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BC Conservation Data Centre: Conservation Status Report

Ascaphus truei
Coastal Tailed Frog


 
Scientific Name: Ascaphus truei
English Name: Coastal Tailed Frog
English Name Synonyms: Pacific Tailed Frog
   
Provincial Status Summary
Status: S4
Date Status Assigned: December 31, 2016
Date Last Reviewed: January 20, 2022
Reasons: This species is restricted to coastal mountain ranges, although widespread and locally common there. It is threatened by habitat loss/degradation resulting from sedimentation, timber harvest and urbanization in the southern portion of its range. In some areas these threats have been potentially reduced by the establishment of Wildlife Habitat Areas (WHAs); effectiveness of the WHA's is currently being researched (K. Paige, pers. comm. 2016). New locations continue to be discovered using environmental DNA technology.
 
Range
Range Extent: F = 20,000-200,000 square km
Range Extent Estimate (km2): 166,000
Range Extent Comments: The range was estimated to be approximately 166,262 km2 in 2016, using all points available at that time (internal CDC calculation). As of 2021 any additional known occurrences were within the convex polygon drawn for this range extent, therefore remains at 166, 262 km2. Coastal Tailed Frog occurs throughout the Cascade and Coast Ranges in British Columbia from west of Smithers (Zymoetz River, to Mayo Creek west of Smithers, to Kyhex Creek and Big Falls Creek), south along the Sunshine Coast and east to Cathedral Provincial Park, the western tributaries to the Tulameen River, and in Easygoing Creek, a tributary of the Ashnola River and up to the Lillooet and Anderson Lake area in the major watersheds of the Merritt Forest District.

It is not found on most offshore islands and generally does not range into lowlands where streams are warmer and more sluggish (COSEWIC 2011h).
Area of Occupancy (km2): G = 501-2,500
Area of Occupancy Estimate (km2): > 600
Area of Occupancy Comments: In 2016, the BC CDC estimated the area of occupancy to be 577 2x2 km grid cells based on unmapped, raw data. Since that time there are approximately 35 known additional observations from eDNA surveys (Hobbs et. al. 2019) and observations on iNaturalist (accessed 2022-01-02). This could increase the number of 2x2 km grid cells to 612. Even with likely more locations still to be found this is still well under the threshold of 2500 2x2 km grid cells.

From COSEWIC 2011h: The index of area of occupancy (IAO) was calculated based on the number of 2 km x 2 km grid cells with distribution records of the species up to the year 2010. There were 325 occupied cells, resulting in an IAO of 1,300 km2 (discrete IAO).
 
Occurrences & Population
Number of Occurrences: D = 81 - 300
Comments: In 2016 the BC CDC calculated the number of occurrences to be approximatly 100 using a five kilometre buffer around the known observations at the time. New locations continue to be detected as a result of eDNA technology and citizen science observations as indicated by the increase in Area of Occupancy. Using a separation distance of one kilometre for unsuitable habitat and five kilometres for suitable, a range estimate for element occurrences is 150-200. At this time, 2021, the BC CDC is not tracking Ascaphus truei, therefore not maintining element occurrences or mapping new ones, thus the estimate.
Number of Occurrences with Good Viability / Ecological Integrity: U = Unknown
Number of Occurrences Appropriately Protected & Managed: E = >40
Comments: From COSEWIC 2011h: Parks protect approximately 15% of the Coastal Tailed Frog?s range in British Columbia; approximately 5% of known occurrences are within protected areas (provincial parks and conservancy areas). Provincial Special Management Areas provide protection to additional areas. A total of 40 Wildlife Habitat Areas, established for species at risk listed under the Forest and Range Practices Act, have been approved for the Coastal Tailed Frog and are in various stages of implementation.
Population Size: H = >1,000,000 individuals
Comments: Very limited work has been done on estimating population size and densities of the Coastal Tailed Frog in B.C. Although population size is unknown there are probably several million based on wide range and number of potentially suitable headwater basins (COSEWIC 2011h).
 
Threats (to population, occurrences, or area affected)
Degree of Threat: B = High
Comments: From COSEWIC 2011h:Tadpoles are vulnerable to local extirpation from massive substrate movements in their creeks. This sensitivity is compounded by road building, logging practices, and run- of-river hydroelectric installations that can alter hydrological regimes and increase fine sediment in channel beds. Increased peak flows can enhance channel instability; lowered base flows can cause channels to dry up in the summer. Fine sediments clog pores among coarse stream bottom substrates, decreasing food availability and eliminating refuges. Numbers of juveniles and adults are reduced in heavily disturbed watersheds. Aforementioned human activities also compromise the quality of forest habitats surrounding stream reaches. Gene flow becomes increasingly limited as the landscape is further fragmented. Over the past few decades, an emerging fungal disease, chytridiomycosis, has resulted in amphibian population declines in many parts of the world and has recently been detected in tailed frogs from the U.S. Rocky Mountains and Coast Mountains. Chytridiomycosis is a potential threat to the Coastal Tailed Frog in British Columbia.

