wood frog

Wood frog is an easily recognized, medium-sized, terrestrial frog. It is 1½″ to 3¼″ long at maturity. Females are much larger than males.

The back (dorsal surface) is smooth to moderately rough. Prominent folds on each side of the back (dorsolateral) extend from the head to near the vent. The folds are light on top, dark on the sides. There are often additional short folds on the back between the dorsolateral folds.

The color varies. It is usually tan or brown, sometimes gray, reddish-brown, or yellowish-green. Females are usually more reddish than males. The back and sides may have dark mottling.

The belly (venter) is white, yellowish-white, or greenish-white and often has dark mottling on the throat and breast. There is a prominent dark mark on each side of the chest near the forelegs (pectoral region).

A prominent dark face mask extends from the snout to just behind the ear covering (tympanum). The tympanum is smaller than the eye. The upper lip is white.

The back legs have horizontal bands that may be dark or faint. The feet are webbed. On the fourth toe two or three joints are free of the webbing. Males have larger “thumbs” and stouter forelegs.

1¼″ to 2⅜″

A short croak repeated several times. Often compared to the quacking of a duck.

The prominent dark face mask, often referred to as a robber’s mask, on a brown frog is a unique identifying characteristic. No other species is similar in overall appearance.

Moist wooded areas, ponds in woods and prairies.

Wood frogs are territorial. Territory size is usually about 100 square meters.

Summer months are spent in moist woods or wooded swamps, bogs or ravines. In late fall the frogs migrate to nearby upland areas to find a site to overwinter.

3 to 4 years

Breeding is explosive. It occurs from late March to late April after the first warm spring rains, often before ice is completely off the pond. Males do not defend territories at this time but frantically swim after and grab other individuals hoping to find a receptive female.

After breeding, the female will deposit 300 to 1,000 eggs in a mass (clutch) loosely attached to emergent vegetation usually near the clutches of other females. Communal egg laying is thought to raise the temperature of the of the communal mass promoting faster development and to protect the inner eggs from leeches and other predators. Metamorphosis occurs at 65 to 130 days. The tadpole is 2¾″ to 2⅜″ long preceding metamorphosis.

Adults overwinter under the shelter of a log, rock, bark, or leaf litter. They are freeze tolerant and can survive multiple freeze-thaw cycles. Glycerine is produced preventing the formation of ice crystals in vital organs.

Males typically live 3 years, females 4 years.

Algae, decaying organic matter, eggs and embryos of some salamanders

Spiders, beetles, bugs, moth larvae, slugs, snails, and other insects and small invertebrates.

Sources

7, 14, 24, 29, 30, 73, 78.

Biodiversity occurrence data published by: Minnesota Biodiversity Atlas (accessed through the Minnesota Biodiversity Atlas Portal, bellatlas.umn.edu, 6/5/2025).

Common

Genus
In 2006, Frost et al. transferred most North American true frogs from the genus Rana to Lithobates, a controversial decision initially met with resistance. While Stuart, Pauly et al., and other systematic reviews rejected the change in 2008 and 2009, the transfer has since gained near-universal acceptance by 2024. Amphibian Research and Monitoring Initiative (ARMI), Catalog of Life, GBIF, ITIS, NatureServe, NCBI, and UniProt, all use the name Lithobates septentrionalis.

In 2016, a consortium of Rana researchers from Europe, Asia, and North America showed that transferring the species to Lithobates caused problems of paraphyly in other genera. In that same year, Yuan et al. returned all North American true frogs to the genus Rana, using subgenera for all of the well-defined species groups within Rana. AmphibiaWeb uses the name Rana septentrionalis.

A recent article (Dubois, Alain et al., 2021) proposed a new “phylogenetic taxonomy and nomenclature” of extant amphibians (subclass Lissamphibia). In the proposed taxonomy, the subgenus Aquarana is raised to full species rank, and Lithobates septentrionalis becomes Aquarana septentrionalis. Amphibian Species of the World uses the name Aquarana septentrionalis.

Wood Frog
Andree Reno Sanborn

Rana sylvatica (Wood Frog)
Allen Chartier

Wood Frog
Nick Scobel

Wood Frog (Rana sylvatica)
WisCBMnetwork

Time-lapse video of a wood frog (Rana sylvatica) thawing.
The Company of Biologists

Mating Wood Frogs, Rana sylvatica
mfb99

Location: Lebanon Hills Regional Park, near the stream that flows into Schulze Lake

Location: near Twin Valley, Mn. in Norman county

Taken in the woods near a creek on a trail ... neat frogs they are...

Location: Mound, MN

Location: Vadnais Heights, MN

This frog has been helping with my landscaping and is happy we are done.

Location: Hemlock Ravine SNA

Location: Pennington Co Mn