The Columbia Spotted Frog may be brown, tan, or gray with irregular-shaped black spots with light-centers. The undersides are cream colored with an orange or salmon-colored pigment usually present on the hind legs and lower abdomen. In some Nevada populations the hind legs and abdomen of frogs are yellow. The hind legs are relatively short relative to body length and there is extensive webbing between the toes on the hind feet. The eyes are upturned. Females may grow to approximately 100 mm (4 inches) snout-to-vent length, while males may reach approximately 75 mm (3 inches) snout-vent length (Nussbaum et al. 1983; Stebbins 1985; Leonard et al. 1993).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Canada, United States
U.S. state distribution from AmphibiaWeb's database: Alaska, Idaho, Montana, Nevada, Oregon, Utah, Washington, Wyoming
Canadian province distribution from AmphibiaWeb's database: Alberta, British Columbia, Yukon
Canada and the United States. Ranges from southeastern Alaska down into Canada (southwestern Yukon, northern British Columbia, western Alberta and east to Saskatchewan) and into the United States (Washington, east of the Cascade Mountains, eastern Oregon, western Montana, southwestern Idaho, central Nevada, western and north-central Wyoming, and north-central Utah (Wright and Wright 1949; Stebbins 1985; Green et al. 1997).
In Washington, the species is known to occur at elevations ranging between 520 m (1720 feet; near Rock Lake, Whitman County) to 950 meters (6400 feet; at Hart’s Pass, Whatcom County) (Leonard et al. 1993).
The Columbia Spotted Frog is a highly aquatic species and nearly always is found in close proximity to water. Breeding habitats include a variety of relatively exposed, shallow-water (<60 cm), emergent wetlands such as sedge fens, riverine over-bank pools, beaver ponds, and the wetland fringes of ponds and small lakes. Vegetation in the breeding pools generally is dominated by herbaceous species such as grasses, sedges (Carex spp.) and rushes (Juncus spp.). After breeding is completed, adults often disperse into adjacent wetland, riverine and lacustrine habitats.
Life History, Abundance, Activity, and Special Behaviors
The timing of breeding varies widely across the species' range owing to differences in weather and climate, but the first visible activity begins in late winter or spring shortly after areas of ice-free water appear at breeding sites (Licht 1975; Turner 1958; Leonard et al. 1996). In Washington's Columbia Basin breeding typically occurs in late March or April, but at high-elevation montane sites breeding does not occur until late May or early June.
Adults exhibit a strong fidelity to breeding sites, with oviposition typically occurring in the same areas in successive years. Males arrive first, congregating around breeding sites, periodically vocalizing "advertisement calls" in a rapid series of 3 to 12 "tapping" notes that have little carrying power (Davidson 1995; Leonard et al. 1996). It is unknown to what extent the weak calls serve to attract females, but they may serve to distribute males at the breeding sites thus minimizing male–male encounters. As a female enters the breeding area, she is approached by and subsequently pairs with a male in a nuptial embrace referred to as amplexus. From several hours to possibly days later, the female releases her complement of eggs into the water while the male, still clinging to the female, releases sperm upon the ova.
Columbia Spotted Frogs have a strong tendency to lay their eggs communally and it is not uncommon to find 25 or more egg masses piled atop one another in the shallows. The egg masses are deposited in still, shallow water, either atop matted grasses or freely floating among clumps of herbaceous wetland plants. The water levels at breeding sites is usually so shallow that the upper portions of the egg masses protrude above the water surface. This habit often results in severe egg mortality from freeze-thaw damage or desiccation if temperatures fall below freezing or if rain ceases for a prolonged period during the embryonic period.
After a few weeks, thousands of small tadpoles emerge and cling to the remains of the gelatinous egg masses. After several days the small hatchling tadpoles begin swimming and feeding upon algae, detritus, and in some cases, bacteria, using their minute brush-like mouthparts. In the Columbia Basin tadpoles may grow to 100 mm (4 inches) total length prior to metamorphosing into froglets in their first summer or fall. At high-elevation montane sites, however, tadpoles barely reach 45 mm in total length prior to the onset of metamorphosis in late fall.
Mortality of eggs, tadpoles, and newly metamorphosed frogs is high, with approximately 5% surviving the first winter (David Pilliod, personal communication). At low-elevation sites sexual maturity is probably attained in two to three years, while three or four years may be required at high-elevation sites (Turner 1960; Licht 1975).
Food includes arthropods (e.g., spiders, insects), earthworms and other invertebrate prey (Whitaker et al. 1982). In turn, Columbia Spotted Frogs may be preyed upon by mink, river otter, raccoon, herons, bitterns, corvids, and garter snakes, while larvae may be consumed by larvae of dragonflies, predaceous diving beetles, fish, garter snakes, and wading birds.
