Adults are 37 to 83 mm in length, and females are larger. Prominent dorsolateral folds extend from the bead to near the vent. The lateral edge of each fold is darker than the medial edge. The smooth to moderately rough back often has short folds between the dorsolateral folds. Toes are webbed, with tow or three phalanges of the fourth toe free of the web. Dorsal coloring may be gray to tan to vivid reddish brown , and is coppery or golden in some individuals. Females are usually more reddish. Black or dark brown markings may be present on the back and sides, and many northern and western specimens have a middorsal white line. A conspicuous dark brown or blackish mask extends from the snout to just behind the tympanum. The white venter is sometimes darkly mottled on the throat and breast, and is smooth except for a granular region under the thighs. There also is a prominint dark marking in the pectoral region. The tympanum is smaller than the eye. Males have paired vocal sacs, stout forelegs, and a "thumb" and enlarged webbing between the toes during the breeding season.

This species occurs in northern North America from Alaska to Labrador (Chubbs and Phillips 1998), south to New Jersey, northern Georgia, and northern Idaho; spotty distribution south to northern Colorado in Rocky Mountains; also disjunctive populations in Arkansas-Missouri (Stebbins 1985, Conant and Collins 1991). Ranges farther north than any other North American amphibian.

Wood frogs, Lithobates sylvaticus, are only native to the Nearctic region. They are found from northern Georgia and in isolated colonies in the central highlands in the eastern to central parts of Alabama, up through the northeastern United States, and all the way across Canada into Alaska. They are found farther north than any other North American reptile or amphibian. They are the only frogs found north of the Arctic Circle.

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Range extends from northern Alaska across boreal Canada to Labrador (Chubbs and Phillips 1998), and south to New Jersey, northern Georgia, and northern Idaho; spotty distribution south to northern Colorado in Rocky Mountains (Hammerson 1999); disjunct populations also occur in Arkansas-Missouri (Stebbins 1985, Conant and Collins 1991). Range extends farther north than that of any other North American amphibian.

R. sylvatica is the only cold-blooded tetrapod known to occur north of the Artic Circle in the Western Hemisphere. It is found over most of Alaska and Canada and over the northeastern part of the United States. Its northern limit lies along the treeline from Alaska to Labrador. Its range extends southward coastally to Maryland and in the Appalachian Mountains to northern Georgia and northeastern Tennessee. The southern edge of the range passes northward through southern Illinois and the norteastern corner of South Dakota, the noreastern half of North Dakota, northern Idoah and westward in Canada to near the Pacific coast. Isolated populations are found in souteastern Wyoming and northern Colorado, in eastern Kansas, in the Ozark Mountains of Arkansas and Missouri, and perhaps in areas north of the Artic tree line.
It is a terrestrial species, often found in or near moist wooded areas, sometimes considerable distances from open water.

Wood frogs range from 3.5 to 7.6 cm. Females are much larger than males. This species exhibits a number of color morphs, usually browns, tans and rust, but can also be found in shades of green and gray. In all cases however, they can be distinguished by a black patch that extends over the tympanum to the base of the front limb. It is this characteristic that causes them to be referred to as the frog with the "robber's mask". They are also known to have a white spot on the upper lip. Most specimens have a light yellowish brown middorsal lateral fold. The underparts of the frogs are yellowish and sometimes greenish-white, with male frogs having more brilliant colors on the ventral aspect of the legs.

Range length: 3.5 to 7.6 cm.

Other Physical Features: ectothermic ; bilateral symmetry

Sexual Dimorphism: female larger; male more colorful

Average mass: 7.88 g.

Average basal metabolic rate: 0.00416 W.

Length: 8 cm

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Methy River (= Methy Lake ?), Saskatchewan, Canada, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: No Further Locality Data, Canada, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Moose River, Ontario, Canada, North America

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1968
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Sex/Stage: Female;
Preparation: Ethanol
Year Collected: 1953
Locality: Murphy, Cherokee, North Carolina, United States, North America
Elevation (m): 462 to 462

Holotype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Sex/Stage: Male;
Preparation: Ethanol
Year Collected: 1953
Locality: Murphy, Cherokee, North Carolina, United States, North America
Elevation (m): 462 to 462

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1965
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1962
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1962
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1962
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1962
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1962
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1962
Locality: Centennial, 8 mi NW of, Albany, Wyoming, United States, North America

