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2014 SOUTHEASTERN NATURALIST 13(1):128–137
Population Demographics of the Florida Bog Frog
(Lithobates okaloosae)
Jeronimo Gomes Da Silva Neto1, Thomas A. Gorman1,*, David C. Bishop1,2,
and Carola A. Haas1
Abstract - Conservation of a target species is often hindered by the absence of basic
demographic information. Lithobates [Rana] okaloosae (Florida Bog Frog) was discovered
in 1982 and occupies only three counties in northwest Florida, with its geographic range
occurring almost exclusively on Eglin Air Force Base. This limited distribution has led to
the listing of the Florida Bog Frog as a species of special concern in Florida. We used a
mark-recapture approach to 1) estimate population sizes and densities of male Florida Bog
Frogs at four sites; 2) estimate recapture rates of males among sites, within years, and between
years; 3) examine the relationship between male body condition and residency time in
breeding sites; and 4) examine the variation in male body condition across sites. Florida Bog
Frog population sizes and densities differed among sites, but not across years. Recapture
rates were high within a breeding season but low between years, suggesting that males have
high site fidelity and survival rates during the breeding season, but that annual mortality or
dispersal rates are high. Lastly, body condition of males did not differ across sites or affect
residency time during the breeding season. Understanding basic demographics of this species
will aid future conservation efforts and management decisions.
Introduction
Lithobates [Rana] okaloosae (Moler) (Florida Bog Frog) is a rare North American
ranid endemic to Walton, Okaloosa, and Santa Rosa counties in northwest
Florida. The species occurs in the Yellow and East Bay river drainages, and all but
three tributaries are within the boundaries of Eglin Air Force Base (Bishop 2005,
Gorman 2009, Moler 1993). This species is associated with shallow, acidic, flowing
seeps and bog overflows that have higher amounts of emergent and submergent
vegetation, and woody debris, and lower levels of canopy cover than unused sites
(Gorman 2009, Gorman and Haas 2011). Factors that impact the structural characteristics
of the streams, such as altered fire regimes or changes in hydrology, have
the potential to impact Florida Bog Frog populations (Jackson 2004, Gorman 2009).
Since the discovery of the Florida Bog Frog in 1982 (Moler 1985), research on this
species has focused on its distribution, movements, habitat selection, and conservation
genetics (e.g., Austin et al. 2011a, b; Bishop 2005; Gorman 2009; Gorman and
Haas 2011; Gorman et al. 2009); however, there is still a lack information on basic
population demographics for this species, which is essential for future conservation
efforts (Bielby et al. 2008).
1Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24061. 2Current
address - The Nature Conservancy, 1417 Stuart Engals Blvd, Mt. Pleasant, SC 29464.
*Corresponding author - gormant@vt.edu.
Manuscript Editor: John Placyk
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2014 Vol. 13, No. 1
Common population metrics include population size, recapture rates, and density
(Govindarajulu et al. 2005). Estimates of population size provide baseline data
that can be used to monitor changes through time. By understanding recapture rates,
we can make predictions on survivorship or dispersal within and between breeding
seasons. Density estimates can be used in combination with measures of habitat
condition to make assumptions on how habitat quality and patch sizes influence
breeding populations. In addition, factors influencing survival during the breeding
season can elucidate the trade-offs between chorus attendance and individual
survival. Even though mate selection may favor males that breed longer, chorus
attendance is an activity that requires an increased energy demand and may negatively
affect survival (Bevier 1997, Greer and Wells 1980, Jacobson 1985, Murphy
1994). The relationship between body condition and how many nights each male
spends calling (i.e., residency) may help explain this trade-off. Further, if we assume
that male body condition can serve as an index of site quality, we can compare
the quality of each site across years.
We present a mark-recapture study of Florida Bog Frogs at four sites. We estimated
population sizes, densities, and recapture rates at multiple sites across
multiple years. Further, we investigated if body condition of males affected residency
time, and whether male body condition differed among sites.
