Coastal Tailed Frog

Taxon, Status, and Ranks Habitat Photos
General Description State Status Comments
Identification Tips Inventory & Research Needs Key Features
Phenology Threats & Mgmt Concerns
Range References Distribution Map

Taxon, Status, and Rank

Species Ascaphus truei     Stejneger, 1899
Family Ascaphidae or Leiopelmatidae
(Tailed Frogs)
Status State Monitor, USFWS Species of Concern
State Rank S4
Global Rank G4

General Description

This is a moderately small (37-50 mm snout-vent length), slender-bodied frog with rough skin. The head is relatively large, flattened and slightly broader than long. The snout tapers anterior to the eyes and is relatively short, and a pale triangle often exists between the eyes and the snout. The pupil is vertical. An eyestripe extends from the snout to the shoulder. The toes are slightly webbed and the outer two hind toes are flattened. The typically dark ground color is usually similar to the substrate of the habitat occupied. The males have a tail-like copulatory organ, tubercles on the palm and forearm and, during the breeding season, small dark pads on the sides of the abdomen.

The tadpole has a somewhat flattened body with dorsal eyes, a ventral suctorial oral disc (mouth) and a low fin that originates at the dorsal tail-body junction. The oral disc covers about 1/3 to 1/2 of the lower body surface. The tip of the tail is broadly rounded and typically has a white spot bordered by black. The spiracle is located on the midbelly (midventral) and the nostrils are located closer to the eyes than the snout.

The eggs are unpigmented, deposited in strings of 40-80 and attached to the undersides of rocks in cool flowing steams.

No vocalizations have been documented. Moreover, Coastal Tailed Frogs lack some of the structures used to make sounds (tongue and vocal sacs) found in other frogs.

See Photos Page.

Identification Tips

The tail appendage of the male is unique among anurans. Tailed frogs look similar to Pacific Treefrogs, but treefrogs have horizontal pupils, circular discs (“toe-pads”) at the tips of their fingers and toes, rounded (rather than flattened) 4th and 5th toes on their hind feet, and typically lighter, bright ground coloration (often with greens or beiges). Great Basin Spadefoots have vertical pupils (the only other Washington anuran that does) but they are typically found only in arid habitats and have black spades on the under side of their rear feet. Tailed frogs have the only tadpole in Washington able to adhere to rocks in fast-flowing streams with a large sucker-like mouth. See Key Features Page.


Present year-round in and near streams. Primarily night active, but tadpoles and frogs can also be observed during the day. Frogs are most active from April to October, but this varies by site and conditions. Mating takes place in the fall. Females are thought to store sperm until eggs are deposited in the summer. Eggs hatch in approximately six weeks. In Washington, the larval phase lasts two to five years depending on location and elevation. Metamorphosis usually takes place in late summer.


In Washington, this species occurs in the Willapa Hills, the Black Hills, and the Cascade and Olympic Mountains. Elevations range from near sea level to 2075 m (6804 ft). Populations in the Blue Mountains were split into a new species – Rocky Mountain Tailed Frog (Ascaphus montanus). See Distribution Map.

For information on the complete range of this species, see NatureServe Explorer.

Habitat and Habits

They are primarily found in or associated with relatively cold, clear, rocky steams in mature forests. All life stages are adapted for life in fast flowing streams. The male’s “tail” is used for internal fertilization to prevent sperm from being washed away. Eggs are attached to the undersides of rocks to keep them in place. The tadpoles have a large ventral suctorial mouth that allows them to feed and move in high-energy streams without loosing contact and unintentionally drifting.

State Status Comments

Endemic to the Pacific Northwest, the Coastal Tailed Frog is a Forests and Fish Agreement (Ffr) target species, one of seven stream-associated amphibians targeted for study specifically because they may incur some risk related to forestry practices. While still relatively common and widespread, considerable Ffr adaptive management funding is been directed at fully understanding the details of Coastal Tailed Frog biology and habitat use (see Current Research). In particular, effort has been devoted toward understanding and avoiding excessive stream temperature alterations and siltation, both potential effects of forestry practices that may be harmful.

Inventory and Research Needs

More research is needed on forestry practices and the best approaches to minimizing harm to tailed frogs and their habitat.

Threats and Management Concerns

This species is vulnerable to management practices that alter the riparian or aquatic zones of streams, especially those that change the moisture regime, increase stream temperature, increase sediment load, reduce woody debris input and change stream bank integrity. Protection of the upper reaches of streams is particularly important for this species.

Current Research

The Cooperative Monitoring Evaluation and Research (CMER) Committee, the Adaptive Management arm of Ffr, has provided funding to the of Washington Department of Fish and Wildlife Habitat Program (Olympia, Principal Investigator, Marc Hayes) to be the lead agency for a multi-stakeholder group (i.e., major and minor private landowners, state and federal agencies, tribes, and an environmental caucus) project developing the Type N Buffer Treatment Effectiveness Study. This is a manipulative study that will compare alternative buffer treatments in non-fishbearing (Type N) headwater streams. Among those treatments is the prescription now applied to headwater streams in Ffr timber-managed landscapes. The design includes both pre-harvest sampling and post-harvest sampling that will occur at intervals over a harvest rotation. Stream-associated amphibians, especially Coastal Tailed Frog (Ascaphus truei), are focal elements of the study design, and will be measured as response variables. The study is intended to inform policy regarding buffer prescriptions on headwater streams.


Corn and Bury (1989), McDiarmid and Altig (1999), Nielson et al. (2001), Nussbaum et al. (1983), Stebbins (1985), Welsh (1990), Zug et al. (2001).


Personal communications: M. Hayes

Hallock, L.A. and McAllister, K.R. 2005. Coastal Tailed Frog. Washington Herp Atlas.

Last updated: February 2005

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