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Green Frog

Lithobates clamitans

Green frog © Joe Crowley

Characteristics

The green frog is a large frog with large, distinct tympani (eardrums) and two prominent dorsolateral folds (folds of skin that run partly down the back). It may be green, bronze, brown or even blue, or a combination of colours, but typically is green on the upper lip. The belly is white with darker lines or spots and occasionally has a yellow tinge. The hind legs have dark banding, and there may be irregular spotting on the back. Males have a bright yellow throat and tympani that are noticeably larger than the eye. In females, the tympani are about the same size as the eyes. The maximum reported size of an adult green frog is 10.8 centimetres. The call of this species is either a single staccato “gunk!” like the sound of a loose banjo string or a single call with several less vigorous repeats: “GUNK, gunk-gunk-gunk …” Listen to the call of green frog (courtesy of Adopt-A-Pond Wetland Conservation Programme).

Green frog © Joe Crowley

Similar Species

American bullfrogs and mink frogs are very similar to the green frog. Bullfrogs do not have a dorsolateral fold but have folds of skin that wrap downward around the tympani. Mink frogs have dark spots or blotches rather than dark banding on the hind legs and often have a yellow belly.

Habitat

Green frogs may be found in or near virtually any shallow, permanent waterbodies such as springs, swamps, brooks, ponds and lakes. Young green frogs use temporary waterbodies in the summer and can be found in almost any pool or puddle in a natural area, including potholes on roads. These frogs hibernate underwater and often bask along shorelines in the summer.

Green frog © Joe Crowley

To view an interactive map of the known ranges of green frogs in Ontario.

Have you seen a green frog?

Beaver River, Uxbridge © Sean Marshall

Biology

The male green frog begins calling in late spring to midsummer, and the species may breed as late as August. The female lays three or four small clutches of eggs, which are draped over submerged vegetation in permanent water. The tadpoles overwinter in water before transforming the following summer. Because of the extended breeding season and long larval period, tadpoles of various sizes and newly transformed frogs can be found during most of the spring and summer.

Adult green frogs eat various small, mainly terrestrial invertebrates and, occasionally, small amphibians. The tadpoles eat suspended matter, organic debris, algae, plant tissue and minute organisms in water. Green frogs may travel over half a kilometre between breeding and overwintering sites.

Other names: Rana clamitans

Green frog blue morph © John Boxall

Threats and Trends

Green frogs continue to thrive throughout much of Ontario. This does not mean that they are not susceptible to habitat loss, pollution, road mortality or predation, but rather that they have, for the most part, survived these threats at the levels at which they have occurred to date. It is unknown what effect increased levels of these threats would have on green frog populations.

Green frog © Peter Ferguson

Current Status and 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 green 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 green 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.

Green frog © John Urquhart

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