34 MONITORING PROGRAMS The problem of declining amphibian popula

29 Pages·2003·3.62 MB·English

MONITORING PROGRAMS
Why Monitor Amphibians? its designation as an International Biosphere
Reserve. Although no other region and no other
The problem of declining amphibian National Park shares the wealth of amphibians
populations has been recognized worldwide, found in the Great Smokies, the entire southern
with credible reports of diminishment or disap- and midsection of the Appalachian chain is
pearance of amphibians from many regions and characterized by a high diversity of amphibians,
habitat types. No single cause for declines has and inventories and monitoring protocols devel-
been demonstrated, although acid precipitation, oped in the Great Smokies may be applicable to
environmental contaminants, introduction of National Park Service, U.S. Forest Service,
exotic predators, disease agents, parasites, and Nature Conservancy, or other properties in the
effects of ultraviolet radiation have been sug- Appalachians.
gested as factors in declining numbers. Indeed,
Several known stressors potentially affect
no one cause may be implicated, and several amphibians in the 2,071.2 km2 (521,000 acre)
factors may interact in such a manner as to
Park (reviewed by Dodd, 2004). Air pollution,
threaten populations (Carey and Bryant, 1995).
particularly long-distance pollution from cities
A major factor in the loss of amphibian popula-
in the nation's mid-region, is a nationally recog-
tions has been and continues to be the loss of
nized problem. Reduced visibility, damage to
habitat. The severity and apparent complexity
plants, and fish kills are documented to be asso-
of the problem led the National Park Service in
ciated with sulfurous and nitrogenous com-
1997 to list amphibian declines as among its
pounds and atmospheric ozone. Low pH is
highest priority research and information needs.
known to have affected survivorship in at least
one aquatic salamander species in the Park.
The problem of declining amphibian popula- Exotic pathogens and parasites have seriously
affected some forest communities, with
tions has been recognized worldwide....
unknown effects on ecosystems. Finally, the
pressure of ten million visitors per year--more
In terms of its significance to amphibians, than any other National Park--seems relatively
the Great Smoky Mountains National Park is benign, but could potentially have subtle effects
more important than almost anywhere else in on sensitive amphibian populations. The exist-
North America. Thirty-one species of sala- ence of these and other unknown stressors sug-
manders have been recorded in the Park, and gest that an inventory and a monitoring program
that number could conceivably increase as are needed to ensure the protection of amphib-
molecular genetic techniques are used to ian populations.
unravel the complex relations among Amphibian Research and Monitoring
populations. Of particular note are the sala- Initiative (ARMI) — In 2000, the President of
manders of the family Plethodontidae, a largely the United States and Congress directed Depart-
North American group that has a center of evo- ment of the Interior (DOI) agencies to develop a
lution and distribution in the southern Appala- plan to monitor the trends in amphibian popula-
chians (Dodd, 2004). Jordan=s Salamander tions on DOI lands and to conduct research into
(Plethodon jordani) is known to occur only in possible causes of declines. The DOI has stew-
the Park, and the salamander fauna is believed ardship responsibilities over vast land holdings
to represent several evolutionary series pro- in the United States, much of which is occupied
gressing from the more aquatic species to those by or is potential habitat for amphibians. The
which are almost totally terrestrial. Thirteen U.S. Geological Survey (USGS) was given lead
species of frogs and toads are historically responsibility for planning and organizing this
reported to inhabit the Park. The biological program, named the Amphibian Research and
importance of the Park has been recognized in Monitoring Initiative (ARMI), in cooperation
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with the National Park Service, U.S. Fish and among others. Once completed, the ATBI will
Wildlife Service, and Bureau of Land Manage- provide baseline data from which to measure
ment. Results of the monitoring program will be species change through time. ATBI=s objectives
available to cooperators, land managers, the are to: (1) complete a comprehensive “check-
scientific community, and the general public. list” of life forms in the Park; (2) gather data to
ARMI’s Internet site is: create range maps for each Park species;
(3)compile natural history information on each
http://edc2.usgs.gov/armi/
species, including its relative abundance, its
National Park Service (NPS) — Recent
response to various climatic conditions, photo-
legislation (National Parks Omnibus Manage-
graphs of each of its life stages, its role in the
ment Act of 1998) and policies of the National
greater ecosystem, its relationship with other
Park Service require that park managers know
species, and digital recordings of its calls or
the condition of natural resources and that they
sounds; and, (4) organize the information gath-
monitor long-term trends in those resources. To
ered and make it available to scientists, educa-
comply with legal and policy requirements, the
tors, land managers, students, and all other
NPS Inventory and Monitoring Program
interested parties via the Internet and other
focuses on attaining the following major
media. More information can be found at:
long-term goals: (1) establish natural resource
http://www.discoverlifeinamerica.org
inventory and monitoring as a standard practice
throughout the NPS that transcends traditional
programs and activities; (2) inventory the natu-
Things to Consider During Planning
ral resources and park ecosystems under NPS
stewardship to determine their nature and
There are at least 10 major items which
status; (3) monitor park ecosystems to better
need to be addressed before starting an inven-
understand their dynamic nature and condition
tory or monitoring program for amphibians,
and to provide reference points for comparisons
especially when under financial or personnel
with other, altered environments; (4)integrate
constraints. These are discussed briefly below
natural resource inventory and monitoring
and, in some cases, more extensively elsewhere
information into NPS planning, management,
within the guide.
