|Common Name:||Wood Frog
|Scientific Name:||Lithobates sylvaticus
At a Glance
Wood Frogs are small to medium-sized frogs, with an average body
length from 2 to 6 centimetres. They have a characteristic black
‘mask’, a broad dark band passing through the eye from snout to
shoulder, bordered below by a white lip line that looks like a
moustache. Wood Frogs come in many colours. They may be light tan,
grey, deep brown, blue-green, or distinctly red, often with dark
spots or mottling on the back and sides. Some individuals have a
single prominent white stripe down the middle of the back. Two broad
light-coloured stripes may also be present on the back. Wood Frogs
have white bellies with some dark mottling at the sides and on the
throat, and they have prominent dorsolateral folds (ridges that run
from the back of the head down the frog’s back). Males and females
look similar, except that males have a dark, swollen thumb during
the breeding season and two throat pouches that inflate when they
call. Females are a few millimetres longer than males.
Tadpoles have a very short, round body and an arched tail fin
that begins high on the back. They are uniformly dark with gold
flecks in lines around the mouth. The belly may be dark with a
silver sheen, or cream coloured with a pinkish iridescence. They may
grow to 5 cm long.
You may often hear male Wood Frogs calling early in the spring,
sounding very much like the quacking of ducks. Don't be fooled! If
you hear "quacking" but can't see any birds, you are probably
listening to a Wood Frog chorus.
Home Sweet Home
Wood Frogs are largely terrestrial, but are not usually found far
from water. They inhabit marshes, riparian areas, wet meadows,
moist brush, and open grassy areas adjacent to such habitats. Wood
Frogs hibernate in the soil, using root channels and burrows made by
other animals. The soil and snow pack provide insulation and
protection to the frogs, which can survive temperatures as low as
-6°C. The frogs actually freeze solid at these low temperatures, but
protect their cells from damage by producing their own “antifreeze”
– really a cryoprotectant. Naturally, scientists are very
interested in this talent!
Wood Frogs breed in seasonal pools, shallow ponds, marshy lake edges, flooded meadows, and
quiet stretches of streams. Tadpoles usually live in the shallowest, warmest parts of
This is the Life
Wood Frogs emerge early from hibernation, moving to breeding sites as snow and ice begin
to melt. Males congregate in shallow clear ponds and will call day and night as long as
the temperature remains above freezing. Their distinctive, throaty, duck-like quacks alert
females to their presence. Mating pairs join together to deposit and fertilize the eggs,
which are densely packed into a soft mass of jelly the size of a plum or orange.
Masses from several females are usually laid together, attached to submerged sticks and
plants or lying freely in the water. Each mass may have as many as 2000 to 3000 eggs.
Outside the breeding season adult Wood Frogs are fairly solitary.
They are most active during the day, foraging far and wide. Egg and
tadpole development are rapid. Even at comparatively low
temperatures; the tadpoles are able to transform into froglets by
mid-summer. Juvenile and adult frogs hibernate terrestrially to
survive cold winter temperatures. Males mature one year after
metamorphosis, while females reach maturity in 2 years. Wood Frogs
seldom live more than three or four years.
What’s on the Menu?
Wood Frogs share the usual frog preference for insects, worms,
snails, millipedes, molluscs, and other small invertebrates.
Tadpoles are herbivores, and feed on algae and other plant material.
Where and When
Wood Frogs are widespread in B.C.’s central and northern
interior, and extend south along the Rocky Mountains to the East
Kootenays. They may be present at elevations of up to 3050 m. They are
found across Canada, and north past the Arctic Circle.
Depending upon weather conditions in local areas, breeding may
occur between early March and June. Wood Frogs are explosive breeders;
while breeding may take a few weeks in more southerly parts of their
distribution, it may occur over only a few days in the north. Egg
laying begins 4 to 6 days after the first frogs appear, and most egg
laying is completed within 7 to 10 days. Eggs can hatch in as few as 4
to 7.5 days depending on temperature. Metamorphosis generally occurs
45 to 80 days after the eggs are laid.
How Are They Doing?
Wood Frogs are widely distributed and are not considered to be at
risk. This species is on the provincial Yellow List of species
managed at the ecosystem level.
How We’re Helping
Reported incidental sightings and amphibian inventory projects
have helped to map the distribution of Wood Frogs in B.C. We’re hoping
to learn more about this species’ ecology and life history.
The Wood Frog is protected under the British Columbia Wildlife Act.
How You Can Help
Learn about Wood Frogs and share your knowledge with others. Contribute your reports
of Wood Frog sightings and breeding calls to B.C. Frogwatch.
- Adults and metamorphosing tadpoles produce repulsive skin secretions
that deter predators such as aquatic insects and shrews. Most adults
give a defensive call, or ‘mercy scream’, when attacked by shrews.
- Wood Frogs are supercool! They are the only North American amphibian
that occurs north of the Arctic Circle. They have an incredible ability
to survive freezing winter temperatures, and in spring, warm up and hop
- It’s a ‘frog-eat-frog’ world. Wood Frogs have been known to eat
smaller frogs in the fall to help them store up energy for a long
- Wood Frogs are so small that they could sit in a coffee cup without
scraping their noses!