Rana cascadaeCascades Frog

Geographic Range

This species lives in the Cascade mountain range in a band from Washington south to the Oregon-California border, with additional populations scattered populations in the mountains of Northern California (AmphibiaWeb 2001).


Lives in streams and ponds in the mountains and coniferous forests 800-2740m. During warm and moist periods, it stays in water and surrounding vegetation. In winter, it hibernates in the soil under the lake bottom (AmphibiaWeb 2001).

  • Aquatic Biomes
  • lakes and ponds

Physical Description

Adult males are usually 50-60mm and females between 50-75mm long. Olive brown in color with a dark strip from the tip of the snout to the forelimbs. Its back and legs are usually covered with dark spots. It has a light, honey-colored underside, and a bright yellow groin with dark mottling. The toes are not fully webbed and have dorsalateral folds. The male has a swollen and darkened thumb base (Stebbins 1985).

The tadpole has a relatively long tail (Northern Prarie Wildlife Research Center 2001).



Breeds between March and August (depending on when snow and ice melt).

Famales lay up to 425 eggs, which hatch in 8-20 days. Larval development takes about three months. Metamorphose by late August or early September and reach sexual maturity at about three years (California Wildlife Habitat Relationships System 2001).

Eggs hatch with better success when not exposed to UV-B radiation (AmphibiaWeb 2001).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)


Diurnal and basks on water-covered rocks. Moves slowly, and often allows close approach. When it senses danger, it tries to swim fast, rather than hiding on the bottom.

The mating call is a low pitched grating, chuckling sound with 4-5 notes per second. A series of rapid clucks or double clucks, each lasting about 0.5 seconds. It calls from either above or below the water (Stebbins 1985).

Food Habits

Aquatic and semiaquatic insectivore (California Wildlife Habitat Relationships System 2001).

Conservation Status

While still common in some areas of suitable habitat in the northern half of its range, there are been substantial declines in populations of R. cascadae in California and Oregon. Likely causes of the decline in California are habitat loss and predation by non-native trout, exacerbated by drought. Effort to suppress fires and cattle grazing in Lassen Volvanic National Park has led to shrub and tree overgrowth of open meadows , filling up the aquatic habitats in which many of the frogs breed. Trout have been introduced into a number of mountain lakes and eat tadpoles.

These reasons may not explain the substantial decline of this species in Oregon. There is some evidence that increased ultraviolet radiation exposure due to depletion of atmospheric ozone may be another important factor in extinction (AmphibiaWeb 2001).


Jill Spielfogel (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature


A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.


having the capacity to move from one place to another.


This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.


2001. "AmphibiaWeb" (On-line). Accessed 3/20/2001 at http://elib.cs.berkeley.edu/aw/.

"Convention on International Trade in Endangered Species of wild fauna and flora" (On-line). Accessed 3/20/2001 at http://www.cites.org/CITES/eng/index.html.

"Endangered Species Act" (On-line). Accessed 3/20/2001 at http://endangered.fws.gov/wildlife.html.

"International Union for Conservation of Nature and Natural Resources" (On-line). Accessed 3/20/2001 at http://www.redlist.org.

California Wildlife Habitat Relationships System, , A042 - Cascades Frog - Rana cascadae. 2001. "A042 Cascades Frog" (On-line). Accessed 3/20/2001 at http://www.dfg.ca.gov/whdab/cwhr/A042.html.

Stebbins, R. 1985. A Field Guide to Western Amphibians and Reptiles. Boston, MA: Houghton Mifflin Company.

Stebbins, R. 1951. Amphibians of Western North America. Berkeley and Los Angeles: University of California Press.

USGS Northern Prairie Wildlife Center, 2001. "Cascades Frog" (On-line). Accessed 7/27/2001 at http://www.npsc.nbs.gov/narcam/idguide/rcascade.htm.