and decision making; and, (5) share NPS
1. There are many amphibians in the southern
accomplishments and information with other
Appalachians and the southeast. A total of
natural resource organizations and form part-
31species of salamanders and 13 species of
nerships for attaining common goals and objec-
frogs have been recorded historically as
tives. Information on the National Park Service
occurring in the Park. Extending the area of
Inventory and Monitoring Program can be
interest to the greater southern Appalachians,
found at: http://www1.nature.nps.gov/im/moni-
the figure increases substantially, by 21 sala-
tor/index.htm #Legislation, and in publications
manders and 1 frog, because of the high lev-
by Silsbee and Peterson (1991) and Peterson
els of endemism of many salamander
and others (1995).
species. Extending the area of interest even
All Taxa Biodiversity Inventory
more, there are approximately 85 species of
(ATBI) — A research effort designed to com-
salamanders and 58 species of frogs within
pile a comprehensive inventory of all life forms
the southeastern United States (or 49.6 per-
in Great Smoky Mountains National Park,
cent of the species in the entire United
ATBI is sponsored by Discover Life in Amer-
States). This figure does not include different
ica, a private nongovernmental organization
subspecies, nor does it include the many
working in partnership with the NPS. The initia-
genetic variants that have been described.
tive has a goal of completing the inventory in as
few as 10 years and is, therefore, an intensive 2. The systematic status of many species of
undertaking. Before the project is completed, it southeastern amphibians is in a flux. It is
will employ the expertise of taxonomists, data likely that there are a number of new and
specialists, zoologists, botanists, and ecologists, unrecognized species of amphibians in the
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southern Appalachians, particularly among must consider such variation when planning
the salamanders. In addition, there is con- when and where amphibians will be
siderable debate among salamander taxono- monitored, and what biases may be associ-
mists over what constitutes a species in ated with interpreting sampling results.
terms of genetic uniqueness, phylogeny, For example, egg mass counts might tell
and reproductive compatibility. Particularly a researcher about the number of egg
in the genera Plethodon and Desmog- masses deposited and, therefore, the num-
nathus, many new “genetic” species have ber of females that reproduced that year.
been described in recent years, especially in Egg mass counts cannot be used to deter-
the southern mountains. Unfortunately, mine population size (often used as a
morphology and coloration may be only of measure of status), however, unless the
limited assistance in identification; many operational sex ratio (that is, the sex ratio of
individuals are impossible to distinguish adults that actually bred successfully) is
phenotypically in the field. There also are known for that year. This ratio is usually
areas where considerable introgression or assumed to be 1:1, but if it is not, estimates
hybridization occurs, especially in the of population size could be in error by
Great Smoky Mountains. This has led to the several orders of magnitude. Also, not all
recognition of species complexes (for individuals breed every year and, thus, pop-
example, the slimy salamanders of the ulation size at a breeding pond may not be
Plethodon glutinosus complex), or even of indicative of overall population size. Even
size-based guilds among the dusky sala- with such data available, population sizes
manders (Desmognathus). As systematists still cannot be estimated inasmuch as the
closely examine other genera (Eurycea, ratio of juveniles to adults is not known for
Pseudotriton), the situation will probably most species. In addition, counting egg
become more complicated. Systematic cer- masses says nothing about whether repro-
tainty may be no better in the frog world, duction was successful, since a variety of
especially in the genera Pseudacris and factors (disease, desiccation, predation) can
Rana, although the taxonomy of frogs
interact to prevent hatching and metamor-
within the southern Appalachians will prob-
phosis. Consequently, it might be possible
ably remain stable.