Holotype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1968
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1968
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1968
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1968
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Paratype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1968
Locality: Fox Park, 0.25 mi N of, Albany, Wyoming, United States, North America
Elevation (m): 2743 to 2743

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Nulato River, Yukon-Koyukuk, Alaska, United States, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1883
Locality: Lake Alloknagik (= Lake Aleknagik), Dillingham, Alaska, United States, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1883
Locality: Lake Alloknagik (= Lake Aleknagik), Dillingham, Alaska, United States, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1883
Locality: Lake Alloknagik (= Lake Aleknagik), Dillingham, Alaska, United States, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1883
Locality: Lake Alloknagik (= Lake Aleknagik), Dillingham, Alaska, United States, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1883
Locality: Lake Alloknagik (= Lake Aleknagik), Dillingham, Alaska, United States, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Moose River, Ontario, Canada, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Saint Catherine's, Ontario, Canada, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Moose Factory, Canada, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1841
Locality: Puget Sound, Locality In Multiple Counties, Washington, United States, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Moose River, Ontario, Canada, North America

Syntype for Rana sylvatica
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Locality: Great Slave Lake, Big Island, Mackenzie District, Northwest Territories, Canada, North America

Habitat and Ecology

Systems

• Terrestrial
• Freshwater

Wood frogs are common in woodlands across their range. They are most commonly found in woodlands in the summer, under stones, stumps and leaf litter in the winter, and wood ponds in the breeding season.

Habitat Regions: terrestrial

Terrestrial Biomes: forest

Comments: Wood frogs inhabit various kinds of wooded habitats, including the edges of ponds and streams and willow thickets and grass/willow/aspen associations. In winter or when otherwise inactive, they hide in logs, humus, leaf litter, or under logs and rocks. In winter upland habitat in eastern Massachusetts, adult males greatly outnumbered adult females in areas close to (within 65 meters of) breeding pools; two wintering areas were not used during the summer active period (Regosin et al. 2003).

Eggs are laid and larvae develop usually in vernal pools and other small fish-free ponds, temporary or permanent, in wooded (usually) or open areas. In the Shenandoah Mountains, breeding adults were 100% faithful to the ponds in which they first bred; approximately 18% of the juveniles dispersed to breed in ponds other than the one of origin (Berven and Grudzien 1991). Experiments and field observations by Hopey and Petranka (1994) indicate that adults are able to assess the presence of fishes in ponds and may change breeding sites accordingly to avoid those with predatory fishes. In northern Minnesota, successful reproduction in acidic bog water either does not occur or is a rare event (Karns 1992).

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Migrates up to several hundred meters between breeding ponds and nonbreeding terrestrial habitats. In Maine, adult and juvenile R. sylvatica readily traveled in excess of 300 m from their pools of origin (Vasconcelos and Calhoun 2004). Bellis (1965) determined that adult and juvenile R. sylvatica in a peat bog had traveled at least 410 m from the nearest breeding pool. Berven and Grudzien (1990) found that dispersing R. sylvatica juveniles traveled an average of 1,208 m from their natal pools.

Usually remains in an area <100 m across after leaving the breeding pond.

In the Shenandoah Mountains, dispersal data indicated than ponds separated by a distance greater than 1000 m should experience little gene flow (Berven and Grudzien 1991). In Minnesota, populations were very similar in allelic frequencies, even at distances greater than several kilometers (Squire and Newman 2002). However, sample sizes and number of loci examined were small, and genetic patterns do not necessarily reflect movement distances.

See Mazerolle (2001) for information on movement patterns in fragmented peat bogs in New Brunswick.

Wood frogs eat a variety of insects and other small invertebrates, especially spiders, beetles, bugs, moth larvae, slugs and snails. Larvae consume algae.

Animal Foods: insects; terrestrial non-insect arthropods; mollusks; terrestrial worms

Plant Foods: algae

Primary Diet: carnivore (Eats non-insect arthropods); herbivore (Algivore)

Comments: Metamorphosed frogs eat various small invertebrates, mostly terrestrial forms. Larvae eat algae, plant tissue, organic debris, and minute organisms in water; capable of eating amphibian eggs and hatchlings and invertebrates as well (Petranka et al., Copeia 1994:691-697; Petranka and Kennedy 1999; Baldwin and Calhoun, 2002, Herpetol. Rev. 33:44-45).

Wood frogs provide important food for many animals as well as helping to control insect populations.

