Site by Bennett Web & Design Co.
2006 SOUTHEASTERN NATURALIST 5(1):1–8
Breeding Biology of a Florida Population of Ambystoma
cingulatum (Flatwoods Salamander) During a Drought
JOHN G. PALIS1,*, MATTHEW J. ARESCO2, AND SANDRA KILPATRICK3
Abstract - Successful long-term monitoring programs of amphibians require the ability
to distinguish natural population fluctuations from human-caused declines. Because
recruitment in populations of pond-breeding amphibians depends on optimal environmental
conditions of rainfall and hydroperiod, extended periods of drought may have
adverse effects. We examined the breeding biology of Ambystoma cingulatum at a
breeding site in northwestern Florida for four consecutive seasons (1999–2002) during
and immediately following a drought. The number of immigrating adults declined
steadily during this period, and larvae and metamorphs were not observed. Potential
explanations for the observed decline in number of adults include disruption of
migration as a result of insufficient rainfall during the breeding season and cumulative
rainfall deficit, lack of juvenile recruitment, and adult attrition. We believe reduction in
number of adults is best explained as attrition of adults without recruitment of juveniles.
Reports of worldwide amphibian declines emphasize the importance of
distinguishing natural fluctuations in amphibian populations from those
resulting from human activities (Blaustein 1994, Pechmann and Wilbur
1994, Pechmann et al. 1991). Among natural causes of population fluctuations
in amphibians, periodic drought is a recurring stress (Stahle et al.
1988). Drought affects pond-breeding amphibians by interfering with breeding
migration of adults (Semlitsch 1985, Semlitsch et al. 1996) and by
destroying eggs or larvae due to shortened hydroperiod (Newman 1987;
Petranka and Petranka 1981; Seale 1982; Semlitsch 1983, 1987; Shoop
1974). At its extreme, drought has been implicated in the decline or extirpation
of amphibian populations (Corn and Fogleman 1984; Dodd 1993, 1995;
Kagarise Sherman and Morton 1993; Semlitsch et al. 1996).
Ambystoma cingulatum (Cope) (Flatwoods Salamander), a Federallythreatened
species (US Fish and Wildlife Service 1999), inhabits mesic Pinus
palustris P. Mill. (longleaf pine)-Aristida stricta Michx. (wiregrass) savannas
and flatwoods from southern South Carolina, through the lower coastal plain
to southern Alabama (Conant and Collins 1991). Adults migrate to isolated
wetlands to breed from October through December (Anderson and
Williamson 1976, Means et al. 1996, Palis 1997a). The larval period lasts 3 to
4 months, typically from December or January through March (Palis 1995).
Although adults spend approximately 90% of the year in nonbreeding habitat
(Palis 1997a), little is known about this phase of the life cycle.
1PO Box 387, Jonesboro, IL 62952. 2Department of Biological Science, Florida State
University, Tallahassee, FL 32306. 3National Forests in Mississippi, 100 West Capital
Street, Suite 1141, Jackson, MS 39206. *Corresponding author - firstname.lastname@example.org.
2 Southeastern Naturalist Vol. 5, No. 1
We studied the effect of drought on the breeding biology of A. cingulatum
at a breeding site in Florida. Specifically, we examined the annual size and
structure of the adult breeding population and determined annual reproductive
success (production of larvae and metamorphs).
We examined the movements of A. cingulatum at Pond 73-04 in the
Apalachicola National Forest, Liberty County, FL (T4S, R8W, S20). Pond 73-
04 is a shallow (< 30 cm), hydrologically-isolated, seasonally-inundated, 0.2-
ha swamp with a canopy of Taxodium ascendens Brongn. (pond cypress),
Nyssa biflora Walt. (blackgum), and Ilex myrtifolia Walt. (myrtle-leaved
holly). The groundcover of the pond is dominated by graminoids including
Rhynchospora inundata (Oakes) Fern. (beakrush), Panicum rigidulum Bosc ex
Nees (panic grass), Aristida palustris (Chapman) Vasey (three-awn grass),
Eriocaulon compressum Lam. (hatpins), and the sedges Carex glaucescens Ell.
and Carex verrucosa Muhl. The pond is bordered to the north, east, and
southeast by a wiregrass-dominated savanna that grades into longleaf pinewiregrass
savanna. In 1960, the US Forest Service (USFS) hand-planted Pinus
elliottii Engelm. (slash pine) adjacent to the west and southwest side of the
pond. Historically, the slash pine plantation was a graminaceous savanna with
scattered longleaf pine. The savanna and plantation were prescribe-burned in
the dormant season 12 times since 1967 (D. Farnsworth, USFS, Bristol, FL,
pers. comm.). Four other isolated swamps occur within 500 m of pond 73-04,
but it is not known if they are used for breeding by A. cingulatum.
