General Adult Description: The Wood Frog is a small species of frog that reaches maximum sizes from 2–3 inches (5.1–7.6 cm) in length. The background coloration is typically tan to light brown and can have hues of reddish-brown or black. Two prominent dark patches, one over each eye, are present and extend through the tympanum. Two dorsolateral ridges are present and can be various colors including rust, tan, or brown. A white stripe occurs along the upper lip that terminates near the forelimb and faint dark stripes can be visible on the upper thigh. Ventral coloration is white. Adult males have an enlarged first digit on their forelimbs that is used to help grasp females during amplexus (breeding). Wood Frogs can easily be differentiated from other species of frogs by the present of the dark mask that extends from the eye through the tympanum.
General Larval Description: Tadpoles are usually brown in body coloration, with clear tail fins that end in a sharp point. The dorsum is light and a light line in present along the edge of the mouth.
Call Description: Male Wood Frogs have a call that is a soft, duck-like cackling, that is often in a rolling series. You can listen to a chorus of Wood Frogs calling here: Rana sylvatica (SD: Roberts Co.)
Behavior: Adults are primarily nocturnal and will consume a wide variety of invertebrates. These frogs generally have a small home range and can be found foraging or resting under logs, leaves, and rocks. Wood Frogs overwinter under only a couple inches of organic material (leaf litter). Because these habitats reach sub-freezing temperatures, the Wood Frog has a remarkable ability to survive by producing large amounts of glucose, which mitigates the damaging effects of freezing and dehydration.
Reproduction: Wood Frogs are early breeders similar to Boreal Chorus Frogs, however, adults only breed over a relatively short period in South Dakota, typically from mid to late April. Females will lay from 1,000–3,000 eggs in large clumps that are frequently attached to vegetation. Eggs hatch in three weeks and tadpoles typically mature in six to nine weeks.
Habitat: Wood Frogs are often associated with vernal pools in deciduous forests across most of their range. Adults can be found away from vernal pools under moist leaf litter or logs after the breeding season. In South Dakota, they can be found in prairie wetlands, often away from deciduous forests or riparian corridors.
Species Range: This species can be found throughout most of New England, across the northern Midwest and farther north into Canada. This is the only species of amphibian to be present within the Arctic Circle.
South Dakota Range: The Wood Frog can only be found in the extreme northeastern corner of the state.
South Dakota Status: This species is monitored by the South Dakota Natural Heritage Program. Any sightings of this species should be reported to South Dakota Game, Fish and Parks (report observation).
Account written by Drew R. Davis and Cyrus J. Sorenson