to count large numbers of egg masses, yet
have none of them actually result in juvenile
3. Species and life stages are sometimes diffi-
recruitment to the population. Status and
cult to distinguish. Even experienced herpe-
long-range impacts to the population could
tologists sometimes have difficulty
be easily misinterpreted.
identifying adult amphibians, and eggs and
larvae pose special identification problems. When inventorying and monitoring
Color and morphology vary considerably amphibians with complex life histories,
among individual amphibians. The ability multiple sampling techniques may be
to distinguish species based on egg mass required, and status interpretation must be
and tadpole morphology is exceptionally restricted to the sector of the population
difficult and is an ability that is rapidly actually sampled. This rather obvious
being lost, as such identification is rarely approach is often ignored, as authors often
taught, and the pool of naturalists who are make general statements as to status and
knowledgeable concerning identification is trends when only a portion of the animal=s
diminishing. There are very few current life cycle was sampled.
color guides to amphibian eggs and larvae,
5. In the field, detectability of amphibians is
even on a local basis.
likely influenced by the following variables,
4. Amphibians have complex life cycles. to a greater or lesser extent, depending on
Because of the extremely varied life histo- species. Some of these variables include:
ries of many amphibians (see Life His- Annual cycles of reproduction–The
tory), inventory and monitoring programs reproductive season may be prolonged, or
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extend for only a few days or weeks. Some pressure may influence amphibian activity
amphibians may be effectively sampled patterns and, thus, detectability.
only during the breeding season Cloud cover/moon brightness–
(Ambystoma sp., Hemidactylium, many Amphibians tend to be more active on
frogs), whereas breeding females of other cloudy nights when humidity levels are
species may disappear underground to higher than they are on clear nights. A
brood eggs (Plethodon) and thus be unde- bright moon tends to inhibit activity, since
tectable. predators may be more effective at detect-
Seasonal events (cold, drought, heat, ing prey on bright nights.
storms) that are usually unpredictable– Prey availability– Amphibians are likely
Cold, heat, and drought generally make to be more abundant in areas with a high
amphibians more difficult to find, whereas diversity of prey items than in areas depau-
tropical depressions and hurricanes, with perate of prey. A few amphibians (Hell-
their heavy rains, may actually bring benders) have specialized diet preferences.
amphibians to the surface in incredible When prey are absent or scarce, specialist
numbers. feeders will also be scarce despite the
Diurnal versus nocturnal activity– otherwise seemingly appropriateness of
Many amphibians are more conspicuous at habitats.
night, when they leave hiding places to for- Note that many of the variables dis-
age, than they are in the day. This is true for cussed above change daily, seasonally, or
both terrestrial and aquatic species. annually (for example, during El Niño
Air, water, and substrate temperature– versus La Niña years).
Amphibians often have rather narrow toler-
6. Species and populations occur in a land-
ances or preferences for particular air,
scape. Some amphibian species are
water, or substrate temperatures. Some spe-
extremely localized geographically
cies prefer rather cool temperatures (for
(Ambystoma opacum in the Great Smok-
example, salamanders living at high eleva-
ies), whereas others are very widespread
tions, and the winter-breeding frogs),
(Desmognathus quadramaculatus). Popula-
whereas others prefer the warm tempera-
tions may be geographically isolated to an
tures of summer. Since temperature
extreme degree (cave species or the
changes with elevation (Dodd, 2004), activ-
crevice-dwelling Aneides aeneus), occur
ity patterns of broadly distributed species
very patchily in a larger landscape, occur in
tend to change seasonally with an increase
a metapopulation structure (Bufo) with
in elevation.
considerable (or little) interchange between
Soil moisture and rainfall–Terrestrial or among metapopulations, or occur over
amphibians are active when soils are moist hundreds of square kilometers of deciduous
and during rainfall, much more so than forest where it is difficult to define the
when soils are dry. Breeding movements limits of a population (many Plethodon).