Methods
Study area
Eglin Air Force Base is a large military installation (>187,000 ha) in northwestern
Florida. The topography of the study area is level to rolling, with the highest
elevation at ≈75 m and slopes that generally range from 0–30% (Eglin Air Force
Base 2002). The upland habitat is dominated by Pinus palustris Mill. (Longleaf
Pine) and Quercus laevis Walter (Turkey Oak) sandhills with interspersed streams.
Our four study sites occurred in the riparian area of three perennial streams: Live
Oak Creek, East Bay River, and Weaver Creek. The study sites were all associated
with either a steephead (i.e., a small ravine associated with perennially wet firstorder
streams that originate from springs; Means 1975, Schumm et al. 1995), such
as Live Oak Tributary, or seepage springs that originated upslope of the “boggy”
riparian areas that constituted the site, such as Live Oak Creek, East Bay River, and
Weaver Creek. All four sites were characterized by predominantly shallow water
with high amounts of emergent vegetation, submergent vegetation, and woody debris,
and moderate levels of canopy cover (Gorman and Haas 2011). The overstory
vegetation associated with these sites was predominantly Cliftonia monophylla
(Lam.) Britton ex Sarg. (Black Titi or Buckwheat Tree), Magnolia virginiana L.
(Sweetbay Magnolia), Chamaecyparis thyoides (L.) Britton, Sterns, & Poggenb.
(Atlantic White Cedar), Cyrilla racemiflora L. (Swamp Titi), and Nyssa sylvatica
Marsh. (Black Gum). All sites were separated from each other by at least 1.3 km,
and the two most distant sites were 20.9 km apart (Fig. 1).
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Sampling methods
2002–2003 sampling. We sampled the Live Oak Tributary study site during the
2002 and 2003 breeding season of Florida Bog Frogs. Each night of sampling usually
lasted 2–3 person h and was terminated when all calling males were captured
and the study site was completely traversed by the observers. We searched the study
site for Florida Bog Frogs on 30 nights in 2002 (27 May–10 September) and 84
nights in 2003 (27 March–3 August). However, we reduced the dataset to no more
than 2 consecutive sampling nights per week to make the distribution of sampling
effort more comparable across years. Unless otherwise noted, we included 16 sampling
nights or 8 two-night sampling periods from 27 May–01 August 2002 and
20 sampling nights or 10 two-night sampling periods from 29 May–29 July 2003.
We used all 84 days from the 2003 sampling season to examine the relationship
between body condition and residency time (see below). We permanently marked
individual Florida Bog Frogs by toe-clipping between 1–3 toes, with never more
than one toe clipped on one foot. Each toe was numbered from 1–18, and the
resulting code uniquely identified each individual (e.g., 6 or 4-10 or 3-7-9). We
georeferenced capture locations with an Asset Surveyor TDC2 GPS unit (Trimble
Navigation Limited, Sunnyvale, CA) with sub-meter resolution. When each individual
was captured for the first time in a season, we measured snout–vent length
Figure 1. Study sites where male Lithobates okaloosae (Florida Bog Frog) where captured
from 2002–2003 and 2006–2008 on Eglin Air Force Base, FL.
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(SVL) to the nearest 0.1 mm using dial calipers and weighed each individual to the
nearest 0.5 g using a 10- or 30-g spring scale (Pesola AG, Baar, Switzerland).
