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Why Monitor Amphibians?
The problem of declining amphibian populations has been recognized worldwide, with credible reports of diminishment or disappearance of amphibians from many regions and habitat types. No single cause for declines has been demonstrated, although acid precipitation, environmental contaminants, introduction of exotic predators, disease agents, parasites, and effects of ultraviolet radiation have been suggested as factors in declining numbers. Indeed, no one cause may be implicated, and several factors may interact in such a manner as to threaten populations (Carey and Bryant, 1995). A major factor in the loss of amphibian populations has been and continues to be the loss of habitat. The severity and apparent complexity of the problem led the National Park Service in 1997 to list amphibian declines as among its highest priority research and information needs.
In terms of its significance to amphibians, the Great Smoky Mountains National Park is more important than almost anywhere else in North America. Thirty-one species of salamanders have been recorded in the Park, and that number could conceivably increase as molecular genetic techniques are used to unravel the complex relations among populations. Of particular note are the salamanders of the family Plethodontidae, a largely North American group that has a center of evolution and distribution in the southern Appalachians (Dodd, 2004). Jordan’s Salamander (Plethodon jordani) is known to occur only in the Park, and the salamander fauna is believed to represent several evolutionary series progressing from the more aquatic species to those which are almost totally terrestrial. Thirteen species of frogs and toads are historically reported to inhabit the Park. The biological importance of the Park has been recognized in its designation as an International Biosphere Reserve. Although no other region and no other National Park shares the wealth of amphibians found in the Great Smokies, the entire southern and midsection of the Appalachian chain is characterized by a high diversity of amphibians, and inventories and monitoring protocols developed in the Great Smokies may be applicable to National Park Service, U.S. Forest Service, Nature Conservancy, or other properties in the Appalachians.
Several known stressors potentially affect amphibians in the 2,071.2 km2 (521,000 acre) Park (reviewed by Dodd, 2004). Air pollution, particularly long-distance pollution from cities in the nation's mid-region, is a nationally recognized problem. Reduced visibility, damage to plants, and fish kills are documented to be associated with sulfurous and nitrogenous compounds and atmospheric ozone. Low pH is known to have affected survivorship in at least one aquatic salamander species in the Park. Exotic pathogens and parasites have seriously affected some forest communities, with unknown effects on ecosystems. Finally, the pressure of ten million visitors per year_more than any other National Park_seems relatively benign, but could potentially have subtle effects on sensitive amphibian populations. The existence of these and other unknown stressors suggest that an inventory and a monitoring program are needed to ensure the protection of amphibian populations.
Amphibian Research and Monitoring Initiative (ARMI) __ In 2000, the President of the United States and Congress directed Department of the Interior (DOI) agencies to develop a plan to monitor the trends in amphibian populations on DOI lands and to conduct research into possible causes of declines. The DOI has stewardship responsibilities over vast land holdings in the United States, much of which is occupied by or is potential habitat for amphibians. The U.S. Geological Survey (USGS) was given lead responsibility for planning and organizing this program, named the Amphibian Research and Monitoring Initiative (ARMI), in cooperation with the National Park Service, U.S. Fish and Wildlife Service, and Bureau of Land Management. Results of the monitoring program will be available to cooperators, land managers, the scientific community, and the general public. ARMIs Internet site is:
National Park Service (NPS) __ Recent legislation (National Parks Omnibus Management Act of 1998) and policies of the National Park Service require that park managers know the condition of natural resources and that they monitor long-term trends in those resources. To comply with legal and policy requirements, the NPS Inventory and Monitoring Program focuses on attaining the following major long-term goals: (1) establish natural resource inventory and monitoring as a standard practice throughout the NPS that transcends traditional programs and activities; (2) inventory the natural resources and park ecosystems under NPS stewardship to determine their nature and status; (3) monitor park ecosystems to better understand their dynamic nature and condition and to provide reference points for comparisons with other, altered environments; (4) integrate natural resource inventory and monitoring information into NPS planning, management, and decision making; and, (5) share NPS accomplishments and information with other natural resource organizations and form partnerships for attaining common goals and objectives. Information on the National Park Service Inventory and Monitoring Program can be found at: http://www1.nature.nps.gov/im/monitor/index.htm#Legislation, and in publications by Silsbee and Peterson (1991) and Peterson and others (1995).