Wood frogs are food for a wide variety of birds, such as herons, and snakes.

Known Predators:

• herons (Ardeidae)
• snakes (Serpentes)

Rana sylvatica preys on:
detritus

Based on studies in:
USA: Michigan (Lake or pond)

This list may not be complete but is based on published studies.

Rana sylvatica is prey of:
Dytiscus
Ambystoma tigrinum

Based on studies in:
USA: Michigan (Lake or pond)

This list may not be complete but is based on published studies.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: > 300

Comments: This species is represented by thousands of occurrences (subpopulations).

>1,000,000 individuals

Comments: Total adult population size is likely more than 1,000,000.

Local tadpole density may exceed 15,000/cubic meter of water (Biesterfeldt et al., Copeia 1993:688-695).

In eastern Massachusetts, density in wintering areas near breeding pools ranged from 0 to 6.3 frogs per 100 sq m (Regosin et al. 2003).

As stated in the reproduction section, males actively search for females during the breeding season; however, they are unable to tell males from females by sight. Sex recognition is accomplished by the males embracing other frogs (regardless of sex) and releasing those that are not fat enough to be females full of eggs. If a male is embraced he lets out a loud croak. A female will also be let go if spawning has already occurred, because of her thin nature.

The call of a wood frog is often compared with the sound of a quacking duck or a squawking chicken. They tend to repeat the call several times in a row when trying to attract females.

Communication Channels: acoustic

Perception Channels: visual ; tactile ; acoustic

Comments: Inactive during cold season in north and at high elevations. Primarily diurnal in northwest and in spring at high elevations, though breeding activities may occur at night as well. Most active in summer in damp conditions.

Wood frogs spend the winter on land and sometimes endure freezing of their blood and other extracellular body fluids. With warming weather they thaw out and proceed with their lives uninjured.

The eggs have a very good tolerance of temperature and those that are laid in water that afterwards freezes are not killed. They develop once temperature rises again. The length of incubation for these eggs varies depending on temperature. If laid in cold waters, then development is slow, and lasts at least a month; if, however, the eggs are laid in waters with a higher temperature, the development is much quicker, lasting only 9 to 10 days. After about a week to a month the eggs hatch and tiny, almost black, tadpoles emerge. The tadpoles are about 38 to 48 mm in length. It can take them a further 61 to 115 days to undergo metamorphosis and become froglets. The froglets are usually very small. They develop into full grown, sexually mature, adults generally within the next 2 years.

Development - Life Cycle: metamorphosis

No information is available on the lifespan of wood frogs.

Range lifespan

Status: wild: 3 (high) years.

Maximum longevity: 5 years Observations: The wood frog is fascinating because it may spend winter with over 50% of its body frozen and no heartbeat or breathing. Their maximum longevity could be underestimated due to lack of precise data. In the wild these animals rarely live more than 3 years (http://www.pwrc.usgs.gov/neparc/).

Even though males do call, they generally have a non-calling behavioral mating tactic. The males move around the breeding area actively searching for a female. Occasionally this results in a male to male fight for a female already in amplexus. Both of these reproductive strategies are typical of explosive breeders. In an explosive breeding situation the success of the male in finding an available and willing female is strictly density-dependent.

Wood frogs are seasonal breeders that begin very early in the spring. They are the first frogs to begin calling, often before the ice is completely off the breeding ponds. These frogs mate as early as March and the breeding season will last until the beginning of May at the very latest. While the calls of these male frogs are very abundant in season, once the breeding season is over you will no longer hear their calls. During the time of the calls however, they create a duck-like quacking sound, described by some as a "lot of chuckling". Once mate choice is accomplished and amplexus occurs, the female will lay a globular egg mass, most often in the deepest part of a pond. Each egg mass measures about 10 to 13 cm in diameter, and can contain from 1000 to 3000 eggs. The masses can either be attached to a twig or grasses, or they can be free standing. After about a week or so the egg mass begins to flatten out, allowing it to rest on the surface of the water. The jelly around the eggs becomes green in color creating a great camouflage. The mass then looks like a floating mass of green pond scum. The green color of the jelly is due to the presence of numerous small green algae. Tadpoles undergo complete metamorphosis in 2 months and reach sexual maturity in approximately 2 years.

Wood frogs have a great deal of selective pressures on both sexes. A larger female is often correlated with a stronger fecundity, for larger females are known to produce larger clutches. This may lead to a higher survival rate in offspring. On the other hand, male mating success is also positively size-dependent, allowing larger females the ability to "win" the male.

