with the USFWS malformed frog survey.

       To date, 21 species of amphibians (15 species of frogs and six species of salamanders) and at least 11 species of reptiles (one crocodilian, two lizards, five snakes, and three turtles) have been reported from SVNWR.  Undoubtedly, many more species will be found as sampling continues, especially among the reptiles.  We are currently examining historical information on the herpetofauna of the refuge, as well as the field notes from early collectors. SEARMI research began at Savannah National Wildlife Refuge in April 2004.

Effort in 2005

       ARMI made three visits to Harris Neck and Savannah NWRs in 2005: 21-25 Mar, 16-22 May, and 25-29 Jul (Table 2).

Results

Harris Neck NWR

       We have detected 13 species of amphibians (12 frogs, one salamander) through the end of July 2005 (Fig 3). Hyla gratiosa was added this year, at Leopard Frog Pond (=Borrow Pit Pond). A total of 15 wetland sites was examined in March, 12 in May, and nine in July. Three new wetland sites were identified: Church Ditch (along main road across from Friendship Baptist Church); Goose Meadow (adjacent to the dirt road along the southeast side of Goose Pond); and Snake Bog (a seepage boggy habitat along the main road near Friendship Baptist Church). Church Ditch only held water after heavy rains in March, and Pseudacris ocularis was heard calling from its margins. Goose Meadow is an extensive shallow water area, but it only holds water after extensive rains. Bufo terrestris bred successfully there in March in large numbers. Water remained in May, but no tadpoles were seen; by July, the area was dry. Snake Bog had choruses of P. ocularis, Hyla femoralis, H. cinerea, and Acris gryllus during night surveys in May, but no tadpoles were seen. On 17 May, two small venomous snakes (Agkistrodon contortrix and Crotalus horridus) were seen on the way into this site from the road, hence our tentative name for this site.

       Night surveys on the paved roads were conducted several times during our stays on the refuge. Amphibians are particularly abundant after heavy rains, and many species can be detected calling; all wetland sites at Harris Neck can be visited within 2 hrs. As a result, we found several species (e.g. Bufo terrestris, Hyla cinerea) distributed essentially everywhere on the refuge. Detailed field notes from CKD are provided from all 3 visits (see Appendix VI).

Savannah NWR

       We have detected 22 species of amphibians (15 frogs; seven salamanders) through 2005, with Eurycea quadridigitata being added this year on the river bluffs along Dodge Tram Road in South Carolina (DT-4, 24 Mar) (Fig 3). In 2005, we sampled ten sites (four wetland, six terrestrial) in Mar; 15 sites in May (11 wetland, four terrestrial), including additional sites on Bear Island; and nine sites in July (five wetland, four terrestrial). The most amphibian species-rich wetland continues to be Kingfisher Pond (DT-2), and this year we observed huge numbers of Rana heckscheri tadpoles at this site in late Jul (662 tadpoles in four traps on 28 July; 470 the next day). Tadpoles of this species form large schools, and we easily observed a large number of tadpoles gulping air as we set and picked up our traps. The rice fields are depauperate in species, although biomass is undoubtedly quite high.  These are the only areas where Siren lacertina and Amphiuma means are found.  Bear Island was rather dry during our visit, and only a few individuals were heard calling (see field notes).

       In March, we were joined by Steve Bennett of the South Carolina Department of Natural Resources, who collected Desmognathus auriculatus for genetic studies from a few sites along Dodge Tram Road. Preliminary evidence suggests that this may represent a new species of lowland dusky salamander. Detailed field notes from CKD are provided from all 3 visits (see Appendix VI).

Water Quality Data

Harris Neck NWR

       We collected water-quality field parameters (pH, conductance, dissolved oxygen, temperature) at 12 ponds sampled in 2005 (Table 6). We measured these parameters at 10 ponds on more than one visit.  Values for pH were generally acidic, with a range from 3.92 to 8.65 and a mean among all samples of 5.95. Conductivity was generally low, less than 0.397 mS/cm at all sites. Dissolved oxygen (DO, mg/l) and % DO varied considerably, ranging from 0.11 mg/l and 1.4% to 14.87 mg/l and 159%. Water temperatures ranged from 13.8 ºC to 28.9 ºC (Table 7).

Savannah NWR

       We collected water-quality field parameters (pH, conductance, dissolved oxygen, temperature) at 10 ponds sampled in 2005 (Table 6). We measured these parameters at 4 ponds on more than one visit.  Values for pH were less acidic than at HNNWR, with a range from 5.08 to 7.03 and a mean among all samples of 6.16. Conductivity was generally low, less than 1 mS/cm in all but four samples. Dissolved oxygen (DO, mg/l) and % DO varied considerably, ranging from 0.21 mg/l and 2.5% to 5.11 mg/l and 52.6%. Water temperatures ranged from 15.3 ºC to 28.9 ºC (Table 7).

Future Plans

       In 2006 ARMI will be transitioning from inventory to monitoring at Harris Neck and Savannah NWRs, and we tentatively have two visits planned for 2006, during spring/summer breeding season. Collections for disease screening will be conducted.

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