may be triggered by a combination of sea- Individuals may be naturally rare or excep-
sonal gonadal development, favorable tem- tionally abundant. Because a species is
perature, and rainfall. unusual or difficult to sample, is not a rea-
Relative humidity– High humidity son to bypass its study. Some of the most
favors amphibian activity; low humidity specialized amphibian species are those
depresses activity. biologists know have declined or are imper-
Barometric pressure– Barometric pres- iled in the southeastern states.
sure is indicative of changing weather con- Although some populations may be huge
ditions; a falling barometer is associated (some terrestrial woodland salamanders,
with weather fronts and rain, and a rising Plethodon, for example), others seem
barometer is associated with clearing or fair small, isolated, and vulnerable
weather. Therefore, a change in barometric (crevice-dwelling, cave, or ravine species).
37
Little is known about how and when these that live or breed in unstable or fluctuating
species disperse or about what mechanisms environments tend to have populations that
allow for the long-term persistence of small fluctuate to a much greater degree. Perhaps
populations. Perhaps individuals move population stability can even be viewed on
more than is recognized; even rare immi- a gradient with environmental stability. If
gration is sufficient to ensure genetic this is true, declines or disappearances of
exchange and prevent stochastic extinction. species living in stable environments might
The demography and “spatial biology” of be more cause for concern than declines in
most amphibians is still poorly understood. species living or breeding in fluctuating
Even if known for a few species, the diver- environments, unless the fluctuating envi-
sity of life histories suggests that generali- ronments are highly isolated. In this case,
zations about persistence will not be easily isolation may prevent recolonization from
forthcoming. source populations and, thus, lead to
7. Populations may be stable or fluctuate declines throughout the landscape.
widely. Much of what is known concerning 8. Virtually nothing is known concerning emi-
amphibian populations has been derived gration, immigration, and natural extinc-
from studies of frogs and salamanders tion. It seems quite reasonable that during
breeding in temporary ponds. The number the course of ecological and evolutionary
of breeding adults and their reproductive history, extinction and recolonization natu-
output (larvae, metamorphs) varies to rally occur, especially in small populations,
extreme proportions from one year to the isolated populations, or populations struc-
next, perhaps in response to environmental tured in metapopulations (as sources and
and ecological conditions (weather, hydro- sinks). Yet herpetologists understand little
period, prey availability). Some species of these processes in southern Appalachian
may live in an area for years, disappear for amphibians. The Europeans seem to have
more data in attempts to understand land-
...biologists have enough data to advance scape-level population changes, but their
environment has been influenced by people
hypotheses about the persistence and
for so long that it is difficult to separate
stability of amphibian populations...
anthropogenic from “natural” causes of
extinction. In any case, colonization and
years, then reappear. For example, popula- other forms of interpopulation movements
tions of European Rana seem to fluctuate may not move in a straight line overland.
cyclically on an 8-year cycle. On the other Animals might follow sinuous topography,
hand, terrestrial plethodontid populations watersheds, streams and rivers, or even sub-
appear rather stable from one year to the surface passages.
next. Detectability may be influenced by Populations of amphibians certainly
weather (drought) even if populations are experience natural turnover (recruitment,
stable. Not much is known concerning the mortality), but little is known about this
stability or fluctuation of semi-aquatic and process or how long it takes for any south-
most aquatic species and populations, espe- ern Appalachian species. Just because some
cially in the southern Appalachians. individuals have the potential
Still, biologists have enough for considerable longevity
data to advance hypotheses does not mean that populations
about the persistence and sta- turn over slowly. Biologists need
bility of amphibian popula- information on the generational
tions, while keeping in mind times for various species.
the caveat concerning excep- 9. Amphibian sampling tech-
tions. Species that live in stable envi- niques. There are as many ways to
ronments tend to have stable populations sample amphibians as there are
from one year to the next, whereas species amphibians (see Sampling Techniques).
38
Each technique has its own underlying
assumptions, biases, and limitations. Until H
ighly qualified researchers and field techni-
relatively recently, these biases were unrec-
cians are absolutely essential for conducting
ognized, not discussed, or simply ignored.