2006–2008 sampling.We resampled Live Oak Tributary and sampled three additional
sites (Live Oak Creek, Weaver Creek, and East Bay River) from May to
August in 2006–2008 (Gorman and Haas 2011). We selected two of the additional
sites to represent different drainages (Weaver Creek and East Bay River), and
selected Live Oak Creek to represent a different stream position on the same drainage
as Live Oak Tributary. All the study sites were sites at which Gorman (2009)
had documented multiple Florida Bog Frogs calling in May 2006. We searched
the study sites for Florida Bog Frogs during two periods (each period consisted of
four consecutive nights) in 2006 and three periods in 2007 and 2008. During each
sampling event, we extensively searched each site, usually for 2–3 person hours, to
capture all calling males. We implanted visible implant alphanumeric (VIA) tags
(Northwest Marine Technologies, Inc., Olympia, WA) into the hindlimb of captured
frogs. We used a blood lancet to make a small incision in the skin and then,
using a tag implanter, inserted the tag between the skin and the adductor muscles
(Buchan et al. 2005, Gorman and Haas 2011). When each individual was captured
for the first time in a season, we measured its SVL to the nearest 0.1 mm using dial
calipers and its weight to the nearest 0.5 g using a 10- or 30-g Pesola™ spring. We
georeferenced capture locations with an Asset Surveyor TDC2 GPS unit (Trimble
Navigation Limited, Sunnyvale, CA) with sub-meter resolution.
Statistical analyses
We used minimum number alive (MNA; i.e., the minimum number of unique
individuals captured within a year) and Lincoln-Peterson (LP) estimates to estimate
population sizes of adult males at individual sites. We calculated LP estimates
by dividing the sampling season in half, so that LP period 1 was the first half of
the sampling season and LP period 2 was the second half. To estimate densities
at each site, we calculated a minimum convex polygon (MCP) in ArcGIS 10.0
(Esri, Redland, CA) for each site using all capture data from all years in which
the site was sampled. This approach resulted in a single area estimate for each of
the four study sites (Table 1). We calculated male Florida Bog Frog densities by
dividing the population size (MNA) at each site during each year by the area of
the corresponding MCP. We presented the data as the number of male Florida Bog
Frogs per 1000 m² because all of the study sites were larger than this conversion
and it provided interpretable density estimates. We used an analysis of variance
(ANOVA) to compare MNA and densities across three sites (Live Oak Tributary,
Live Oak Creek, and Weaver Creek) over three years (2006–2008). We excluded
one site (East Bay River) from the population, density, and recapture analyses, because
it was not sampled in 2006. If the overall ANOVA was significant, then we
used a Student’s t-test on least squares means to evaluate pair-wise comparisons.
Lastly, we calculated recapture rates within years, between years, and at each site,
and compared them among three sites (Live Oak Tributary, Live Oak Creek, and
Weaver Creek) over three years (2006–2008) using an ANOVA. We used an alpha
level of 0.05 to evaluate differences.
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To examine the relationship between body condition and residency time, we
used data that were collected during the entire sampling period 27 March–3 August
2003 (84 days) from one site (Live Oak Tributary). We developed a linear
regression model that related log-transformed snout–vent length (SVL) and logtransformed
body weight of captured male Florida Bog Frogs and used the residuals
as the body condition index (BCI) (Băncilă et al. 2010). We then developed a linear
regression to relate BCI to the number of nights individual frogs spent in the chorus
during the 2003 breeding season. Additionally, we used an ANOVA to compare BCI
of males from all sites over two years (2007–2008).
Results
We captured a total of 161 adult male Florida Bog Frogs at four sites. Out of
the 161 males captured, 94 were captured at Live Oak Tributary from 2002–2003
and 2006–2008, 24 at East Bay River from 2007–2008, 22 at Weaver Creek from
2006–2008, and 21 at Live Oak Creek from 2006–2008 (Table 1). MNA was higher
for 2002 compared to 2003 (28 vs. 16). During 2006–2008, we captured the most
males in 2006 (43), and the least in 2007 (32) (Table 1). Male Florida Bog Frog
densities were different among sites (F2,4 = 24.90, P = 0.006), but population sizes
(all values for population size given in the text are for MNA unless otherwise indicated)
were not quite statistically different at the α = 0.05 level among sites (F2,4
= 5.42, P = 0.07), and across years there was no difference (population size: F2,4
= 2.24, P = 0.22; density: F2,4 = 2.80, P = 0.17) during the 2006–2008 sampling
period. Live Oak Tributary had the largest population size and highest density, and
both measures exceeded those at Weaver Creek (population size: P = 0.05, density:
P = 0.003) and Live Oak Creek (population size: P = 0.04, density: P = 0.005),
neither of which was different from the other (population size: P = 0.93, density: P
= 0.41) (Table 1).