All Taxa Biodiversity Inventory (ATBI) __ A research effort designed to compile a comprehensive inventory of all life forms in Great Smoky Mountains National Park, ATBI is sponsored by Discover Life in America, a private nongovernmental organization working in partnership with the NPS. The initiative has a goal of completing the inventory in as few as 10 years and is, therefore, an intensive undertaking. Before the project is completed, it will employ the expertise of taxonomists, data specialists, zoologists, botanists, and ecologists, among others. Once completed, the ATBI will provide baseline data from which to measure species change through time. ATBI’s objectives are to: (1) complete a comprehensive “checklist” of life forms in the Park; (2) gather data to create range maps for each Park species; (3) compile natural history information on each species, including its relative abundance, its response to various climatic conditions, photographs of each of its life stages, its role in the greater ecosystem, its relationship with other species, and digital recordings of its calls or sounds; and, (4) organize the information gathered and make it available to scientists, educators, land managers, students, and all other interested parties via the Internet and other media. More information can be found at:
There are at least 10 major items which need to be addressed before starting an inventory or monitoring program for amphibians, especially when under financial or personnel constraints. These are discussed briefly below and, in some cases, more extensively elsewhere within the guide.
1. There are many amphibians in the southern Appalachians and the southeast. A total of 31 species of salamanders and 13 species of frogs have been recorded historically as occurring in the Park. Extending the area of interest to the greater southern Appalachians, the figure increases substantially, by 21 salamanders and 1 frog, because of the high levels of endemism of many salamander species. Extending the area of interest even more, there are approximately 85 species of salamanders and 58 species of frogs within the southeastern United States (or 49.6 percent of the species in the entire United States). This figure does not include different subspecies, nor does it include the many genetic variants that have been described.
2. The systematic status of many species of southeastern amphibians is in a flux. It is likely that there are a number of new and unrecognized species of amphibians in the southern Appalachians, particularly among the salamanders. In addition, there is considerable debate among salamander taxonomists over what constitutes a species in terms of genetic uniqueness, phylogeny, and reproductive compatibility. Particularly in the genera Plethodon and Desmognathus, many new “genetic” species have been described in recent years, especially in the southern mountains. Unfortunately, morphology and coloration may be only of limited assistance in identification; many individuals are impossible to distinguish phenotypically in the field. There also are areas where considerable introgression or hybridization occurs, especially in the Great Smoky Mountains. This has led to the recognition of species complexes (for example, the slimy salamanders of the Plethodon glutinosus complex), or even of size-based guilds among the dusky salamanders (Desmognathus). As systematists closely examine other genera (Eurycea, Pseudotriton), the situation will probably become more complicated. Systematic certainty may be no better in the frog world, especially in the genera Pseudacris and Rana, although the taxonomy of frogs within the southern Appalachians will probably remain stable.
3. Species and life stages are sometimes difficult to distinguish. Even experienced herpetologists sometimes have difficulty identifying adult amphibians, and eggs and larvae pose special identification problems. Color and morphology vary considerably among individual amphibians. The ability to distinguish species based on egg mass and tadpole morphology is exceptionally difficult and is an ability that is rapidly being lost, as such identification is rarely taught, and the pool of naturalists who are knowledgeable concerning identification is diminishing. There are very few current color guides to amphibian eggs and larvae, even on a local basis.
4. Amphibians have complex life cycles. Because of the extremely varied life histories of many amphibians (see Life History), inventory and monitoring programs must consider such variation when planning when and where amphibians will be monitored, and what biases may be associated with interpreting sampling results.
For example, egg mass counts might tell a researcher about the number of egg masses deposited and, therefore, the number of females that reproduced that year. Egg mass counts cannot be used to determine population size (often used as a measure of status), however, unless the operational sex ratio (that is, the sex ratio of adults that actually bred successfully) is known for that year. This ratio is usually assumed to be 1:1, but if it is not, estimates of population size could be in error by several orders of magnitude. Also, not all individuals breed every year and, thus, population size at a breeding pond may not be indicative of overall population size. Even with such data available, population sizes still cannot be estimated inasmuch as the ratio of juveniles to adults is not known for most species. In addition, counting egg masses says nothing about whether reproduction was successful, since a variety of factors (disease, desiccation, predation) can interact to prevent hatching and metamorphosis. Consequently, it might be possible to count large numbers of egg masses, yet have none of them actually result in juvenile recruitment to the population. Status and long-range impacts to the population could be easily misinterpreted.
When inventorying and monitoring amphibians with complex life histories, multiple sampling techniques may be required, and status interpretation must be restricted to the sector of the population actually sampled. This rather obvious approach is often ignored, as authors often make general statements as to status and trends when only a portion of the animal’s life cycle was sampled.
