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Coastal Tailed Frog

Ascaphus truei

What do they look like?

Tailed frogs have small bodies that are adapted to their life in streams. Their lungs are much smaller than many other frogs and toads. The ends of their toes are hard, which helps them crawl on rocks at the bottom of the stream. Their rough skin is about the same color as the stream bottom, so it is tan, brown, or olive green. Their heads are big and flat, and they have a light mark in a triangle shape between their nose and eyes. A dark stripe goes from their nose out to their shoulder. They don't have eardrums or ear membranes, so they can't hear. This is probably because they would hear the sound of the water all of the time. Tailed frogs get their name from the short tail on males. Tailed frogs are usually 2.2 to 5.1 cm long, and males are smaller than females. (Adams and Pearl, 2005; Leonard, et al., 1993; Metter, 1964; Stebbins, 2003)

Tailed frog tadpoles are only about 11 mm long when they hatch. They can get up to 65 mm long before they transform into frogs. They are black or brownish-gray with black specks. They also have a white dot on the tip of the tail and a copper-colored bar between the eyes and snout. To adapt to life in stream currents, their bodies are flattened and the tails are shrunken. Their mouth is shaped like a sucker, so it can attach to rocks. Tailed frogs lay eggs under rocks in shallow water. The eggs are in a jelly-like string and don't have any color. (Adams and Pearl, 2005; Leonard, et al., 1993; Metter, 1964; Stebbins, 2003)

  • Sexual Dimorphism
  • sexes alike
  • female larger
  • sexes shaped differently
  • Range length
    2.2 to 5.1 cm
    0.87 to 2.01 in

Where do they live?

Tailed frogs live in northwestern North America. Most of them live from northwestern California north to the Portland Canal and the Nass River in British Columbia, Canada. They are found from the coast of the Pacific Ocean to the Cascade Mountains. Other groups of them live in the Blue Mountains in southeastern Washington and northeastern Oregon, and also in the northern Rocky Mountains of northern Idaho and western Montana. (Adams and Pearl, 2005; Leonard, et al., 1993; Mallory, 2004; Stebbins, 2003)

What kind of habitat do they need?

Tailed frogs live in clear, cold streams in the mountains that are made up of small pools of water. This means that they live on hillsides, but not ones that are very steep or very flat. They can be found right on the coast or up high in the mountains. They need streams that stay cool even in summer. They look for hard stream bottoms that are better for laying their eggs and hibernating in winter. Their larvae take a long time to develop, so they need streams that flow year-round. They live in streams next to old forests, and find shelter in the plants living next to the water. Having plants along the stream also keeps the stream temperature even and stops the stream bottom from getting too sandy or dirty. (Adams and Pearl, 2005; Mallory, 2004; Metter, 1964; Wallace and Diller, 1998)

  • Aquatic Biomes
  • rivers and streams
  • Range elevation
    0 to 2557 m
    0.00 to 8389.11 ft

How do they grow?

Female tailed frogs attach their eggs to the bottom of big rocks or boulders in the stream. The eggs hatch about 6 weeks later. Tadpoles have a big yolk sac that they use for food during the winter. After their mouth is able to suck, they can eat other animals. After 1 to 4 years, they transform into frogs. The transformation can take up to 60 days. On the coast, young tailed frogs have their own young when they are 2 or 3 years old. In the mountains, they have their own young when they are 8 or 9 years old. (Adams and Pearl, 2005; Leonard, et al., 1993; Mallory, 2004; Stephenson and Verrell, 2003; Wallace and Diller, 1998)

How do they reproduce?

