Oregon Spotted Frog / Grenouille maculée de l'Oregon
The Oregon Spotted Frog is a large brown true frog with ill defined spots which may have light
centres. It has dorsolateral ridges
and a dark mask with a light stripe on the upper jaw. Its toes are fully webbed and the
eyes are slightly upturned. The
tympanum is prominent. The underside may be yellow, orange or red with dark mottling
on the throat. Maximum adult size is 10 cm. The two species of Spotted Frogs are very
similar and very closely related. It has only recently been recognized that they are two
different species. The Oregon Spotted Frog differs from the Columbia Spotted Frog in
having a smaller head.
is a series of short, rapid grunts which build in intensity. The entire call may last
up to ten seconds. It is not known if the call differs between the two species.
The Spotted Frogs may be confused with Northern
Red-legged Frogs which differ in having incomplete webbing on the toes and not having
upturned eyes. Northern Red-legged Frogs do not have mottling on the throat and are always
yellow beneath with red wash on the underside of the legs and the belly.
Northern Leopard Frogs have much more distinct dark
spots with light rings around them. The other true frogs found within its range do
not have spots.
The Oregon Spotted Frog is restricted to extreme southwestern British Columbia, adjacent
areas of Washington and parts of Oregon and northern California.
Spotted Frogs are found in permanent water in alpine and subalpine areas with mixed
coniferous or subalpine forests.
Breeding occurs early in spring and egg masses are laid communally with each consisting of
700-1,500 eggs. They hatch in about four days. Larvae may transform by the end of summer or
overwinter as tadpoles and transform the following year. They may take up to six years to
Spotted Frogs are primarily aquatic and when frightened will swim to the bottom and remain
still. Differences in natural history between the two species have not been explored.
The Oregon Spotted Frog is very rare in British Columbia. The original known population
appears to be extirpated but a new
population was recently discovered.