BC Conservation Data Centre: Species Summary
Rana pretiosa
Oregon Spotted Frog
| Scientific Name: | Rana pretiosa Baird and Girard, 1853 | ||||||||||
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| English Name: | Oregon Spotted Frog | ||||||||||
| Classification / Taxonomy | |||||||||||
| Scientific Name - Concept Reference: | Frost, D. R. 1985. Amphibian species of the world. A taxonomic and geographical reference. Allen Press, Inc., and The Association of Systematics Collections, Lawrence, Kansas. v + 732 pp. | ||||||||||
| Classification Level: | Species | ||||||||||
| Species Group: | Vertebrate Animal | ||||||||||
| Species Code: | A-RAPR | ||||||||||
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| Conservation Status / Legal Designation | |||||||||||
| Global Status: | G2 (Oct 2013) | ||||||||||
| Provincial Status: | S1 (Jan 2022) | ||||||||||
| BC List: | Red | ||||||||||
| Provincial FRPA list: | |||||||||||
| Provincial Wildlife Act: | |||||||||||
| COSEWIC Status: | Endangered (May 2011) | ||||||||||
| SARA Schedule: | 1 - Endangered (Jun 2003) | ||||||||||
| General Status Canada: | 1 - At Risk (2005) | ||||||||||
| Ecology & Life History | |||||||||||
| General Description: | This frog has upturned eyes, usually small bumps and tubercles on the the back and sides, and short hind legs relative to body length, and hind feet that are fully webbed (Leonard et al. 1993). The head is marked with a faint mask, and a light jaw stripe extends to the shoulder. Black spots are scattered on the head, back, sides, and legs. The dark spots have ragged edges and light centers and usually are associated with a tubercle or raised area of skin. The spots become larger and darker, and the edges become more ragged, with age (Hayes 1994). Juveniles are usually brown or, occasionally, olive green on the back and white, cream, or flesh-colored with reddish pigments on the underlegs and abdomen (McAllister and Leonard 1997). Adults range from brown to reddish brown but tend to become redder with age. Large, presumably older, individuals may be brick red over most of the dorsal surface (McAllister and Leonard 1997). Red surface pigment on the adult abdomen increases with age, and the underlegs of adults are a vivid orange red. Tan to orange folds along the sides of the back (dorsolateral folds) extend from behind the eye to midway along the back (McAllister and Leonard 1997). This is a medium-sized frog about 44-105 millimeters (1.7 to 4.1 inches) in body (snout-vent) length (McAllister and Leonard 1997, Rombough et al. 2006). Adult females are typically larger than adult males (the latter reach only about 75 mm (3 inches) (Leonard et al. 1993). The weak call consists of a rapid series of 6-9 low clucking notes, sometimes described as sounding like a distant woodpecker's tapping. This species generally vocalizes only during the breeding season (Leonard et al. 1993); however vocalizations have been heard during the fall (Leonard et al. 1997). |
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| Global Reproduction Comments: | The life cycle involves distinct stages: eggs, larvae, and metamorphosed individuals. Breeding occurs as early as February or March at lower elevations and as late as late May or early June at higher elevations (Leonard et al. 1993), and at a particular elevation southern populations likely tend to breed earlier than do northern populations. Breeding occurs in February at sea level in British Columbia. In central Oregon, the period from first oviposition to first hatching occurred in mid- to late April (Bowerman and Pearl 2010). Where freezing occurs, breeding generally occurs as early as winter thaw permits. In at least some areas breeding is "explosive" and occurs primarily within a period of 1-2 weeks (Pearl and Hayes 2005). Reproductive females likely breed once each year and deposit one egg mass per breeding event, and they usually lay eggs communally in clusters containing up to several hundred egg masses, often in the same location year after year. Eggs survive freezing air temperatures and ice cover for up to several days (Bowerman and Pearl 2010), hatch in 3-21 days, depending on temperature. Metamorphosis occurs in mid- to late summer (Nussbaum et al. 1983). Individuals first breed when 1-3 years old (females generally at 2-3 years), depending on the elevation and latitude (mature at greater age at high elevations). Most individuals live not more than a few years, but some may live more than a deacde (see USFWS 2009). | ||||||||||
| Migration Characteristics: (Global / Provincial) | |||||||||||
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Nonmigrant: Local Migrant: Distant Migrant: Within Borders Migrant: |
Y / Y / N / na / |
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| Global Migration Comments: | Individuals regularly move short to long distances between breeding and nonbreeding habitats. Movements of several hundred meters are not unusual, and intensive studies or use of appropriate methodology such as radiotelemetry indicate that much longer movements occur. In Washington, three frogs (one male and two females) in Washington moved a distance of 2.4 kilometers along a creek from the point where they were marked (McAllister and Walker 2003). In Oregon, two juveniles were recaptured 1.2 kilometers and 1.4 kilometers downstream from where they were initially marked, and one adult female moved 2.8 kilometers downstream (Cushman and Pearl 2007). In some locations individuals routinely make annual migrations of 0.5-1.3 kilometers between breeding and overwintering sites (J. Bowerman, pers. comm., 2006, cited by USFWS 2009). Adults can be found in the same general location in successive years (Hayes 1998). In Washington, four females had home ranges not larger than 5 hectares (average 2.2 hectares) (Watson et al. 2003). These frogs are capable of colonizing sites within at least several hundred meters of an existing population, if there is adequate riparian/wetland habitat between areas, at least seasonally (Watson et al. 2003). |