5. In the field, detectability of amphibians is likely influenced by the following variables, to a greater or lesser extent, depending on species. Some of these variables include:
Annual cycles of reproduction __ The reproductive season may be prolonged, or extend for only a few days or weeks. Some amphibians may be effectively sampled only during the breeding season (Ambystoma sp., Hemidactylium, many frogs), whereas breeding females of other species may disappear underground to brood eggs (Plethodon) and thus be undetectable.
Seasonal events (cold, drought, heat, storms) that are usually unpredictable __ Cold, heat, and drought generally make amphibians more difficult to find, whereas tropical depressions and hurricanes, with their heavy rains, may actually bring amphibians to the surface in incredible numbers.
Diurnal versus nocturnal activity __ Many amphibians are more conspicuous at night, when they leave hiding places to forage, than they are in the day. This is true for both terrestrial and aquatic species.
Air, water, and substrate temperature __ Amphibians often have rather narrow tolerances or preferences for particular air, water, or substrate temperatures. Some species prefer rather cool temperatures (for example, salamanders living at high elevations, and the winter-breeding frogs), whereas others prefer the warm temperatures of summer. Since temperature changes with elevation (Dodd, 2004), activity patterns of broadly distributed species tend to change seasonally with an increase in elevation.
Soil moisture and rainfall __ Terrestrial amphibians are active when soils are moist and during rainfall, much more so than when soils are dry. Breeding movements may be triggered by a combination of seasonal gonadal development, favorable temperature, and rainfall.
Relative humidity __ High humidity favors amphibian activity; low humidity depresses activity.
Barometric pressure __ Barometric pressure is indicative of changing weather conditions; a falling barometer is associated with weather fronts and rain, and a rising barometer is associated with clearing or fair weather. Therefore, a change in barometric pressure may influence amphibian activity patterns and, thus, detectability.
Cloud cover/moon brightness __ Amphibians tend to be more active on cloudy nights when humidity levels are higher than they are on clear nights. A bright moon tends to inhibit activity, since predators may be more effective at detecting prey on bright nights.
Prey availability __ Amphibians are likely to be more abundant in areas with a high diversity of prey items than in areas depauperate of prey. A few amphibians (Hellbenders) have specialized diet preferences. When prey are absent or scarce, specialist feeders will also be scarce despite the otherwise seemingly appropriateness of habitats.
Note that many of the variables discussed above change daily, seasonally, or annually (for example, during El Nino versus La Nina years).
6. Species and populations occur in a landscape. Some amphibian species are extremely localized geographically (Ambystoma opacum in the Great Smokies), whereas others are very widespread (Desmognathus quadramaculatus). Populations may be geographically isolated to an extreme degree (cave species or the crevice-dwelling Aneides aeneus), occur very patchily in a larger landscape, occur in a metapopulation structure (Bufo) with considerable (or little) interchange between or among metapopulations, or occur over hundreds of square kilometers of deciduous forest where it is difficult to define the limits of a population (many Plethodon). Individuals may be naturally rare or exceptionally abundant. Because a species is unusual or difficult to sample, is not a reason to bypass its study. Some of the most specialized amphibian species are those biologists know have declined or are imperiled in the southeastern states.
Although some populations may be huge (some terrestrial woodland salamanders, Plethodon, for example), others seem small, isolated, and vulnerable (crevice-dwelling, cave, or ravine species). Little is known about how and when these species disperse or about what mechanisms allow for the long-term persistence of small populations. Perhaps individuals move more than is recognized; even rare immigration is sufficient to ensure genetic exchange and prevent stochastic extinction. The demography and spatial biology of most amphibians is still poorly understood. Even if known for a few species, the diversity of life histories suggests that generalizations about persistence will not be easily forthcoming.
7. Populations may be stable or fluctuate widely. Much of what is known concerning amphibian populations has been derived from studies of frogs and salamanders breeding in temporary ponds. The number of breeding adults and their reproductive output (larvae, metamorphs) varies to extreme proportions from one year to the next, perhaps in response to environmental and ecological conditions (weather, hydroperiod, prey availability). Some species may live in an area for years, disappear for years, then reappear. For example, populations of European Rana seem to fluctuate cyclically on an 8-year cycle. On the other hand, terrestrial plethodontid populations appear rather stable from one year to the next. Detectability may be influenced by weather (drought) even if populations are stable. Not much is known concerning the stability or fluctuation of semi-aquatic and most aquatic species and populations, especially in the southern Appalachians.
