Rana sylvatica: the Wood Frog

Identification: The wood frog is a small, brown frog easily distinguished by the dark mask around its eyes and the quack-like mating call made by the males in spring. Although it varies significantly in color from brown to tan to red-brown, its raccoon-like eye mask distinguishes it from all other North American species.

Where to find Wood Frogs: Wood frogs can be found in ponds during their brief springtime mating season, which occurs sometime between March and May, depending on the latitude of the population. They ususally congregate in small, temporary ponds, and the chorus of males can often be heard from some distance away. The male's call sounds remarkably like a duck's quack, and a chorus of calling males creates a constant, and loud, sound. The frogs will fall silent if the pond is approached, but the males are usually easily visible floating on the surface of the water. If approached with caution, they can be observed at quite close range. At any sudden movement, however, they will dart below the surface and hide in leaf litter, where they are hard to find. Within several minutes they re-emerge, and the chorus begins to resume. Pairs in amplexus (the male grasping the female in preparation for fertilizing her eggs) can sometimes be observed in ponds. Egg masses consist of several hundred eggs encased in a clear jelly, which often becomes obscured with green algae after the first week or so. The eggs are usually laid in large clusters at the edge of ponds; they are hard to tell apart from the eggs of other species of frogs. Tadpoles, which hatch about two weeks after the eggs are laid, have olive or brown backs flecked with black and gold. Their bluish-white bellies have an iridescent tint, and their tails are short, with high, transparent fins mottled with black.

During the rest of the year, wood frogs can be found in both coniferous and deciduous forests, sometimes a significant distance from water. They are especially likely to be active in the early morning, or after a heavy rain.

Range: wood frogs have the northern-most range of any North American frog, and are the only one to be found north of the Arctic Circle. Their range begins in north Georgia, extending from western Virginia west to Kentucky, the edge of Illinois, Minnesota, and part of North Dakota. Farther west, the border between Canada and the United States forms the approximate southern border of their range. They are found north into Alaska, Northwest Territories, and Quebec.

More information:

Species account
Reproduction
Natural History and Habitat
Taxonomic History
Freezing ability
Advertisement call
Useful References
List of museums with specimens available
Useful Links
Bibliography