Pickerel frog
Rana palustris

Fig. 28. Pickerel frog

Pickerel frogs and leopard frogs are the two species of ranids in Ohio that are characteristically large-spotted or blotched. Blotches are scattered along the flanks or sides in both species, but their shape and arrangement between the dorsolateral folds is of utmost importance to their identification. In pickerel frogs the chocolate-brown blotches are rectangular and are arranged in two rows (Fig. 28), whereas they are elliptical and randomly dispersed in leopard frogs.

The old adage "a bird in the hand is worth two in the bush" applies here in trying to distinguish between the pickerel and leopard frogs. If in doubt, capture the animal – not an easy undertaking because both species are swift, long jumpers. Once caught, the identification can be made by checking the color on the inside concealed surface of the thigh; in pickerel frogs it is bright yellow or yellow orange while in leopard frogs it is brilliant white.

• Dark, rectangular blotches on the back of the pickerel frog are arranged in two rows between the dorsolateral folds.

• Concealed surfaces of the femoral area are yellow or orange.

Pickerel frogs often wander some distance from streams, but they prefer rocky, cool, wooded ravines streams, seeps and springs found in the eastern part of Ohio. They emerge from hibernation at the bottom of ponds or streams and become active in mid-March and remain so through late October. Breeding activity extends from late March through early May and usually takes place as leopard frogs are finishing reproductive activities for the year. The nearly spherical masses of 700-3000 eggs are laid in permanent or temporary ponds attached to branches below the surface. When laid, the eggs average 1.6 mm in diameter, but the two envelopes soon swell to 4 mm. Transformation occurs in June through August, 87-95 days after the eggs were laid, and small frogs 19-26 mm in length can then be located under rock slabs or beside creeks and ponds. Sexual maturity is reached in two years from oviposition (egg laying).

The skin secretions are particularly irritating to people and toxic to some predators. Many frog-eating snakes will not eat pickerel frogs. Herpetologists soon learn not to place other species of amphibians in the same container with pickerel frogs because the toxins will soon kill the other species.

Pickerel frogs range in size from 45-75 mm as adults and females tend to be larger. Males have paired vocal sacs, stout forearms, and swollen thumbs. Their descending snore-like calls have little carrying power (Fig. 29).

	Fig. 29. Call of the pickerel frog

Call of the pickerel frog (60 seconds, 470 KB)
Excerpt (11 seconds, 87 KB)

• The call of the pickerel frog consists of descending, drawn-out, snore-like sounds that have little carrying power.

• The dominant frequency of the call illustrated is 2100 Hz, and the call duration is 1.5 seconds.

• The broad band around 3000 Hz, above the pulses of the pickerel frog, was produced by a constant chorus of spring peepers in the background. The chorus of peepers is very evident in the audio clip.