Still, biologists have enough data to advance hypotheses about the persistence and stability of amphibian populations, while keeping in mind the caveat concerning exceptions. Species that live in stable environments tend to have stable populations from one year to the next, whereas species that live or breed in unstable or fluctuating environments tend to have populations that fluctuate to a much greater degree. Perhaps population stability can even be viewed on a gradient with environmental stability. If this is true, declines or disappearances of species living in stable environments might be more cause for concern than declines in species living or breeding in fluctuating environments, unless the fluctuating environments are highly isolated. In this case, isolation may prevent recolonization from source populations and, thus, lead to declines throughout the landscape.
8. Virtually nothing is known concerning emigration, immigration, and natural extinction. It seems quite reasonable that during the course of ecological and evolutionary history, extinction and recolonization naturally occur, especially in small populations, isolated populations, or populations structured in metapopulations (as sources and sinks). Yet herpetologists understand little of these processes in southern Appalachian amphibians. The Europeans seem to have more data in attempts to understand landscape-level population changes, but their environment has been influenced by people for so long that it is difficult to separate anthropogenic from “natural” causes of extinction. In any case, colonization and other forms of interpopulation movements may not move in a straight line overland. Animals might follow sinuous topography, watersheds, streams and rivers, or even subsurface passages.
Populations of amphibians certainly experience natural turnover (recruitment, mortality), but little is known about this process or how long it takes for any southern Appalachian species. Just because some individuals have the potential for considerable longevity does not mean that populations turn over slowly. Biologists need information on the generational times for various species.
10. The human-based constraints on sampling, inventorying, and monitoring amphibian populations on Federal lands must to be considered at the outset. These include:
Money __ (equipment, personnel, emergencies, meetings, data analysis, publication) __ The single biggest limitation Highly qualified researchers and field technicians are absolutely essential for conducting inventory and monitoring programs. affecting inventory and monitoring projects is the amount of money available to conduct the programs, which ultimately will determine the number of researchers hired, the type of techniques used, the number of species monitored, and the number of locations visited. Inventory and monitoring programs should be designed to make the best use of the available funding to ensure scientific rigor, rather than try to be “all things to all people.”
People __ (principal investigator, experienced field crews, biometricians, GIS, administrative support, field support) __ The identification of amphibians in the Great Smoky Mountains and elsewhere in the southern Appalachians is often difficult, and there is no substitute for experienced judgment. Resource managers should not assume that field assistants can be trained easily and quickly, or that volunteers can take the place of experienced biologists. Just as few persons would expect ecologists to conduct genetic analyses, current field research is a collaborative effort needing a variety of experts. When planning an inventory or monitoring program, agreements or arrangements need to be in place to ensure that field researchers have the needed biometric, landscape, and other types of support necessary for data analysis and interpretation.
Highly qualified researchers and field technicians are absolutely essential for conducting inventory and monitoring programs.
Time __ Inventory and monitoring programs take time to carry out. For amphibian monitoring programs, a minimum of 10 years of data collection is not unreasonable to begin to understand population status and to measure the extent of variation associated with sampling data. Sampling time is dependent upon the life history characteristics of the species in question. For example, a monitoring program might provide reliable trend-analysis data for a short-lived species if sampling was conducted every year for 10 years at locations throughout the species’ range within the Park; for a long-lived species, the duration of sampling might have to extend for 20 to 30 years before researchers could be confident in recognizing trends. In addition, trends resulting from human perturbation sometimes are difficult to separate from natural, often stochastic, population changes, except during catastrophic population collapse. It might be difficult to separate human-caused change from natural population variation without a long-term data set. Unfortunately, conflicts may arise when answers are needed by resource managers (for example, “We need to know the status of the Park’s amphibians for the annual report”). However, resource managers must recognize that short-term projects are ineffective and may give misleading results. Inventory and monitoring programs need time and patience.
Safety __ The minimum number of persons necessary to conduct amphibian field research involves two-person field crews. This is to ensure safety in case of injury, accident, or other medical emergency. Assume that emergencies will occur. Field crews should carry radios or cell phones and emergency first aid kits. Both heat stress and hypothermia are possible when sampling amphibians over long time periods in the southern Appalachians. Yellowjackets, venomous snakes, and bears are other park denizens requiring occasional attention.
Logistics __ Can researchers get to locations with the people and equipment in a reasonable amount of time and effort? Given logistical constraints, how many sites can be sampled and over what area? The failure to consider logistical constraints is one of the most common errors when setting up inventory and monitoring programs.