The Florida panhandle experienced drought conditions due to three consecutive
years of below average rainfall. Average annual rainfall for
Wewahitchka, FL (12.5 km west of our study site) is 160.6 cm. In 1999,
2000, and 2001, rainfall at Wewahitchka was 18.7, 56.7, and 18.7 cm below
average, respectively. Rainfall data for Wewahitchka in 2002 are incomplete;
however, rainfall at Apalachicola (41.5 km south) was 9.7 cm above
average. October–December rainfall totals for Wewahitchka were 3.9, 6.2,
and 15.5 cm below normal in 1999, 2000, and 2001, respectively. In 2002,
however, October–December rainfall at Wewahitchka was 38.4 cm above
average (Northwest Florida Water Management District 2005).
Drift fence monitoring
Ambystoma cingulatum movements into and out of pond 73-04 were
monitored from 1999–2002 with funnel traps set along a pond-encircling
drift fence. Prior to construction of the drift fence, we cleared a 0.5-m wide
path through the graminaceous vegetation surrounding the pond. We constructed
the 46-cm high drift fence from 61-cm wide aluminum flashing. The
bottom 15 cm of the fence was buried in the soil to prevent animals from
burrowing beneath. The fence was 250 m long and averaged 5 m from the
pond edge (as defined by obligate wetland vegetation). Animals were
2006 J.G. Palis, M.J. Aresco, and S. Kilpatrick 3
captured in 84-cm-long x 20-cm-wide aluminum window screen funnel traps
having dual interior funnel openings 5 cm in diameter (Enge 1997). We
placed 23 pairs of traps at approximately 11-m intervals against both sides of
the drift fence (46 traps total). Each trap contained a moistened 5- x 10-cm
sponge and was shaded by a 40.5-cm square of tempered masonite.
Because A. cingulatum breeding migrations coincide with rainfall (Palis
1997a), we opened traps prior to predicted precipitation and closed them when
conditions conducive to amphibian movement ended (i.e., number of amphibian
captures sharply declined). In 2000–2001, we opened traps a minimum of
20 days per month, during dry as well as wet weather, to increase our
opportunity to capture more species. We checked traps daily when they were
open. Before initiation of the study and between trapping periods (i.e., May–
September), we opened eight, 1-m-long gaps in the drift fence to permit
movement of animals into and out of the pond basin. Prior to trapping in 2000,
2001, and 2002, we re-cleared vegetation up to 0.25 m from both sides of the
fence. We trapped from 4 October 1999 to 4 May 2000, 4 October 2000 to 15
February 2001, 5 October 2001 to 12 April 2002, and 15 October to 20
December 2002. Trapping into May 2000 and April 2002 allowed us to sample
for emigrating A. cingulatum metamorphs. We recorded water depth at a
gauge set in the deepest portion of the basin to track hydroperiod, and we
recorded rainfall in a rain gauge adjacent to the pond.
Each A. cingulatum was measured to the nearest mm with a plastic rule
(snout-vent length [SVL]: tip of snout to posterior edge of vent), weighed to
the nearest 0.01 g on a portable electronic balance, and marked with a unique
combination of toe clips before being released on the opposite side of the
fence. When available, we used natural deformities in place of toe-clipping.
Scissors were dipped in isopropyl alcohol between each use. Because toeclips
sometimes regenerate (Semlitsch 1987), we also marked animals with a
bio-compatible fluorescent elastomer (Northwest Marine Technology, Inc.,
Shaw Island, WA) in 2000–2001 and 2001–2002. We injected the elastomer
just beneath the skin of the legs or the abdomen at the insertion of the legs of
A. cingulatum following anaesthetization with tricane methanosulfunate
(MS-222). We also determined the sex of each animal (presence of a swollen
cloaca indicated a male).