Recapture rates were the lowest in 2002 ( average = 0.54) during the 2002–2003
(Table 2) sampling period. During 2006–2008, recapture rates were highest in 2007
(0.64) and lowest in 2006 (0.58) (Table 2). The highest recapture rates between
Table 1. Minimum number alive (MNA), Lincoln–Peterson estimates (LP) (standard deviation in
parentheses), and density estimates (D; number of individuals/1000 m²) of adult male Lithobates
okaloosae (Florida Bog Frog) captured during five years at four different sites (area of each site is
listed after each site name) on Eglin Air Force Base, FL.
Live Oak Live Oak East Bay Weaver
Tributary (1415 m²) Creek (2609 m²) River (1638 m²) Creek (7518 m²)
Year MNA LP D MNA LP D MNA LP D MNA LP D
2002* 28 29.0 (1.4) 19.8 - - - - - - - - -
2003* 16 17.2 (2.0) 11.3 - - - - - - - - -
2006 23 26.8 (8.9) 17.9 14 18.2 (13.4) 5.4 - - - 6 6.0 (0.0) 0.8
2007 13 12.3 (2.5) 10.1 2 2.0 (0.0) 0.8 9 9.0 (0.0) 5.5 8 8.0 (0.0) 1.1
2008 14 12.7 (1.2) 10.9 5 5.0 (0.0) 1.9 15 15.0 (0.0) 9.2 8 9.5 (3.9) 1.1
*Sampling methods used in 2002–2003 differ from those used in 2006–2008.
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years (0.14) occurred 2002–2003; the lowest (0.07) occurred 2006–2007, but
2007–2008 was just slightly higher (0.09). From 2006–2008, Live Oak Creek had
the highest average within-year recapture rate (0.63), and Weaver Creek had the
lowest (0.54) (Table 2). Within-year recapture rates (F8,84 = 0.74, P = 0.65) were not
different among sites or across years from 2006–2008. Overall, recapture rates were
high within a season (range = 0.47–0.78, mean = 0.61, SE = 0.02), but low between
years (range = 0.07–0.14, mean = 0.10, SE = 0.02).
As expected, there was a strong relationship between weight and SVL (R2 = 0.91).
We used the residuals of this relationship as our estimate of BCI. We found no relationship
between BCI on initial capture and the number of nights a male attended the
chorus (i.e., number of capture nights; R2 = 0.035, P = 0.26; Fig. 2). Also, when examining
data at all four sites from 2007–2008, we detected no differences in male body
condition among sites or among years (F7,66 = 1.53, P = 0.17).
Discussion
This study provides the first quantitative assessment of population metrics of
Florida Bog Frogs. From 2006–2008, one site (Live Oak Tributary) had both higher
population size and density than the other two sites (Table 1). This result suggests that
Table 2. Within-year recapture rates at four different sites where adult male Lithobates okaloosae
(Florida Bog Frog) were captured on Eglin Air Force Base, FL.
Site 2002 2003 2006 2007 2008 Mean
East Bay River - - - 0.73 0.58 0.65
Live Oak Tributary 0.54 0.62 0.62 0.67 0.64 0.62
Live Oak Creek - - 0.62 0.50 0.78 0.63
Weaver Creek - - 0.49 0.66 0.47 0.54
Mean - - 0.58 0.64 0.62 -
Figure 2. Relationship between
initial body condition
and number of nights in the
chorus for male Lithobates
okaloosae (Florida Bog Frog)
captured in 2003 at Live Oak
Creek Tributary, on Eglin Air
Force Base, FL. Body conditions
were derived from the residuals
resulting from a linear
regression model that related
log-transformed snout–vent
length (SVL) and log-transformed
body weight of captured
male Florida Bog Frogs.
