Rana cascadae

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)..

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

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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).

This species occurs in the Cascade Mountains from northern Washington south to northern California, USA. Populations isolated from the main Cascade Mountains complex occur in the Olympic Mountains, Washington; Mount Shasta and Lassen Peak area, California; and the Trinity Mountains, California (Stebbins 1985b; Nussbaum, Brodie and Storm 1983; Pearl and Adams 2005). Its range is generally between 665 and 2,450m asl, although some Washington populations might occur at lower altitudes. Its prehistoric range might have included much lower altitudes (Leonard et al. 1993).

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).

Biogeographic Regions: nearctic (Native )

Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) Range extends from the Cascade and Olympic mountains of northern Washington south to northern California. Populations in the Olympic Mountains of Washington and the Trinity Alps, Mt. Shasta, and Mt. Lassen areas of California are notably disjunct from the primary distribution along the main Cascade axis (Pearl and Adams 2005). Historical locations at low elevations in Washington suggest that the species formerly may have been more broadly distributed (Leonard et al. 1993). Historical elevational range extended from around 400 to 2,500 meters.

endemic to a single nation

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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).

Length: 8 cm

This species differs from Rana pretiosa in having a less conspicuous light-colored upper jaw stripe, a dark mask, nostrils that are farther apart and lower on the snout, and eyes that are not turned upward as much. It differs from Rana aurora in having distinct black spots on the back, yellowish (rather than red) color on lower abdomen and underside of legs, and generally rougher skin (Stebbins 2003).

Habitat and Ecology

Systems

• Terrestrial
• Freshwater

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).

Terrestrial Biomes: mountains

Aquatic Biomes: lakes and ponds

Comments: Cascades frogs inhabit wet mountain meadows, sphagnum bogs, ponds, lakes, and streams, in open or patchy coniferous forests. Generally they are closely associated with water, but they sometimes move from one drainage to another by crossing over high mountain ridges. These frogs hibernate in mud at the bottom of ponds and in spring-water saturated ground up to at least 75 meters from a pond (Briggs 1987). Breeding sites are quiet ponds, where eggs are laid in open shallow water or among submerged vegetation.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

This species is not known to exhibit well-defined migrations, but it may shift seasonally among different habitats.

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

Comments: Adults are mainly invertivorous. Larvae eat algae, detritus, plant tissue, and minute organisms in water.

10,000 - 1,000,000 individuals

Comments: This species is abundant in many parts of its range (Leonard et al. 1993). For example, in mountain meadows in Oregon, numbers were estimated to be hundreds within an area of less than 1 hectare (Nussbaum et al. 1983).

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 - 300

Comments: This species is represented by a large number of occurrences (subpopulations. Hundreds of unique locations are known in Washington, but some of these are likely no longer extant, and others should be combined into single occurrences (Dvornich et al. 1997). Oregon has approximately 70 occurrences. Few occurrences remain in California (Fellers and Drost 1993), where Altig and Dumas (1971) mapped 12 collection sites.

Comments: This species is inactive during the colder months.

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).

Breeds in spring-summer, March to mid-August, soon after ice and snow melt (Stebbins 1985). In a particular pond, most eggs are laid over a period of just a few days. Each female lays a mass of 300-500 eggs, often in aggregations. Larvae metamorphose into small frogs usually about 2-3 months after the eggs were laid. Individuals first breed probably after their third hibernation (Nussbaum et al. 1983). Typical life span is not more than 5 years.

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 1996
  Vulnerable

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).

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: near threatened

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Moderately small range in mountains from Washington to northern California; many extant populations; common in some areas but has declined in other areas, particularly at the edges of the range; impacts of airborne agrochemicals may be contributing to the decline.

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Moderate to broad.

United States

Rounded National Status Rank: N3 - Vulnerable

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).

Population

Population Trend

Global Short Term Trend: Relatively stable to decline of 30%

Comments: Trend over the past 10 years or three generations is uncertain, but area of occupancy, population size, number of occurrences, and habitat quality probably are slowly declining or relatively stable in the large majority of the range.

Global Long Term Trend: Decline of 30-50%

Comments: Surveys in the mid- to late 1990s in Olympic and Mount Ranier national parks, Washington, found no evidence of a decline (Adams et al. 2001, Tyler et al. 2002), and the species rebounded after the eruption of Mount St. Helens (Karlstrom 1986; Crisafulli and Hawkins 1998; C. Crisafulli, personal communication, cited by Pearl and Adam 2005).

