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A Guide to the Amphibians
and Reptiles of California


Coastal Tailed Frog  - Ascaphus truei

Stejneger, 1899
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Coastal Tailed Frog Habitat range map
Range in California: Red

Dot-locality range map.


observation link



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Coastal Tailed Frog Coastal Tailed Frog Coastal Tailed Frog
  Adult, Del Norte County  
Coastal Tailed Frog Coastal Tailed Frog Coastal Tailed Frog
Adult, Del Norte County © Alan Barron Adult, Del Norte County Adult female, Mendocino County (captured and handled under state Scientific Collecting Permit and released at point of capture.) © Adam Clause
Coastal Tailed Frog Coastal Tailed Frog  
Adult, Del Norte County Pupil is Vertical  
     
Coastal Tailed Frogs From Outside of California
Coastal Tailed Frog
Coastal Tailed Frogs
Coastal Tailed Frog
Adult, Pacific County, Washington Adults in amplexus, Multnomah Co., Oregon © 2000 Brad Moon

Tailed frog amplexus is inguinal - the male clasps the female around her pelvis, unlike most of our frogs which use axial amplexus - the male grasps the female around her forelimbs.
Adult, Pacific County, Washington
     
The "Tail" or Male Copulatory Organ
Tailed Frog
Tailed Frog
Tailed Frog
Adult male tailed frog* showing his tail-like copulatory organ. This organ, an extension of the cloaca, is used to transfer sperm into the female's cloaca during amplexus. She then holds the fertilized eggs for 9 or 10 months when she swims under a large stone on the bottom of a fast-moving creek and attaches the eggs to the bottom of the stone. This internal fertilization strategy lets tailed frogs breed in fast-moving water without the eggs washing away, which would happen if they were laid and fertilized on the surface of the water.
* Ascaphus montanus
 
Tadpoles
Coastal Tailed Frog tadpole Coastal Tailed Frog tadpole Coastal Tailed Frog tadpole
Tadpole feeding in daylight,
Multnomah County, Oregon

Most tadpoles have mouths at the front of the head, but the mouth of a Coastal Tailed Frog tadpole is underneath the head, which is flattened. The mouth position and head shape, along with specialized folds that create suction, help a tadpole cling to a rock surface while keeping its body close to the rock. This allows it to scrape food off the surface of underwater rocks in fast-moving creeks without letting the swift current wash it downstream.
Coastal Tailed Frog tadpole Coastal Tailed Frog tadpole Coastal Tailed Frog tadpole
Tadpole feeding at night (underwater)
Del Norte County, showing the
white spot on the tail tip.
Underside of the head of a tadpole, Del Norte County, showing the mouth underneath the head. Tadpole feeding underwater in daylight,
Multnomah County, Oregon
Coastal Tailed Frog tadpole Coastal Tailed Frog tadpole Coastal Tailed Frog tadpole
Metamorph which has not yet absorbed its tail, Del Norte County © Alan Barron Tadpole, Del Norte County
© Alan Barron
   
Habitat
Coastal Tailed Frog Habitat Coastal Tailed Frog Habitat tailed frog habitat
Habitat, Mendocino County Habitat, Del Norte County Habitat, Del Norte County
Coastal Tailed Frog Habitat  
Habitat, Del Norte County Habitat, Del Norte County  

More pictures of this frog and its habitat from the Northwest can be seen here.


Short Videos
Coastal Tailed Frog Coastal Tailed Frog Tadpole  
Several views of a male Coastal Tailed Frog at a small forested creek in the Oregon Cascade Mountains. A Coastal Tailed Frog tadpole forages on the rocks of a small pool in a small creek in the Oregon Cascade Mountains. You can also see its unique sucker-like mouth working from the other side of the glass of a small aquarium.  
     
Description
 
Size
A small frog, aduts are 1-2 inches in length (2.5 - 5.1 cm). (Stebbins, 2003)

Appearance
A flat, toadlike frog with fairly rough skin.
The pupil is vertical.
The fingertips are hardened like claws to help the frog crawl among rocks on stream bottoms.
Lungs are reduced in size to decrease buoyancy, and respiration takes place through the skin.
Color and Pattern
Coloring matches the colors of rocks around the stream inhabited - usually olive, brown, gray, or reddish above with yellow and gray mottling, a pale yellow or greenish triangle on the snout and a dark eye stripe.
Male/Female Differences
Males are smaller than females.
Larvae (Tadpoles)
Tadpoles are black or brown, usually with a white spot on the tip of a long tail, and a large sucker-like mouth, which they use to cling to rocks in the fast-moving stream.

