Ascaphus truei
(Tailed Frog)

Tailed Frog

Key Characteristics:

Adult Characteristics Tadpole Characteristics Egg Characteristics

Lack a tympanum

Sucker-like mouth

Non-pigmented eggs

Wide fifth toe
on hind feet

White spot
on tail tip

Attached to bottom of stones in streams

Males have averted
cloacal "tail"

. .

Males don't call

. .

Pupil is vertical

. .

General Description:
These small frogs usually attain sizes of around 40-50mm (2 in.), and are variably colored ranging from brown, reddish-brown, green, or gray, with some degree of mottling.  A dark eye line is often present (Nussbaum et al. 1983).  Perhaps the most obvious feature is the "tail" on males, which is actually an intermittent organ used to transfer sperm to females. The fifth toes on the hind feet are wider than the other toes. Tailed Frogs lack tympanic membranes, and it's believed that they don't have a mating call. Their pupils vertical.

  Tailed Frog tadpoles are unique in that they have a sucker-like mouth. This helps them attach to rocks, which allows them to maintain their position in the swift mountain streams where they live.

  The eggs of Tailed Frogs are found attached to the bottom of stones in streams and they are unpigmented.  The eggs are around 4-5mm (0.2 in.) in diameter.

Idaho Distribution:
  Tailed Frogs are distributed throughout the central and north central forests of Idaho where suitable habitat is found.

  Found from sea level to over 2000 m, in clear, cold, swift-moving mountain streams. May be found on land during wet weather, near water in humid forests, or in more open habitat. Stays on moist streambanks during dry weather.

  Tailed Frogs are found in permanent, cool mountain streams or under stream side debris. The adults can forage up to 25m from stream in wet conditions; although this is generally at night (Nussbaum et al. 1983).  The larvae are generally found attached to smooth rocks in streams.

  Larvae feed mostly on diatomsGlossary term. Adults eat wide variety of insects and other invertebrates.

  Breeds from May through October (late August and September in Idaho). Fertilization is internal; male has tail-like copulatory organ. Clutch size averages 44-75 eggs, which are laid in July, and hatch from August through September. Larval period lasts 2-4 yr in mountains and northern areas, and 1 yr in a few coastal Oregon populations. Inland populations metamorphose after 3 yr; metamorphosis starts in July and ends in September. Adults may not breed until 7-8 yrs old, or 6-8 yrs after metamorphosis.



Unprotected nongame species

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Important State References:
Cassirer, E.F. 1995. Wildlife inventory, Craig Mountain, Idaho. Idaho Dept. Fish & Game, Lewiston. 182 pp.

Species description, key characteristics and original work by John Cossel Jr. © 1997
Species ecological information from Groves et al. ©1997.
Original images provided by Charles R. Peterson and Charlotte C. Corkran,© 1997
Design and Optimization by Ean Harker©1999, 2000.
DAI layout by
Stephen Burton, and Mike Legler © 1999.