In addition to sampling for A. cingulatum metamorphs at the drift fence,
we looked for evidence of reproductive success by sampling for late-stage
larvae. We searched for larvae by dipnetting through inundated herbaceous
vegetation with a 4-mm mesh dipnet in March 2002 and in February and
March 2003. Dipnetting all appropriate microhabitats for A. cingulatum
larvae in February or March is an established means to determine presence
or absence of this species (Bishop et al., 2006, Palis 1997b). In addition to
our efforts, personnel of the Florida Fish and Wildlife Conservation Commission
(FWC) dipnetted the site using the same technique during statewide
A. cingulatum surveys (March 2001–2003; D. Cook and M. Wilson, FWC,
Tallahassee, FL, pers. comm.).
4 Southeastern Naturalist Vol. 5, No. 1
We computed the number of A. cingulatum captured (excluding recaptures)
per rainy night during the October–December migration period for
each year. We also compared October–December rainfall totals at our study
site among years using a Chi-square goodness of fit test.
We omitted the single female captured in both 1999–2000 and 2000–
2001 from the following analyses. We used a Chi-square test to determine if
the ratio of males to females differed from parity in 1999–2000, the only
season during which sample sizes were sufficiently large to permit statistical
testing. For all four years combined, we used a t-test to compare SVL of
males and females and ANCOVA (controlling for SVL) to compare initial
capture mass of males with gravid females and non-gravid/spent females.
For non-gravid/spent females we used the initial capture weight of nongravid
females and recapture weight of spent females; multiple recaptured
spent females were not included in this analysis.
We captured 30 A. cingulatum during or following rainfall at the drift
fence from 1999–2002; 21 in 1999–2000, six in 2000–2001 (including a
recapture from 1999–2000), three in 2001–2002, and one in fall 2002. The
capture rate of migrants during October–December declined from 1.9 salamanders
per rainy night in 1999, to 0.4 in 2000, 0.15 in 2001, and 0.1 in 2002
(Fig. 1). We did not capture any metamorphs.
The sex ratio (9M:12F) of immigrating adults did not differ from parity
in 1999–2000 (χ2 = 0.43, df = 1, P = 0.5). We captured too few animals in
2000–2001 (2M:4F), 2001–2002 (1M:2F), and fall 2002 (1M) to statistically
examine sex ratio. Females were slightly longer (SVL; 59.4 ± 6.9 mm; mean
± 1 SD) than males (54.3 ± 6.5 mm; t = -2.02, df = 27, P = 0.05). The mass of
males (4.4 ± 1.1 g) and nongravid/spent females (3.9 ± 1.3 g) did not differ
(F1,18 = 1.93, P = 0.182); however, the mass of gravid females (8.0 ± 2.5 g)
was greater than that of males (F1,20 = 9.56, P = 0.006).
Figure 1. Number of Ambystoma
cingulatum and amount of rainfall
from October–December 1999,
2000, 2001, and 2002 at Pond 73-
04, Apalachicola National Forest,
Liberty County, FL.
2006 J.G. Palis, M.J. Aresco, and S. Kilpatrick 5
The SVL of A. cingulatum increased during the first three years of this
study. Salamanders (males and females combined) captured in 1999–2000
averaged 55 mm SVL (range = 42–64), whereas those captured in 2000–
2001 averaged 61 mm (range = 56–68), and those captured in 2001–2002
averaged 68 mm (range = 64–71). The single male captured in fall 2002 was
44 mm SVL. This individual’s size and emaciated appearance suggested it
was a yearling (Palis 1997a).
We captured only one individual, a female, in successive years. When
first captured (1999), this individual was 53 mm SVL, weighed 2.5 g, and
was not gravid. The following year (2000), she was 61 mm SVL, weighed
6.0 g, and was gravid.
Total rainfall from October through December varied significantly
among years (χ2 = 34.28, df = 3, P < 0.001). More rain fell in fall 1999
(222.9 mm) and fall 2002 (229.0 mm) than in fall 2000 (138.2 mm) or fall
2001 (156.0 mm). The pond filled and dried four times between December
1999 and May 2000, was dry from December 2000 to late February 2001,
held water from early January to mid-April 2002, and held water from mid-
October 2002 through at least March 2003. Neither we nor FWC personnel
captured larvae during dipnet surveys.