Life History and Behavior
Activity
Mostly nocturnal, but often seen moving on creek banks in daylight.
Adults are usually active from April to October, depending on the locality.

Tadpoles emerge at night to forage on rocks. At times they can be found out foraging in daylight.
Defense
To escape predators Tailed Frogs jump into the water, tuck in their limbs, and let the water quickly carry them downstream away from danger.
Longevity
Adults are relatively long-lived - it has been speculated that they can live up to 15 - 20 years.
Voice
A male tailed frog has no vocal sacs and apparently does not vocalize, most likely due to the noisy stream environment it inhabits which would overwhelm any vocalization. Tailed frogs also have no external ear membrane to help them hear sounds.
(Other frog species that inhabit fast-moving waters do vocalize with a sound too high-pitched to be heard by humans that can be heard over the noise of the water, and others produce sounds underwater.)
Diet and Feeding
Adults and juveniles eat a wide variety of invertebrates, whatever is in season.
Adults feed along stream banks and in the nearby forest at night and sometimes during daylight.

Tadpoles emerge at night to forage on rocks. They sometimes crawl up onto rocks out of the water, probably to feed. Tadpoles have been found with ingested diatoms, algae, and desmids, and conifer pollen in their guts.
Breeding
Reproduction is aquatic.
Fertilization is internal.

Reproduction is often delayed until four or five years after a frog has transformed from a tadpole.

Most breeding apparently occurs in early fall (though it has been reported May through October). Adults do not travel to a breeding location, they breed in the cold, swift streams they inhabit.
Females breed every year, but those in coastal populations may breed only every other year. 

By mid-August to September, males have developed black, horny tubercles on each forefoot and forearm. These help a male hold on to a female during amplexus.

Males of this species do not have vocal sacs so they don't call to attract a mate as most frogs do. It is not known exactly how males and females find each other and how females choose a mate. They most likely meet using chemical signals.

Tailed frogs have evolved an internal fertilization strategy which lets them breed in fast-moving water without the eggs washing away, which would happen if they were laid and fertilized on the surface of the water. Ascaphus is the only genus of frogs which fertilizes internally through copulation. During successful mating the tail-like organ, an extension of the cloaca, becomes erect and directed forward. The smaller male clasps his arms around the female's pelvis (inguinal amplexus) and inserts his erected cloacal extension into the female's cloaca to transfer his sperm. This copulation lasts 24 - 30 hours. The female then stores the sperm, using it to fertilize the eggs months later.
Eggs
She lays the eggs the following spring and summer after the spring runoff, generally in June and July. Aproximately 25 - 96 eggs are laid in continuous strings under large rocks. Eggs hatch into tadpoles in 3 - 6 weeks, usually in August and September.

Little is known about Coastal Tailed Frog nest sites and ovoposition timing.
On August 3rd, 2005 a nest site in Mendocino County was found within a seep about 39 inches (1 m) above the confluence of the seep and a fish-bearing stream . The canopy vegetation was primarily 40-year-old Coast Redwood and Douglas-fir enclosed 89 per cent. 25 eggs were attached in a continuous string to the bottom of a rock measuring about 5 x 4 1/2 inches (126 × 118 mm). On August 18th, all eggs had hatched and 5 tadpoles were seen in the seep.
Matthew O. Goldsworthy. Herpetological Review 38(1), 2007
Tadpoles and Young
Metamorphosis takes from one to four years. Montane populations may require longer.
Tadpoles always spend at least one winter in the stream.
Where recently-transformed juveniles go after metamorphosis is not well known, but it appears that they disperse into the forest in the fall.

Habitat
Inhabits cold, clear, rocky streams in wet forests. They do not inhabit ponds or lakes. A rocky streambed is necessary for cover for adults, eggs, and larvae. After heavy rains, adults may be found in the woods away from the stream. I found two adults under rocks about twenty meters from a creek in May. Occasionally they inhabit areas without trees. (According to Stebbins, A. truei quickly established itself on treeless terrain created by the eruption of Mt. St. Helens in Washington.) 