Regulations __ (permits, access, restrictions on research techniques, collecting) __ Regulations can impede research results and limit the types of data collected. Researchers need to clearly understand the limitations imposed upon them by regulations, whether local, state, or national. Likewise, administrators need to recognize that some regulations can impede scientific progress. In some cases, it may be impossible to obtain scientific data given impositions upon research access or techniques.
Collaborations __ (intra-agency, Federal, state, other researchers, land managers) __ Biologists working on amphibian inventory and monitoring programs should be knowledgeable about previous research and keep other researchers informed of their progress. When possible, ongoing research should be incorporated into the inventory or monitoring program to facilitate data sharing and partitioning of resources. Agency personnel need to facilitate research, especially for congressional or departmentally mandated programs.
Administrative Policy __ (hiring restrictions, equipment-ordering procedures, contracts) __ Administrative delays need to be anticipated and alternative plans or policy established to allow science crews to be in the field conducting research when the animals are likely present.
Of the 44 amphibian species historically reported from the Park, two species (Green Salamander, Northern Cricket Frog) probably no longer occur within the Park; one species (Northern Leopard Frog) may not occur, and four species (Mole Salamander, Common Mudpuppy [perhaps], Mud Salamander, Eastern Spadefoot) are so rare that designing a meaningful species-based monitoring program for them is impossible. However, two of these species (the Mole Salamander and the Eastern Spadefoot) are known only from the same locality (Gum Swamp), which is also a major amphibian breeding site within the Park. Monitoring the amphibians at this site may result in occasional observations of these two restricted and rare species. Likewise, a monitoring program developed for the Hellbender might result in additional captures of the Common Mudpuppy, thus making it feasible to sample both species simultaneously.
The following suggestions are made to facilitate monitoring the amphibians of Great Smoky Mountains National Park. It is unlikely that all species within the Park can be monitored every sampling year, although careful planning may help to increase the number of species monitored through time.
2. Concentrate on areas of special species richness, such as the Cane Creek drainage, Cades Cove (especially Gum Swamp (fig. 18), Gourley Pond (fig. 20), Methodist Church Pond (fig. 22), Stupkas Sinkhole Pond (fig. 30), Big Spring Cove (the Finley-Cane sinkhole ponds), and the high elevation spruce-fir forest (fig. 3).
3. Concentrate on problem areas. The only currently recognized problem area for amphibians in Great Smoky Mountains National Park is Gourley Pond in Cades Cove. Amphibians breeding at this site have contracted iridovirus infections, and large numbers of larvae have died. Because of the disease threat (Chinchar, 2002), this location should be monitored every year throughout the breeding and metamorphic season, about mid-March to late July, depending on water levels.
4. Periodically check areas of known occurrence for certain species. There are a few areas within the Park where certain salamanders and frogs are known to occur with regularity; these locations can be visited periodically to determine continued presence and, possibly, relative abundance. The following are examples: Long-tailed Salamanders in Gregorys Cave and at other cave entrances; Cave Salamanders in Stupkas Cave; Southern Zigzag Salamanders in Whiteoak Sink and in the uvala surrounding Bull Cave; Seepage Salamanders along the road bordering Hazel Creek; American Bullfrog tadpoles in Abrams Creek at the Abrams Creek Ranger Station; Eastern Narrow-mouthed Toads at Shields Pond (fig. 31). If sampled during appropriate seasonal and weather conditions, these species should be found at the locations mentioned; if not, it could be an indication of concern. Unfortunately, it may be difficult to interpret such present/not observed data without information on the same species outside the Park.
Pond-woodland pool breeding amphibians __ If researchers decide to monitor the pond-woodland pool breeding amphibians within Great Smoky Mountains National Park, no great difficulty is encountered. This is because there are so few known locations that visiting each site two or more times per year can be planned very easily. One visit should be planned in the early spring (late March to mid-April), with a second visit in early summer (late May to mid-June). Coupled with at least one or two call surveys in Cades Cove and periodic call surveys at other locations, biologists should be able to determine whether most species are present, obtain counts of egg masses, and categorize the abundance of calling males. Because of the existing disease threat, Gourley Pond should be visited at least once every 3 to 4 weeks from February/March to July/August.
