Rocky Mountain Tailed Frog - Ascaphus montanus
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:
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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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