Prior to COSEWIC 2011h report:
Threats to some of the breeding habitat has been potentially reduced due to the protection afforded by the establishment of Wildlife Habitat Areas (WHAs). Monitoring of these sites is required to determine the effectiveness of these WHAs.
Fewer larvae are found in creeks with higher sediment loads and higher water temperatures; thus logging practices that increase siltation and water temperatures probably adversely affect populations (Nussbaum et al. 1983; Dupuis and Bunnell 1997; Dupuis 1999). Tailed frogs have declined following clearcut logging (Welsh 1990; Bury et al. 1991; Dupuis and Friele 1995). Corn and Bury (1989) and Richardson and Neill (1995) found a lower frequency of occupied creeks in logged drainages than in undisturbed ones; and Dupuis and Steventon (1999) found that tadpole densities were significantly lower in clearcut streams than in buffered or undisturbed streams. These results suggest that logging renders some previously suitable creeks unsuitable. The vulnerability of tadpoles to these threats is a function of local geology and geomorphology; tadpoles in streams running through competent rock that resists erosion are probably less at risk than others (Dupuis 1999). In the Chilliwack River drainage, lowest densities and biomass of tadpoles were found in streams flowing through dense, second-growth forests (Richardson and Neill 1995; J. Richardson, pers. comm.); this pattern is ascribed to low food levels within these creeks (J. Richardson, pers. comm.). It was also found that adults were twice as abundant in mature stands than in clearcut sites and that immatures were found throughout the clearcut sites. This difference might be due to juveniles moving through clearcut sites without taking up residency, or because they have higher mortality rates which could reduce local abundance through decreased reproduction (Matsuda and Richardson 2005).
Road building/upgrades such as along the Sea-to-Sky highway (Ascaphus Consulting 2003) and other development in mountainous areas may have adverse affects to Tailed Frog streams.
In 2010, samples of Coastal Tailed Frogs in BC were tested for the presence of Bd (an aquatic fungus that causes the disease chytridiomycosis in amphibians); however it was not detected (Govindarajulu et al. 2013). It has, however, been found in Tailed Frog populations in the U.S (True 2009; Hossack et al. 2010).
 
Trend (in population, range, area occupied, and/or condition of occurrences)
Short-Term Trend: U = Unknown
Comments: It is likely that there has been a decline in the number of water courses that are suitable for Coastal Tailed Frogs particularly in the Lower Mainland, however there hasn't been long term monitoring that would corroborate this. Much of the focus with Coastal Tailed frogs has been finding new locations both by visual surveys and by eDNA.
The last COSEWIC report stated that there is no information on population fluctuations or trends for the Coastal Tailed Frog in B.C (COSEWIC 2011h).
Long-Term Trend: U = Unknown
 
Other Factors
Intrinsic Vulnerability: B=Moderately vulnerable
Comments: This species has a long larval stage (up to five years), slow maturity (about 7 years) and relatively low dispersal rate which makes it vulnerable to local extirpation. All life stages also have a narrow termperature tolerance (Dupuis 1999).
Environmental Specificity: B=Narrow. Specialist or community with key requirements common.
Comments: Breeding for this species is restricted to cool, fast-flowing creeks that are permanently flowing. Elevation, creek gradient, bank width, streambed substrates, and bedload are other features that may restrict suitability of a creek for breeding (Dupuis 1999; Gyug 2001). Juveniles and adults require older forests with stable, moist microclimates and enough structural diversity to provide refuge sites and food (COSEWIC 2011h).
Other Rank Considerations:
 
Information Gaps
Research Needs:
Inventory Needs: Inventories, particularly ones that concentrate on finding adults and getting full larval counts, should continue. Area-constrained searches for larvae are useful in documenting relative abundance (Resources Inventory Committee 2000), and thus for trend analysis.
 
Stewardship
Protection: The species is listed in the Identified Wildlife Management Strategy under the Forest Practices Code of British Columbia Act. Procedures for the establishment of General Wildlife Measures to determine appropriate management practices within established areas should be made available to resource managers.
Management: Maintaining a stream's natural sediment and bedload movement is critical to reproductive success. With this in mind, protection of areas should take into account the geological substrate of the area (Dupuis and Friele 1995), particularly during road building adjacent to the water couse. Determine the survival requirements, including habitats and dispersal requirements of metamorphosed frogs, particularly the effect of fragmenting the surrounding landscape. Further work is needed on the relationship between tadpole abundance (known to be related to creek stability and size) and elevation, aspect, slope and debris flow frequency.
 
