Northern Red-legged Frog / Grenouille à pattes rouges du Nord
The Northern Red-legged Frog is a large, true frog with clear
dorsolateral ridges. The colour
varies from reddish brown to grey and there may be some dark specks or blotches. In
northern populations, these dark blotches do not have light centres. The
tympanum is indistinct and the
toes are not fully webbed. This species may be distinguished from other frogs by the light
stripe on its jaw bordering a dark mask and by its yellow underside with red on the lower
abdomen and hind legs. Adults can reach 13 cm.
The Northern Red-legged Frog has a weak throaty
two to three seconds. Calling sometimes occurs deep under water and does not carry far.
The only true frogs which naturally co-exists with the Northern Red-legged Frog are the
Columbia Spotted Frog and the
Oregon Spotted Frog. All these species have a
light stripe on the jaw, but the Spotted Frogs may have a mask or reddish undersides
although not always. In contrast to the Northern Red-legged Frog, the toes of the Spotted
Frogs are fully webbed and the eyes are slightly upturned. The
Wood Frog looks superficially like a
Northern Red-legged Frog as it does have a mask and may have dark specks on it. Wood Frogs
are occasionally reddish above however their underside is white with dark mottling.
The Northern Red-legged Frog has a very limited distribution in Canada, being only found in
southwestern British Columbia, Vancouver Island and other nearby islands. This
distribution continues southward along the west coast of the United States and into
Northern Red-legged Frogs are usually found in or near well vegetated permanent water. In
parts of their range they may be found at up to 2,400 m above sea level.
Breeding occurs in late winter or early spring. Eggs are laid in a loose cluster on the
surface of permanent water bodies. Their eggs are more susceptible to overheating than
most other frog eggs and so they require stable water temperatures.
The Northern Red-legged Frog is less aquatic than the Spotted Frogs and may be found at
the shoreline or foraging on land.
The Northern Red-legged Frog has declined on central Vancouver Island. Competition from
introduced Bullfrogs and Green Frogs, and logging activity may be the problem. This
species has also declined throughout much of its range in the United States. The Northern
Red-legged Frog has been designated Special Concern by