mink frog

Mink frog is a medium size frog, 1¾″ to 3″ long at maturity.

The background color is olive-brown to green. The back and sides are covered with dark brown spots or mottling. The chin, throat, and belly are yellowish-white, and may have gray spotting or mottling. The skin is smooth, not warty. When rubbed the skin emits a mink-like odor that has been compared to rotting onions. Raised ridges (dorsolateral folds) on the back, if present, are usually weakly developed. Few individuals have prominent dorsolateral folds.

The disk covering the ear opening (tympanum) in males is larger than the eye. In females it is the same size or slightly smaller than the eye.

The hind feet has a broad web covering all of the toes, with only the tip of the fourth toe free.

1¾″ to 3″

Green frog (Lithobates clamitans) always has well-defined dorsolateral folds on the back. The hind feet are only partially webbed. The skin does not produce a rotting onion odor when rubbed.

Lakes, ponds, slow areas of rivers, deep bogs.

Adults can often be seen sitting on lily pads.

Males: 3 years

Females: 4 years

Between late May and August the female lays a mass of 500 to 4,000 eggs under water on the submerged stem of an aquatic plant. The egg mass often detaches and sinks to the bottom. The amount of time the eggs take to hatch is variable.

When the egg hatches a tadpole emerges. Some tadpoles metamorphose into froglets after about one year, others require two years. At the time of metamorphosis the froglets are almost 60% of their final adult size.

To avoid freezing, overwintering tadpoles and adults hibernate in the mud at the bottom of the same water they inhabited the rest of the year. They enter hibernation in late September and emerge in late April or early May.

Most mink frogs live only 1 or 2 years after metamorphosis. Males sometimes survive 3 years, females sometimes 4 years.

Algae

Spiders, snails, dragonflies, whirligig and other beetles, earthworms, and other invertebrates.

Sources

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

Biodiversity occurrence data published by: Minnesota Biodiversity Atlas (accessed through the Minnesota Biodiversity Atlas Portal, bellatlas.umn.edu, 6/4/2025).

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.

Rana [Lithobates] septentrionalis
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