Declines in Oregon were cited by Nussbaum et al. (1983) and Blaustein and Wake (1990), but other data do not suggest exceptionally low site occupancy rates (Brown 1997, unpublished data cited by Pearl and Adams 2005), and the species remains widespread in some areas of the northern and central Oregon Cascades, and it has shown a capacity to rebound from short-term declines (Olson 1992, Brown 1997, Pearl and Adams 2005). In Oregon, 22 percent of historical populations have disappeared (see Fite et al. 1998).

Surveys suggest that R. cascadae remains present in portions of the Trinity Alps and Marble Mountains, California, but are rare to nonexistent in other Californian portions of the historical range (G. Fellers, H. Welsh, personal communications, cited by Pearl and Adams 2005). This species has declined greatly in the vicinity of Lassen Volcanic National Park at the southern end of the range in northern California; a survey of 16 historical sites plus 34 additional sites with suitable habitat yielded only two frogs at a single locality (Fellers and Drost 1993). More recent surveys (1992-2002) detected Cascade frogs at only 4 of 400 sites; population sizes were small at all four sites, and as of 2002, frogs had disappeared from two of these four sites (G. Fellers, personal communication, cited by Pearl and Adams 2005). Jennings and Hayes (1994) and Fellers and Drost (1993) estimated that this species is extirpated from about 99 percent of its southernmost population clusters (Mt. Lassen and surroundings) and 50 percent of the total historical distribution in California.

Degree of Threat: Medium

Comments: Causes of declines are not fully known, but introduced trout, UV-B radiation, fungal pathogens, and loss of open meadow habitat due to fire suppression have been suggested (Hayes and Jennings 1986, Fellers and Drost 1993, Blaustein et al. 1994, Kiesecker and Blaustein 1995, Fite et al. 1998, Adams et al. 2001).

Declines in Lassen Volcanic National Park apparently are due to a combination of local factors, including (1) presence of non-native predatory fishes that have restricted available habitat and limited dispersal of frogs, (2) gradual loss of open meadows and associated aquatic habitats, and (3) loss of breeding habitat due to drought (Fellers and Drost 1993). In this region, fire suppression and cessation of cattle grazing have increased the natural invasion of shrubs and trees into open meadows; former open breeding sites are now clogged with vegetation (Fellers and Drost 1993).

Decline may be related to sensitivity of eggs to increased levels of ultraviolet radiation resulting from ozone depletion (Blaustein et al. 1994), but spectral characteristics of natural waters likely shield eggs from detrimental physiological effects in all but the clearest waters (Palen et al. 2002). Increased solar radiation also may be damaging frog retinas (Fite et al. 1998).

Eggs are highly susceptible to the pathogenic fungus Saprolegnia ferax, which may be introduced during fish stocking (Kiesecker and Blaustein 1997).

Cascades frogs seem to be sensitive to habitat fragmentation. Dispersal is limited by moisture-temperature conditions (Blaustein et al. 1995). However, adults regularly range onto mountain slopes far from aquatic or wetland habitats when conditions are suitably moist (G. Hammerson, pers. obs.). and may have better dispersal ability than currently documented. For example, R. cascadae was among the first amphibians to recolonize sites after the eruption of Mount St. Helens in the southern Washington Cascades and now is common there (Karlstrom 1986; Crisafulli and Hawkins 1998; C. Crisafulli, personal communication, cited by Pearl and Adam 2005).

Agrochemicals may be a threat in some areas. Davidson et al. (2002) found support for the hypothesis that airborne agrochemicals have contributed to the decline. Fertilizers such as urea may pose a threat; in laboratory studies, juveniles were unable to sense and avoid toxic levels (Hatch et al. 2001). Nitrites may affect behavior and metamorphosis of larvae (Marco and Blaustein 1999).

An Oregon study failed to detect short-term changes in breeding phenology that might be attributable to climate change (Blaustein et al. 2001).

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.

Major Threats

Conservation Actions

Biological Research Needs: An improved understanding of microhabitat associations and interactions with introduced fish is needed to assist with conservation measures for the species (Olson 2001).

Global Protection: Many (13-40) occurrences appropriately protected and managed

Comments: Many occurrences are in national parks (e.g., Olympic, Mt. Ranier, Crater Lake) or in designated wilderness areas.

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).