There are two chorus frog species in Ontario: the western and the boreal 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 western 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 three dark stripes down the back. In some individuals, the stripes are broken into dots, dashes or small blotches. 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. Listen to the call of the western chorus frog (courtesy of Adopt-A-Pond Wetland Conservation Programme).
The boreal chorus frog is almost identical to the western chorus frog but has slightly longer 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 boreal chorus frog, the pulse rate is shorter and faster.
The western chorus frog inhabits forest openings around woodland ponds but can also be found in or near damp meadows, marshes, bottomland swamps and temporary ponds in open country, or even urban areas. This frog breeds in almost any fishless pond with at least 10 centimetres of water, including quiet, shallow, usually temporary waterbodies with vegetation that is submerged or protrudes from the water, and especially in rain-flooded meadows and ditches, and in temporary ponds on floodplains. The western chorus frog overwinters underground or under surface cover, such as fallen logs.
View an interactive map of the known ranges of western chorus frogs in Ontario.
Western chorus frogs breed very early in the spring, often while ice is still present, and may begin calling as early as mid-March. Typically, most calling occurs in April. These frogs may call day or night, usually in tandem with spring peepers. The female lays a series of small egg masses, which are attached to vegetation. The eggs hatch within a few weeks, and the tadpoles finish transforming by early summer or midsummer. They usually mature in one year 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: striped chorus frog, midland chorus frog, Hyla triseriata, Pseudacris nigrita triseriata
Threats and Trends
Populations of western chorus frogs have been documented to have declined by 37 percent in Quebec and 30 percent in Ontario in the last 10 years. The causes of this decline include habitat loss and fragmentation. In particular, the forests and seasonal wetlands these frogs use as breeding habitat are being developed for agriculture and urban expansion.
Current Status and Protection
The western chorus frog is currently listed as Not at Risk under the Ontario Endangered Species Act, 2007. The Carolinian population (south and west of Toronto) is listed as Not at Risk, and the Great Lakes–St. Lawrence population (east and north of Toronto) is listed as Threatened under the federal Species at Risk Act. These acts offer protection to individuals and their habitat. The species has no protection under the Ontario Fish and Wildlife Conservation Act. The habitat of this species is further protected in Ontario by the Provincial Policy Statement under the Planning Act. The International Union for Conservation of Nature lists the global status of the western chorus frog as Least Concern. The species’ status was last confirmed in January 2010. Additional detail about legal protection for species at risk in Ontario is available on our Legal Protection page.
Learn more about reptile and amphibian conservation and what you can do to help these species on our Reptile and Amphibian Stewardship page.