wood frog

LC - Least Concern

N5 - Secure

S5 - Secure

not listed

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.

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, 13, 14, 24, 29, 73.

Common

Genus
In 2006 most North American true frogs were transferred from the genus Rana to the genus Lithobates by Frost et al. The change was controversial and was not accepted by all authorities. In 2008 and 2009 the change was rejected by Stuart, Pauly et al., and by other systematic reviews. 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.

Species
Most sources, including GBIF, ITIS, NatureServe, iNaturalist, and Amphibian Species of the World, use the name Lithobates sylvaticus. A few, including NCBI, UniProt, and AmphibiaWeb, use the name Rana sylvatica. AmphibiaWeb suggests using the original name followed by the subgenus name in parentheses. However, the correct placement of this species has not been determined. Rana sylvatica is the only North American Rana species that is not classified into a subgenus.

Wood Frog...

Taken in the woods near a creek on a trail near Twin Valley, Mn. in Norman county on 5-26-19..neat frogs they are...

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

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