Mink frog Ryan Bolton

Mink Frog
(Lithobates septentrionalis)

Other names: Rana septentrionalis

This frog has a pungent, musky odour, like that of a mink.

Characteristics

The mink frog is medium sized, olive to brown in colour and may have dark spots or mottling on the sides and hind legs, which have no dark bands. The belly is yellowish and the dorsolateral folds (folds of skin running down each side of the back) may be prominent, partial or absent. This species has large tympani (eardrums) and slightly upturned eyes. The webbing on the hind feet reaches the last joint of the longest toe. Adult mink frogs over 7.5 centimetres long have been recorded. The call of this species consists of a rapid series of three or more croaks, which sound like the tapping of a metal hammer on wood. A large chorus of mink frogs sounds like popcorn popping. Listen to the call of the mink frog (courtesy of Adopt-A-Pond Wetland Conservation Programme).

Similar Species

The green frog is nearly identical in appearance to the mink frog, and both species exhibit substantial variation in colour. The green frog has a white belly with darker lines or spots and occasionally a yellowish tinge, and dark banding on the hind limbs. It is important that observations of mink frogs submitted to the Ontario Reptile and Amphibian Atlas include photographs to help in verifying identification. If possible, photographs should show the whole body and hind legs.

Habitat

Mink frogs are highly aquatic and rarely found on land. They inhabit large, cold, permanent ponds, lakes and slow-moving rivers with abundant vegetation, as well as sphagnum bogs. The eggs and tadpoles develop in permanent lakes and ponds. Both tadpoles and adults hibernate underwater.

 

Biology

Mink frogs breed from late spring through midsummer. Choruses increase in intensity through the night and peak before dawn. The female deposits a globular mass that may contain several thousand eggs, but these egg masses have never been observed in the wild. Where the female deposits her eggs is not known. The tadpole stage lasts one to two years and, after transforming into frogs, individuals reach sexual maturity in another year or two. The average adult lifespan of this species is not known.

Mink frogs eat various small invertebrates obtained mostly among aquatic plants in open water. The adults seem to be more skittish than adult green frogs and bullfrogs.

Threats & Trends

Mink frogs, like many fauna, are threatened by habitat loss and degradation. The highly aquatic nature of this species probably means that it is less at risk of being killed on roads than more migratory species. Mink frog populations are believed to be stable, but little data is available to support this assumption. Data on the current distribution of mink frogs in northern Ontario is also lacking.

Current Status & Protection

Neither the Committee on the Status of Species at Risk in Ontario nor the Committee on the Status of Endangered Wildlife in Canada has assessed the status of the mink frog. The species has no protection under the Ontario Fish and Wildlife Conservation Act. The International Union for Conservation of Nature lists the global status of the mink frog as Least Concern. The species’ status was confirmed in 2010.

Learn more about reptile and amphibian conservation and what you can do to help these species on our Reptile and Amphibian Stewardship page.

 

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Range

To view an interactive map of the known ranges of mink frogs in Ontario, click here.

The mink frog is found predominantly in Canada, from southern Manitoba to Labrador. In Ontario, this species has not been recorded in the northwestern third of the province. In the United States, the mink frog is found in some Great Lakes basin states.

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