There are two chorus frog species in Ontario: the boreal and the western chorus frog. Prior to 1989, they were considered to be one species. Like many species in the treefrog family, they are more often heard than seen.
The boreal chorus frog is small and smooth skinned, and varies in colour from green-grey to brown. A dark stripe runs through the eye and a white stripe along the upper lip. This species is distinguished from most other treefrogs by the three dark stripes down the back. In some individuals, the stripes are broken into dashes or dots. The maximum size of the adult is just under four centimetres. The breeding call of this species resembles the sound made by running a fingernail along the teeth of a comb.
The western chorus frog is almost identical to the boreal chorus frog but has shorter hind legs. These two frogs are best distinguished by their call or location; in Ontario, their distributions do not overlap. Their calls are very similar, but in the call of the western chorus frog, the pulse rate is longer and slower.
The boreal chorus frog inhabits forest openings around woodland ponds but may be found in the vicinity of any body of non-flowing water. This frog breeds in almost any fishless pond with at least 10 centimetres of water, including splash pools, roadside ditches, flooded fields, beaver ponds, marshes, swamps, shallow lakes and other water bodies with little or no current, often those lacking tree cover. The boreal chorus frog overwinters on upland sites near water, usually under logs or underground.
View an interactive map of the known ranges of boreal chorus frogs in Ontario.
Boreal chorus frogs breed very early in the spring, calling day and night, often before the winter ice has completely melted. The female lays series of small egg masses, which are attached to submerged vegetation. The eggs hatch within a few weeks, and the tadpoles finish transforming by early summer or midsummer. They usually mature in one to two years and rarely live longer than three years. Chorus frogs can survive being frozen and are among the first frogs to emerge in the spring. They feed on small insects and other invertebrates, and are eaten by a wide variety of predators.
Other names: Pseudacris nigrita septentrionalis, Chorophilus septentrionalis
Threats and Trends
Habitat loss and degradation are threats to any given local population of the boreal chorus frog, but no major threats affect this species as a whole, and it is not believed to be in any significant decline.
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 boreal chorus 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 boreal chorus 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.