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some sites (e.g., Live Oak Tributary) may be capable of supporting larger breeding
populations and thus have greater conservation value for this rare anuran. However,
we did not find a difference in BCI among sites, and this result may indicate that
despite the higher population size supported at some sites, males even in smaller populations
are finding adequate resources. Additionally, the MCP method to calculate
the area for each study site is likely an over-estimate, because it may include habitat
that is not suitable for Florida Bog Frogs. Florida Bog Frogs are capable of using
small patches of habitat as noted by their limited movements (Gorman et al. 2009),
and it is likely that some sites were more heterogeneous than others. The site with the
highest densities, Live Oak Tributary, appeared to be more homogenous and provide
a greater amount of suitable contiguous habitat despite being the smallest study site
overall. The difference in densities may reflect the spatial distribution of microhabitats
(Gorman and Haas 2011) or the habitat quality of the sites.
While we did not explicitly estimate survival rates because of small sample
sizes, the relatively high recapture rates within a year suggest that survival is high
within a breeding season. During the breeding season, males usually have limited
movement, spending several nights at a calling location before moving to a new
nearby location (Gorman et al. 2009). Conversely, recapture rates were very low
between years and may indicate a low overwinter survival rate. Relatively little
information on ranid frog longevity or annual survival is available, and several
previous studies used recapture rates as uncorrected estimates of minimum annual
survivorship (Wells 2007). Recapture rates of Florida Bog Frogs of 7–14% between
years in this study fell within two uncorrected estimates of minimum annual
survivorship (i.e., recapture rates) reported for Ranidae (Hylarana eythraea = 5%
and Rana temporaria = 31%; Wells 2007). Uncorrected estimates of between-year
recapture rates for seven species of Hylidae, several of which are similar in body
size to L. okaloosae, averaged 32% (Wells 2007), more than twice as high as our
observed recapture rates for Florida Bog Frogs. In addition, estimates of annual
survivorship of ranid frogs based on recapture data corrected for capture probability
or based on life-table data were substantially higher in eight studies reviewed
by Wells (2007), with an average of 54% (range = 0–84%). However, the rates we
observed may be biased low because we calculated recapture rates using data for
males only, and male anurans are known to have higher annual mortality (Wood et
al. 1998). Our annual survival data were calculated across three periods, separated
by four years, and we saw consistently low survival. By contrast, survival rates may
vary greatly within and across years in frog species from more strongly seasonal
climates, as has been reported in a six-year study of European water frogs (Pelophylax
[Rana] lessonae (Camerano) [Pool Frog] and P. kl. Esculenta (L.) [Edible
Frog]; Anholt et al. 2003).
Florida Bog Frog tadpoles overwinter at breeding sites (Bishop 2005, Moler
1992), hence adults likely are already more than two years old when they first
breed. Metamorphs are often encountered in late spring and early summer and are
unlikely to attain breeding status within the same season (based on their body size
compared to breeding adults). It is not known whether some tadpoles metamorphose
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within the same year as they hatch, which is a strategy used by the closely related
Lithobates clamitans Latreille (Green Frog; Martof 1956) and may lead to breeding
at an earlier age. Martof (1956) found that Green Frogs were capable of both
overwintering as a tadpole or as a metamorph, depending on the date that an egg
mass was deposited.
The low recapture rates between successive years may also be related to dispersal
after the breeding season. During rain events, frogs are able to disperse farther,
possibly moving outside of the sampling area between years (Bishop 2005, Gorman
et al. 2009). We currently have very limited knowledge on the dispersal patterns
of this species, which limits our ability to make predictions about the effects of
dispersal and mortality on the population dynamics at a location.
