Southern Leopard Frog Lithobates sphenocephalus

Description: Adult Morphology: A medium-sized, brown frog with dark dorsal blotches. These blotches are irregularly arranged in between the dorso-lateral ridges. Many individuals have green dorsal coloration and some frogs may be almost entirely green. The underbelly is white and the legs are banded. Dorso-lateral folds are usually light yellow in coloration.

Size: This species may grow over 3 in (45-80 mm) in length.

Larvae: A large, brown tadpole that usually grows to around 3 in (~70 mm) long. There is some mottling on the tailfin.

Eggs: Females lay eggs in globular masses of up to 5,000 eggs.

Similar Species: Both plains (Lithobates blairi) and northern (L. 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 (L. palustris) are similar in appearance, but have more rectangular, organized blotches and a bright yellow wash around the groin and hind legs.

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.

Activity: Southern leopard frogs are generally active from late February through November depending on the weather.

Breeding Season: 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 metamorphose during the following spring.

Taxonomy: Southern leopard frogs (Lithobates sphenocephala utricularia) are in the family ranidae which is represented in Indiana by eight species. All Indiana ranids were formerly placed in the genus Rana, but have since been moved to the genus Lithobates. Its close relatives, the northern leopard frog (L. pipiens) and the plains leopard frog (L. blairi) are also found in Indiana. Southern leopard frogs are generally not found alongside northern leopard frogs in Indiana, but either species may co-occur with plains leopard frogs. There are clear morphological differences between larvae of the southern and plains leopard frog which makes the former better adapted for ponds and the latter well-adapted for sluggish streams, indicating that these two species may use different breeding habitat even when found in close proximity to one another.

Ecology: Habitat: 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.

Diet: Southern leopard frogs feed on various small invertebrates.

Reproduction and Life History: 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.

Call: The call is a cackling laugh that is repeated at irregular intervals.

Conservation: Unlike its northern counterpart, southern leopard frogs have 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.

Literature

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 39.1:91-96.

Brodman, R. 2003. Amphibians and Reptiles from Twenty-three Counties of Indiana. Proceedings of the Indiana Academy of Science 112.1:43-54.

Caldwell, J. P. 1986. Selection of Egg Deposition Sites: A Seasonal Shift in the Southern Leopard Frog, Rana sphenocephala. Copeia 1:249-253.

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

Hillis, D. M. and T. P. Wilcox. 2005. Phylogeny of the New World True Frogs (Rana). Molecular Phylogenetics and Evolution 34.2:299-314.

Hillis, D. M., J. S. Frost, and D. A. Wright. 1983. Phylogeny and Biogeography of the Rana pipiens Complex: A Biochemical Evaluation. Systematic Biology 32.2:132-143.

Hillis, D. M. 1982. Morphological Differentiation and Adaptation of the Larvae of Rana berlandieri and Rana sphenocephala (Rana pipiens Complex) in Sympatry. Copeia 1:168-174.

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

Ryan, T. J. and C. T. Winne. 2001. Effects of Hydroperiod on Metamorphosis in Rana sphenocephala. American Midland Naturalist 145.1:46-53.

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.

Distribution Map
Distribution map of Southern Leopard Frog (Lithobates sphenocephalus)
Photographs