The wood frog is an amphibian and member of the Ranidae family of true frogs. Its scientific name is Rana sylvatica. These frogs are widely distributed throughout the Nearctic ecozone, from the Appalachian Mountains in the U.S. state of Georgia to Alaska. A black band stretches across their head, covering both eyes, and is one of their most identifiable features. Reproduction begins in early spring and lasts through most of May.
A terrestrial animal, the wood frog can be found in woodlands, usually near a water source. It can be found as far south as the Appalachian Mountains in Georgia, throughout much of the Northeastern United States, in nearly all of Canada, and most of Alaska. Among all species of amphibians, the wood frog is the only one to have been observed north of the Arctic Circle. Wood frogs hibernate through the winter by burying themselves in the top layer of soil or beneath leaves and are unique in their ability to survive the freezing temperatures of the season.
A wood frog’s blood and most of its tissues can freeze without damaging the frog. When spring arrives, if not frozen completely, they will thaw and return to their daily habits. Their average length is 1.4 to 3 inches (3.5 to 7.6 cm), and they usually weigh no more than .28 ounces (7.8 grams). The relatively large discrepancy in length between frogs is due to the larger size of female wood frogs compared to males.
Coloration is usually brown and tan, though grays and greens have also been noted. Males are more colorful than females, but regardless of color or sex, wood frogs can always be distinguished from other frogs by their so-called “robber mask,” a black stripe that stretches across both eyes to the ear drums. Dorsolateral ridges run the length of their backs, and males have swollen thumbs. The wood frog’s front feet are not fully webbed due to their predominantly terrestrial nature.
During reproduction, males will often find space near water and call to females to initiate mating, though calling is not necessary if a female is already present. Their call sounds similar to a duck quacking. After a male and female have undertaken amplexus, the female will often lay as many as 3,000 individual eggs, in a nearby body of water. Tadpoles undergo complete transformation into adult frogs in the span of two months. In two years they reach sexual maturity.