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| Habitats: (Type / Subtype / Dependence) |
Lakes / Lake / Obligate
Lakes / Pond/Open Water / Obligate Riparian / Gravel Bar / Facultative - frequent use Riparian / Riparian Forest / Facultative - frequent use Riparian / Riparian Herbaceous / Facultative - frequent use Riparian / Riparian Shrub / Facultative - frequent use Stream/River / Stream/River / Facultative - frequent use Wetland / Bog / Obligate Wetland / Fen / Obligate Wetland / Marsh / Obligate Wetland / Swamp / Obligate |
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| Global Habitat Comments: |
The Oregon spotted frog is highly aquatic and generally avoids dry uplands. It is rarely found far from permanent quiet water. Usually it occurs in vegetated shallows or among grasses or sedges along the margins of streams, lakes, ponds (including those behind beaver dams), oxbows, springs, and marshes (Hodge 1976, Licht 1986, Watson et al. 2003, Chelgren et al. 2008). Individuals move among seasonal habitats usually along flooded or saturated corridors (Watson et al. 2003). In Washington, overland movements were very rare (Watson et al. 2003). Breeding occurs usually in shallow water in pools, ponds, or other quiet waters, among moderate or dense herbaceous vegetation, often close to shore but sometimes far from away from the edge (Pearl et al. 2009). Oviposition sites may be devoid of water later in the year. In Washington, frogs used deeper permanent pools in the dry season; in the coldest periods they buried themselves at the base of dense vegetation in shallow water under ice (Watson et al. 2003). In central Oregon, breeding habitats were natural or anthropogenic and ranged from small, seasonally flooded oxbow ponds to larger channels and marshes within an extensive wetland complex; most sites had extensive emergent and submergent vegetation (Bowerman and Pearl 2010). Wintering sites are in springs, slow-flowing channels, or deep open water (Hallock and Pearson 2001, Chelgren et al. 2008). Pearl and Hayes (2004) reviewed available literature and summarized habitat relationships as follows. Oregon spotted frogs are generally associated with wetland complexes > 4 ha in size with extensive emergent marsh coverage that warms substantially during seasons when the frogs are active at the surface. The expanse of inundation in wetlands often varies greatly between spring and fall, but sites always include some permanent water adjacent to seasonally inundated habitat. Field observations and recent telemetry data suggest the frog utilize different wetland microhabitats for breeding, the nonbreeding active season (summer and portions of spring and fall), and overwintering. Breeding sites are generally associated with seasonally flooded, shallowly sloping benches that are vegetated with the previous year's emergent vegetation and are relatively unshaded. The frogs' shallow-water breeding habitat may contribute to relatively frequent stranding of the communally deposited egg masses and substantial egg mortality. Limited data suggest that adults may move little during the nonbreeding active season and may prefer microhabitats of moderate vegetation density that are near aquatic refuges. |
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| Food Habits: |
Herbivore:Immature
Invertivore: Adult |
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| Global Food Habits Comments: | The diet includes a wide variety of insects (e.g., beetles, flies) as well as mollusks, crustaceans, and spiders, and adults sometimes eat other amphibians such as newly metamorphosed red-legged frogs, western toads, or newly hatched conspecifics (McAllister and Leonard 1997, Pearl and Hayes 2005). Larvae eat algae, organic debris, carrion, plant tissue, and minute organisns in water. | ||||||||||
| Global Phenology: |
Diurnal: Adult, Immature
Hibernates/aestivates: Adult, Immature |
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| Global Phenology Comments: | Activity may occur year-round at low elevations (Jones et al. 2005). Relatively little activity occurs during the coldest periods in winter, though frogs may actively move within the aquatic habitat in winter, even under ice (Hallock and Pearson 2001, Hayes et al. 2001, Risenhoover et al. 2001). | ||||||||||
| Provincial Phenology: (1st half of month/ 2nd half of month) |
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| Colonial Breeder: | Y | ||||||||||
| Length(cm)/width(cm)/Weight(g): | 10/ / | ||||||||||
| Elevation (m) (min / max): |
Global:
Provincial: |
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| Distribution | |||||||||||
| Endemic: | N | ||||||||||