Before tailed frogs mate, the male swims suddenly or lunges at the female. Males mate with more than one female in the same season. (Adams and Pearl, 2005; Leonard, et al., 1993; Mallory, 2004; Stephenson and Verrell, 2003; Wallace and Diller, 1998)

Female tailed frogs reproduce every other year, while males may mate every year. They mate in the fall, but females lay eggs in June or July. They lay a double string of 44 to 85 small eggs, and attach them to the bottom of a rock in the stream. The eggs hatch into tadpoles 6 weeks later. They stay tadpoles for 1 to 4 years, depending on where they live. On the coast, they stay tadpoles for 1 to 3 years, and in the mountains, they stay tadpoles for 3 to 4 years. When they transform into frogs, their tail becomes part of their body, and they get an adult mouth and legs. They are totally mature when they are 2 to 8 years old, which also depends on where they live. (Adams and Pearl, 2005; Leonard, et al., 1993; Mallory, 2004; Stephenson and Verrell, 2003; Wallace and Diller, 1998)

  • How often does reproduction occur?
    Tailed frog females breed biennially, while males may breed annually.
  • Breeding season
    Tailed frogs breed from September through October (fertilization) and females lay eggs from June to July (oviposition).
  • Range number of offspring
    44 to 85
  • Average time to hatching
    6 weeks
  • Range age at sexual or reproductive maturity (female)
    2.5 to 4 years
  • Average age at sexual or reproductive maturity (female)
    3 years
  • Range age at sexual or reproductive maturity (male)
    1.5 to 4 years
  • Average age at sexual or reproductive maturity (male)
    3 years

Scientists don't know much about parental care in tailed frogs.

How long do they live?

Tailed frogs can live up to 14 years or more, which is longer than most frogs. (Adams and Pearl, 2005; Daugherty and Sheldon, 1982)

  • Range lifespan
    Status: captivity
    14 (high) years

How do they behave?

Tailed frogs are often active and looking for food at night. They typically stay close to the stream, but sometimes travel a ways into the forest. Tadpoles are active in the day or at night, depending on whether there are predators around. Tailed frogs are much less active in the winter, but they don't hibernate. (Adams and Pearl, 2005; Leonard, et al., 1993; Mallory, 2004; Metter, 1964)

Home Range

Scientists don't know how big their territories are.

How do they communicate with each other?

Tailed frogs don't call like most frogs, because they don't have the body parts to make or hear sound. They don't have a tongue, vocal sacs, ear bones, or eardrums. This means that they rely on sight and touch to interact with each other. They probably use chemical signals to communicate too, but more research is need to understand how. (Adams and Pearl, 2005; Hallock and McAllister, 2005; Leonard, et al., 1993; Stephenson and Verrell, 2003; Vitt and Caldwell, 2009)

What do they eat?

Tailed frog tadpoles primarily eat diatoms scraped off from underwater rocks. Conifer pollen and filamentous algae may also be incorporated into their diet. Post-metamorphic juveniles and adults, on the other hand, will forage for various insects and terrestrial arthropods alongside their stream habitat or in adjacent riparian vegetation. Spiders, ticks, mites, and snow fleas are all potential prey. Snails are an additional prey species juveniles and adults. However, because it lacks a tongue attached at the front of its mouth, tailed frogs do not have the ability to flip their tongue out to take prey, a trait seen in most other anurans. (Adams and Pearl, 2005; Leonard, et al., 1993; Mallory, 2004)

Tailed frog tadpoles mostly eat a kind of algae called diatoms that they scrape off rocks underwater. They also eat pollen from pine trees and other kinds of algae. After they become frogs, they eat insects and arthropods that they find alongside the stream. They eat spiders, ticks, mites, snow fleas, and snails. Most other frogs flick their tongue out to catch prey, but tailed frogs can't because their tongue isn't attached to the front of their mouth. (Adams and Pearl, 2005; Leonard, et al., 1993; Mallory, 2004)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • zooplankton
  • Plant Foods
  • algae

What eats them and how do they avoid being eaten?

Tailed frogs are eaten by many kinds of animals like some snakes, insects, amphibians, fish, and birds. Adults are eaten by common garter snakes, shrews and western terrestrial garter snakes. Tadpoles are eaten by bugs called hellgrammites, larval Cope’s giant salamanders and Pacific giant salamanders, as well as trout, sculpins and dippers. (Adams and Pearl, 2005; Leonard, et al., 1993; Lund, et al., 2008)

  • These animal colors help protect them
  • cryptic

What roles do they have in the ecosystem?

