| Species | Rana cascadae Slater, 1939 |
| Family | Ranidae (True Frogs) |
| Status | None |
| State Rank | S3S4 |
| Global Rank | G3G4 |
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This is a medium-sized frog with a slender body, relatively smooth skin, two distinct parallel ridges of skin (dorsolateral folds) on the dorsal sides of the body, and an eye mask. Adults grow to about 75 mm snout-vent length. The dorsal color is tan, brown or olive-brown with inky black spots with distinct margins. The undersides of the legs and margin of the abdomen are honey yellow. Black and cream to greenish-yellow mottling is present on the sides of the body at the juncture between body and legs (the groin). The legs are long and webbing on the toes does not extend past the first joint on the longest toe. Juveniles resemble adults but may not have the distinct yellow coloration on the undersurfaces. Mature males have gray swollen pads, called nuptial pads, on the thumbs.
Larvae-The tadpole has an oval body with dorsal eyes. The dorsal fin terminates posterior to the tube for moving respiratory water out of the body (spiracle) and is relatively low. The tail tip is pointed. At hatching, the tadpoles are dark brown but appear black in most light. As they grow, they develop metallic pigmentation that is silvery or brassy. Tadpoles grow to between 50 to 75 mm total lengths before metamorphosis.
Eggs –Individual egg masses are globular and roughly the size of a grapefruit. The eggs are laid communally with many (sometimes 60 or more) females depositing their eggs next to or on top of the eggs of other females. Individual egg masses may also be present in the vicinity of the communal cluster(s). The egg masses are laid near the water surface in shallow water (less than 15 cm deep). Some egg masses in the communal cluster may break the water surface. The egg masses are not attached to vegetation.
Voice –The advertisement call is a series of weak, slow, low croaks or chuckles. One must be in close vicinity to the breeding site to hear the males. Males call during the day. Intensity increases on sunny days.
See Photos Page.
Frogs - The presence of dorsolateral folds distinguishes all native True Frogs (ranid species) from other anurans in Washington State. The native True Frogs including Cascades Frog, Northern Red-legged Frog, Oregon Spotted Frog and Columbia Spotted Frog are brownish colored frogs that are similar in general appearance. Cascades Frogs are distinguished by the honey-yellow coloration on the abdomen and undersides of the legs and the following traits: 1) the groin has weak mottling of black and greenish yellow or cream where dorsal coloration meets ventral coloration but it is unlike the distinct patch of multiple colors seen in Northern Red-legged frogs, 2) the dorsal spots are inky black with distinct edges that are neither ragged or blurred, 3) dorsolateral folds are present along the entire dorsal margins, 4) the eyes are oriented outward (laterally) so that only a portion of the pupil is visible when the frog is viewed from above, and 5) webbing is reduced between the toes so that the webbing on the longest toe does not extend past the first joint and the webbing is concave when the toes are pulled apart.
Some Cascades Frogs have a small amount of red pigmentation on the underside of the body but not to the extent seen in the Red-legged, Oregon Spotted and Columbia Spotted frogs. Small juvenile Northern Red-legged Frogs and both species of Spotted Frogs often lack the red or orange ventral pigmentation. Small juvenile Cascades Frogs may lack the yellow ventral pigmentation.
The American Bullfrog and American Green Frog, introduced True Frogs, have a distinct fold (supratympanic fold) from the posterior edge of the eye, around the top of the external ear (tympanum) and ending at the shoulder; and typically exhibit green coloration on the face.
Lastly, Cascades Frogs typically occur at higher elevations than the Northern Red-legged Frog, American Bullfrog and American Green Frog.
Larvae- Pacific Treefrog tadpoles differ in having eyes along the outline of the head when viewed from above. Western Toad tadpoles are black dorsally and ventrally, have minimal if any metallic flecking, have flattened bodies, have a tail fin that does not extend onto the back and have narrowly placed dorsal eyes on top of the head. Large American Bullfrog and Green Frog tadpoles have distinct black spots over the body on a khaki-colored dorsal ground color and the abdomen is an opaque yellow (intestines not visible) with no metallic pigment (Bullfrog) or coppery sheen (Green Frog). The tadpoles of the Northern Red-legged Frog, Oregon and Columbia Spotted frogs, and Cascades Frog are similar enough that distinguishing them in the field is challenging (see Recommended Field Guides and Keys on the Home Page).