Breeding interval: Wood frogs breed once yearly.

Breeding season: March to May

Range number of offspring: 1000 to 3000.

Range time to hatching: 9 to 30 days.

Average age at sexual or reproductive maturity (female): 2 years.

Average age at sexual or reproductive maturity (male): 2 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous

Average age at sexual or reproductive maturity (male)

Sex: male: 547 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 912 days.

Female wood frogs provide their eggs with yolk before laying them. Once the eggs are laid and fertilized, the parents abandon them.

Parental Investment: pre-fertilization (Provisioning, Protecting: Female)

Wood frogs emege from dormancy on land and migrate up to several hundred meters to breeding pools, where they breed explosively in winter or early to late spring, with the latest breeding in the far north or high elevations. Eggs are laid in winter in the Ozarks and southern Appalachians, late February in Maryland, February-March in Missouri, mainly March in southern New England, mostly late May-early June in Colorado; mean date of breeding increases 5.2 days per degree of latitude (Guttman et al. 1991). In a particular pool, most egg deposition occurs over a brief period of several days. Eggs hatch in about 1-2 weeks. Larvae metamorphose into small frogs in spring or summer, within a few months after egg deposition. The period from fertilization to emigration from the pond averages about 11 weeks in Michigan, 13 weeks in Maryland, 15-16 weeks in Virginia (Riha and Berven 1991). In Maryland, 20,262 juveniles emerged from a single pond in one year (Berven 1988). Individuals become sexually mature in 2-3 years (in Maryland, females mainly in 2 years, rarely in 1 year; Berven 1988).

Antifreeze protects from cold: North American wood frog
 

The blood of the North American wood frog helps it survive freezing temperatures for as long as seven months via a natural antifreeze.

     
  "The North American wood frog (Rana sylvatica), for instance, can survive freezing temperatures for as long as seven months, relying on a natural antifreeze in its blood to protect its organs." (Morell 2001)
  Learn more about this functional adaptation.

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 11
Species: 69
Species With Barcodes: 1

Though wood frogs are fairly common in most areas of appropriate habitat, loss of habitat to agriculture and suburban development has put them on the list of "species of special concern" in some areas.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Reasons: Widespread in North America, abundant in many areas; not of conservation concern in the vast majority of the range, though many local populations have declined as a result of agricultural and residential development and intensive timber harvesting practices.

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Very narrow to narrow.

Population

Population Trend

Global Short Term Trend: Relatively stable (=10% change)

Comments: Population trend is unknown but probably stable to slightly declining.

Global Long Term Trend: Increase of 10-25% to decline of 30%

Comments: Likely relatively stable in extent of occurrence, likely less than 25% decline in in population size, area of occurrence, and number/condition of occurrences.

Major Threats

Comments: This species is not threatened overall, but threats to local populations include intensive timber harvesting practices that reduce canopy closure, understory vegetation, uncompacted forest litter, or coarse woody debris (moderately to well-decayed) in areas surrounding breeding sites (deMaynadier and Hunter 1999). Negative impacts of intensive timber harvesting extend at least 25-35 meters into uncut forest (deMaynadier and Hunter 1998).

Wood frogs are not likely to be at risk from present acidification inputs in the Rocky Mountains (Corn and Vertucci 1992).

Conservation Actions

Restoration Potential: Readily colonizes newly constructed suitable breeding habitat (Hopey and Petranka 1994). See Guttman et al. (1991) for information on a population that was successfully reintroduced into a portion of St. Louis County, Missouri.

Global Protection: Very many (>40) occurrences appropriately protected and managed

Comments: This species occurs in many national parks, wildlife refuges, and wilderness areas, however, protection of land may not protect the species where declines may be caused by acidification, ozone depletion, disease, or other causes.

Wood frogs, along with other amphibians, are great indicators of environmental health. Recent population declines in species of amphibians should be of great concern. Wood frogs may also help to control pests.

Positive Impacts: research and education; controls pest population

Comments: Collins (1990) listed Colorado-Wyoming populations as a separate species, "Rana maslini," but this taxon is not recognized by most authorities (see Porter 1969, Bagdonas and Pettus 1976, Hammerson 1999, Crother et al. 2000, Frost 2010).

See Zeyl (1993) for information on allozyme variation and divergence among some populations in the central part of the range.