There was no relationship between body condition and the number of nights individual
males were detected (i.e., residency time) within a season. Some anurans
show a relationship between energy expenditure and number of days active in a
chorus (Murphy 1994). The condition of an individual at the beginning of the chorus
tenure and how fast an individual loses such condition may influence residency
in the chorus. Because we did not record the weight of each individual at each time
they were captured, we are unable to calculate rate of change in body condition.
Body condition likely affects species of frogs that have short and intense breeding
seasons (e.g., toads) or form large, dense choruses (e.g., treefrogs) more than prolonged
breeders like Florida Bog Frogs. Species with prolonged breeding seasons
may space themselves throughout the breeding habitat, which may influence foraging
behavior, mating success, and chorus tenure (Gorman et al. 2009, Wells 1977).
In addition, aggressive interactions between prolonged breeders have been reported
(Ritchie et al. 2008). Finally, rainfall patterns, permanence of breeding sites, and
predator pressure may influence chorus tenure (Bateson 1993). Body condition
alone was not a good indicator of how long a male Florida Bog Frog remains active
in the chorus.
Our intensive study at four locations confirms that Florida Bog Frog breed in
very small aggregations (2–29 males) that persist for several years. Although our
study sites likely were located too far apart to detect dispersal of marked individuals,
we assume that these small breeding aggregations must be connected through
dispersal either of tadpoles, metamorphs, or adults, a pattern confirmed by genetics
work (Austin et al. 2011a). We recaptured very few marked individuals between
years. Further study will be necessary to explore whether this low recapture rate
is the result of high mortality rates or non-breeding season dispersal events. In
conclusion, it appears that maintaining a network of small breeding sites is necessary
to ensure persistence of species that occur in naturally patchy wetland habitats
(Shoemaker et al. 2013), including Florida Bog Frogs.
Acknowledgments
This research was supported by the Natural Resources Branch (Jackson Guard) of Eglin
Air Force Base and Fralin Life Science Institute’s Summer Undergraduate Research Fellowship
(SURF) Program. We thank K. Gault and B. Hagedorn of Jackson Guard for their
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long-term support of this project. We thank S. Eddie, J. Homyack, J. Kern, K. Landry, L.
Oztoloza, L. Phillips, B. Rincon, and S. Ritchie for help collecting this data. Also, we thank
C. Proctor for guidance on the GIS portion of this paper.
Literature Cited
Anholt, B.R., H. Hotz, G.-D. Guex, and R.D. Semlitsch. 2003. Overwinter survival of Rana
lessonae and its hemiclonal associate Rana esculenta. Ecology 84:391–397.
Austin, J.D., T.A. Gorman, and D.C. Bishop. 2011a. Assessing fine-scale genetic structure
and relatedness in the micro-endemic Florida Bog Frog. Conservation Genetics
12:833–838.
Austin J.D., T.A. Gorman, D. Bishop, and P. Moler. 2011b. Genetic evidence of contemporary
hybridization in one of North America’s rarest anurans, the Florida Bog Frog.
Animal Conservation 14:553–561.
Băncilă, R.I., T. Hartel, R. Plăiaşu, J. Smets, and D. Cogălniceanu. 2010. Comparing three
body-condition indices in amphibians: A case study of Yellow-bellied Toad, Bombina
variegata. Amphibia-Reptilia 31:558–562.
Bateson, P. 1993. Mate choice: Male-male competition and mate choice in anuran amphibians.
University of Cambridge, New York, NY.
Bevier, C.R. 1997. Breeding activity and chorus tenure of two neotropical hylid frogs.
Herpetologica 53:297–311.
Bielby, J., N. Cooper, A.A. Cunningham, T.W.J. Garner, and A. Purvis. 2008. Predicting
susceptibility to future declines in the world’s frogs. Journal of Herpetology 38:370–380.
Bishop, D.C. 2005. Ecology and distribution of the Florida Bog Frog and Flatwoods Salamander
on Eglin Air Force Base. Ph.D. Dissertation. Virginia Polytechnic Institute and
State University, Blacksburg, VA.
