Southern Leopard Frog Rana sphenocephala

Adult from Jennings County

Identification

Adults are medium-sized, brown frogs with dark dorsal blotches. These blotches are irregularly arranged in between the dorsolateral ridges. Many individuals have green dorsal coloration and some frogs may be almost entirely green. The underbelly is white and the legs are banded. Dorsolateral folds are usually light yellow in coloration. This species may grow over 3 in (45-80 mm) in length.

Adult male with eggs from Jennings County
Juvenile from Decatur County

Female Southern Leopard Frogs lay their eggs in globular masses of up to 5,000 eggs. Southern Leopard Frog tadpoles are large, brown, and usually grow to around 3 in (~70 mm) long. There is some mottling on the tailfins of the tadpoles.

Both Plains (Rana blairi) and Northern (R. pipiens) Leopard Frogs are similar in appearance to this species. Northern Leopard Frogs have light green "halos" around each spot that this species lacks and they lack the light center to the tympanum. The dorso-lateral folds of Plains Leopard Frogs are broken and inset near the hind legs. Southern leopard frog vocalizations are distinctive, but require careful study before making a definitive identification as they are similar to the other leopard frog species' calls. Pickerel Frogs (R. palustris) are similar in appearance, but have more rectangular, organized blotches and a bright yellow wash around the groin and hind legs.

Call

The call of this species resembles a cackling laugh that is repeated at irregular intervals. Listen to the call courtesy of the Indiana DNR.

Ecology and Conservation

Southern Leopard Frogs are most often found in open marshy areas or along larger rivers. They will also inhabit smaller creeks and ponds, but tend to avoid extensive forested areas. Southern Leopard Frogs are often seen sitting along the water's edge or partially submerged in shallow water, but they will wander further from water during the summer. Leopard Frogs will often leap away from the water and into tall grass when disturbed. Southern Leopard Frogs are generally active from late February through November depending on the weather. Southern Leopard Frogs feed on various small invertebrates.

Open marsh from Jackson County
Grassland marsh from Jefferson County

Marshes and backwater sloughs are favored breeding sites for this species, but shallow portions of larger lakes and rivers are also utilized. During the early spring, females will lay eggs in communal clumps in shallow water to maximize thermal opportunities for keeping the eggs warm. However, frogs that breed during the fall will often disperse their eggs throughout the pond in small clumps due to warmer temperatures. Like other wetland breeding frogs, larvae will develop more rapidly as the wetland dries. Southern Leopard Frogs typically begin calling sometime during March and continue through May. Eggs hatch around a week after being deposited and tadpoles from the spring breeding season metamorphose during June or July. There is also evidence of a fall breeding season in southern Indiana and Southern Leopard Frogs will breed during September and October if there is enough rain. Eggs may take one or two weeks to hatch, but the presence of predators can speed up the rate at which the eggs develop. Tadpoles from the fall breeding season undergo metamorphosis during the following spring.

Unlike its northern counterpart, the Southern Leopard Frog has not experienced noticeable population declines in Indiana. However, pesticides and other agricultural pollutants can negatively affect development and reproduction of frogs breeding in contaminated wetlands. Despite this, the species tends to adapt fairly well to disturbed habitat and is present in both suburban and agricultural landscapes.

Distribution

Southern Leopard Frogs occur throughout the southeastern United States; west to eastern Texas and north into southern Indiana and Illinois as well as along much of the east coast. This species is generally abundant throughout the southern half of the state, but is absent from much of southeastern Indiana. A diagonal line could be drawn from northern Vermillion County to eastern Jefferson County that would roughly separate the range of northern and Southern Leopard Frogs in Indiana. Though hybridization has been suspected at some sites, these two frogs seem to have little overlap in Indiana.

Taxonomy

Some scientists recognize two species of the Southern Leopard Frog (Rana sphenocephala); under this taxonomic system, Indiana is home to the Coastal Plains Leopard Frog (R. s. utricularia) subspecies. Frost et al. (2006) recommended placing these frogs in the genus Lithobates, but other authors argue against this, instead suggesting the recognition of subgenera within the monophyletic Rana (e.g., Pauley et al. 2009; Yuan et al. 2016). Southern Leopard Frogs belong to the family Ranidae, which is diverse and widespread worldwide and includes eight species of frogs in Indiana.

Literature Cited

Bridges, C. M. 2000. Long-Term Effects of Pesticide Exposure at Various Life Stages of the Southern Leopard Frog (Rana sphenocephala). Archives of Environmental Contamination and Toxicology 39:91-96.

Brodman, R. 2003. Amphibians and Reptiles from Twenty-three Counties of Indiana. Proceedings of the Indiana Academy of Science 112:43-54.

Caldwell, J. P. 1986. Selection of Egg Deposition Sites: A Seasonal Shift in the Southern Leopard Frog, Rana sphenocephala. Copeia 1986:249-253.

Conant, R. and J. T . Collins. 1998. Reptiles and Amphibians of Eastern and Central North America. Third Edition, Expanded. Houghton Mifflin, New York, NY.

Frost, D. R., T. Grant, J. Faivovich, R. H. Bain, A. Haas, C. F. Haddad, R. O. De Sa, A. Channing, M. Wilkinson, S. C. Donnellan, and C. J. Raxworthy. 2006. The amphibian tree of life. Bulletin of the American Museum of Natural History:1-291.

Hillis, D. M. and T. P. Wilcox. 2005. Phylogeny of the New World True Frogs (Rana). Molecular Phylogenetics and Evolution 34:299-314.

Hillis, D. M., J. S. Frost, and D. A. Wright. 1983. Phylogeny and Biogeography of the Rana pipiens Complex: A Biochemical Evaluation. Systematic Biology 32:132-143.

Hillis, D. M. 1982. Morphological Differentiation and Adaptation of the Larvae of Rana berlandieri and Rana sphenocephala (Rana pipiens Complex) in Sympatry. Copeia 1982:168-174.

Minton, S. A. Jr. 2001. Amphibians and Reptiles of Indiana. Indiana Academy of Science, Indianapolis, IN.

Pauly, G.B., D. M. Hillis, and D. C. Cannatella. 2009. Taxonomic freedom and the role of official lists of species names. Herpetologica 65:115-128.

Ryan, T. J. and C. T. Winne. 2001. Effects of Hydroperiod on Metamorphosis in Rana sphenocephala. American Midland Naturalist 145:46-53.

Saenz, D., J. B. Johnson, C. K. Adams, and G. H. Dayton. 2003. Accelerated Hatching of Southern Leopard Frog (Rana sphenocephala) Eggs in Response to the Presence of a Crayfish (Procambarus nigrocinctus) Predator. Copeia 2003:646-649.

Yuan, Z. Y., W. W. Zhou, X. Chen, N. A. Poyarkov, Jr., H. M. Chen, N. H. Jang-Liaw, W. H. Chou, N. J. Matzke, K. Iizuka, M. S. Min, and S. L. Kuzmin. 2016. Spatiotemporal diversification of the true frogs (genus Rana): a historical framework for a widely studied group of model organisms. Systematic Biology, 65:824-842.

Distribution Map
Distribution map of Southern Leopard Frog (Rana sphenocephala)
Photographs