What is the First Sign of Spring?

By Courtney Leermakers

It’s that time of year again, when outside temperatures slowly begin to increase so you decide to go for a walk near your neighborhood pond. You’re humming to the beat of a song that has been stuck in your head all day when suddenly you hear a loud chorus of screams and some activity in the water. You contact your niece who is studying ecology (that’s me!) and ask what the noises are that you heard. “Well,” I say, “It is most likely Wood Frogs, Western Chorus Frogs, or Spring Peepers, because they are the first to emerge from hibernation to call.”

Some of the best indications of spring’s arrival are the sounds of Wood Frogs (a series of sharp quacks- click here to listen!),Western Chorus Frogs (resembling the sound of rubbing your thumb against the teeth of a comb- click here to listen!), and Spring Peepers (single, loud, high-pitched repeated peeps- click here to listen!) beginning to call. They usually begin to call  on warm nights following rainfall from late March until mid-April (Adopt-A-Pond, 2020).  

You can identify a Wood Frog by the tan or reddish body and dark mask across its eyes. The body changes color from dark red to light tan depending on the temperature to better thermoregulate (Adopt-A-Pond, 2020). You can usually find this frog calling near vernal pools in forested areas. They will live under the leaf litter after mating season and while overwintering.  The Wood Frog has such a unique biology, which makes them highly adapted to withstand freezing temperatures. Shockingly, the Wood Frog can withstand 60% -70% of the water in their body freezing, and consistent -6°C temperatures (Ontario Nature, 2020). Brrr!

A Western Chorus Frog is easily distinguishable by the tan body and three dark lines running down its back. They can be found in a variety of habitats including woodlands, marshes, and meadows. You may be able to find them in fishless ponds with shallow water, which may just be a ditch at the side of the road, with tall emergent vegetation (Adopt-A-Pond, 2020). They also are adapted to emerge early and sometimes can be heard calling even when ice is still on the pond. The Great Lakes/St. Lawrence – Canadian Shield population is listed as Threatened under the Species at Risk Act, and therefore is a protected species . The biggest threats facing Western Chorus Frog are habitat loss and degradation caused by urbanization, fragmentation, agriculture, and pesticide use (Species at Risk Public Registry, 2015).   

If you do not first identify a Spring Peeper by their loud chorus of peeps, you can easily distinguish the light tan body and a dark X-shaped marking on their back (Adopt-A-Pond, 2020). Similar to the Wood Frog, they mate in temporary woodland ponds and can be found hiding under debris or leaf litter. They also have the ability to withstand freezing temperatures, which allows them to be one of the first to emerge (Adopt-A-Pond, 2020). 

To start off this field season, our team is currently involved in two frog survey projects. First, in late March we set up acoustic monitors throughout the Toronto Zoo grounds and in Rouge National Urban Park. These monitors record nearby sounds for 3 minutes every hour and will be left at our field sites until August. Once taken down, the recordings from the monitors will be analyzed for frog calls. This will allow us to determine where certain frogs or toads, including the Western Chorus Frog, are using breeding habitat.

Secondly, we’re participating in Blazing Star Environmental’s Western Chorus Frog monitoring program (Hall, 2020). This is a long-term, range-wide monitoring program that anyone can participate in! We are following their protocols at five sites on the Toronto Zoo property. All of this data will go towards identifying the location of at-risk frog species so that we can better understand where these animals are living, and take appropriate actions to conserve them. With the Adopt-A-Pond Spring Toad Festival in full swing (April 30th-May 2nd 2021), it is important to reflect on these indicator species. Frogs are not only indicators of spring, but also ecosystem health as frogs are sensitive to decreased wetland vegetation, pollution, and land fragmentation, especially in urban environments (Toronto and Region Conservation Authority, 2015). You can get involved in frog conservation by submitting your sightings to FrogWatch Ontario! This citizen science application allows you to take pictures, sound recordings, and locations of frogs in your area. This will give us information on the presence and absence of local frog species (https://report.adoptapond.ca/ ).The next time you are walking around a pond,make sure to listen for these early emergent frog species and document your observation using FrogWatch!

Curious about the frogs and toads in Ontario? Check out our online species guides on frogs, toads, their eggs, and tadpoles by clicking here! Send us an email at aap@torontozoo.ca to order laminated identification guides!


Adopt-A-Pond. (2020). Adopt A Pond – Species Guides. Toronto Zoo. https://www.torontozoo.com/adoptapond/speciesguides

Hall, K. (2020, January 29). Join the Chorus: Volunteers Needed for Large-Scale Monitoring of a Small-Scale Frog. Adopt-A-Pond News. https://adoptapond.wordpress.com/2020/01/30/join-the-chorus-volunteers-needed-for-large-scale-monitoring-of-a-small-scale-frog/

Ontario Nature. (2020, February 7). Wood Frog | Reptiles & Amphibians in Ontario. .

Toronto and Region Conservation Authority (TRCA). 2015. Terrestrial Long-Term Monitoring: Spatial and Temporal Trends 2008-2014.

Species at Risk Public Registry. (2015, December). Imminent Threat Assessment for the Western Chorus Frog. https://sararegistry.gc.ca/default.asp?lang=En&n=CE6C8EB9-1#:~:text=As%20identified%20in%20the%20federal,linear%20infrastructures%2C%20as%20well%20as