The Chorus Frog

Who is this little frog that is leaving such a positive footprint on our environment?

Many people are unaware that the residual natural environments in the Outaouais and Montérégie regions of Quebec are home to our smallest frog: the Western chorus frog.

Western chorus frogs are very small members of the hylid family, with an average length of about 2.5 cm. Given their shy nature, they are hard to spot. Their slightly granular skin ranges from brown to olive grey. Do you know that this species’ pigmentation changes colour based on the time of day? These frogs tend to be darker in the daytime and in colder temperatures, and lighter at night or in warmer temperatures. Western chorus frogs are also distinguished by the three dark stripes (sometimes broken up into blotches) running down their backs. Dark lateral stripes also extend from the snout to the groin, which easily differentiates them from young wood frogs who only sport a mask. Tiny suction cups on their toe pads are typical of all tree frogs, but less developed on chorus frogs, making them less agile climbers than other species, such as the gray treefrog. One can hear their characteristic call between April and May: a long and sharp ascending screech sounding like fingernails dragging down the teeth of a metal comb.

Why Are Chorus Frogs Vulnerable?

The chorus frog’s breeding cycle occurs from late March to early July in temporary rather than permanent aquatic environments (visit Parc La Futaie for more information). But while the tadpoles in these ephemeral wetlands are protected from certain predators, they are still particularly vulnerable to premature drought caused by climatic variations or other factors, such as high temperatures, low precipitation, drainage and infilling, etc. Le maintien d’une population locale dépend, minimalement, d’un nombre suffisant de milieux humides dont l’ennoiement dure jusqu’à la fin de juin.

Being very small, chorus frogs would barely travel more than 250 metres from their natal pond. Humid environments, whether small or broad, are essential to their survival and to the survival of other species as well (explore the Boisé Du Tremblay to learn more).

Throughout the summer, adult chorus frogs feed in high grasses or on the forest floor (visit Centre Plein Air Brossard to learn more about their feeding habits).

The Western chorus frog* is now listed as an endangered species in Canada and vulnerable to extinction in Quebec. Chorus frogs in southern Quebec are still legally named Western chorus frogs (Pseudacris triseriata), but recent genetic tests show that they are, in fact, boreal chorus frogs (Pseudacris maculata), a close cousin, and the same species living in northern Quebec near James Bay, although there is no contact between them.

Regardless of their name, the anthropic pressures on chorus frog habitats in southern Quebec and Ontario remain significant and their population is declining. Urban and peri-urban expansion, as well as changes in agricultural practices are causing a continuous loss of habitats and breeding sites. The designation of southern Quebec’s chorus frogs as a threatened and endangered species is more than justified as their situation continues to worsen. Taking action to protect their habitats, therefore, remains a top priority (visit the Boisé Du Tremblay wildlife reserve to find out more on this type of protection), with a focus on improving the quality and conservation connectivity of their habitats (discover the artificial ponds of Mont-Saint-Bruno National Park).