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[call details here]

Description
A medium-sized frog. Brown to olive brown on back. Inky black spots, usually well defined, on back. Dark spotting on legs. Few or no black flecks between spots. Lower abdomen and underside of rear legs yellow, orange-yellow, or yellowish tan. Groin usually bright yellow with dark mottling. Lower sides yellowish or cream. Dorsolateral folds. Male has darkened and enlarged thumb base (Stebbins 1985). Males measure 50-60 mm in snout-vent length, females, 50-75 mm (Ronald and Dumas 1971).

Range overlaps slightly with ranges of Rana pretiosa (Spotted frog) and R. Aurora (Red-legged frog). R. pretiosa has a more conspicuous light-colored upper jaw stripe and nostrils that are set closer together an higher on the snout than R. cascadae. R. Aurora usually has red mottling on its groin and generally has smoother skin than R. cascadae (Stebbins 1985)..

Distribution and Habitat

Country distribution from AmphibiaWeb's database: United States

U.S. state distribution from AmphibiaWeb's database: California, Oregon, Washington

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (57 records).

Cascade Mts., from northern Washington south through Oregon to California border. Isolated populations in Olympic Mts. of Washington, Mt. Shasta and Lassen Peak area of California, and Trinity Mts. of California. Lives at elevations of 800-2740 m, almost to timberline. Inhabits small streams, meadow puddles, ponds, and lakes, usually in open coniferous forest. Found in water or among grass, ferns and riparian vegetation (Stebbins 1985).

Life History, Abundance, Activity, and Special Behaviors
Call is either a low-pitched, grating, chuckling sound, resembling that of Rana aurora (Red-legged Frog), with 4-5 notes per second, or a series of rapid clucks or double clucks, each about .5 seconds long. Calls from above or below water's surface (Stebbins 1985). Diurnal (active during the day). Breeds from March to mid-Aug., soon after pond ice begins to thaw (Stebbins 1985).

Trends and Threats
Declining in much of its range.

Rapid decline in southernmost portion of range began after 1978. Apparently, Rana cascadae had mostly vanished from the vicinity of Lassen Volcanic National Park in California by 1993. Fellers and Drost (1993) searched 16 historical and 34 additional sites in this area in 1991 and found only one male and one female frog, both in a stream draining into Crumbaugh Lake. Causes of the decline here seem to be a combination of introduced predators and habitat destruction. Non-native predatory trout restrict habitat and limit dispersal. Drought dries up the ponds, streams, and pools which serve as breeding habitat. And the succession of meadows and their associated streams and open pools to thickets and forests also destroys breeding habitat (Fellers and Drost 1993).

In Oregon and Washington, numbers are very high in suitable habitat (Nussbaum et al. 1983). Nevertheless, the frog has declined extremely in Oregon. Although abundant there in the early 1970's, 80% of 30 Oregon populations that Andrew Blaustein has monitored since the mid 1970's have disappeared (Blaustein and Wake 1990). Blaustein et al. found R. cascadae embryos to display low photolyase activity when reared in the lab. Lack of high levels of photolyase may inhibit the repair of DNA damaged by UV-B radiation, leaving the embryos vulnerable UV-B-induced mortality. Blaustein et al. also conducted experiments at two sites in the Oregon Cascades, at elevations of 1190 and 2000 m, and found that R. cascadae embryos shielded from ambient UV-B radiation hatch with better success than those exposed to direct sunlight, suggesting that UV-B induced embryo mortality may be responsible for R. cascadae population declines (Blaustein et al. 1994). A similar experiment by Blaustein et al. (1995) found a synergism between ambient UV-B and disease. In the Oregon Cascades, at two sites (elevations of 1220 and 2000 m) ambient UV-B and the algal pathogen Saprolegnia ferax were both observed to be factors that reduced hatching success of R. cascadae embryos, but the reduction was amplified when embryos were exposed to both factors.

Relation to Humans
In the vicinity of Lassen Volcanic National Park, the common management practices in parks and wilderness of suppressing natural fire regimes and cessation of cattle grazing has sped the natural invasion of shrubs and trees into open meadows, thereby filling in or choking with vegetation the ponds, streams, and marshes where the frog used to breed (Fellers and Drost 1993).

Possible reasons for amphibian decline

General habitat alteration and loss
Prolonged drought
Secondary succession
Disease
Climate change, increased UVB or increased sensitivity to it, etc.