Trends and Threats
Its range overlaps with a number of protected areas. Northern populations seem to be stable but other populations are declining, especially in some areas of Utah and Wyoming and possibly Idaho. Threats include habitat degradation from cattle grazing, agriculture, and logging as well as oil and gas exploration, and depletion of water tables and spring habitat from water development and diversion for irrigation. Pollution from mosquito control agents might be a threat (Hammerson 2004).
In a novel approach to understanding gene flow between populations of R. luteiventris in the Bighorn Crags, Salmon River Mountains, Idaho, Murphy et al. (2010) have used gravity modelling (previously used only in economic geography and transportation analyses). Functional connectivity between R. luteiventris-occupied sites was found to be positively correlated with site productivity (measured by heat load index) and frost-free period between sites. Functional connectivity was negatively correlated with local presence of predatory trout, between-site distance, and between-site topographic complexity. The authors concluded that Bighorn Crags populations were already inhabiting very marginal habitat, due to climatic, thermal, and topographic factors, and that infrequent bursts of successful reproduction were sustaining these populations. Thus stresses that may push them over the edge (metaphorically) include the presence of introduced predatory trout and climate change, if pond permanence and moisture availability in dispersal habitat are reduced.
Possible reasons for amphibian decline
General habitat alteration and loss
Intensified agriculture or grazing
Subtle changes to necessary specialized habitat
Local pesticides, fertilizers, and pollutants
Long-distance pesticides, toxins, and pollutants
Predators (natural or introduced)
Since nearly the time of its original description in 1853, the systematics of the "Western Spotted Frog" group has been a source of some confusion and debate. In 1996, however, a team led by David M. Green published the results of a study on the genetics of Spotted Frogs and concluded that the group actually contained two "sibling" species—the Oregon Spotted Frog and the Columbia Spotted Frog
(Green et al. 1996, 1997). The decision to "split" the species was based upon the results of laboratory studies that indicated significant genetic differences, despite a lack of reliable morphological differences. Because the two species have allopatric ranges, they may be reliably identified based upon the location where a frog is encountered.
Davidson, C. (1995). Frog and Toad Calls of the Pacific Coast: Vanishing Voices (recording). Library of Natural Sounds, Cornell Laboratory of Ornithology, Ithaca.
Green, D. M., Kaiser, H., Sharbel, T. F., Kearsley, J. and McAllister, K. R. (1997). ''Cryptic species of spotted frogs, Rana pretiosa complex, in western North America.'' Copeia, 1997, 1-8.
Green, D. M., Sharbel, T. F., Kearsley, J. and Kaiser, H. (1996). ''Postglacial range fluctuation, genetic subdivision and speciation in the western North American Spotted Frog complex, Rana pretiosa.'' Evolution, 50, 374-390.
Hammerson, G. 2004. Rana luteiventris. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.3. www.iucnredlist.org. Downloaded on 11 October 2010.
Leonard, W.P., Brown, H.A., Jones, L.L.C., McAllister, K.R., and Storm, R.M. (1993). Amphibians of Washington and Oregon. Seattle Audubon, Seattle.
Leonard, W.P., Leonard, N. P., Storm, R.M., and Petzel, P.E. (1996). ''Rana pretiosa (Spotted Frog). Behavior and reproduction.'' Herpetological Review, 27(4), 195.
Licht, L.E. (1975). ''Comparative life history features of the Western Spotted Frog, Rana pretiosa, from lowland and high-elevation populations.'' Canadian Journal of Zoology, 53(9), 1254-1257.
Murphy, M. A., Dezzani, R., Pilliod, D. S., and Storfers, A. (2010). ''Landscape genetics of high mountain frog metapopulations.'' Molecular Ecology, 19, 3634-3649.
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.
Stebbins, R. C. (1985). A Field Guide to Western Reptiles and Amphibians. Houghton Mifflin, Boston.
Turner F.B. (1960). ''Population structure and dynamics of the Western Spotted Frog, Rana p. pretiosa Baird and Girard, in Yellowstone National Park, Wyoming.'' Ecological Monographs, 30(251-278).
Turner, F.B. (1958). ''Life history of the Western Spotted Frog in Yellowstone Park.'' Herpetologica, 14, 96-100.
Whitaker, J.O., Cross, S.P., Skovlin, J.M., and Maser, C. (1982). ''Food habits of the Spotted Frog (Rana pretiosa) from managed sites in Grant County, Oregon.'' Northwest Science, 57(2), 147-154.
Wright, A. H. and Wright, A. A. (1949). Handbook of Frogs and Toads of the United States and Canada. Comstock Publishing Company, Inc., Ithaca, New York.
Written by William Leonard (Mollusca1 AT home.com), Washington Department of Transportation, Environmental Affairs
First submitted 2000-07-04
Edited by Kellie Whittaker (2010-10-11)
Species Account Citation: AmphibiaWeb 2010 Rana luteiventris: Columbia Spotted Frog <http://amphibiaweb.org/species/5317> University of California, Berkeley, CA, USA. Accessed Jul 5, 2020.
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Citation: AmphibiaWeb. 2020. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 5 Jul 2020.
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