Buchan, A., L. Sun, and R.S. Wagner. 2005. Using alpha-numeric fluorescent tags for individual
identification of amphibians. Herpetological Review 36:43 –44.
Eglin Air Force Base. 2002. Integrated natural resource management plan 2002–2006. Air
Armament Center Eglin Air Force Base, FL.
Gorman T.A. 2009. Ecology of two rare amphibians of the Gulf Coastal Plain. Ph.D. Dissertation.
Virginia Polytechnic Institute and State University, Blacksburg, VA.
Gorman, T.A., and C.A. Haas. 2011. Seasonal microhabitat use and selection of syntopic
populations of Lithobates okaloosae and Lithobates clamitans clamitans. Journal of
Herpetology 45:313–318.
Gorman, T.A., D.C. Bishop, and C.A. Haas. 2009. Spatial interactions between two species
of frogs: Rana okaloosae and R. clamitans clamitans. Copeia 2009:138–141.
Govindarajulu, P., R. Altwegg, and B.R. Anholt. 2005. Matrix-model investigation of
invasive species control: Bullfrogs on Vancouver Island. Ecological Applications
15:2161–2170.
Greer, B.J., and K.D. Wells. 1980. Territorial and reproductive behavior of the tropical
American frog Centrolenella fleischmanni. Herpetologica 36:318–326.
Jackson, D.R. 2004. Management guidance document for species at risk on Eglin Air Force
Base, Niceville, Florida: Florida Bog Frog (Rana okaloosae). Final report to US Fish
and Wildlife Service, Panama City, Florida. Florida Natural Areas Inventory, Tallahassee,
FL.
Jacobson, S.K. 1985. Reproductive behavior and male mating success in two species of
glass frogs (Centrolenidae). Herpetologica 41:396–404.
Southeastern Naturalist
137
J. Gomes Da Silva Neto, T.A. Gorman, D.C. Bishop, and C.A. Haas
2014 Vol. 13, No. 1
Martof, B. 1956. Growth and development of the Green Frog, Rana clamitans, under natural
conditions. American Midland Naturalist 55:101–117.
Means, D.B. 1975. Competitive exclusion along a habitat gradient between two species of
salamanders (Desmognathus) in western Florida. Journal of Biogeography 2:253–263.
Moler, P.E. 1985. A new species of frog (Ranidae: Rana) from northwestern Florida. Copeia
1985:379–383.
Moler, P.E., (Ed.). 1992. Rare and Endangered Biota of Florida. Volume Three: Amphibian
and Reptiles. University Press of Florida, Gainesville, FL.
Moler, P.E. 1993. Rana okaloosae. Catalogue of American Amphibians and Reptiles
561:1–3..
Murphy, C.G. 1994. Chorus tenure of male Barking Treefrogs, Hyla gratiosa. Animal Behaviour
48:763–777.
Ritchie, S.C., B.K. Rincon, and T.A. Gorman. 2008. Ranid aggression and interspecies
amplexus. Herpetological Review 39:80.
Schumm, S.A., K.F. Boyd, C.G. Wolff, and W.J. Spitz. 1995. A ground-water sapping landscape
in the Florida Panhandle. Geomorphology 12:281–297.
Shoemaker, K.T., A.R. Breisch, J.W. Jaycox, and J.P. Gibbs. 2013. Re-examining the
minimum viable population concept for long-lived species. Conservation Biology DOI:
10.1111/cobi.12028.
Wells, K.D. 1977. Territoriality and male mating success in the Green Frog (Rana clamitans).
Ecology 58:750–762.
Wells, K.D. 2007. Ecology and Behavior of Amphibians. University of Chicago Press,
Chicago, IL.
Wood, K.V., J.D. Nichols, H.F. Percival, and J.E. Hines. 1998. Size-sex variation in survival
rates and abundance of Pig Frogs, Rana grylio, in Northern Florida wetlands. Journal of
Herpetology 32:527–535.