Currently, sampling protocols have been inventory and monitoring programs.
receiving a great deal of experimental
examination. It is unlikely that a single sam-
pling technique can be used to sample an affecting inventory and monitoring projects
entire community. Some of the techniques is the amount of money available to con-
listed below are not mutually exclusive. duct the programs, which ultimately will
determine the number of researchers hired,
Active sampling (easy to use) the type of techniques used, the number of
(cid:127) Time constrained-- species monitored, and the number of loca-
number of observers x time sampled; tions visited. Inventory and monitoring pro-
catch; visual encounter grams should be designed to make the best
(cid:127) Area constrained-- use of the available funding to ensure scien-
using plots, transects [visual encounter tific rigor, rather than try to be Aall things to
surveys], habitat defined
all people.@
(cid:127) Sweep samples--for larvae People (principal investigator, experi-
(cid:127) Call surveys-- enced field crews, biometricians, GIS,
breeding or territorial adult frogs administrative support, field support) –
(cid:127) Egg mass counts Highly qualified researchers and field tech-
nicians are absolutely essential for conduct-
Easy passive sampling ing inventory and monitoring programs.
(observer need not be present; no harm to animals)
The identification of amphibians in the
(cid:127) Coverboards--
Great Smoky Mountains and elsewhere in
various sizes, shapes, configurations,
the southern Appalachians is often difficult,
materials
and there is no substitute for experienced
(cid:127) PVC pipes--in ground or on trees
judgement. Resource managers should not
(cid:127) Larval litterbags
assume that field assistants can be trained
(cid:127) Automatic audio data loggers-- easily and quickly, or that volunteers can
for recording calling frogs
take the place of experienced biologists.
Just as few persons would expect ecologists
Intensive passive sampling
to conduct genetic analyses, current field
(labor, time, and financially expensive).
research is a collaborative effort needing a
(cid:127) Traps and fences must be checked regu-
variety of experts. When planning an inven-
larly, generally daily, for accurate
tory or monitoring program, agreements or
results and to prevent mortality.
arrangements need to be in place to ensure
(cid:127) Traps (aquatic or terrestrial): funnels,
that field researchers have the needed bio-
bottles, minnow, wire basket
metric, landscape, and other types of sup-
(cid:127) Drift fences, with pitfalls and/or funnel
port necessary for data analysis and
traps, sometimes in conjunction with
interpretation.
PVC pipes or coverboards
Time – Inventory and monitoring pro-
grams take time to carry out. For amphibian
10. The human-based constraints on sampling,
monitoring programs, a minimum of
inventorying, and monitoring amphibian
10years of data collection is not unreason-
populations on Federal lands must to be
able to begin to understand population sta-
considered at the outset. These include:
tus and to measure the extent of variation
Money (equipment, personnel, emer- associated with sampling data. Sampling
gencies, meetings, data analysis, publica- time is dependent upon the life history
tion) – The single biggest limitation characteristics of the species in question.
39
For example, a monitoring program might and limit the types of data collected.
provide reliable trend-analysis data for a Researchers need to clearly understand the
short-lived species if sampling was con- limitations imposed upon them by regula-
ducted every year for 10 years at locations tions, whether local, state, or national. Like-
throughout the species= range within the wise, administrators need to recognize that
Park; for a long-lived species, the duration some regulations can impede scientific
of sampling might have to extend for 20 to progress. In some cases, it may be impossi-
30 years before researchers could be confi- ble to obtain scientific data given imposi-
dent in recognizing trends. In addition, tions upon research access or techniques.
trends resulting from human perturbation Collaborations (intra-agency, Federal,
sometimes are difficult to separate from state, other researchers, land managers) –
natural, often stochastic, population Biologists working on amphibian inventory
changes, except during catastrophic popu- and monitoring programs should be knowl-
lation collapse. It might be difficult to sep- edgeable about previous research and keep
arate human-caused change from natural other researchers informed of their
population variation without a long-term progress. When possible, ongoing research
data set. Unfortunately, conflicts may arise should be incorporated into the inventory or
when answers are needed by resource man- monitoring program to facilitate data shar-
agers (for example, “We need to know the ing and partitioning of resources. Agency
status of the Park=s amphibians for the personnel need to facilitate research, espe-
annual report”). However, resource manag- cially for congressional or departmentally
ers must recognize that short-term projects mandated programs.
are ineffective and may give misleading
Administrative Policy (hiring restric-
results. Inventory and monitoring programs
tions, equipment-ordering procedures, con-
need time and patience.
tracts) – Administrative delays need to be
Safety – The minimum number of per-
anticipated and alternative plans or policy
sons necessary to conduct amphibian field
established to allow science crews to be in
research involves two-person field crews.
the field conducting research when the
This is to ensure safety in case of injury,
animals are likely present.
accident, or other medical emergency.
