Lithobates septentrionalisMink Frog

Geographic Range

The Mink frog is found in Minnesota, Wisconsin, northern Michigan, and in northern New York. They are also found in Canada ranging from Quebec to the southeastern portions of Manitoba (Mossman et al 1999).

Habitat

They enjoy permanent wetlands since they are primarily aquatic creatures, but they will move on the land if the conditions are damp and covered in heavy forest (Reptiles & Amphibians of Minnesota 1999).

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

Physical Description

Adult length: 4.8 to 7.6 cm

Their backs are green, olive, or brown with irregular blotches. The dorsolateral folds are poorly developed or sometimes even absent in this species. Webbing extends to its fifth digit on its hind feet. Their undersides are whitish or yellowish. They have round spots or stripes on the upper parts of their hind legs. There is some sexual dimorphism. Male Mink frogs have larger tympanums than females. Males also often have a bright yellow throat compared to the white or pale yellow throat of the female. The tadpoles prior to metamorphosis have a dorsal coloration that is green, olive, or brown with scattered spots. Tadpoles also have a yellowish underside with a long pointy tail (Harding 1997).

Development

Reproduction

Mink frogs do not begin to breed until late May and usually end in August. Males vocalize while floating on the water (Reptiles & Amphibians of Minnesota 1999). In the Great Lakes area the eggs are deposited in June and July. An average female will lay between 500 and 4,000 eggs in one cluster. The cluster may be laid up to a meter under the water and will eventually sink to the bottom before hatching. The tadpoles are in the larvae stage for about a year before metamorphosing into froglets. It takes the female about two years to become sexually mature whereas it takes the males only about a year to become mature (Harding 1997).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    730 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    547 days
    AnAge

Lifespan/Longevity

  • Range lifespan
    Status: wild
    6 (high) years
    AnAge

Behavior

Mink frogs are usually found where there are a lot of water lilies. They use these lilies as a way of protection from predators (Mossman et al 1999). The Mink frog produces an odor when handled.

Food Habits

Mink frogs have a largely aquatic diet. They feed mainly on spiders, snails, dragonflies, whirligig, and beetles, all of which can be found on the surface of the water or on lily pads. Mink frog tadpoles feed mainly on algae (Harding 1997).

Conservation Status

Reports have stated that Mink frog populations are declining, but they are not in serious trouble yet. The decline might be due to competition from the green frog, a larger, ubiquitous species (Harding 1997).

Contributors

Karri Kauzlarich (author), Michigan State University, James Harding (editor), Michigan State University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

References

Harding, J. 1997. Amphibians and Reptiles of the Great Lakes Region. MI: The University of Michigan Press.

LeClerc, J. "Reptiles & Amphibians of Minnesota: Mink Frog" (On-line). Accessed November 17, 1999 at http://earthvision.asu.edu/~joe/Minnesota-Herpetology/frogs_toads/Mink_frog.html.

Mossman, M., J. Sauer, G. Gough, L. Hartman, R. Hay. 1998. "The Wisconsin Frog and Toad Survey home page" (On-line). Accessed November 17, 1999 at http://www.mbr-pwrc.usgs.gov/wifrog/from.htm.

Think Quest, "Mink Frogs" (On-line). Accessed November 17, 1999 at http://library.advanced.org/11034/index.htm.