Northern leopard frog
Rana pipiens

Leopard frogs receive their name from the round to elliptical, light-edged blotches or spots randomly distributed over the back and sides (Fig. 31). The inside concealed surface of the thigh is immaculate white, not yellow as in the pickerel frog. This medium-sized frog ranges from 58-77 mm in total length when reproductively mature, with females averaging larger than males. During the mid-March or early April breeding season males have paired vocal sacs and stout forearms with swollen thumb bases.

Fig. 31. Northern leopard frog

• Leopard frogs have round to elliptical, light-edged blotches randomly arranged between the dorsolateral folds. The concealed surface of the femoral area is white, not yellow as in the pickerel frog.

• Note the paired vocal sacs in the photograph.

The leopard frog is also called the meadow frog or grass frog because it often wanders in meadows or fields away from water after the breeding season. Leopard frogs are more common in open areas than in heavily wooded habitats. As a rule of thumb, a blotched frog along a heavily wooded stream or around a woodland pond in northeastern Ohio is probably a pickerel frog, whereas one observed in a field away from a stream or pond is probably a leopard frog.

Leopard frogs hibernate on the substrate of ponds (but not buried in mud) and are active from mid-March through late October in Ohio. Breeding takes place in both permanent and temporary ponds or in sluggish sections of streams. Eggs are laid in large, flattened masses of 3000-6000 below surface and usually attached to vegetation (Fig. 30). The eggs are 1.7 mm in diameter but swell to 5 mm when hydrated. Tadpoles reach 65-83 mm in length before transforming, 70-110 days after egg laying. Recently transformed froglets of 17-28 mm total length can be seen beginning in July. Sexual maturity is achieved two to three years from the egg stage, and the expected longevity is six to nine years.

Fig. 30. Eggs of the leopard frog

• Eggs of the leopard frog are laid in large, flattened, globular masses of 3000-6000 below the surface of the water and are usually attached to vegetation.

• The eggs measure 1.7 mm in diameter when laid but soon swell to 5 mm upon hydration.

Leopard frogs are found throughout the state but have become rare east of Cleveland away from the lakeplain. Where leopard frogs are common, large choruses form in spring. The call, a guttural, vibrant snore or belch lasting two or three seconds has little carrying power (Fig. 32).

	Fig. 32. Call of the leopard frog

Call of the leopard frog (76 seconds, 599 KB)
Excerpt (9 seconds, 76 KB)

• The call is a vibrant, rattling snore or belch lasting two to three seconds interspersed with occasional woodfrog-like clucking grunts.

• The call in the spectrogram has a dominant frequency of 1325 Hz and a call duration of 2.7 seconds.

• The broad band around 3000 Hz, above the pulses of the leopard frog, was produced by a mixed chorus of spring peepers and western chorus frogs that are heard loudly in the audio clip.