Eggs – The Cascades Frog, Oregon Spotted Frog and Columbia Spotted Frog typically lay their eggs in communal clusters that consist of many (up to 60 or more) egg masses laid next to or on top of each other in shallow (≤ 15 cm) water. Although there are some subtle differences, one can not reliably distinguish the egg masses in the field. At some sites in Oregon, Cascades Frogs and Oregon Spotted Frogs will even lay eggs in the same communal clusters. Range differences, and to some extent elevation, can be used in some areas to determine the more likely species. Raising tadpoles to confirm identification may be necessary in some circumstances. Collection of any amphibian life stage requires a Washington Department of Fish and Wildlife scientific research permit.
The egg mass of the Northern Red-legged Frog looks similar to a single Cascades Frog egg mass. The Northern Red-legged Frog egg mass will, however, be attached to some type of vegetation if it is available; will typically be in deeper water (> 15 cm); and the individual eggs (ova) are typically much larger averaging almost twice the diameter [3.5 mm] in Northern Red-legged Frogs versus the others species (close to 2 mm).
The Northwestern Salamander has a fist-sized globular egg mass that is solid to the touch, always attached to vegetation and the animal pole of the egg (ovum) and the embryos are brown not dark brown or black.
See Key Features Page.
Breeding behavior starts as soon as ice has melted and waters at the oviposition sites have reached approximately 8° C. This is typically between April and June. Breeding is explosive with all females laying eggs within a short period of time. Development time to hatching takes two to four weeks depending on temperature and sun exposure. The larval period is about two months long. Overwintering behavior is currently (2009) being studied by Central Washington University graduate student April Barreca.
In Washington, Cascades Frogs occur in the Pacific Coast, North Cascades, West Cascades and East Cascades ecoregions.See Distribution Map.
For information on the complete range of this species, see NatureServe Explorer.
Cascade Frogs are found primarily at higher elevations (most above 2000 ft. [610 m] in Washington) with suitable breeding sites. It is not unusual to find them away from water bodies. However, most individuals are found in the vicinity of standing or flowing water. They can be active both day and night. Cascades Frogs can be abundant at sites where they occur.
Breeding habitats include a variety of still water bodies that generally persist for at least two months after snow melt. Breeding sites include wetlands, ponds, lakes, flooded meadows, small alpine ponds and still water edges of small creeks. Eggs are laid in shallow open areas that receive sun. Tadpoles are bottom feeders that prefer muddy or silty substrate in shallow water.
This is a common species that remains widespread throughout its historical habitat in Washington.
Monitoring of populations is recommended due to general declines of True Frogs (ranid species). Annual egg mass surveys to determine number of breeding females (one egg mass per adult female) is the most efficient method for monitoring populations of this species for long-term trend analyses.
April Barreca, a graduate student at Central Washington University, is studying overwintering behavior of Cascade Frogs in the Wenatchee National Forest. She is radio-tracking frogs to their overwintering locations to determine if adequate overwintering habitat influences abundance and distribution.
The authors are unaware of any published reports of Cascades Frog declines in Washington. Results of surveys in Olympic National Park in the late 1990s found Cascades Frogs to be among the most commonly encountered pond breeding species and no evidence of declines was reported. They have also re-colonized sites at Mount St. Helens. Declines have, however, been reported from Oregon and most severely from California.
Bury and Adams (2000), Leonard et al. (1993), NatureServe (website accessed March 2009), Nussbaum et al. (1983).
Personal communications: April Barreca, M. Blouin, C. Crisafulli, M. Hayes
Hallock, L.A. and McAllister, K.R. 2009. Cascades Frog. Washington Herp Atlas. http://www1.dnr.wa.gov/nhp/refdesk/herp/
Last updated: May 2009