green frog

Green frog is a mid-sized, 2¼″ to 3½″ long, true frog. It is the second largest frog in Minnesota after only the American bullfrog.

The back (dorsal surface) is smooth to moderately rough and green or brownish-green. It usually has small, irregular, dark spots and is usually brighter colored toward the front. Prominent folds on each side of the back (dorsolateral folds) extend from just behind the disk-shaped membrane covering the ear opening (tympanum) to just over halfway down the back. Another ridge begins just behind the eye and curves downward behind the tympanum.

The side of the face is green. The tympanum on males is larger than the eye. On females it is about the same size as the eye.

The belly is white and often has dark mottling on the throat, jaw, and under the hind legs. Males have a single inflatable vocal sac. It is internal, not visible. The throat on mature males is yellow.

The hind legs have dark horizontal bands. The webbing on the hind feet extends to the tips of the first through third toes, to the second joint on the fourth toe, and not quite to the tip on the fifth toe.

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The description above refers to the northern subspecies, green frog (Lithobates clamitans melanota).

2¼″ to 3½″

The mating call is usually described as the sound of plucking a loose banjo string, “plunk”. The call is a single note but is often repeated. It can be heard from May through July. No other frogs in Minnesota sound similar.

American bullfrog (Rana catesbeiana) is larger. It lacks a dorsolateral ridge.

Semi-permanent or permanent wetlands: large marshes, streams, deep ponds, larger lakes, and roadside ditches.

Green frogs are often seen on a shore within one quick leap to a body of water. They hunt by sitting still and waiting for prey to cross their path.

5 to 10 years

Adults emerge from hibernation from April to June. Males call from May to July. Mating takes place in late spring or early summer. After mating, the female lays a single floating mass of 1,000 to 5,000 eggs in water. The mass is flat and about 12″ in diameter. The eggs hatch in 3 to 7 days, depending on temperature. Most tadpoles overwinter and metamorphose into adults the following spring. Males become sexually active one year after metamorphosis, females 2 or 3 years. Adults hibernate in the mud under debris, under stones, or under water that does not completely freeze.

Organic debris, algae, plant tissue, and minute organisms in the water.

Insects, crayfish, fish, snails, small snakes, other frogs—any animal that will fit in its mouth.

Sources

4, 7, 14, 24, 29, 30, 73, 76, 78.

Common in eastern United States. At the western edge of its range in Minnesota.

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 clamitans.

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 clamitans.

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 clamitans becomes Aquarana clamitans. Amphibian Species of the World uses the name Aquarana clamitans.

Some authorities, including AmphibiaWeb and NatureServe, recognize two subspecies: the southern subspecies, bronze frog; and the northern subspecies, green frog, also called northern green frog.

… from our pond

Male

Male

Green Frog (Rana clamitans melanota)
Andree Reno Sanborn

Rana clamitans (Green Frog)
Allen Chartier

Rana clamitans (Green Frog)
John Clare

Green Frog
TheSnakeLibrary

Northern Green Frog (Rana clamitans melanota)
WisCBMnetwork

Green frogs - Rana clamitans (HD)
Bart B. Van Bockstaele

Luciearl
8/16/2024

Location: Cass County

Location: St Michael, MN

… from our pond

Location: Near Courthouse Lake in Chaska, MN. (Carver County, MN.)

Location: Crow Wing County, Deerwood