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Lithobates sphenocephalus sphenocephalusFlorida Leopard Frog

By Thomas Meade

Geographic Range

Southern leopard frogs are found from New Jersey in the north and south through the Coastal Plain to Florida. The range extends westward through Kentucky, southern Indiana, southern Illinois, eastern Iowa, eastern Oklahoma, and eastern Texas. ("Leopard Frog Rana sphenocephala", 2006)

Habitat

Southern leopard frogs are found near freshwater habitats in their range. During summer they disperse from the water and settle in moist vegetation. These frogs can be found anywhere from 1 to 5 km from their aquatic habitats. Eggs and larvae develop in still, shallow water, occasionally in brackish water. (Hammerson, 2007)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • temporary pools

Physical Description

Southern leopard frogs are slender frogs, with long legs and sharply pointed heads. They have prominent dorsolateral folds that extend from behind the eye to the hips. The tympanum is about the size of the eye and occasionally has a small white dot in the middle. The distinguishing feature of southern leopard frogs is the lack of digital pads on its toes. The back and sides are green and brown with distinct round spots. Average adult length is 80 mm. This species is sexually dimorphic: males tend to be smaller than females. Males also possess paired vocal sacs and enlarged thumbs and forearms to increase chances of successful reproduction. (Butterfield, et al., 2006; Hammerson, 2007; Knapp, 2006)

  • Sexual Dimorphism
  • female larger
  • sexes shaped differently
  • Range length
    20 to 130 mm
    0.79 to 5.12 in
  • Average length
    80 mm
    3.15 in

Development

Newly-hatched tadpoles are between 20 and 25 mm long. They eventually reach a length of 65 to 70 mm before transformation. The entire tadpole stage of life is usually around 90 days. The tadpole's tail bears dark spots when metamorphosis is imminent. Once fully transformed, the young frog will be approximately 20 mm long. (Knapp, 2006)

Reproduction

Breeding is typically initiated by rain, prompting males to call to females. However, southern leopard frogs call during any month of the year, except July and August. Breeding calls are harsh, guttural croaks. (Butterfield, et al., 2006)

Breeding occurs in fall, winter, and early spring. Eggs are laid just below the water's surface in a firm cluster about 90 mm wide and 40 mm thick and containing several hundred eggs per cluster. Often breeding frogs will congregate and lay numerous clusters of eggs in a small area. (Knapp, 2006)

  • Breeding interval
    Southern leopard frogs breed once annually.
  • Breeding season
    Breeding occurs from November to March in the southern portion of their range and March to June in the northern parts of their range.
  • Range time to hatching
    53 to 60 days
  • Range age at sexual or reproductive maturity (female)
    2 to 3 years
  • Range age at sexual or reproductive maturity (male)
    4 to 6 months

Rana spenochephala shows little to no parental investment in their offspring after laying an egg cluster. Once the eggs are laid, they are left to survive on their own. (Oliver, 1955)

  • Parental Investment
  • no parental involvement

Lifespan/Longevity

Life expectancy in the wild remains unknown. The majority of southern leopard frogs probably do not survive their first year. Adults known to hibernate in northern parts of their range, suggest they can live at least 2 to 3 years. Other species of leopard frog average 6 to 9 years of age. (Beane and Godfrey, 2007; Beane and Godfrey, 2007)

Behavior

Southern leopard frogs are nocturnal; they hide during the day in vegetation at the edge of the water. When threatened, these frogs avoid predators by entering the water and swimming away. When on land jumps are high and in often in sequences of 3 at a time. Southern leopard frogs are solitary outside of the breeding season, when they occur in large breeding colonies. (Knapp, 2006)

Home Range

The home range of Lithobates sphenocephalus sphenocephalus is unknown. It may be similar to other ranids, such as northern leopard frogs (Lithobates pipiens), which ranges from 8 to 16 km. ("Anura- Territory Size", 2006)

Communication and Perception

Southern leopard frogs use a short, guttural trill at rate of 10 to 12 per second. This sound is compared to chicken clucks or the sound made by rubbing your fingers across as balloon. They have paired vocal sacs that are spherical when inflated. This species uses a variety of calls in the breeding season. The call travels farther than those of related species. Males are also likely to use visual cues when competing for mates and tactile cues are used during mating. (Hammerson, 2007; Knapp, 2006)

Food Habits

Mature southern leopard frogs are primarily invertivores, feeding on terrestrial arthropods. Immature larvae are herbivorous, feeding on algae, plant tissue, and organic debris. Larger individuals will occasionally eat small vertebrates, although this is rare. (Hammerson, 2007)

  • Animal Foods
  • mammals
  • amphibians
  • insects
  • terrestrial non-insect arthropods
  • terrestrial worms
  • Plant Foods
  • wood, bark, or stems
  • algae

Predation

In addition to being a staple in the diet of many aquatic predators (great blue herons, river otters, grackles, southern water snakes, brown water snakes, northern black snakes, peninsular ribbon snakes, and water moccasins), humans also eat southern leopard frogs (particularly the legs). Lithobates sphenocephalus sphenocephalus is captured in large numbers to be used for fishing bait, scientific research, and classroom teaching. (Butterfield, et al., 2006)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Southern leopard frogs play a valuable role in the food chain. Birds, river otters, large fish, and many snake species prey on them. In turn, southern leopard frogs prey on smaller frogs, insects, and larvae.

