Description: Adult Rocky Mountain Tailed Frogs are small frog with a large head, a vertical pupil, broad and flattened outer hind toes and no ear drum. They vary in color from tan or brown to olive green or red, and there is often a distinct, dark-edged copper bar between the eyes. Males have a short, conical extension of the cloaca, the source of the name "tailed frog", which is used for copulation. The tadpoles posses an oral disc modified into a sucker for clinging to rocks in swift currents. They are mottled black and tan with a prominent black-bordered white spot at the tip of the tail.

Habitat: The habitat of the tailed frog is cold, fast-moving streams with cobblestone bottoms. They are mostly aquatic, but adults may emerge during cool, wet conditions to forage terrestrially. The amount of cobbles found in streams have been shown to be good indicators of tadpole abundance, more of each leading to an increase in tadpoles.

Thermal tolerance range in adults is exceptionally low relative to other North American anurans. Adults have been observed to exhibit extreme philopatry, however, movements and migrational habits of Ascaphus have not been well documented.

During the day, adults seek cover under submerged substrates in the stream, or occasionally under similair surface objects close to the stream. Individualys have also been found in crevices in spray drenched clif walls near waterfalls. During winter, individuals are less active, especially inland, and appear to retreat beneath large logs and boulders. Tadpoles require cool streams and smooth-surfaces stones with a minimum diameter of 2.2 inches. Tadpoles probably spend most fo their time attached to such substrates by a large oral sucker. The large, sucker-like mouth parts of the tadpoles are a second distinctive feature of the species, enabling survival in turbulant waters unsuitable for other frogs. They prefer turbulant water to smooth, swiftly flowing water.

Range: Found in Oregon and Washington east to northwestern Montana and Idaho. Many separate populations can be found.

Diet: Adults forage primarily terrestrially along stream banks, but also occasionally feed underwater. A wide variety of food items are taken, including both aquatic and terrestrial larval and adult insects, other arthropods (especially spiders), and snails. Tadpoles consume small quantities of filamentous green algea and desmids. Large quantities of conifer pollen are consumed seasonally by tadpoles.

Reproduction: Breeeding season last from May through September, and females deposit their eggs in strings under rocks in fast -moving streams. Larvae take one to four years to metamorphose in the cool fast-moving streams.

When attempting to mate, males will lunge at the female, wrapping a forelimb around them to secure them initially in an inguinal plexus formation (males wrap their digits around female anterior to the pelvic region, placing their head on the back and close to the rear of the female) and then in a ventral amplexus formation (female is flipped over and makle and female venters face each other). From here, the male inserts the "tail" into the female, and squeezes the female to gain leverage before thrusting. During this process the female is relatively still, occasionally kicking during the insertion process.

In some situations there is a male-male competition for the female. In these situations, both males compete to enter the amplexus formation, eventually one establishes a better hold on the female and expelling the other male from the breeding process. Usually the male that is larger is more likely to succeed.

Taxonomy: Until 2001, the genus was believed to be monotypic, the single species being the tailed frog (Ascaphus truei - Stejneger, 1899). However, in that year, Nielson, Lohman, and Sullivan published evidence that proimoted the Rocky Mountain Tailed Frog (Ascaphus montanus) from a subspecies to its own species. Since then, the former species has been formerly called the Coastal Tailed Frog