Lithobates sphenocephalus sphenocephalus

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.

• Biogeographic Regions
• nearctic nearctic
  • native native

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.

• Habitat Regions
• temperate temperate
• freshwater freshwater

• Terrestrial Biomes
• forest forest

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

• Wetlands
• marsh marsh
• swamp swamp
• bog bog

• Other Habitat Features
• suburban suburban
• riparian riparian

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.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger
• sexes shaped differently

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.

• Development - Life Cycle
• metamorphosis metamorphosis

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.

• Mating System
• polygynous polygynous

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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • external external
• oviparous oviparous

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.

• 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.

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.

• Key Behaviors
• saltatorial saltatorial
• natatorial natatorial
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary

Home Range

The home range of Rana sphenocephala is unknown. It may be similar to other ranids , such as northern leopard frogs ( Rana pipiens ), which ranges from 8 to 16 km.

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.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Other Communication Modes
• choruses choruses

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

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.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • eats non-insect arthropods
• herbivore herbivore
  • folivore folivore
  • algivore

• Animal Foods
• mammals
• amphibians
• insects
• terrestrial non-insect arthropods
• terrestrial worms

• Plant Foods
• wood, bark, or stems
• algae

• Other Foods
• detritus detritus

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). Rana sphenocephala is captured in large numbers to be used for fishing bait, scientific research, and classroom teaching.

• Anti-predator Adaptations
• cryptic 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.

Economic Importance for Humans: Positive

Southern leopard frogs are raised and eaten by humans, particularly their large rear legs. Rana sphenocephala 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.

• Positive Impacts
• food 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.

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.

Other Comments

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

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

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

References

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

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

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 .

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 .