Southern Leopard Frog

Photo of Southern Leopard Frog -- Courtesy of Walter Knapp ( )

Photo Courtesy of Walter Knapp ( )

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Biological Characteristics


Rana utricularia (previously called R. sphenocephala and previously classified within R. pipiens) is a brown or green frog with 2 or 3 rows of elongated spots between conspicuous continuous dorsolateral ridges, and few spots on the sides (Conant and Collins, 1998; Behler and King, 1979).  Distinctive marks include a light spot in the center of the tympanum, a light stripe along the upper jaw, and horizontal pupils (Conant and Collins, 1998; Behler and King, 1979).  The back feet are extensively webbed, the front feet are not webbed, and they have long legs and pointed toes (Conant and Collins, 1998; Behler and King, 1979).  The males vocal sacs are distinctly spherical when inflated and lay at a loose angle or fold inward (Florida) when at rest (Conant and Collins, 1998).  The usually length ranges from 2-3 inches long, but can reach length up to 5 inches (Conant and Collins, 1998). 

Status in Estuaries

The southern leopard frog is found in shallow freshwater marshes, in slightly brackish marshes along the coast, and densely vegetated upland in the summer (Conant and Collins, 1998).  The southern frogs breed year round, and the northern frogs from March to June, laying egg masses with up to 20,000 eggs each in shallow water (Behler and King, 1979).  Eggs hatch within one month and metamorphosis occurs 6 months to 2 years later (Behler and King, 1979).  Lifespan is unknown for southern leopard frog, but averages 69 years for other leopard frogs, with sexual maturity reached in 23 years.

Abundance and Range

Found from Long Island, New York, south throughout Florida, and west to central Texas (Conant and Collins, 1998). The most ubiquitous frog in the southeast, commonly caught for frogs legs (Behler and King, 1979). 

Site Fidelity

Restricted to site by water pathways and distances between water sources.

Ease of Census

Easy to census egg masses, breeding frogs entering and exiting pools, or calling frogs in the breeding season.

Feeding Habits

Food items include insects, spiders, crustaceans, and anything else that can be caught (Behler and King, 1979).  Feeding distance limited to vicinity of water source.

Southern Leopard Frog Contaminant Exposure Data


Organochlorine Contaminants


Concentrations in Adults and Juveniles


In a laboratory experiment, lethal concentrations of endrin and toxaphene were measured (Hall and Swineford, 1980).  The lethal concentration (LC50) of endrin was 0.006 ppm for young larvae over 8 days, 0.006 ppm for older larvae treated for 8 days, and 0.005 ppm for sub-adults treated for 8 days. The LC50 of toxaphene was 0.168 ppm for young larvae treated for 8 days, 0.065 ppm for young larvae treated for 15 days, 0.032 ppm for young larvae treated for 30 days, and 0.378 ppm for sub-adults treated for 8 days.  Based on measured concentrations of toxaphene in the water, 0.018 ppm was the no-effect concentration for larvae.  Concentrations (μg/g) in sub-adults (N=2-8) after exposure (treatment concentration indicated in parentheses) were: 0.70 (0.010 endrin); 0.43 (0.012 endrin); 0.85 (0.016 endrin); 1.3 (0.022 endrin); 2.8 (0.030 endrin); 2.2 (0.058 toxaphene); 4.1 (0.078 toxaphene); 4.3 (0.15 toxaphene); 4.5 (0.28 toxaphene); 28 (0.76 toxaphene).


In a laboratory experiment, larvae (N=290) were exposed to endrin and toxaphene (Hall and Swineford, 1981).  The effective concentrations causing behavioral abnormalities in 50% of the larvae after 24 hours were 193 ppb toxaphene and 13 ppb endrin.  The lethal concentrations, causing mortality in 50% of the larvae after 96 hours were 130 ppb toxaphene and 9 ppb endrin 9. 


Concentrations in Eggs


In a laboratory experiment, lethal concentrations of endrin and toxaphene were measured (Hall and Swineford, 1980).  The LC50 of endrin was 0.025 ppm for eggs over 4 days and was not different from controls for eggs over 8 days.  The LC50 of toxaphene was 0.651 ppm for eggs treated 15 days, 0.060 ppm for eggs treated 20 days, 0.046 ppm for eggs treated 24 days, and was not different from controls in eggs treated for 8 days. 


Cholinesterase-Inhibiting Pesticides


No residue data available.


Trace Elements, Metals, and Metalloids


Southern leopard frog tadpoles (N=56) were collected from 4 Carolina Bays within the Savannah River Site, South Carolina in 1997 (Burger and Snodgrass, 2001). All specimens had non-detectable levels of Hg. Metal levels were significantly higher in the digestive tract than other body compartments for all metals. Digestive tracts and tails were removed to compare body compartments. Overall geometric means are listed in ng/g wet weight.

