Columbia spotted frogs are found in isolated populations throughout the Pacific Northwest, encompassing southeastern Alaska, the southwestern Yukon, northern British Columbia, and western Alberta, east to Saskatchewan. They are also found east of the Cascade Mountains, including Washington state, eastern Oregon, western Montana, southwestern Idaho, central Nevada, western/north-central Wyoming, and north-central Utah. (Davis and Verrell, 2005; "Rana luteiventris - Thompson, 1913", 2011)
Adult frogs prefer relatively still freshwater areas, such as ponds, lakes, or slow moving streams, with an abundance of sunlight and constant water temperatures. Depth may vary from a few centimeters to 1.5 meters; in general, shallower waters are used during mating and reproduction, and deeper waters are utilized as temperatures drop or water levels increase due to rainfall. In colder areas of their range, these frogs will stay near springs and undercut stream banks, where the water will not freeze. They may require deep silt or muck during times of hibernation and torpor. Emergent vegetation is necessary for adults, and especially tadpoles. Their elevational range varies widely between populations, from sea level to 3,048 m. ("Rana luteiventris - Thompson, 1913", 2011; Reaser and Pilliod, 2012; "Species Fact Sheet: Columbia spotted frog Rana luteiventris", 2010)
Adults are medium-sized, reaching lengths of 65 mm (males) to 100 mm (females). Dorsal coloration ranges from brown to tan or olive-green, with dark black or brown irregularly-shaped spots on the back, sides and legs; spots typically have lighter center. The ventral surface is white or off-white (yellow in some populations), typically with bright pink/salmon coloration on the lower abdomen and/or hind legs legs (adults only, more extensive in females). Another characteristic of Columbia spotted frogs is a white or yellowish stripe running along their upper lip. This species has a narrow snout and upturned eyes. They have shorter legs and more extensively webbed feet than other Rana species. Dorsal skin folds are present, giving a somewhat roughened appearance. Sexually mature males have rough nuptial toe pads. (Cossel Jr., 2000; Davis and Verrell, 2005; Patla and Keinath, 2005; "Species Fact Sheet: Columbia spotted frog Rana luteiventris", 2010)
Tadpoles are approximately 8-10 mm long at hatching and 70-75 mm at metamorphosis (maximum 90 mm). Coloration is typically brown or brownish-green, with gold flecks dorsally, and silvery in color ventrally; the intestines are visible through the skin. The tail is long, thick, and relatively colorless, although it usually has gold or black flecks. (Cossel Jr., 2000; Davis and Verrell, 2005; "Species Fact Sheet: Columbia spotted frog Rana luteiventris", 2010)
As is typical for Rana species, Columbia spotted frogs have a life cycle that icludes metamorphosis. Egg masses, with each egg measuring 10-12 mm in diameter, are laid in shallow (10-20 cm deep), still water. These masses may be colonized by algae, which potentially increases the temperature and speeds developmental rates of embryos. Developmental rate is affected by local conditions, including air and water temperature, and cloud cover (solar radiation). Upon hatching, tadpoles are typically 8-10 mm long. They often take cover in vegetation, such as cattails and bulrushes. Metamorphosis has been recorded as beginning when tadpoles reach approximately 70-75 mm in length. The time it takes tadpoles to complete metamorphosis into frogs varies with location and environmental conditions, but is reported as anywhere from 56 to 209 days; individuals undergoing metamorphosis can be found from late July through the first freeze. (Patla and Keinath, 2005; Reaser and Pilliod, 2012; "Species Fact Sheet: Columbia spotted frog Rana luteiventris", 2010)
Columbia spotted frogs emerge from overwintering sites and migrate overland or through wetlands to reach breeding locations between late February and early July (those populations at higher elevations and latitudes emerge in the later part of this time range). In higher elevations, there are often remaining patches of winter snow and ice present when breeding occurs. Males usually emerge first, and congregate in small, shallow areas of ponds, lakes, marshes, springs, or even ephemeral pools. They do not actively search for mates, which is a unique characteristic of this species. Calling spots are also where eggs are communally laid and fertilized, and are usually along the margin of the water. Males will wait and vocalize, mostly at night, until females have arrived. Vocalization can be done both under and above water. It is very sporadic and faint, with the sound carrying 25 m or less. Mating begins as soon as females arrive. Males use their front feet to grasp females behind their forelimbs; they may remain joined this way for days (though females are still mobile), until eggs are deposited. At this point, they are fertilized externally. Females leave a breeding area after depositing eggs while males remain, likely mating with multiple females. (Davis and Verrell, 2005; Patla and Keinath, 2005; Reaser and Pilliod, 2012)