| Global Range Comment: | Range extends from southwestern British Columbia south through the eastern side of the Puget/Willamette Valley trough and the Columbia River gorge in south-central Washington to the Cascades Range at least to the Klamath Valley in Oregon (and at least formerly to northeastern California); the species is considered extirpated from the Willamette Valley, northeastern California, and much of its range in western Washington (Hayes 1997, Pearl and Hayes 2005). More than two-thirds of known extant populations are along the crest and eastern slope of the Cascade Range in central Oregon (Hayes 1997, Cushman and Pearl 2007, Pearl et al. 2009). Elevational range extends from near sea level in the Puget Trough lowlands in Washington to around 1,500 meters in the Oregon Cascades and locations in western Oregon (Dunlap 1955, Hayes 1997, McAllister and Leonard 1997). At the northern range limits, occurrences are unlikely to occur at elevations above 200 meters (Pearl and Hayes 2004). | ||||||||||
| Authors / Contributors | |||||||||||
| Global Information Author: | Hammerson, G. | ||||||||||
| Last Updated: | Jul 07, 2011 | ||||||||||
| Provincial Information Author: | |||||||||||
| Last Updated: | |||||||||||
| References and Related Literature | |||||||||||
2001. Oregon Spotted Frog. B.C. Minist. Environ., Lands and Parks, Wildl. Branch. 2pp. |
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B.C. Ministry of Environment. Recovery Planning in BC. B.C. Minist. Environ. Victoria, BC. |
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Backhouse, F. 2002. Oregon Spotted Frog. B.C. Minist. Water, Land and Air Prot. Biodiv. Branch. 6pp. |
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Behler, J. L., and F. W. King. 1979. The Audubon Society field guide to North American reptiles and amphibians. Alfred A. Knopf, New York. 719 pp. |
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Briggs, J. L., Sr. 1987. Breeding biology of the Cascade frog, Rana cascadae, with comparisons to R. aurora and R. pretiosa. Copeia 1987:241-245. |
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Corn, P. S., and F. A. Vertucci. 1992. Descriptive risk assessment of the effects of acidic deposition on Rocky Mountain amphibians. J. Herpetol. 26:361-369. |
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COSEWIC. 2000c. COSEWIC assessment and status report on the Oregon spotted frog Rana pretiosa in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 22 pp. |
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Green, D. M., H. Kaiser, T. F. Sharbel, J. Kearsley, and K. R. McAllister. 1997. Cryptic species of spotted frogs, Rana pretiosa complex, in western North America. Copeia 1997:1-8. |
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Green, D. M., T. F. Sharbel, J. Kearsley, and H. Kaiser. 1996. Postglacial range fluctuation, genetic subdivision and speciation in the western North American spotted frog complex, Rana pretiosa. Evolution 50:374-390. |
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Green, D.M. 1986a. Systematics and evolution of western North American frogs allied to Rana aurora and Rana boylii: karyological evidence. Systematic Zoology 35:273-282. |
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Green, D.M. 1986b. Systematics and evolution of western North American frogs allied to Rana aurora and Rana boylii: electrophoretic evidence. Systematic Zoology 35:283-296. |
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Green, D.M., and R.W. Campbell. 1984. The Amphibians of British Columbia. Royal B.C. Mus. Handb. No. 45. 101pp. |
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Kiesecker, J. M., and A. R. Blaustein. 1997. Influences of egg laying behavior on pathogenic infection of amphibian eggs. Conservation Biology 11:214-220. |
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Nussbaum, R.A., E.D. Brodie, Jr., and R.M. Storm. 1983. Amphibians and Reptiles of the Pacific Northwest. University Press of Idaho, Moscow, Idaho. 332 pp. |
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Orchard, S.A. 1988. Species Notes for Amphibians. Vol. 4 in A.P. Harcombe, tech. ed. Wildlife Habitat Handbooks for the Southern Interior Ecoprovince. B.C. Minist. Environ., Lands and Parks, Wildl. Branch, Tech. Rep. R-18. 38pp. |
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Ovaska, K, S. Lennart, C Engelstoft, L. Matthias, E. Wind and J. MacGarvie. 2004. Best Management Practices for Amphibians and Reptiles in Urban and Rural Environments in British Columbia. Ministry of Water Land and Air Protection, Ecosystems Standards and Planning, Biodiversity Branch |
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Pearl, C.A, and M.P. Hayes. 2004. Habitat associations of the Oregon spotted frog (Rana pretiosa): A literature review. Final Report. Washington Dep. Fish and Wildl., Olympia, WA, USA. |
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Spahr, R., L. Armstrong, D. Atwood, and M. Rath. 1991. Threatened, endangered, and sensitive species of the Intermountain Region. U.S. Forest Service, Ogden, Utah. |
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Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp. |
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Turner, F.B. and Dumas, P.C. 1972. Rana pretiosa. Catalogue of American Amphibians and Reptiles. 119:1-4. |
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Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.
Suggested Citation:
B.C. Conservation Data Centre. 2011. Species Summary: Rana pretiosa. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Oct 4, 2024).