Herpetological Research at
 Lower Suwannee/Cedar Keys National Wildlife Refuge

1 May 2003

Investigators:                                                      click images to enlarge
Margaret Gunzburger, Dr. C. Kenneth Dodd, Jr., Jamie Barichivich, Jennifer Staiger

Background:
In response to documented declines of amphibians, the U.S. Geological Survey (USGS), as directed by Congress in 2000, initiated the Amphibian Research and Monitoring Initiative (ARMI).  The primary goal of ARMI is to monitor trends in amphibian populations on DOI lands and conduct research into causes if declines are observed. USGS herpetologists in the southeastern ARMI region (SE ARMI) are responsible for monitoring amphibians in Florida, Georgia, Alabama, South Carolina, North Carolina, Tennessee, Puerto Rico, and the US Virgin Islands.  To date, SE ARMI personnel have established monitoring sites at several DOI lands in the southeast.  As part of ARMI, we will conduct an inventory of the herpetofauna on the Lower Suwannee/Cedar Keys National Wildlife Refuge and establish a long-term monitoring program for amphibians on the Refuge.

Inventory:
The objective of the inventory is to establish a current amphibian species list for the Refuge. A robust inventory of amphibian species richness is necessary to design the long-term monitoring study.  To develop the list we will use a variety of methods to capture and observe amphibians in all habitats throughout the Refuge.  We propose to conduct general surveys and trapping across upland and wetland habitats and on many of the pine/palm islands. General surveys include field searching for animals under cover objects (i.e., logs and rocks), listening for calling frogs (i.e., aural surveys with frog loggers), and road cruising. Trapping methods include using dip nets, seine nets, funnel traps, "siren" traps, turtle traps, and Goin dredges. We will also install drift-fence arrays with associated funnel traps to facilitate our herpetological inventory.  We will focus much of our inventory work at wetlands because this should allow us to maximize detection probability for most amphibian species on the Refuge. In addition to amphibians, we will document our observations of reptiles and generate a current reptile species list for the Refuge.

Amphibian Monitoring:
The objective of monitoring is to determine long-term trends of amphibian populations on the Refuge. To do this we propose to establish numerous semi-permanent sampling stations at randomly chosen sites across broad habitat types (i.e., intensive sites). We also will conduct less intensive sampling at numerous randomly chosen locations (i.e., extensive sites).  The exact number and location of these sites will be determined later in consultation with Refuge staff, biometricians, and SE ARMI herpetologists.

Intensive Sites—At intensive sites we may erect a drift fence array consisting of metal flashing or silt fence buried ca. 20 cm in the ground.  Wire-screen funnel traps will be placed at the ends of the drift fences to capture animals. Traps will be shaded and checked frequently to keep mortality of trapped animals to a minimum. A grid of PVC pipes (some hung on trees, others placed upright in the ground) and cover boards may be established at intensive sites or other sites on the Refuge.  Intensive sites will likely be monitored four times a year with multiple visits during each sample period. PVC pipes and cover boards will remain in place constantly, but funnel traps will only be deployed during sample periods.  If intensive sites are located at wetlands, the wetlands will be sampled (see above methods) during each sample period in which they hold water.

To help us design our long-term monitoring strategy we will install drift-fence arrays at 10 stations (5 north and 5 south of the Suwannee River) in various habitats during the inventory phase of our work.  Arrays will be installed at upland and wetland sites.  Drift fences will be erected in "Y" pattern (three sections of drift fence) at most sites, but several pond sites will have four sections of fence placed around the pond edge.  Screen funnel traps will be deployed at the drift fences and checked regularly, usually every day, depending on weather conditions and amphibian and reptile activity.  Traps will be opened and suspended in trees when we are not sampling.  Trapping at drift fences for monitoring purposes will usually be conducted monthly, depending on weather events and availability of USGS personnel.  Refuge staff will also conduct trapping at the 10 array sites as time and personnel permit.