Assume that emergencies will occur. Field
crews should carry radios or cell phones Species and Locations to Monitor
and emergency first aid kits. Both heat
stress and hypothermia are possible when Of the 44 amphibian species historically
sampling amphibians over long time peri- reported from the Park, two species (Green
ods in the southern Appalachians. Yellow- Salamander, Northern Cricket Frog) probably
jackets, venomous snakes, and bears are no longer occur within the Park; one species
other park denizens requiring occasional (Northern Leopard Frog) may not occur, and
attention. four species (Mole Salamander, Common Mud-
Logistics – Can researchers get to loca- puppy [perhaps], Mud Salamander, Eastern
tions with the people and equipment in a Spadefoot) are so rare that designing a meaning-
reasonable amount of time and effort? ful species-based monitoring program for them
Given logistical constraints, how many is impossible. However, two of these species
sites can be sampled and over what area? (the Mole Salamander and the Eastern Spade-
The failure to consider logistical con- foot) are known only from the same locality
straints is one of the most common errors (Gum Swamp), which is also a major amphibian
when setting up inventory and monitoring breeding site within the Park. Monitoring the
programs. amphibians at this site may result in occasional
Regulations (permits, access, restric- observations of these two restricted and rare
tions on research techniques, collecting) – species. Likewise, a monitoring program devel-
Regulations can impede research results oped for the Hellbender might result in
40
additional captures of the Common Mudpuppy, (cid:127) Stream-associated species (especially
thus making it feasible to sample both species with conspicuous larvae): Black-bellied
simultaneously. Salamander, Blue Ridge Two-lined Sala-
The following suggestions are made to mander, Black-chinned Red Salamander,
Spring Salamander.
facilitate monitoring the amphibians of Great
Smoky Mountains National Park. It is unlikely (cid:127) (Primarily) Terrestrial salamanders:
that all species within the Park can be moni- Jordan=s Salamander, Southern Gray-
tored every sampling year, although careful cheeked Salamander, Northern Slimy
Salamander, Southern Red-backed Sala-
planning may help to increase the number of
mander, Southern Zigzag Salamander,
species monitored through time.
Imitator Salamander, Pigmy Salamander.
1. Concentrate on certain species, especially
those that may be in biological decline else- 2. Concentrate on areas of special species
where within their range or are limited in richness, such as the Cane Creek drainage,
distribution within the Park. Some of these Cades Cove (especially Gum Swamp
species are: (fig.18), Gourley Pond (fig. 20), Metho-
(cid:127) Large stream and river-dwelling species: dist Church Pond (fig. 22), Stupkas Sink-
hole Pond (fig.30), Big Spring Cove (the
Hellbender.
Finley-Cane sinkhole ponds), and the high-
(cid:127) Pond-breeding species: Spotted Sala-
elevation spruce-fir forest (fig. 3).
mander, Marbled Salamander, Eastern
Red-spotted Newt, Four-toed Salamander, 3. Concentrate on problem areas. The only
Northern Green Frog, Wood Frog. currently recognized problem area for
Figure 30. Biologist sampling with sweep net in Stupkas Sinkhole Pond in Cades Cove.
41
amphibians in Great Smoky Mountains surrounding Bull Cave; Seepage Sala-
National Park is Gourley Pond in Cades manders along the road bordering Hazel
Cove. Amphibians breeding at this site have Creek; American Bullfrog tadpoles in
contracted iridovirus infections, and large Abrams Creek at the Abrams Creek Ranger
numbers of larvae have died. Because of the Station; Eastern Narrow-mouthed Toads at
disease threat (Chinchar, 2002), this loca- Shields Pond (fig. 31). If sampled during
tion should be monitored every year appropriate seasonal and weather condi-
throughout the breeding and metamorphic tions, these species should be found at the
season, about mid-March to late July, locations mentioned; if not, it could be an
depending on water levels. indication of concern. Unfortunately, it may
be difficult to interpret such present/not
4. Periodically check areas of known occur-
observed data without information on the
rence for certain species. There are a few
same species outside the Park.