Whole body: As 63.6, Cd 81.1, Cr 383, Pb 911, Mn 84,800, Se 230. Body: As 27.4, Cd 45.4, Cr 165, Pb 212, Mn 75,500, Se 173. Tail: As 30.1, Cd 46.8, Cr 165, Pb 69.9 Mn 44,500, Se 205. Digestive tract: As 129, Cd 121, Cr 697, Pb 1,710, Mn 116,000, Se 301.




No residue data available

Southern Leopard Frog Contaminant Response Data


Organochlorine Contaminants


A laboratory experiment was conducted to determine the effects of endrin and toxaphene on tadpoles (Hall and Swineford, 1980).  Endrin exposure led to hyper-irritability and spastic activity terminating in tetany, which led to death.  Toxaphene exposure led to hyperirritability, followed by a narcotic effect that corresponded with the dose, tadpoles contracted their axial muscles rhythmically leading to a whirling motion or a prolonged stupor, and eventually death.  At the end of the 30-day test, animals in the higher dose groups for toxaphene were lighter in weight. 


Cholinesterase-Inhibiting Pesticides


Eggs were collected from temporary ponds near Starkville, Mississippi (Fulton and Chambers, 1985). Mortality for tadpoles in exposured to phenyl saliginen cyclic phosphate in the laboratory was 6% (N=210) at 500 ppb, and 99% (N=140) at 1000 ppb.  Abnormal embryos (extreme edema in abdomen, deformed spine, fluid filled blisters on body or tail) were found in 53% or tadpoles at 500 ppb, and 100% at 1000 ppb. 


In a laboratory and field experiment in 1988, Rana sphenocephala and R. blairi were exposed to esfenvalerate; data for the two species is combined (Materna et al., 1995).  The effect concentration for 50% of tadpoles for convulsive twitching and tail kinking was 3.40 μg/L at 18C and 6.14 μg/L at 22C.  The LC50 for 22C was 7.29 μg/L, and mortality was less than 50% at all concentrations tested at 18C.  In the field study, tadpoles were exposed to concentrations between 0 and 10 μg/L.  These tadpoles also exhibited decreased activity (at or above 3.6 μg/L), convulsions, tail kinking, and death (close to linear dose-response for mortality).  Percent survival was 97% in control enclosures, and 26.5% in 10 μg/L.  Tadpoles in the control group were generally smaller than those in the treatment groups at metamorphosis, although total biomass was larger in the controls. 


Eggs were collected from a pond near the University of Missouri-Columbia research park, transferred to the laboratory, and exposed to carbaryl for 24 hours (Bridges, 1999).  Of the control tadpoles, 77% were active, and of the treated tadpoles, 48% were active.  Tadpole exposure did not affect the rate of predation by Notopthalmus viridescens


Between 1996 and 1998, egg masses were collected from 10 sites in Illinois, Texas, South Carolina, Missouri (4 groups were collected in MO), Mississippi, Tennessee, and Virginia (Bridges and Semlitsch, 2000).  Mean time (hours) to death for the tadpoles treated with carbaryl was: 25 SC, 15 IL, 26 MS, 23 MO1, 20 TN, 14 MO4, 12 MO2, 8 MO3, 47 TX, and 9 VA.  Time spent active was decreased in all tadpole groups treated with carbaryl as compared to controls, except MO1 and TX. 


In 1997, 10 egg masses were collected from the University of Mississippi Field Station, raised in the laboratory for five weeks, and transferred to mesocosms (Britson and Threlkeld, 2000).  Mesocosms were treated with atrazine, chlorpyrifos, MeHg, and some were UV filtered.  Of 6480 individuals in the experiment, 9 were deformed though there was not an association with the treatments. A total of 2,107 individuals survived the experiment. 


In April 1998, egg masses were collected from a pond in Wilson County, Tennessee, and treated in the laboratory with carbaryl at various life stages (Bridges 2000).  Hatching success and embryo survival were not affected by treatments.  Mortality of tadpole and individuals treated though all life stages in the 0.40 and 1.0 mg/L treatments was over 90% and was significantly greater than in all other treatments.  Mortality and mean age to metamorphosis in the 0.16 mg/L treatment was not significantly different from controls.  Of the tadpoles that survived to 2 weeks, 18% of those exposed to carbaryl had deformities (failure of ventral surface of integument to close, extra or missing limbs, kinked tails).  Of the individuals treated as tadpoles and those treated though all life stages, 80% exhibited tail kinks.  Individuals treated as eggs had decreased mass at metamorphosis. 


