General Adult Description: The Northern Leopard Frog is similar in appearance to the Plains Leopard Frog (Rana blairi). Adults often measure from between 2–4 inches (5.1–10.2 cm) in length. Adult Northern Leopard Frogs have a variable background color that can be tan, brown, or bright green and is covered in large dark blotches. A prominent white dorsolateral fold is continuous from the eye down to the hind legs. The ventral coloration is solid white. Adult males have an enlarged first digit on their forelimbs that is used to help grasp females during amplexus (breeding). Northern Leopard Frogs can easily be differentiated from Plains Leopard Frogs by the presence of unbroken dorsolateral folds (the Plains Leopard Frog has broken dorsolateral folds). Two different color phases of Northern Leopard Frogs exist: burnsi and kandiyohi (see photos). Burnsi phase Northern Leopard Frogs lack any spots and are just a bronze, tan, or light green color, but they still have the same overall body shape and dorsolateral folds as normal individuals do. Kandiyohi phase Northern Leopard Frogs are heavily mottled (lots more small dark blotches throughout), giving them a unique appearance.
General Larval Description: Tadpoles are usually greenish to brownish in coloration with few, faint dark markings. These tadpoles are robust in size, reaching lengths of 1.5–2 inches (3.8–5 cm). The intestinal coil is visible through the venter. Tadpoles of this species are difficult to discern from Plains Leopard Frog tadpoles but can be easily differentiated from American Bullfrog tadpoles that have a mottled venter and are covered in small black marks.
Call Description: Male Northern Leopard Frogs have a call that consists of a drawn-out rattling snore that lasts three or more seconds followed by several grunts or chuckled notes. The call often starts off soft then grows louder.
Behavior: Adults are primarily nocturnal and will consume a wide variety of invertebrates. During the day, individuals are often found along the shore in vegetation. When startled, individuals will jump into the water and often remain submerged for several minutes. During winter months, adults and juveniles bury into the mud at the bottom of deep aquatic habitats to avoid freezing.
Reproduction: Northern Leopard Frogs primarily breed from late May through June in South Dakota. Females lay eggs in large clumps often attached to vegetation. Tadpoles typically undergo metamorphosis in late July and August.
Habitat: Northern Leopard Frogs can be found at most aquatic habitats that occur in their range, including dugout ponds, wetlands, reservoirs, oxbow lakes. Individuals are primarily found at these aquatic sites, but during wet, humid nights individuals can disperse into upland habitats.
Species Range: Northern Leopard Frogs have a large distribution across much of the northern United States and Canada, including New England and Great Lakes states, the upper Midwest, and the Rocky Mountains south to New Mexico.
South Dakota Range: The Northern Leopard Frog can be found throughout the state.
South Dakota Status: This species is not listed by South Dakota Game, Fish and Parks.
Account written by Drew R. Davis