Large stream and river-dwelling amphibians __ The Hellbender is the sole large stream- or river-dwelling species to be monitored in Great Smoky Mountains National Park. The largest population inhabits Little River from the Park entrance at Townsend for several kilometers within the Park, although the maximum distance upstream has not been determined. Smaller populations are found in lower Deep Creek and in the Oconaluftee River. The Little River population would, therefore, be the most important population to monitor annually. Periodic sampling should be conducted at the ...there are at least 25 watersheds within Great Smoky Mountains National Park, totaling > 3,400 km of streambed. other locations and in potential habitat elsewhere within the Park (see Nickerson and others, 2002).
Streams and creek-dwelling amphibians __ Depending on how precisely watersheds are defined, there are at least 25 watersheds within Great Smoky Mountains National Park, totaling > 3,400 km of streambed. Nearly each meter of every stream likely contains salamanders. Sampling the amphibian fauna of these streams depends largely on: (1) objective (certain species or areas of interest); (2) money and personnel (how many field crews are available and can be hired); and, (3) time available to conduct the surveys. Obviously, it is necessary to define these limitations prior to undertaking a stream monitoring program. When deciding where to conduct a stream/creek amphibian monitoring program, researchers should decide first what they hope to accomplish. For example, if using “percentage of area occupied” (PAO) analyses (see Data Handling), many more sites can be sampled than by using intensive sampling or mark-recapture techniques. The objective will fit the analysis; this will be discussed in more detail in Data Handling.
Given the caveats of people and time constraints, it will be necessary to narrow the choice of stream locations to be sampled. Some ideas are listed in the following section. However, a biologist needs to remember that, as a rule, the more sites that are sampled, the greater confidence are the results. The goal of sampling is to determine reliable estimates of variance associated with capture or sighting probabilities, or with estimates of population size; variance estimates will be more reliable with a greater number of sites surveyed than with a small number of sites.
Limit sampling to a subset of watersheds: randomly pick watersheds to sample from throughout the Park. Each watershed is assigned a number and a computer program can then be used to select a random subset of the watersheds for survey. Streams to be sampled within the watershed are randomly selected in the same manner. The location of the exact part of the stream to be sampled can be specified randomly (very impractical in difficult-to-access mountainous country) or stratified by stream order, elevation, vegetation type, access, or some other selective criterion. For example, biologists may limit their survey to second order streams between 900 and 1,400 m within 1 mile by trail from a road access. A GIS can be used to generate the extent of such habitat with these criteria, locate potential sampling sites, and randomly select those to be sampled.
Limit sampling to a subset of streams: randomly select streams for sampling from throughout the Park. Each stream is assigned a number, and a computer program can be used to select a random subset of the streams for sampling. The location of the exact part of the stream can be specified randomly or stratified by stream order, elevation, vegetation type, access, or some other selective criterion, as in the example above. A GIS can be used to generate the extent of such habitat with these criteria, locate potential sampling sites, and randomly select those for sampling.
Specific locations can be selected for sampling, such as all streams draining into Tennessee, all streams draining into Cades Cove or Cataloochee Valley, or, all streams located on the western side of the Park. The same general procedure for site selection and stratification is followed. However, the more limited the area sampled, the more restricted generalizations about status must become. Researchers could not sample all the streams draining Mt. LeConte and then extrapolate their results concerning stream-dwelling salamander status to the entire Park, the eastern side of the Park, or even to nearby Mt. Guyot.
Terrestrial amphibians __ Choosing terrestrial sites to sample for terrestrial salamanders is very similar to choosing stream sites, but without the streams. There is no well defined physiographic feature, such as a watershed or stream course, with which to initially stratify the area to be sampled. Biologists are left with the questions: which species or amphibian community should be sampled, what habitats should be targeted, what areas should sampling be concentrated, and what degree of access is possible? Because the Park covers a large area (2,071.2 km2), much of it in difficult terrain and without easy trail access, stratification of the terrestrial area to be sampled is absolutely necessary. How many sites can be sampled will depend on personnel, time available for sampling, and logistics. As with stream sampling, active sampling rather than passive sampling techniques will allow for more sites to be sampled, but the types of information that may be obtained will be correspondingly limited.
Unusual terrestrial amphibians __ There are only a few salamanders that may qualify in this category, such as the Southern Zigzag Salamander currently known from only two areas within the Park (Whiteoak Sink; entrance to Bull Cave), and the cave entrance-inhabiting salamanders of Gregorys Cave, the Calf Caves, and Stupkas Cave (especially Long-tailed and Cave Salamanders). As with sampling pondbreeding amphibians, these sites could be checked annually to verify the presence of these species. Detailed studies, using mark-recapture techniques, would be necessary to establish population size and trends through time.
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