Rocky Mountain Tailed Frog - Ascaphus montanus
(see State Rank Reason below)
State Rank Reason (see State Rank above)
Species is apparently secure and not at risk of extirpation or facing significant threats in all or most of its range.
- Details on Status Ranking and Review
ScoreF - 20,000-200,000 km squared (about 8,000-80,000 square miles)
Comment70,521 square Kilometers from Natural Heritage Program range maps
ScoreE - Relatively Stable (±25% change)
CommentAlthough forest management practices and fire regimes have changed over the last century it is unlikely that the amount of habitat for this species has changed more than 25%. Loss of old growth timber may have contributed to a reduction in suitable habitat, but the extent of the impact on this species is unknown.
ScoreU - Unknown. Short-term trend in population, range, area occupied, and number and condition of occurrences unknown.
CommentTo date surveys have not been conducted with enough frequency to determine trend
ScoreG - Slightly threatened. Threats, while recognizable, are of low severity, or affecting only a small portion of the population or area.
CommentDegradation of stream habitat through logging or wildfire
SeverityLow - Low but nontrivial reduction of species population or reversible degradation or reduction of habitat in area affected, with recovery expected in 10-50 years.
CommentGiven current forest management practices, impacts should not persist for more than 50 years
ScopeLow - 5-20% of total population or area affected
CommentSpecies is found across a large area so impact to large portions of the population would be unlikely
ImmediacyLow - Threat is likely to be operational within 5-20 years.
CommentPossible within the next 20 years, but is not imminent.
ScoreB - Moderately Vulnerable. Species exhibits moderate age of maturity, frequency of reproduction, and/or fecundity such that populations generally tend to recover from decreases in abundance over a period of several years (on the order of 5-20 years or 2-5 generations); or species has moderate dispersal capability such that extirpated populations generally become reestablished through natural recolonization (unaided by humans).
CommentThis species has high fecundity, a moderate age of maturity, and recruitment can be low.
ScoreB - Narrow. Specialist. Specific habitat(s) or other abiotic and/or biotic factors (see above) are used or required by the Element, but these key requirements are common and within the generalized range of the species within the area of interest.
CommentSpecies is associated with montane streams within forested areas across western Montana.
Raw Conservation Status Score
3.5 + 0 (geographic distribution) + 0 (environmental specificity) + 0 (long-term trend) + 0.75 (threats) = 4.25
Adults are gray or brown with gray, brown, or occasionally yellow blotches; the skin has a distinctly bumpy texture. Adult body length is 1.5 to 2 inches. The outer toe of the hind foot is broader than the other toes. Tailed frogs have no external ear drum. The male has a bulbous "tail" that acts as a penis. Eggs and Tadpoles: Approximately 50 eggs are laid in rosary-like strings attached to the underside of rocks. The tadpole (up to 2 inches long) is unique in that it has a large mouth modified into a sucker; color is variable.
No other frog or toad has the outer toe of the hind foot broader than the other toes; all other frogs and toads have external ear drums.
Western Hemisphere Range
Observations in Montana Natural Heritage Program Database
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
Non-migratory. Has no breeding migration (Daugherty 1982).
Rocky Mountain Tailed Frogs are found in and along small, swift, cold mountain streams. Eggs are laid during late summer and take approximately 4 weeks to hatch. Tadpoles take 1 to 4 years to metamorphose, depending on water temperature. Sexual maturity in Montana is attained at 6 or 7 years of age (the latest of any North American amphibian). Forested streams. In Flathead area, larvae are found only in streams with temperature under 16 C. Prefer fast streams, less than 14 ft wide, with substrate of slabby-flat bottomed rocks with little aquatic vegetation (Franz and Lee 1970).
Larva feed almost exclusively on diatoms, though also pollen (Metter 1964, Franz 1970) Adults: opportunistic; forage at night in forest near streams. Prey on invertebrates, mainly terrestrial but also aquatic forms (Metter 1964, Bury 1970, Daugherty 1982).
Low reproductive potential: reproductive maturity age 7 to 8; 2 year cycle with first clutch at age 9 (Daugherty 1982). Extremely philopatric; probably very little gene flow between populations (Daugherty 1982).
Mate August to September; sperm stored overwinter (Metter 1964). Ovipost late June to July; hatch August to September but remain in nest (under rocks in stream) until yolk is consumed, October to November or later. Metamorphose July to September of year 4 (ca. 60 days required) (Daugherty 1979). Development of eggs under natural conditions is discussed by Franz (1970).
- Literature Cited AboveLegend: View Online Publication
- Bury, R.B. 1970. Food similarities in the tailed frog, Ascaphus truei, and the Olympic salamander, Rhyacotriton olympicus. Copeia 1970: 170-171.
- Daugherty, C.H. and A.L. Sheldon. 1982a. Age-determination, growth, and life history of a Montana population of the tailed frog Ascaphus truei. Herpetologica 38(4): 461-468.
- Franz, R. and D.S. Lee. 1970. The ecological and biogeographical distribution of the tailed frog, Ascaphus truei, in the Flathead River drainage of northwestern Montana. Bulletin of the Maryland Herpetological Society 6: 62-73.
- Metter, D.E. 1964a. A morphological and ecological comparison of two populations of the tailed frog Ascaphus truei Stejneger. Copeia 1964: 181-195.
- Additional ReferencesLegend: View Online Publication
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- [USFWS] US Fish and Wildlife Service. 1994. Endangered and threatened wildlife and plants; animal candidate review for listing as endangered or threatened species. Federal Register 59(219): 58982-59028.
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