Rana luteiventris

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).

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.

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.

This species is known to occur in North America from extreme southeastern Alaska, southwestern Yukon, northern British Columbia, and western Alberta south through Washington east of the Cascades, eastern Oregon, Idaho, and western Montana to Nevada (disjunctive, Mary's, Reese, and Owyhee river systems), southwestern Idaho (disjunctive), Utah (disjunctive, Wasatch Mountains and west desert), and western and north-central (disjunctive) Wyoming (Stebbins 1985; Green et al. 1996, 1997). Disjunctive populations occur on isolated mountains and in arid-land springs. It occurs from sea level to about 3,000m asl (Stebbins 1985).

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) Extreme southeastern Alaska, southwestern Yukon (Slough 2002), northern British Columbia, and western Alberta south through Washington east of the Cascades, eastern Oregon, Idaho, and western Montana to Nevada (disjunct, Mary's, Reese, and Owyhee river systems), southwestern Idaho (disjunct), Utah (disjunct, Wasatch Mountains and west desert), and western and north-central (disjunct) Wyoming (Green et al. 1996, 1997; Stebbins 2003). Disjunct populations occur on isolated mountains and in arid-land springs. Elevational range extends from near sea level to about 3,048 meters (10,000 feet) (Stebbins 2003).

The Wasatch Front population (R. luteiventris pop. 1) occurs in isolated springs or riparian wetlands in Juab, Sanpete, Summit, Utah, Tooele, and Wasatch counties; extirpated from the Salt Lake Valley and tributaries to the Jordan River and Great Salt Lake (USFWS 2002). Currently, there are seven localized populations that comprise the Wasatch Front population or DPS. The largest known concentration is currently in the Heber Valley; the remaining six locations are Jordanelle/Francis, Springville Hatchery, Holladay Springs, Mona Springs Complex/Burraston Ponds, Fairview, and Vernon (USFWS 2002).

The West Desert (Bonneville) population (R. luteiventris pop. 2) occurs in eastern Nevada and western Utah, mainly in two large spring complexes, with several additional concentrations in smaller nearby springs; it is extiprated from the northern portions of the historical range.

The Great Basin population (R. luteiventris pop. 3) occurs in southwestern Idaho, southeastern Oregon, and Nevada; it includes all Nevada populations of R. luteiventris except a small population on the eastern border of White Pine County, which is included in the West Desert population.

Length: 10 cm

Habitat and Ecology

Systems

• Terrestrial
• Freshwater

Comments: Highly aquatic; rarely found far from permanent quiet water; usually occurs at the grassy/sedgy margins of streams, lakes, ponds, springs, and marshes (Hodge 1976, Licht 1986). May disperse into forest, grassland, and brushland during wet weather, and may traverse uplands to reach wintering sites (Pilliod et al. 2002). Uses stream-side small mammal burrows as shelter (Blomquist and Tull 2002). Overwintering sites in the Great Basin include undercut stream banks and spring heads (K. Hatch, pers. comm., cited by Blomquist and Tull 2002). Wintering sites in central Idaho included deep lakes (Pilliod et al. 2002). Breeds usually in shallow water in ponds or other quiet waters. See Munger et al. (1998) for quantitative information on habitat in southwestern Idaho.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some 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.

In central Idaho, frogs moved up to 1030 m from breeding sites to reach summer habitats; females (the more mobile sex) moved an average of less than 500 m from breeding or overwintering sites to summer foraging areas; many frogs remained at or near breeding ponds; some males moved up to 1.5 km between lakes that had no riparian corridor; a few frogs moved up to at least 1.8 km away from breeding ponds, but the nature of these long movements is uncertain (Pilliod et al. 2002). Pilliod et al. (in Koch et al. 1997) reported that individual high mountain lake populations of R. luteiventris in Idaho are actually interdependent and are part of a larger contiguous metapopulation that includes all the lakes in the basin. In Nevada, Reaser (1996; in Koch et al. 1997) determined that one individual of R. luteiventris traveled over 5 km in a year.

In a three-year study of R. luteiventris movement within the Owyhee Mountain subpopulation of the Great Basin population in southwestern Idaho, Engle (2000) PIT-tagged over 1800 individuals but documented only five (of 468) recaptures over 1,000 m from their original capture point. All recaptures were along riparian corridors and the longest distance between capture points was 1,765 m. Although gender differences were observed, 88 percent of all movement documented was less than 300 m from the original capture point. Engle (2001) found a two-year-old individual 6.5 km downstream from its natal pond (a year after being marked and released).

Though movements of up to 6.5 km have been recorded, these frogs generally stay in wetlands and along streams within 1 km of their breeding pond (Turner 1960, Hollenbeck 1974, Bull and Hayes 2001, Pilliod et al. 2002). Frogs in isolated ponds may not leave those sites (Bull and Hayes 2001).

Comments: Opportunistic. Eats a wide variety of insects as well as different mollusks, crustaceans, and arachnids. Larvae eat algae, organic debris, plant tissue, and minute organisns in water.

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

Estimated Number of Occurrences: 81 to >300

Comments: Represented by many and/or large occurrences throughout most of the range (Hodge 1976, Nussbaum et al. 1983), though the disjunct southern populations are limited in number.

See additional information for Wasatch Front, West Desert, and Great Basin populations (Rana luteiventris pops. 1, 2, and 3).

100,000 - 1,000,000 individuals

Comments: Total adult population size is unknown but surely exceeds 100,000. Numerous in many areas in Canada and the Rocky Mountains.