Extensive Sites—No permanent equipment will be deployed at extensive sites. At these sites we will use time-constrained searches (turning natural cover and looking through leaf litter) and funnel traps at upland sites and dip nets and frog loggers at wetland sites.  Only one sample period will be conducted at extensive sites. The sample period will most likely consist of 2-3 consecutive days.  These sites will be located a various points throughout the Refuge.

Treefrog Research Project
A common and widespread management practice on public lands is the use of prescribed fire. However, the effects of fire on amphibians in the southeast are poorly known. To gain a better understanding of the impacts of prescribed fire on amphibian populations at the Refuge, we propose to use PVC pipe refugia to study short-term effects of fire on selected population parameters of treefrogs.  We do not know how many pipes will be needed to capture and mark enough frogs to estimate population sizes at our study sites. Therefore, we propose to conduct a pilot study in 2003 by setting up two 100m X 100m grids of PVC pipe refugia at two flatwoods sites on the Refuge.  We will choose one site that is scheduled to receive prescribed fire and one that is not.  Pipes (1 in., schedule 40, 1 m long) will be placed at 10 m intervals throughout each grid. Thus, 121 pipes will be set in the ground at each of the two grids. Once frogs have colonized the pipes, which do not actually trap frogs but simply provide retreat sites, we will conduct several mark/recapture sessions (in conjunction with our inventory work) to determine if enough frogs are available to estimate population size at each grid.  Population parameters will be assessed prior to burning and frogs will be evicted from the pipes and the pipes removed at both sites prior to one site being burned. The pipes will be replaced after the fire and frogs allowed to recolonize the pipes before another round of mark/recapture is conducted. We will compare our results between the two grids pre- and post-burn to estimate population mortality associated with the fire, age and sex specific impacts of the fire, and recolonization rate at the burned site. If the pilot study proves fruitful, we will consult with our biometricians and Refuge staff to design a broader study of similar nature.

Disease Monitoring:
The objective of disease monitoring is to establish baseline data on the health of several target amphibian species so that potential declines caused by disease can be detected and dealt with.  Following USGS standard operating procedures we propose to collect individuals of three species (to be determined) to send to our National Wildlife Health Center. We would need to collect 10 breeding age adults, 10-15 tadpoles, and 2-3 partial egg masses for each species.  We also propose to collect specimens of any sick or dead amphibians we encounter. The target periods for baseline disease monitoring depends on the species sampled and environmental conditions (i.e., when breeding ponds hold water).

Abiotic Parameters:
The objective of collecting abiotic parameters is to identify factors that influence distribution, activity, and detection probability of amphibians. Examples of abiotic parameters that we propose to collect at each sample site include relative humidity; air, water (at wetlands), and soil temperature; pH and salinity (at wetlands); etc. Cooperators from the USGS Water Resources Division will collect water samples from several of our study sites in 2003. We may also collect soil samples.

Species Vouchers:
The objective of collecting voucher specimens is to create an archived record of species presence on the Refuge. All voucher specimens will be donated to the herpetology collection at the Florida Museum of Natural History at the University of Florida. Vouchers will consist of preserved specimens, digital photos of individuals, and acoustic recordings of calling frogs. Specimens to be preserved include road-killed amphibians and reptiles and several individuals of relatively common species.  Rare or listed species will be vouched with digital photos, or a single individual may be collected, especially the first individual of the species found during our surveys.

Some species of salamanders and frogs are difficult to identify while they are larvae. Therefore, we propose to occasionally collect several individuals per putative species and rear them in the lab to confirm species identification.  After these individuals are reared to metamorphosis and the species is confirmed, they will be preserved as vouchers.

Deliverables:
We will provide the Refuge:

• A checklist list of herpetofauna species encountered on the Refuge
• A link to our website with photos and descriptions of herpetofauna species encountered on the Refuge
• A laminated poster about our work at the Refuge and species observed
• A list of voucher specimens collected with museum catalog numbers
• Digital photos of species observed on the Refuge
• Upon request--reports summarizing our work at the Refuge