Geographical Range
The range of this frog in California is from near Anchor Bay, Mendocino county, north along the coast to the Oregon Border and as far east as near Big Bend, Shasta County.
The species ranges farther north through the Cascades Mountains of Oregon and Washington and along the north coast of British Columbia, almost to Alaska.
Elevational Range
From near sea level to 8400 ft. (2560 m.)

Notes on Taxonomy
Two species of Ascaphus, A. truei, and A. montanus, the Rocky Mountain Tailed Frog, are recognized.

Conservation Issues  (Conservation Status)
Tailed Frog populations may be severely reduced as a result of the sedimentation and warming of streams caused by timber harvesting and road building, but (Lannoo 2005) there is no published evidence of a broad scale decline.

Taxonomy
Family Leiopelmatidae
Tail-wagging Frogs Mivart, 1869
Genus Ascaphus
Tailed Frog Stejneger, 1899
Species truei
Coastal Tailed Frog

Stejneger, 1899
Original Description
Stejneger, 1899 Tailed Frog

from Original Description Citations for the Reptiles and Amphibians of North America © Ellin Beltz

Meaning of the Scientific Name
Ascaphus: - Greek: a - without, and Greek: skaphis spade - notes the lack of a metatarsal spade
truei
: - honors True, Frederick W.

from Scientific and Common Names of the Reptiles and Amphibians of North America - Explained © Ellin Beltz

Alternate Names
Western Tailed Frog
Tailed Frog

Related or Similar California Frogs
Rana boylii - Foothill Yellow-legged Frog
Rana aurora - Northern Red-legged Frog

Ascaphus montanus
- Rocky Mountain Tailed Frog

More Information and References
California Department of Fish and Wildlife

AmphibiaWeb

Stebbins, Robert C., and McGinnis, Samuel M.  Field Guide to Amphibians and Reptiles of California: Revised Edition (California Natural History Guides) University of California Press, 2012.

Stebbins, Robert C. California Amphibians and Reptiles. The University of California Press, 1972.

Stebbins, Robert C. A Field Guide to Western Reptiles and Amphibians. 3rd Edition. Houghton Mifflin Company, 2003.

Behler, John L., and F. Wayne King. The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, 1992.

Powell, Robert., Joseph T. Collins, and Errol D. Hooper Jr. A Key to Amphibians and Reptiles of the Continental United States and Canada. The University Press of Kansas, 1998.

Corkran, Charlotte & Chris Thoms. Amphibians of Oregon, Washington, and British Columbia. Lone Pine Publishing, 1996.

Jones, Lawrence L. C. , William P. Leonard, Deanna H. Olson, editors. Amphibians of the Pacific Northwest. Seattle Audubon Society, 2005.

Leonard et. al. Amphibians of Washington and Oregon. Seattle Audubon Society, 1993.

Nussbaum, R. A., E. D. Brodie Jr., and R. M. Storm. Amphibians and Reptiles of the Pacific Northwest. Moscow, Idaho: University Press of Idaho, 1983.

Bartlett, R. D. & Patricia P. Bartlett. Guide and Reference to the Amphibians of Western North America (North of Mexico) and Hawaii. University Press of Florida, 2009.

Elliott, Lang, Carl Gerhardt, and Carlos Davidson. Frogs and Toads of North America, a Comprehensive Guide to their Identification, Behavior, and Calls. Houghton Mifflin Harcourt, 2009.

Lannoo, Michael (Editor). Amphibian Declines: The Conservation Status of United States Species. University of California Press, June 2005.

Wright, Albert Hazen and Anna Wright. Handbook of Frogs and Toads of the United States and Canada. Cornell University Press, 1949.

Mattison, Chris. Frogs and Toads of the World. Cassell Illustrated, London, 1992.
Conservation Status

The following status listings come from the Special Animals List and the Endangered and Threatened Animals List which are published by the California Department of Fish and Wildlife.




Organization
Status Listing
U.S. Endangered Species Act (ESA) None
California Endangered Species Act (CESA) None None
California Department of Fish and Wildlife DFG:SSC California Species of Special Concern
Bureau of Land Management
USDA Forest Service
 

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