See additional information for Wasatch Front, West Desert, and Great Basin populations (Rana luteiventris pops. 1, 2, and 3).

In the Toiyabe Range in Nevada, Reaser (2000) captured 887 individuals over three years, with average mid-season density ranging from 2 to 24 frogs per 150 m of habitat.

Comments: May move overland in spring and summer after breeding. Inactive in winter in north.

Breeds in February at sea level in British Columbia, mid-March at 1395 m in Utah, May-June at 2377 m in Wyoming; generally as early as winter thaw permits. In northeastern Oregon, eggs were not deposited on days when maximum water temperature was below 9.4 C; at 18 sites, duration of egg deposition ranged from 1 to 20 days (Bull and Shepherd 2003). Females may lay egg masses in communal clusters. Eggs hatch in 3-21 days (12-21 days in northeastern Oregon, Bull and Shepherd 2003), depending on temperature. Metamorphosis occurs by fall or tadpoles may overwinter and metamorphose the following spring. Sexually mature in 2-6 years, depending on location and elevation (matures at greater age at high elevations). In Wyoming, individual females breed yearly at low elevations, every 2-3 years at high elevations (Nussbaum et al. 1983).

Current Listing Status Summary

Status: Candidate
Date Listed:
Lead Region:   California/Nevada Region (Region 8) 
Where Listed: Great Basin DPS

For most current information and documents related to the conservation status and management of Rana luteiventris, see its USFWS Species Profile

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

Canada

Rounded National Status Rank: N4 - Apparently Secure

United States

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Moderately large range in the Pacific Northwest and Rocky Mountains; still common in British Columbia and the Rocky Mountains; southern, disjunct populations in the Great Basin are declining and face major threats, including habitat loss/degradation (especially dewatering), exotic species, and possibly global climate change; a recent conservation agreement has improved the status of the Wasatch Front and West Desert populations, which nevertheless remain of conservation concern.

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Moderate to broad.

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.

Population

Population Trend

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

Comments: See additional information for Wasatch Front, West Desert, and Great Basin populations (Rana luteiventris pops. 1, 2, and 3).

Global Long Term Trend: Increase of 10-25% to decline of 30%

Comments: Relatively stable in most of the range, but populations in the arid southern portion of the range have declined. Significant declines have occurred in some areas of Utah and Wyoming. Possibly has declined in Idaho, but numbers still apparently are high (Phillips 1990; Groves, pers. comm., 1992). See additional information for Wasatch Front, West Desert, and Great Basin populations (Rana luteiventris pops. 1, 2, and 3).

Degree of Threat: Medium

Comments: Some local populations are threatened by various forms of habitat degradation and by direct impacts of non-native species. This species is not likely to be at risk from present acidification inputs in the Rocky Mountains (Corn and Vertucci 1992). Possibly global climate changes are a factor in the decline of some populations in the arid southern part of the range (Hayes and Jennings 1986). At the embryonic stage, UV-B radiation currently does not seem to be contributing to population declines (Blaustein et al. 1999). Range-wide, most populations are not significantly unthreatened. See additional information for Wasatch Front, West Desert, and Great Basin populations (Rana luteiventris pops. 1, 2, and 3).

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.

Major Threats

Conservation Actions

Management Requirements: See Mullen (1999) for a brief description of a draft conservation strategy and agreement for spotted frogs in northeastern Nevada.

For the Wasatch Front population, USFWS (2002) concluded that the focus of conservation efforts can reasonably shift to acquisition of additional occupied and unoccupied, suitable habitats and range expansion efforts, including: (1) Land protection mechanisms, such as conservation easements and fee-title acquisitions generally provide the most long-term benefits for sensitive species. Voluntary conservation actions on parcels of private land may provide site-specific benefits to the frog. Future conservation should continue to focus on land acquisition and easements that include buffer zones sufficient to minimize direct and indirect impacts from land use as well as protection and maintenance of dispersal or migration corridors. Furthermore, steps should be taken to protect water sources (i.e., Juab Valley) where potential threats are identified. (2) Although there is no specific number of populations necessary to prevent extinction, reintroduced populations provide ecological redundancy in ecological function and genetic and demographic stochasticity. There are several habitats already identified which may provide suitable reintroduction sites. Future conservation should include reestablishment of spotted frog populations, and associated research and land management necessary to maintain new populations in: (a) Areas where populations previously occurred if suitable habitat remains and (b) other suitable habitat within the natural range of the species. (3) Some Wasatch Front spotted frog populations are notably small in size and vulnerable to risks of detrimental genetic processes (inbreeding, loss of genetic diversity) and demographic uncertainty. Springville Hatchery/T-Bone Bottom population is particularly vulnerable based on its current size and decreasing trend. Actions should be taken to augment or through some other process, increase the size of this population. Furthermore, the current trend should be evaluated to determine if specific land or water use activities are exacerbating the decrease. If specific threats are identified, priority should be placed on reducing these threats such that the population would remain secure into the future.

Global Protection: Few to several (1-12) occurrences appropriately protected and managed

Comments: Somewhat protected in several federal and state parks and refuges, though management usually ignores this species.

See additional information for Wasatch Front, West Desert, and Great Basin populations (Rana luteiventris pops. 1, 2, and 3).

Needs: See additional information for Wasatch Front, West Desert, and Great Basin populations (Rana luteiventris pops. 1, 2, and 3).