Procedures and methods

       Historical Information. - Information on southeastern amphibians may be contained in numerous publications (e.g., scientific and popular literature and agency publications), unpublished reports, and museum collections. As part of initiating amphibian monitoring programs in the southeastern U.S., USGS personnel will determine the extent of information available on amphibians within DOI-administered lands. Initially, we will focus on lands selected for intensive sampling and monitoring, but through time we will assemble a database on all DOI lands in the southeastern US and Caribbean. In addition to published literature, agencies, museums, and Natural Heritage Programs will be contacted to determine historical species presence and the types of habitats where species are found. Data collection will be coordinated with the Database Management Program administered by the Patuxent Wildlife Research Center (see below).

       Inventories. - Although the distribution of amphibians is reasonably well understood on certain DOI lands, such as in the Great Smoky Mountains National Park (Dodd, 2004), this is not the case for most units of the National Park Service and National Wildlife Refuges. This study plan recognizes that there is a need to survey amphibian species richness and distribution patterns on many DOI lands prior to selecting species to be monitored and sampling protocols. Some of the inventory techniques available to sample amphibians are the same as those used to monitor populations (see below). However, inventory protocols will be used to determine species presence rather than long-term population trends. Thus, sampling will occur over a large area to include all habitat types; multiple sampling techniques may be employed; and sampling may be restricted by time (that is, it may be extensive rather than site intensive).

       Inventories are part of the Resource Survey component of the conceptual framework developed by USGS in connection with ARMI. Inventories will be conducted on a variety of DOI lands, including National Park Service administered lands (within the NPS Regional Networks framework) and on U.S. Fish and Wildlife Service administered National Wildlife Refuges. Inventories will be conducted on Index Sites when such data are not already available.

       All sampling techniques employ some variation of a time constraint approach whereby search or trap effort is quantified and results are expressed in catch per unit effort of sampling. In all cases, characteristics of the environment/habitat, sampling conditions, and the number of animals observed or captured by species are recorded. Examples of such techniques include: visual searches while walking predetermined paths or transects; searching cave walls; searches of terrestrial leaf litter and under surface debris (logs, rocks, coarse woody debris); searches of aquatic habitats by moving stream debris or by using dipnets to look for adults and larvae; snorkeling for large salamanders; road surveys during favorable activity periods (e.g., during rain near breeding ponds).

       Frogs may be inventoried by listening for calls during the breeding season, although not all frogs are easily sampled this way. Some frogs call very softly and may not be heard except in their immediate vicinity. When conducting inventories using calls, it may be necessary to categorize the numbers of animals calling categorically, for example: 1 (1 calling), 2 (2-5 calling), 3 (6-10 calling), 4 (>10 calling), 5 (large chorus). This is because it is often very difficult to determine how many frogs are calling when a chorus is in progress. In southern wet prairies, literally hundreds or thousands of males may call simultaneously.

       In certain instances, it may be desirable to inventory amphibians using specialized techniques, such as by employing traps (e.g., soft or hard minnow traps), modified crayfish traps (Johnson and Barichivich, 2004), coverboards, PVC pipe (Zacharow et al., 2003), debris bags (Pauley and Little, 1998; Waldron et al., 2003) or drift fences with pitfalls. Each of these techniques has sampling biases (see below), although they are useful to determine the presence of some species in certain habitats (techniques discussed in Heyer et al., 1994). Dodd (2003) and Dodd et al. (in press) have reviewed amphibian sampling and monitoring techniques, the biases associated with the techniques, and what types of data the techniques provide to researchers.

       DOI Resource Survey and Index Sites (with acreage) of major importance are as follows:

National Park Service

1,506,539 729,000 521,000 116,000 46,000 14,000 11,000 8,200

Everglades

Big Cypress

Great Smoky Mountains

Big South Fork

Timucuan

Little River Canyon

Congaree Swamp

Chickamauga

Fish and Wildlife Service

396,000 68,000 64,229 52,935 34,500 24,904 19,400 2,761

Okefenokee

St. Marks

Cape Romain

Lower Suwannee

Wheeler

Savannah

Lake Woodruff

Harris Neck

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