Tadpoles were exposed to ultraviolet radiation A and B (UV-A and UV-B; 365 and 313 nm light) and carbaryl in the laboratory (Little et al., 2000) .  The UV-A was applied for 14 hours per day, and the UV-B for 5 hours during the same time period.  They were exposed to 0, 1.24, 1.76, and 2.57 mg/L of carbaryl, at 4.0, 65, and 0.002 μW/cm2.  Mortality by day 2 without UV was 10, 14 and 21% for 1.24, 1.76, and 2.51 mg/l of carbaryl, respectively; at 4.0 μW/cm2, it was 93.3, 93.3 and 100%; mortality was 16.7% for larvae exposed to light alone.  At 65 μW/cm2, mortality was 100% on day 1 when combined with carbaryl, and 78% alone. 


Trace Elements, Metals, and Metalloids


In a mesocosm experiment in 1990 and 1991 in Laurel, Maryland, the number of southern leopard frogs caught and the frequency of capture remained constant throughout the season and across treatments (control, Al, and Al with acid) and soil types (clay and loam) (Sparling et al., 1995).  The acidified treatment mesocosms had a pH between 5.0 and 5.5, and the control mesocosms had a pH between 6.0 and 6.8. 


In the laboratory, frogs (10 per treatment) were exposed to 0, 1.4, 3.9, 12.0, 110.0, and 487.0 μg Hg/l (McCrary and Heagler, 1997). The 96-hour LC50 was 6.59 μg Hg/l. 




Tadpoles were exposed to ultraviolet radiation A and B (UV-A and UV-B; 365 and 313 nm light) and weathered petroleum (from and abandoned mine in California) in the laboratory (Little et al., 2000).  The UV-A was applied for 14 hours per day, and the UV-B for 5 hours during the same time period.  They were exposed to 0% (0 mg/l), 5.0% (1.52 mg/l), and 10% (2.83 mg/l) solutions of the water-soluble fraction of the petroleum at 0.002, 2, and 17 μW/cm2.  Mortality was 0% in the 5 and 10% petroleum solutions without UV light, and 100% in the 5 and 10% solutions with 17 μW/cm2.  At 2 and 17 μW/cm2 without petroleum, mortality was 0%.  

References for Southern Leopard Frog

Behler, J.L. and F.W. King.  1979.  The Audubon Society Field Guide to North American Reptiles and Amphibians.  Alfred A. Knopf, Inc., New York.

Bridges, C.M.  2000.  Long-term effects of pesticide exposure at various life stages of the southern leopard frog (Rana sphenocephala). Arch. Environ. Contam. Toxicol.  39:91-96.

Bridges, C.M.  1999.  Predator-prey interactions between two amphibian species: effects of insecticide exposure.  Aquatic Ecol. 33:205-211.

Bridges, C.M. and R.D. Semlitsch.  2000.  Variation in pesticide tolerance of tadpoles among and within species of Ranidae and patterns of amphibian decline. Cons. Biol. 14:1490-1499.

Britson, C.A. and S.T. Threlkeld.  2000.  Interactive effects of anthropogenic, environmental, and biotic stressors on multiple endpoints in Hyla chrysoscelis.  J. Iowa Academy of Science 107:61-66.

Burger, J. and J. Snodgrass. 2001. Metal levels in Southern Leopard Frogs from the Savannah River Site: Location and body compartment effects. Environ. Res. Section A 86:157-166.

Conant, R. and J.T. Collins.  1998.  A Field Guide to Reptiles & Amphibians Eastern and Central North America.  Houghton Mifflin Company, New York.

Fulton, M.H. and J.E. Chambers.  1985.  The toxic and teratogenic effects of selected organophosphorus compounds on the embryos of three species of amphibians.  Toxicol. Letters 26:175-180.

Hall, R.J. and D. Swineford.  1980.  Toxic effects of endrin and toxaphene on the southern leopard frog Rana sphenocephala.  Environ. Pollut. Series A Ecological and Biological 23:53-66.

Hall, R.J. and D.M. Swineford.  1981.  Acute toxicities of toxaphene and endrin to larvae of 7 species of amphibians.  Toxicol. Letters 8:331-336.

Little, E.E., R. Calfee, L. Cleveland, R. Skinker, P.A. Zaga, and M.G. Barron.  2000.  Photo-enhanced toxicity in amphibians: synergistic interactions of solar ultraviolet radiation and aquatic contaminants.  J. Iowa Acad. Sci. 107:67-71.

Materna, E.J., C.F. Rabeni, and P.T.W. La. 1995. Effects of the synthetic pyrethroid insecticide, esfenvalerate, on larval leopard frogs (Rana spp.).  Environ. Toxicol. Chem. 14:613-622.

Mccrary, J.E. andM.G. Heagler. 1997. The use of a simultaneous multiple species acute toxicity test to compare the relative sensitivities of aquatic organisms to mercury.  J. Environ. Sci. Health Part A. Environ. Sci. Engineer. Toxic Hazardous Substance Control 32:73-81.

Sparling, D.W., T.P. Lowe, D. Day, and K. Dolan. 1995. Responses of amphibian populations to water and soil factors in experimentally-treated aquatic macrocosms.  Arch. Environ. Contam. Toxicol. 29: 455-461.