During the 4-year study period, the number of A. cingulatum entering
Pond 73-04 to breed dropped from 21 to one. The decline in the number of A.
cingulatum migrating to pond 73-04 in 2000 and 2001 may have been due to
insufficient rainfall. October–December rainfall totals at pond 73-04 in 2000
and 2001 were 84.7 mm and 66.9 mm less, respectively, than the same
period in 1999. Furthermore, October–December rainfall totals at
Wewahitchka were 62.2 mm and 155.2 mm below average in 2000 and 2001,
respectively. Like other southeastern coastal plain amphibians (Semlitsch et
al. 1996), A. cingulatum may not migrate to breeding sites during breeding
seasons with abnormally low rainfall.
We expected an increase in the number of immigrants in fall 2002,
when October–December rainfall at pond 73-04 was 6.1mm, 90.8 mm, and
73.0 mm higher than 1999, 2000, and 2001, respectively. Contrary to our
expectation, we captured only one immigrant in fall 2002. This apparent
lack of stimulation to initiate migration of large numbers of A. cingulatum
to Pond 73-04 in fall 2002 suggests that movement is not simply a matter
of sufficient rainfall during the breeding season. Other factors, including
cumulative rainfall during the year or over a period of years, adult pond
fidelity, juvenile recruitment, and adult attrition could have influenced the
size of the fall 2002 breeding population.
Due to several years of reduced rainfall (cumulative rainfall deficit of
94.0 cm from 1999–2001 at Wewahitchka), the moisture threshold for movement
of most A. cingulatum may not have been met in fall 2002 despite
receiving slightly more rain in fall 2002 than fall 1999, the year when 21
immigrants were captured. Other than the proximate cues of rainfall and
6 Southeastern Naturalist Vol. 5, No. 1
temperature (Palis 1997a), nothing is known regarding the environmental
cues used by A. cingulatum to initiate migration to breeding sites. Further,
several years of below-normal rainfall could have reduced feeding opportunities
resulting in the lack of acquisition of energy reserves required for
reproductive activity (Semlitsch et al. 1996).
The reduction in the number of A. cingulatum migrating to Pond 73-04
to breed may have also been due to abandonment of this site for other
nearby wetlands. Although we cannot discount this possibility based on
our data, we believe this scenario is unlikely for the following reasons.
First, adults of other ambystomatids are typically philopatric, returning to
the same site to breed in multiple years (Blackwell et al. 2003, Raymond
and Hardy 1990, Semlitsch et al. 1993, Vasconcelos and Calhoun 2004),
even those that have been destroyed (Pechmann et al. 2001, Shoop 1968).
Breeding-site fidelity has also been observed in A. cingulatum (Palis
1997a). However, the number of identifiable recaptures in that study was
low due to the high frequency of natural toe deformities which reduced
effectiveness of toe-clipping as a means of identifying individuals between
years (J.G. Palis, unpubl. data). Second, we have no evidence that the
wetlands within 500 m of pond 73-04 had significantly different hydrologic
regimes from those observed at Pond 73-04. In fact, hydrologic
regimes similar to that of Pond 73-04 were observed in known/potential A.
cingulatum breeding sites across much of the Florida panhandle during the
drought (J.G. Palis, unpubl. data; D. Bishop, Virginia Polytechnic Institute
and State University, Blacksburg, VA, pers. comm.; K. Enge, FWC,
Quincy, FL, pers. comm.; D. Printiss, The Nature Conservancy, Bristol,
FL, pers. comm.). Therefore, we see no compelling reason for adult A.
cingulatum to abandon Pond 73-04 for nearby wetlands.
The reduction in the breeding population may also have resulted from the
lack of juvenile recruitment into the population during the study period. We
did not detect A. cingulatum larvae or metamorphs at Pond 73-04 during the
study. Lack of juvenile recruitment in amphibians is often followed by a
reduction in the size of the adult breeding population (Berven 1990, Semlitsch
et al. 1996, Sjogren 1991). Coincident with the lack of recruitment into
amphibian breeding populations is an increase in body size of adults (Dodd
1993, Richter and Seigel 2002). We observed such an increase in adult body
size, suggesting an aging population (Richter and Seigel 2002). Although the
lifespan of A. cingulatum in the wild is unknown, captives have lived no more
than four years (Palis and Means 2005). If the lifespan of A. cingulatum in the
wild is comparable to that in captivity, droughts lasting ≥ 4 years could
potentially have negative consequences for A. cingulatum populations.