Comments
The Cascades frog is rather non-mobile in its behavior, often allowing one to inspect it closely (Stebbins 1985).

This species was featured as News of the Week on July 5, 2015:

Rana cascadae is in decline throughout much of its range, and its near extirpation in the Lassen Peak region of northern California was an early example of the general decline of amphibians that has attracted so much attention. Piovia-Scott et al. (2015) studied the relationship of the chytrid pathogen (Batrachochytrium dendrobatidis, Bd) to juvenile survival of R. cascadae in a lake in the Klamath Mts., and a lake in the southern Cascade Mts., northern California. In the first site, Section Line Lake, abundance of juvenile frogs declined by more than 99% between 2009 and 2012, and Bd was 5 times as prevalent as in the other lake, where no clear trend was recorded. Lab experiments showed that the virulence of Section Line Lake Bd was much greater than isolates from other lakes, and genomic differences were also recorded. The study highlights the significance of local processes in host-pathogen dynamics and population declines. (Written by David Wake)

This species was featured as News of the Week on December 22, 2014:

While Rana cascadae is relatively widespread in montane habitats from northern California into southern British Columbia, declines attributed to the chytrid fungus Batrachochytrium dendrobatidis (Bd) seem focused in northern California populations. Piovia-Smith et al. (2014) studied virulence of Bd from two lakes suffering declines, finding that isolates from the midst of the decline were more virulent and induced greater mortality of juvenile frogs than Bd isolated from a more stable frog population. In genomic studies, the virulent isolate showed unusual features, including chromosomal differences. Specific genomic and phenotypic features of Bd might account for differences in mortality within species from different localities, as well as differences among species of amphibians. (Written by David Wake)

See another account at californiaherps.com.

References

Altig, R., and Dumas, P. C. (1971). ''Rana cascadae Slater. Cascades Frog.'' Catalogue of American Amphibians and Reptiles. Society for the Study of Amphibians and Reptiles, 105.1-105.2.

Badarco (1962). "Wildlife observation on file at Lassen Volcanic National Park, Mineral, California."

Blaustein, A. R., Hoffman, P. D., Hokit, D. G., Kiesecker, J. M., Walls, S. C., and Hays, J. B. (1994). "UV repair and resistance to solar UV-B in amphibian eggs: A link to population declines?" Proceedings of the National Academy of Sciences of the United States of America, 91(5), 1791-1795.

Blaustein, A. R., and Wake, D. B. (1990). "Declining amphibian populations: A global phenomenon?" Trends in Ecology and Evolution, 5(7), 203-204. [link]

Borrel, A. E. (1924). "Field notes on file at the Museum of Vertebrate Zoology, University of California, Berkeley."

Fellers, G. M., and Drost, C. A. (1993). ''Disappearance of the Cascades Frog Rana cascadae at the southern end of its range, California, USA.'' Biological Conservation, 65(2), 177-181.

Grinnell, J. (1925). ''Field notes on file at the Museum of Vertebrate Zoology, University of California, Berkeley.''

Grinnell, J., Dixon, J., and Linsdale, J. M. (1930). Vertebrate natural history of a section of northern California through the Lassen Peak region. Univ. California Press, Berkeley, California.

Kiesecker, J. M., and Blaustein, A. R. (1995). "Synergism between UV-B radiation and a pathogen magnifies amphibian embryo mortality in nature." Proceedings of the National Academy of Sciences of the United States of America, 92(24), 11049-11052.

Nussbaum, R. A., Brodie, E. D., Jr., and Storm, R. M. (1983). Amphibians and Reptiles of the Pacific Northwest. University of Idaho Press, Moscow, Idaho.

Sage, R. D. (1974). "Field notes on file at the Museum of Vertebrate Zoology, University of California, Berkeley."

Stebbins, R. C. (1951). "Field notes on file at the Museum of Vertebrate Zoology, University of California, Berkeley."

Stebbins, R. C. (1952). "Field notes on file at the Museum of Vertebrate Zoology, University of California, Berkeley."

Stebbins, R. C. (1985). A Field Guide to Western Reptiles and Amphibians. Houghton Mifflin, Boston.

Species Account Citation: AmphibiaWeb 2021 Rana cascadae: Cascades Frog <https://amphibiaweb.org/species/4998> University of California, Berkeley, CA, USA. Accessed Jan 27, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 27 Jan 2025.

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