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Canadian Herpetological Society





Société d'herpétologie du Canada



Pseudacris triseriata
Western Chorus Frog / Rainette faux-grillon de l'Ouest


Western Chorus Frog

Description
The Western Chorus Frog is a small, smooth skinned treefrog. Colour varies from green-gray to brown. There is a dark stripe through the eye and a white stripe along the upper lip. It is distinguished from most other treefrogs by the three dark stripes down the back. In some individuals the stripes are broken. Maximum adult size about 4 cm.

Call
The breeding call is very similar to the Boreal Chorus Frog but is shorter and faster in pulse rate. It resembles the sound of drawing your finger down the teeth of a comb.

Confusing Species
The Western Chorus Frog is almost identical to the Boreal Chorus Frog. It has longer hind legs but is best distinguished by its call or location. In Canada their distributions do not overlap.

Distribution
In Canada, the Western Chorus Frog is found only in southern Ontario and along the Ottawa and upper St. Lawrence river valleys in Quebec. It is also found through much of the eastern United States and overlaps with the Boreal Chorus Frog in the central United States. It was introduced to Corner Brook Newfoundland in the 1960's but apparently is now extirpated from there.

Habitat
The Western Chorus Frog's preferred habitat is forest openings around woodland ponds. They will breed in almost any fishless pond with at least 10 cm of water, including roadside ditches, gravel pits, flooded fields, beaver ponds, marshes, swamps or shallow lakes.

Reproduction
Western Chorus Frogs breed very early in the spring and may begin as early as March although most calling is in April. They may chorus during the day as well as at night. A series of small egg masses are laid and attached to vegetation. Eggs hatch within a few weeks and tadpoles finish transforming by early summer. They are usually mature in one year and rarely live beyond three.

Natural History
Chorus Frogs hibernate beneath logs or underground and are freeze-tolerant. They 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.

Conservation Concerns
There is no evidence for decline in Ontario populations of the Western Chorus Frog, however, it has declined throughout the St. Lawrence Valley in Quebec as a result of habitat loss. A population introduced to Newfoundland is apparently now extirpated.