After at least three consecutive years of apparent reproductive failure,
the number of A. cingulatum migrating to Pond 73-04 declined precipitously.
Whether the decline continued after the termination of this study or
was of sufficient magnitude to cause the extirpation of the population that
breeds at Pond 73-04 is unknown. Studies of longer duration are needed to
address these questions, as well as to separate such environmentally induced
population declines from human-caused population declines. Nonetheless,
2006 J.G. Palis, M.J. Aresco, and S. Kilpatrick 7
our observations suggest that protection of clusters of A. cingulatum breeding
sites, especially those with different hydrologic regimes, is necessary to
guard against population declines at any one breeding site resulting from
stochastic events such as drought.
We gratefully acknowledge funding provided by the US Fish and Wildlife Service
(USFWS; L. LaClaire) and The National Council for Air and Stream Improvement (T.B.
Wigley). We thank the following individuals who contributed to the success of this
study: G. Anglin, W. Baker, A. Colaninno, D. Cook, D. Farnsworth, F. Fulford, M.
Gunzburger, S. Johnson, L. Kirn, L. Morgan, T. Ostertag, D. Printiss, C. Rankin, J.
Ruhl, C. Sterrett, K. Studenroth, B. Wigley, M. Wilson, and the Liberty Wilderness
Crossroads Camp Crew. We also thank S. Richter and two anonymous reviewers for
comments that improved this manuscript. Our study was authorized by a US Forest
Service Special Use Permit, USFWS permit TE008077-1, and FWC permit WV99431.
J.G. Palis dedicates this manuscript to the memory of his late father, Leonard.
Anderson, J.D., and G.K. Williamson. 1976. Terrestrial mode of reproduction in
Ambystoma cingulatum. Herpetologica 32:214–221.
Berven, K.A. 1990. Factors affecting population fluctuations in larval and adult
stages of the Wood Frog (Rana sylvatica). Ecology 71:1599–1608.
Bishop, D.C., J.G. Palis, K.M. Enge, D.J. Printiss, and D.J. Stevenson. 2006.Capture
rate, body size, and survey recommendations for larval Flatwoods Salamanders
(Ambystoma cingulatum). Southeastern Naturalist 5(1):9–16.
Blackwell, E.A., R.A. Angus, G.R. Cline, and K.R. Marion. 2003. Natural growth
rates of Ambystoma maculatum in Alabama. Journal of Herpetology 37:608–612.
Blaustein, A.R. 1994. Chicken little or Nero’s fiddle? A perspective on declining
amphibian populations. Herpetologica 50:85–97.
Conant, R., and J.T. Collins. 1991. A Field Guide to the Reptiles and Amphibians of
Eastern and Central North America. Houghton Mifflin, Boston, MA. 450 pp.
Corn, P.S., and J.C. Fogleman. 1984. Extinction of montane populations of the Northern
Leopard Frog (Rana pipiens) in Colorado. Journal of Herpetology 18:147–152.
Dodd, Jr., C.K. 1993. Cost of living in an unpredictable environment: The ecology of
Striped Newts, Notophthalmus perstriatus, during a prolonged drought. Copeia
Dodd, Jr., C.K. 1995. The ecology of a sandhills population of the Eastern Narrowmouthed
Toad, Gastrophryne carolinensis, during a drought. Bulletin of the
Florida Museum of Natural History 38:11–41.
Enge, K.M. 1997. A standardized protocol for drift-fence surveys. Florida Game and
Fresh Water Fish Commission Technical Report 14. Tallahassee, FL.
Kagarise Sherman, C., and M.L. Morton. 1993. Population declines of Yosemite Toads
in the eastern Sierra Nevada of California. Journal of Herpetology 27:186–198.
Means, D.B., J.G. Palis, and M. Baggett. 1996. Effects of slash pine silviculture on a
Florida population of Flatwoods Salamander. Conservation Biology 10:426–437.
Newman, R.A. 1987. Effects of density and predation on Scaphiopus couchi tadpoles
in desert ponds. Oecologia 71:301–307.
Northwest Florida Water Management District. 2005. Monthly rainfall totals. Available
at: www.nwfwmd.state.fl.us. Accessed 14 January 2005.
