Ascaphus truei 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Amphibia Anura Ascaphidae

Scientific Name: Ascaphus truei
Species Authority: Stejneger, 1899
Common Name(s):
English Coastal Tailed Frog, Bell's Toad, American Ribbed Toad, American Discoglossoid Toad, American Bell Toad, Pacific Tailed Frog, Tailed Frog
Taxonomic Source(s): Frost, D.R. 2013. Amphibian Species of the World: an Online Reference. Version 5.6 (9 January 2013). Electronic Database. American Museum of Natural History, New York, USA. Available at:

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2015
Date Assessed: 2015-08-25
Assessor(s): IUCN SSC Amphibian Specialist Group
Reviewer(s): Stuart, S.N.
Contributor(s): Hammerson, G.A. & Adams, M.
Facilitator/Compiler(s): Sharp, D. & Hobin, L.
Listed as Least Concern in view of the large extent of occurrence, large number of sub-populations and localities, and presumed large population size.
Previously published Red List assessments:
2004 Least Concern (LC)

Geographic Range [top]

Range Description: Range includes the Cascade Mountains and Pacific coastal areas of North America from west-central British Columbia, Canada, south to northwestern California, USA (Nielson et al. 2001, Stebbins 2003).
Countries occurrence:
Canada (British Columbia); United States (California, Oregon, Washington)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species has many extant occurrences distributed throughout the range. Total population size is unknown but probably exceeds 10,000. It is common in suitable habitat. Its long-term trend is probably relatively stable in terms of extent of occurrence. There has been an unknown degree of decline in population size, area of occupancy, and number/condition of locations. Its short-term population trend is probably declining based on habitat trends, but few population data are available.
Current Population Trend: Unknown
Additional data:
Population severely fragmented: No

Habitat and Ecology [top]

Habitat and Ecology: Can be found in clear, cold swift-moving mountain streams with coarse substrates. Primarily in older forest sites, required microclimatic and microhabitat conditions are more common in older forests (Welsh 1990). Diller and Wallace (1999) reported that canopy cover, temperature, and forest age in managed forests were not significantly different between occupied and unoccupied stream reaches in northern California; however, this probably reflects past timber harvest patterns. Animals may be found on land during wet weather near water in humid forests or in more open habitat. During dry weather it stays on moist stream-banks and lays eggs in long strings under stones in water.
Systems: Terrestrial; Freshwater

Use and Trade [top]

Use and Trade: There are no records of this species being utilized.

Threats [top]

Major Threat(s): It is sensitive to logging and road building (Leonard et al. 1993). In addition to clearing of habitat for road building, pollution resulting from road building is also a threat, which happens when sedimentation occurs as a result of poorly constructed roads. Logging and construction practices that increase water temperatures and siltation might have an adverse effect on tailed frog sub-populations (Nussbaum et al. 1983, Welsh and Ollivier 1998). See also Bury and Corn (1988) and Corn and Bury (1989) for information on negative effects of timber harvest. Diller and Wallace (1999) emphasized that current timber harvest practices are not as detrimental as those used in the past. Despite negative effects of logging, this species frequently occurs in many young forests that have been harvested one or more times in the past. Sensitivity to timber harvest might depend on surface geology and harvest practices (Adams and Bury 2002, Welsh and Lind 2002).

Conservation Actions [top]

Conservation Actions: Conservation Actions 
The species range includes many national parks and wilderness areas. 

Conservation Needed
Protection and management of cool, forested, unsilted streams and stream corridors is a basic conservation need.

Citation: IUCN SSC Amphibian Specialist Group. 2015. Ascaphus truei. The IUCN Red List of Threatened Species 2015: e.T54414A78905810. . Downloaded on 29 November 2015.
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