Wood Frog (Lithobates sylvatica)
Wood frogs occur further north than any other amphibian in North America. They are common throughout the forested regions of the NWT from the Alberta border north to the Mackenzie Delta.
|
Photo: M. Fournier
|
This wide range in the north is due to a variety of relatively unique adaptations to the northern climate. The wood frog hibernates under leaves and other debris on the forest floor, depending on snow cover and its ability to tolerate slight (-6°C) sub-zero temperatures for its survival. The wood frog can remain active at relatively low temperatures and has the most rapid development from egg to adult of any North American frog. Eggs are laid in globular masses, submerged and often attached to sedges or other aquatic vegetation. Several females may lay their eggs in close proximity. After breeding in ponds and marshes these frogs disperse to damp woodland, although they may remain around pond margins for much of the summer.
|
Identification
The wood frog is smooth skinned and variable in colour, ranging from brown, tan, or grey to pinkish. It has a dark eye mask, white jaw stripe and creamy underside often with dusky mottling. There may be a light stripe running down the middle of the back. When adults emerge from hibernation in spring they may appear uniformly dark above, not obviously showing the characteristic dark eye mask and white jaw stripe.
|
Photo: M. Fournier
|
|
Photo: M. Fournier
|
Adults range up to 50 mm in length but first year frogs are approximately half this size. Tadpoles undergo metamorphosis and froglets appear in July. Similar to adults emerging from hibernation in spring, froglets may appear uniformly dark above. The call of the wood frog is most commonly described as a low, often rapid quack and is sometimes mistaken for the call of a duck.
|
Distribution of the Wood Frog
|