Palis, J.G. 1995. Larval growth, development, and metamorphosis of Ambystoma
cingulatum on the Gulf Coastal Plain of Florida. Florida Scientist 58:352–358.
8 Southeastern Naturalist Vol. 5, No. 1
Palis, J.G. 1997a. Breeding migration of Ambystoma cingulatum in Florida. Journal
of Herpetology 31:71–78.
Palis, J.G. 1997b. Distribution, habitat, and status of the Flatwoods Salamander
(Ambystoma cingulatum) in Florida, USA. Herpetological Natural History 5:53–65.
Palis, J.G., and D.B. Means. 2005. Ambystoma cingulatum. Pp. 608–609, In M.J.
Lannoo (Ed.). Amphibian Declines: The Status of United States Species. The
University of California Press, Berkeley, CA. 1094 pp.
Pechmann, J.H.K., and H.M. Wilbur. 1994. Putting declining amphibian populations
in perspective: Natural fluctuations and human impacts. Herpetologica 50:65–84.
Pechmann, J.H.K., D.E. Scott, R.D. Semlitsch, J.P. Caldwell, L.J. Vitt, and J.W.
Gibbons. 1991. Declining amphibian populations: The problem of separating
human impacts from natural fluctuations. Science 253:892–895.
Pechmann, J.H.K., R.A. Estes, D.E. Scott, and J.W. Gibbons. 2001. Amphibian
colonization and use of ponds created for trial mitigation of wetland loss. Wetlands
Petranka J.W., and J.G. Petranka 1981. On the evolution of nest-site selection in the
Marbled Salamander, Ambystoma opacum. Copeia 1981:387–391.
Raymond, L.R., and L.M. Hardy. 1990. Demography of a population of Ambystoma
talpoideum (Caudata: Ambystomatidae) in northwestern Louisiana.
Richter, S.C., and R.A. Seigel. 2002. Annual variation in the population ecology of
the endangered frog, Rana sevosa Goin and Netting. Copeia 2002:962–972.
Seale, D.B. 1982. Physical factors influencing oviposition by the Wood Frog, Rana
sylvatica, in Pennsylvania. Copeia 1982:627–635.
Semlitsch, R.D. 1983. Structure and dynamics of two breeding populations of the
Eastern Tiger Salamander, Ambystoma tigrinum. Copeia 1983:608–616.
Semlitsch, R.D. 1985. Analysis of climatic factors influencing migrations of the
salamander, Ambystoma talpoideum. Copeia 1985:477–489.
Semlitsch, R.D. 1987. Relationship of pond drying to the reproductive success of the
salamander Ambystoma talpoideum. Copeia 1987:61–69.
Semlitsch, R.D., D.E. Scott, J.H.K. Pechmann, and J.W. Gibbons. 1993. Phenotypic
variation in the arrival time of breeding salamanders: Individual repeatability and
environmental influences. Journal of Animal Ecology 62:334–340.
Semlitsch, R.D., D.E. Scott, J.H.K. Pechmann, and J.W. Gibbons. 1996. Structure
and dynamics of an amphibian community: Evidence from a 16-year study of a
natural pond. Pp. 217–248, In M.L. Cody and J. Smallwood (Eds.). Longterm
Studies of Vertebrate Communities. Academic Press, New York, NY. 597 pp.
Shoop, C.R. 1968. Migratory orientation of Ambystoma maculatum: Movements
near breeding ponds and displacements of migrating individuals. Biological
Shoop, C.R. 1974. Yearly variation in larval survival of Ambystoma maculatum.
Sjogren, P. 1991. Extinction and isolation gradients in metapopulations: The case of the
Pool Frog (Rana lessonae). Biological Journal of the Linnean Society 42:135–147.
Stahle, D.W., M.K. Cleaveland, and J.G. Hehr. 1988. North Carolina climate
changes reconstructed from tree rings: AD 372 to 1985. Science 240:1517–1519.
Vasconcelos, D., and J.K. Calhoun. 2004. Movement patterns of adult and juvenile
Rana sylvatica (LeConte) and Ambystoma maculatum (Shaw) in three restored
seasonal pools in Maine. Journal of Herpetology 38:551–561.
US Fish and Wildlife Service. 1999. Endangered and threatened wildlife and plants:
Final rule to list the Flatwoods Salamander as a threatened species. Federal