Tailed frog tadpoles are sometimes the top plant-eaters in their water environment. Once they transform into frogs, then they interact with predators and prey both on land and in the water. (Mallory, 2004)

Do they cause problems?

There are no known negative impacts of tailed frogs on humans.

How do they interact with us?

Tailed frogs are sensitive to changes in their habitat. This means that they could be an early warning species for conservationists about the health of their habitat. (Adams, 1993)

Are they endangered?

Tailed frogs are not endangered according to the IUCN Red List, but are a "Species of Concern" according to the United States Fish and Wildlife Endangered Species List. They may be affected by harvesting trees for wood and also construction, because these activities make streams warmer and fill them with sand or sediment. (Adams and Pearl, 2005; Hammerson and Adams, 2010; "Tailed frog (Ascaphus truei)", 2010)


Ashley Potter (author), Michigan State University, James Harding (editor), Michigan State University, Rachelle Sterling (editor), Special Projects, Catherine Kent (editor), Special Projects.


U.S. Fish and Wildlife Service. 2010. "Tailed frog (Ascaphus truei)" (On-line). Species Profile. Accessed November 26, 2010 at

Adams, M., C. Pearl. 2005. Amphibian Declines: The Conservation Status of United States Species. Ascaphus truei. Berkley, CA: University of California Press.

Adams, M. 1993. Summer Nests of the Tailed Frog (Ascaphus truei) from the Oregon Coast Range. Northwestern Naturalist, 74/1: 15-18. Accessed November 26, 2010 at

Daugherty, C., A. Sheldon. 1982. Age-Determination, Growth, and Life History of a Montana Population of the Tailed Frog (Ascaphus truei). Herpetologica, 38/4: 461-468.

Hallock, L., K. McAllister. 2005. "Coastal Tailed Frog" (On-line). Accessed November 26, 2010 at

Hammerson, G., M. Adams. 2010. "Ascaphus truei" (On-line). The IUCN Red List of Threatened Species. Accessed November 26, 2010 at

Leonard, W., H. Brown, L. Jones, K. McAllister, R. Storm. 1993. Amphibians of Washington and Oregon. Seattle, WA: Seattle Audubon Society.

Lund, E., M. Hayes, T. Curry, J. Marsten, K. Young. 2008. Predation on the Coastal Tailed Frog (Ascaphus truei) by a Shrew (Sorex spp.) in Washington State. Northwestern Naturalist, 89: 200-202. Accessed November 26, 2010 at

Mallory, A. 2004. Coastal Tailed Frog: Ascaphus truei. Accounts and Measures for Managing Identified Wildlife: Southern Interior Forest Region, 2004: 77-86. Accessed November 26, 2010 at

Metter, D. 1964. A Morphological and Ecological Comparison of Two Populations of the Tailed Frog, Ascaphustruei Stejneger. Copeia, 1964/1: 181-195. Accessed November 26, 2010 at

Stebbins, R. 2003. A Field Guide to Western Reptiles and Amphibians. New York, NY: Houghton Mifflin.

Stephenson, B., P. Verrell. 2003. Courtship and mating of the tailed frog (Ascaphus truei). Journal of Zoology, 259/1: 15-22. Accessed November 26, 2010 at

Vitt, L., J. Caldwell. 2009. Herpetology, 3rd Edition. Burlington, MA: Academic Press.

Wallace, R., L. Diller. 1998. Length of the Larval Cycle of Ascaphus truei in Coastal Streams of the Redwood Region,Northern California. Journal of Herpetology, 32/3: 404-409. Accessed November 26, 2010 at

University of Michigan Museum of ZoologyNational Science Foundation

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Potter, A. 2012. "Ascaphus truei" (On-line), Animal Diversity Web. Accessed November 29, 2023 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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