areas within the Park where certain sala-
manders and frogs are known to occur with 5. If particularly cost-effective monitoring
regularity; these locations can be visited techniques are available for certain spe-
periodically to determine continued pres- cies, use them. For example, all breeding
ence and, possibly, relative abundance. male frogs in the Park emit loud calls to
Thefollowing are examples: Long-tailed attract females. Species that are extremely
Salamanders in Gregorys Cave and at other difficult to find at most times of the year,
cave entrances; Cave Salamanders in such as the Upland Chorus Frog (Pseudac-
Stupkas Cave; Southern Zigzag Sala- ris feriarum), can be readily detected
manders in Whiteoak Sink and in the uvala calling on a wet spring night throughout
Figure 31. Biologist looking for tadpoles at Shields Pond in Cades Cove.
42
Cades Cove. The presence and relative
abundance of other breeding frogs that are
...there are at least 25 watersheds within
spatially limited within the Park (such as
Great Smoky Mountains National Park, totaling
the Eastern Narrow-mouthed Toad, Gastro-
phryne carolinensis, at Shields Pond in > 3,400 km of streambed.
Cades Cove; fig. 31) can be detected by
using automated call-monitoring devices
without the continued presence of observ-
ers. As another example, the presence of other locations and in potential habitat else-
certain salamander larvae can be detected where within the Park (see Nickerson and oth-
passively using inconspicuously placed leaf ers, 2002).
litterbags. Larval Spring and Black-chinned Streams and creek-dwelling
Red Salamanders are detected in higher
amphibians– Depending on how precisely
numbers using these bags compared to
watersheds are defined, there are at least
other search methods.
25watersheds within Great Smoky Mountains
National Park, totaling >3,400km of
Choosing Sampling Sites
streambed. Nearly each meter of every stream
likely contains salamanders. Sampling the
Pond-woodland pool breeding
amphibians – If researchers decide to amphibian fauna of these streams depends
monitorthe pond-woodland pool breeding largely on: (1) objective (certain species or
amphibians within Great Smoky Mountains areas of interest); (2)money and personnel
National Park, no great difficulty is encoun- (how many field crews are available and can be
tered. This is because there are so few known hired); and, (3) time available to conduct the
locations that visiting each site two or more surveys. Obviously, it is necessary to define
times per year can be planned very easily. One
these limitations prior to undertaking a stream
visit should be planned in the early spring (late
monitoring program. When deciding where to
March to mid-April), with a second visit in
conduct a stream/creek amphibian monitoring
early summer (late May tomid-June). Coupled
program, researchers should decide first what
with at least one or twocall surveys in Cades
they hope to accomplish. For example, if using
Cove and periodic call surveys at other loca-
“percentage of area occupied” (PAO) analyses
tions, biologists should be able to determine
(see Data Handling), many more sites can be
whether most species are present, obtain counts
of egg masses, and categorize the abundance of sampled than by using intensive sampling or
calling males. Because of the existing disease mark-recapture techniques. The objective will
threat, Gourley Pond should be visited at least fit the analysis; this will be discussed in more
once every 3to4weeks from February/March detail in Data Handling.
to July/August. Given the caveats of people and time
Large stream and river-dwelling constraints, it will be necessary to narrow the
amphibians – The Hellbender is the sole large
choice of stream locations to be sampled. Some
stream- or river-dwelling species to be moni-
ideas are listed in the following section. How-
tored in Great Smoky Mountains National Park.
ever, a biologist needs to remember that, as a
The largest population inhabits Little River
rule, the more sites that are sampled, the greater
from the Park entrance at Townsend for several
confidence are the results. The goal of sampling
kilometers within the Park, although the maxi-
is to determine reliable estimates of variance
mum distance upstream has not been deter-
associated with capture or sighting probabili-
mined. Smaller populations are found in lower
Deep Creek and in the Oconaluftee River. The ties, or with estimates of population size; vari-
Little River population would, therefore, be the ance estimates will be more reliable with a
most important population to monitor annually. greater number of sites surveyed than with a
Periodic sampling should be conducted at the small number of sites.
43