As spring comes alive with the sound of frogs croaking, there is one group in particular, tree frogs, that continue to fascinate us with their big sounds from such a small size.
With seven species of tree frogs in Canada, they can be found across most of the country. However, despite their general distribution many of us may never see a tree frog due to their small size and their ability to camouflage with their background. Tree frogs are typically grey, green or brown with many species able to undergo changes in their colour depth. While a few species are commonly found close to the ground, most live in trees and shrubs. The sticky disks on their toes help them adhere to bark, branches and twigs where many forage for insects.
Canadian tree frogs may be most noticeable in the spring as males begin calling for a mate. Some species, such as Spring Peepers and Chorus Frogs, are well known for their singing at this time. After mating, females lay their eggs in water either in small masses or as single eggs.
Most Canadian tree frogs are freeze tolerant and spend their winters under only leaf litter, rocks, logs or tree bark. That is, they freeze solid over the winter and appear completely lifeless, but when they thaw out in spring they become active once again.
Find out which tree frogs occur in your area:
Western Chorus Frog (Pseudacris triseriata) and Boreal Chorus Frog (Pseudacris maculata)
Western Chorus Frogs and Boreal Chorus Frogs are very similar in appearance and behaviour although they differ in their Canadian distributions. Western Chorus Frogs are found only in southern Ontario and southern Quebec whereas Boreal Chorus Frogs are found from Quebec west to British Columbia, the Northwest Territories and slightly into the Yukon.
Reaching a maximum size of only four centimetres long, both species have smooth skin and can be grey, green or brown in colour. They have a dark stripe through the eye and a white stripe below it, along the top lip. They also have three dark dorsal stripes that are sometimes broken.
In the spring, during breeding time, Western and Boreal Chorus Frogs are commonly found in temporary bodies of water or shallow water with no fish or current, typically with grassy edges. Females deposit up to 800 eggs in small masses. Eggs quickly hatch into tadpoles, becoming frogs by mid-summer. Beyond breeding season they can be found in open habitat near ponds.
Their diet consists of insects and other invertebrates. Their winters are spent either below ground or under logs. These species are not as accomplished at climbing as other tree frogs; they climb no higher than a small shrub.
Cope’s Gray Tree Frog (Hyla chrysoscelis) and Gray Tree Frog (Hyla versicolor)
Cope’s Gray Tree Frog and the Gray Tree Frog are identical in appearance and can only be distinguished from each other by their distribution and their calls. In Canada, Cope’s Gray Tree Frogs are found only in Manitoba and possibly western Ontario whereas Gray Tree Frogs are found from Manitoba east to New Brunswick. The Cope’s Gray Tree Frog has a faster and higher pitched trill than that of the Gray Tree Frog.
Both species reach a maximum size of six cm and are rough skinned with variable blotches of green, grey and/or brown but have the ability to change to blend in. The inside of their thighs is orange and they have large toe pads.
These species are usually found high up in trees and shrubs and, in breeding season, along the edge of ponds and in temporary bodies of water including ditches. Breeding doesn’t occur until late in the spring. The female may lay a total of 2,000 eggs that are divided into smaller masses and attached to aquatic plants. Within five days the eggs hatch and approximately two months later the tadpoles transform into frogs. Both species feed on insects and other invertebrates. These tree frogs spend their winters under only leaf litter and snow.
Spring Peeper (Pseudacris crucifer)
The Spring Peeper has a broad Canadian distribution from Manitoba east to Nova Scotia. They can range in colour from brown to grey but their distinguishing feature is an “X” shape on their back. They have large toe pads and only reach three cm in size.
They are one of the earliest frogs to sing in the spring.
They breed basically wherever there is water but are sensitive to the impacts of urbanization. Females can lay up to 1,000 eggs either in masses or as single eggs. The eggs hatch into tadpoles about a week later and after two months they are fully-formed frogs. Their diet consists of mosquitoes, worms and aphids. They spend their winters under leaves, logs or tree bark.
Pacific Tree Frog (Pseudacris regilla)
The Canadian range for this rough-skinned tree frog is limited to British Columbia. Pacific Tree Frogs are typically green or brown but they do have the ability to change shades quite quickly. They have a dark stripe that runs through each eye and large sticky toe pads. They can obtain lengths up to five cm.
Pacific Tree Frogs are commonly found close to the ground. By early spring, females have laid masses of eggs which transform into frogs after two months. They feed on worms, flies and beetles. Pacific Tree Frogs can be heard all year long singing their familiar call.
Blanchard’s Cricket Frog (Acris blanchardi)
These frogs have also gone by the name of Northern Cricket Frog (Acris crepitans) and were once considered a subspecies (Acris crepitans blanchardi) but have since been elevated to its own species based on genetic differences They can be identified by their rough, warty looking skin that is usually brown or grey. A distinguishing feature is a dark “V” mark located between their eyes. This species does not have large toe pads. Adults typically are no larger than four cm.
Northern Cricket Frogs are most commonly found in marshes, quarries and even ditches where you can generally hear them calling as early as June. Females may lay as many as 400 eggs that hatch into tadpoles in only three or four days, becoming frogs in five to ten weeks. Insects make up a large part of their diet and they spend their winters under rocks or logs.
Cricket Frogs once occurred at Point Pelee and on Pelee Island, Ontario – the southernmost tip of Canada. Both populations are now gone and the species no longer occurs in Canada (it is Extirpated), although this species still occurs in the United States.
Threats and What You Can Do
Amphibians are an essential part of the environment as regulators of insect populations and as indicators of environmental health. But frogs are paying the price for our actions as their numbers continue to decline. Pesticides and other contaminants are entering their bodies through their permeable skin. They are also facing habitat loss, being hit by cars and hunted by domestic cats.
You can help all frogs in your area by avoiding the use of pesticides. Avoid handling frogs but if you do, such as children at the cottage, ensure you don’t have any products on your hands like insect repellant, sunscreen or synthetic hand cream.
You can also help by providing areas of vegetation for shelter and hunting and by building a pond with sloped sides with natural vegetation along the edge.
For more information on how you can help these creatures, see our All About Amphibians and Reptiles section and our FAQ section.