Columbia spotted frogs are among the earliest breeding amphibians, which allows for development and metamorphosis before ponds dry up during summer months. The breeding season ranges from late February to early January, with higher elevations mating later in the year. It is estimated that each female may produce 150-500 eggs, although there have been reports of over 2000 eggs being produced by a single female; eggs from multiple females join together in large, communal, gelatinous masses of thousands, which aids in survival, as egg masses are able to retain heat from the day through cool spring nights. However, communal egg laying can also have a negative effect on the population; unexpectedly dry conditions and decreasing water levels can cause egg masses to become stranded or entangled in emergent vegetation, exposing them to both predators and dessication. Age at sexual maturity varies between populations, from 1-4 years for males and 2-6 years for females (Cossel Jr., 2000; Davis and Verrell, 2005; Patla and Keinath, 2005; Reaser and Pilliod, 2012)
Lifespan in the wild varies greatly by population. A study of Columbia spotted frogs in Yellowstone National Park suggested that males live 10 years, while females live 12 to 13 years. In a Nevada population, the oldest recorded female was 7 years old, while the oldest males were 3 years old or younger. In general, it is thought that frogs living in colder areas have shorter lifespans. (Patla and Keinath, 2005; Reaser and Pilliod, 2012)
Columbia spotted frogs enter hibernation during winter months. Typical overwintering areas include springs, spring-fed water holes, beaver dams, and pond bottoms (including those under ice). They emerge from hibernation once air temperatures have been 13-16°C for a few days, or following a large rainstorm. Whether from warmer temperatures or rainfall, emergence will not occur at temperatures below 10°C. The frogs then begin to migrate to breeding sites, by way of riparian corridors. Hibernation and breeding sites are often not far apart. After breeding, most adults migrate to summer foraging habitats, usually near a more permanent body of water, where they stay until late August or early September, before returning to winter habitats. These frogs are mostly diurnal, and are typically solitary outside of breeding season. (Patla and Keinath, 2005; Pilliod, et al., 2002; Reaser and Pilliod, 2012)
Columbia spotted frogs are not known to defend any territory, although they do exhibit breeding site fidelity. Overwintering, breeding, and foraging sites may cover a wide range; range size varies greatly between populations, and may be tens to thousands of square meters. (Reaser and Pilliod, 2012)
During mating season, male Columbia spotted frogs call to females in a chorus at night (occasionally during daytime as well) from above and below the water's surface, consisting of 6-9 low pitched clucking or knocking sounds. These vocalizations may get louder if another frog approaches, most likely in an attempt attract a potential mate. When held by the back, the frogs will emit a release call and if attacked, they will emit an alarm call: a shriek lasting about 6 seconds. These frogs also perceive their environments through visual, chemical, and vibrational channels. (Davis and Verrell, 2005; Nafis, 2013)
Adults are opportunistic, diurnal feeders, typically feeding within 10-12 m of a water body. Diet items vary depending on location, but typically include a wide variety of insects (Orders Coleoptera, Diptera, Hemiptera and Hymenoptera), as well as crustaceans, mollusks, earthworms, and arachnids. Larvae eat mainly algae, plant matter, and organic debris. ("Rana luteiventris - Thompson, 1913", 2011; Patla and Keinath, 2005)
The most common predator of adults and tadpoles are garter snakes (Thamnophis sp). Fishes, some larger insects, and salamanders may also prey on tadpoles and metamorphosing young. Adults may be prey for a variety of birds and mammals. The primary defensive strategy is to remain motionless and quiet; they may also dive into deeper water if threatened. If captured, they emit screams and may thrash about wildly. Anecdotal evidence suggests that captured frogs may release a mild toxin from skin glands. (Patla and Keinath, 2005; Reaser and Pilliod, 2012)
Columbia spotted frogs serve as both predators and prey in their ecosystems. A variety of parasites have been reported to use these frogs as hosts, including nematodes, lung flukes, and leeches. ("Rana luteiventris - Thompson, 1913", 2011; Patla and Keinath, 2005; Reaser and Pilliod, 2012)
There are no known positive economic impacts of Columbia spotted frogs on humans.