The respiratory tracts of some ranid frogs are susceptible to infection by a group of lung worms. ("AWAKE- Plants and Wildlife", 2002; Butterfield, et al., 2006)

Economic Importance for Humans: Positive

Southern leopard frogs are raised and eaten by humans, particularly their large rear legs. Lithobates sphenocephalus sphenocephalus is also a common frog to be used for dissection by many science classes. These frogs eat large amounts of pest insects, such as mosquitoes. (Knapp, 2006)

  • Positive Impacts
  • food
  • research and education
  • controls pest population

Economic Importance for Humans: Negative

After heavy rains many frogs are killed on busy roads and highways. Also, a large chorus of frogs can be loud and sometimes be a disturbance at night in suburban areas. (Hammerson and Hedges, 2007; Knapp, 2006)

Conservation Status

Listed as "Least Concern" in view of its wide distribution, presumed large population, and because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. (Hammerson and Hedges, 2007)

Other Comments

This species was known by the name Rana utricularia until the late 1990s.

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Thomas Meade (author), Radford University, Karen Powers (editor, instructor), Radford University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

choruses

to jointly display, usually with sounds, at the same time as two or more other individuals of the same or different species

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

freshwater

mainly lives in water that is not salty.

herbivore

An animal that eats mainly plants or parts of plants.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

marsh

marshes are wetland areas often dominated by grasses and reeds.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polygynous

having more than one female as a mate at one time

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

suburban

living in residential areas on the outskirts of large cities or towns.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

visual

uses sight to communicate

References

AWAKE. 2002. "AWAKE- Plants and Wildlife" (On-line). Accessed December 10, 2007 at http://www.kentuckyawake.org/plantsWildlife/lifehistory.cfm?instanceID=18321.

U.S. Geogological Survey. Anura- Territory Size. 2006. Accessed December 10, 2007 at http://www.pwrc.usgs.gov/neparc/Products/RiskAssessPDFs/Anura/TerritorySize_Anura.pdf.

US Department of the Interior. Leopard Frog Rana sphenocephala. Gainesville: South East Amphibian Research and Monitoring Initiative. 2006. Accessed September 15, 2007 at http://cars.er.usgs.gov/herps/Frogs_and_Toads/R_sphenocephala/r_sphenocephala.html.

Beane, J., M. Godfrey. 2007. "North Carolina Wildlife Profiles- Southern Leopard Frog" (On-line). Accessed December 10, 2007 at http://www.ncwildlife.org/pg10_OutdoorKids/Profiles/southleopfrog.pdf.

Butterfield, B., M. Lannoo, P. Nanjappa. 2006. "Rana sphenocephala" (On-line). Amphibiaweb. Accessed September 15, 2007 at http://amphibiaweb.org/cgi/amphib_query?where-genus=Rana&where-species=sphenocephala&account=amphibiaweb.

Hammerson, G. 2007. "Rana sphenocephala" (On-line). Accessed September 15, 2007 at http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Rana+sphenocephala.

Hammerson, G., B. Hedges. 2007. "2007 IUCN Red List" (On-line). Accessed December 10, 2007 at http://www.iucnredlist.org/search/details.php/58723/all.

Knapp, W. 2006. "Southern Leopard Frog- Frogs and Toads of Georgia" (On-line). Accessed December 10, 2007 at http://wwknapp.home.mindspring.com/docs/southern.leopard.frog.html.

McCallum, M., S. Trauth, M. Mary, C. McDowell, B. Wheeler. 2004. Fall Breeding of the Southern Leopard Frog (Rana sphenocephala) in Northeastern Arkansas. Southeastern Naturalist, Volume 3, Issue 3: 401-408. Accessed September 15, 2007 at http://www.bioone.org/perlserv/?request=get-document&doi=10.1656%2F1528-7092%282004%29003%5B0401%3AFBOTSL%5D2.0.CO%3B2.

Oliver, J. 1955. North American Amphibians and Reptiles. New York, New York: D. Van Nostrand Company, Inc..

Saenz, D., J. Johnson, C. Adams, G. Dayton. 2003. Accelerated Hatching of Southern Leopard Frog (Rana sphenocephala) Eggs in Response to the Presence of a Crayfish (Procambarus nigrocinctus) Predator. BioOne, Volume 2003, Issue 3: 646-649. Accessed September 15, 2007 at http://www.bioone.org/perlserv/?request=get-document&doi=10.1643%2FCE-02-172R1.

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