The Western Chorus Frog is a small tree frog of about 2.5 cm long and weighs about 1 gram. They are light brown in colour and have a dark line extending their entire length, three dark stripes on their back, and a white line that runs along the upper lip. This frog is generally hard to find by sight but they are easy to identify from their call, which is similar to the sound of running your finger across the teeth of a comb. However, it can be difficult to distinguish when calling amongst spring peepers as they can sound similar.
Like most frogs, the Western Chorus Frog is insectivorous, and will eat small invertebrates like flies, mosquitoes, ants, beetles, moths, caterpillars, grasshoppers, snails, slugs, and spiders. Tadpoles will feed on different types of algae. Western Chorus Frogs will forage for their food by remaining still and hidden, snapping up any food that comes within range.
Biology and Behaviour:
The Western Chorus Frog emerges from hibernation and heads to their breeding grounds in late March. They will inhabit temporary water sources until late August when they dry up. This is thought to help lessen the prevalence of predation that occurs in more permanent wetlands. Chorus frogs tend to forage in more terrestrial habitats, and they can also often occupy sites with significant agricultural cover or urban land use if the vegetation characteristics are suitable.
Western Chorus Frogs will breed in early spring and begin calling in mid-March. Most calling occurs throughout the month of April, and can happen day or night, often in tandem with Spring Peepers. The female will lay a bunch of small egg sacks that attach to vegetation near water. Eggs will hatch within a few weeks and tadpoles will transform into frogs by early or mid summer.
Adults tend to only breed once in their life and they will only survive for a year. Although some have been thought to live up to 3 years, it is a rare occurrence.
Western Chorus frogs are prey to a variety of predators, including birds such as raptors and herons, predatory fish, and predatory reptiles like snakes.
- The Spring Peeper looks very similar in size and overall appearance. A defining attribute of the Spring Peeper is a dark “X” located behind the head. Although this “X” is not always present, the Western Chorus Frog can be differentiated by the three lines running down their back
- The Boreal Chorus Frog used to be considered the same species as the Western Chorus Frog until 1989. They can be distinguished by both call and location- they have a shorter pulse rate when they call and their habitats do not overlap in Ontario
Conservation and recovery strategies:
Since the Canadian Shield population is listed as Threatened, both the species and their habitat are protected. Next steps to increase populations are to protect their current known habitats and rehabilitate any areas that can support them. This is done through land acquisition and stewardship. The Federal Government is also working to try and reduce the use of harmful fertilizers and pesticides, especially in the agricultural sector. There are also a great deal of knowledge gaps with the Western Chorus Frog. More surveys and monitoring protocols have been put in place for Ontario and Quebec, and people are encouraged to report any sounds or sightings. Historical locations of the Western Chorus Frog are also being researched, and strategies are in place to limit urbanization in these areas.
COSEWIC. 2008. COSEWIC Assessment and Update Status Report on the Western Chorus Frog Pseudacris triseriata in Canada Carolinian population Great Lakes/St. Lawrence – Canadian Shield population. Ottawa. vii + 47 pp. (www.sararegistry.gc.ca/status/status_e.cfm).
Environment Canada. 2015. Recovery Strategy for the Western Chorus Frog (Pseudacris triseriata), Great Lakes / St. Lawrence – Canadian Shield population, in Canada, Species at Risk Act Recovery Strategy Series, Environment Canada, Ottawa, vi + 50 pp
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