There are no known negative economic effects of Columbia spotted frogs on humans.
The IUCN Red List identifies Columbia spotted frogs as a species of Least Concern, due to their wide distribution and presumed large population. As of June 2013, the US Fish & Wildlife Service identifies their Great Basin Distinct Population Segment as a candidate species, but other populations have no special federal status. The Utah Department of Natural Resources includes this species on its Sensitive Species List, the Washington Department of Fish & Wildlife lists it as a State Candidate species, and the Oregon Department of Fish & Wildlife lists is as a Sensitive-Critical species. Threats facing this species include loss or modification of habitat by human activities, introduced predators, acid rain, and adverse climate conditions. Certain northern populations have seen significant declines in numbers, as much of their habitat has been converted to agricultural use. ("Washington State Species of Concern Lists", 2013; Davis and Verrell, 2005; ODFW, 2008; Patla and Keinath, 2005; "Utah Sensitive Species List", 2011)
Columbia spotted frogs were formerly considered a subspecies, Rana pretiosa). Genetic studies supported the split of these two subspecies into distinct species, which is how they are currently classified, and Rana pretiosa. Genetic analysis also supports this species-level distinction, along with the discovery of three distinct clades (northern, Great Basin, and Utah) within previously recognized populations of Columbia spotted frogs. These clades may be different enough to warrant designation as separate species, but more study is required. (Funk, et al., 2008; Green, et al., 1997), along with Oregon spotted frogs (
Madison Swendner (author), Sierra College, Jennifer Skillen (author), Sierra College, Jeremy Wright (editor), University of Michigan-Ann Arbor.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
to jointly display, usually with sounds, at the same time as two or more other individuals of the same or different species
particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
fertilization takes place outside the female's body
union of egg and spermatozoan
mainly lives in water that is not salty.
An animal that eats mainly plants or parts of plants.
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
An animal that eats mainly insects or spiders.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
makes seasonal movements between breeding and wintering grounds
eats mollusks, members of Phylum Mollusca
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
having more than one female as a mate at one time
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
specialized for leaping or bounding locomotion; jumps or hops.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
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2013. "Washington State Species of Concern Lists" (On-line). Washington Department of Fish & Wildlife. Accessed July 01, 2013 at http://wdfw.wa.gov/conservation/endangered/All/.
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Funk, W., C. Pearl, H. Draheim, M. Adams, T. Mullins, S. Haig. 2008. Range-wide phylogeographic analysis of the spotted frog complex (Rana luteiventris and Rana pretiosa) in northwestern North America. Molecular Phylogenetics and Evolution, 49/1: 198-210. Accessed July 02, 2013 at http://fresc.usgs.gov/products/papers/2021_Funk.pdf.
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Hammerson, G. 2011. "Rana luteiventris (Columbia Spotted Frog)" (On-line). The IUCN Red List of Threatened Species. Accessed March 22, 2012 at http://www.iucnredlist.org/apps/redlist/details/58649/0.
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Pilliod, D., C. Peterson, P. Ritson. 2002. Seasonal migration of Columbia spotted frogs (Rana luteiventris) among complementary resources in a high mountain basin. Canadian Journal of Zoology, 80/11: 1849-1862. Accessed May 05, 2012 at http://www.ingentaconnect.com/content/nrc/cjz/2002/00000080/00000011/art00003.
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