Version
Author: L. Ramsay, L. Gelling, S. Cannings and L. Westereng
Date: January 20, 2022
 
References
Ascaphus Consulting. 2003. Tailed Frog sampling in creeks along the Sea-toSky Highway. Report prepared for Min. Transportaion and Highways, Vancouver, BC. 9pp.
Aubry, K.B., and P.A. Hall. 1991. Terrestrial amphibian communities in the southern Washington Cascade Range. Pages 327-337 in L. F. Ruggio, K. A. Aubry, A.B. Carey and M.H. Huff, eds. Wildlife and vegetation in unmanaged Douglas-fir forests. U. S. Forest Service, PNW Research Station, Portland, OR. PNW-GTR-285.
Brown, H.A. 1975. Temperature and development of the tailed frog, Ascaphus truei. Comp. Biochem. Physiol. 50A:397-405.
Bury, R.B. et al. 1991. Aquatic amphibian communities in Oregon and Washington. Pages 353-362 in L.F. Ruggerio (ed.) Wildlife and vegetation of unmanaged Douglas-fir forests. US Forest Service. Pacific Northwest Research Station, Portland, OR. PNW-GTR-285.
Corkran, C., and C. Thoms. 1996. Amphibians of Oregon, Washington and British Columbia - A field identification guide. Lone Pine Publ. Co., Edmonton, AB. 175pp.
Corn, P. S., and R. B. Bury. 1989. Logging in western Oregon: responses of headwater habitats and stream amphibians. Forest Ecology and Management 29:39-57.
Corn, P.S., and R.B. Bury. 1991. Terrestrial amphibian communities in the Oregon Coast Range. Pages 305-317 in L. Ruggiero, K. Aubry, A. Carey and M. Huff, tech. coords., Wildlife and vegetation of unmanaged Douglas-fir forests. U.S. Dep. Agric. For. Serv., Gen. Tech. Rep. PNW-GTR-285, Pacific Northwest Stn., Portland, OR.
COSEWIC. 2011f. COSEWIC assessment and status report on the Coastal Tailed Frog Ascaphus truei in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xii + 53 pp.
Dupuis, L. A., and D. Steventon. 1999. Riparian management and the tailed frog in northern coastal forests. Forest Ecology and Management 124:35-43.
Dupuis, L., and P. Friele. 1995. Riparian management and the tailed frog. Unpubl. rep. submitted to B.C. Minist. For., Smithers. 18pp.
Dupuis, L.A. 1999. Status Report on the Tailed Frog, Ascaphus truei, in Canada. Committee of the Status of Endangered Wildlife in Canada. Ottawa. 46pp.
Dupuis, L.A., and F. Bunnell. 1997. Status and distribution of the Tailed Frog in British Columbia. Rep. submitted to For. Renewal B.C. 21pp. plus appendices.
Environment and Climate Change Canada. 2016v. Management Plan for the Coastal Tailed Frog (Ascaphus truei) in Canada [Proposed]. Species at Risk Act Management Plan Series. Environment and Climate Change Canada, Ottawa. 2 parts, 3 pp. + 49 pp.
Govindarajulu et al. 2013. Batrachochytrium dendrobatidis surveillance in British Columbia 2008-2009, Canada. 5pp. 
 
Green, D.M. 1999. British Columbia Amphibians: A taxonomic catalogue. B.C. Minist. Environ., Lands and Parks, Victoria. Wildl. Bull. No. B-87. 22pp.
Gyug, L. W. 2001. Tailed frog inventory, Merritt Forest District: Project report 2001. Unpublished report submitted to Southern Interior Region, B.C. Ministry of Water, Land and Air Protection, Kamloops. 30pp.
Hawkins, C., M. Murphy, N. Anderson, and M. Wilzbach. 1988. Density of fish and salamanders in relation to riparian canopy and physical habitat in streams of the northwestern United States. Can. J. Fish Aquat. Sci. 40:1173-1185.
Hobbs J, Round J.M, Allison M.J, et al. 2019. Expansion of the known distribution of the coastal tailed frog, Ascaphus truei, in British Columbia, Canada, using robust eDNA detection methods. PLoS ONE 14(3): e0213849
Hobbs, J. and Goldberg, C. 2015. Pacific Water Shrew and Coastal Giant Salamander inventory and method assessment environmental DNA (eDNA) study. 
Hobbs. J. 2017. Bridge and Seton Watersheds: Tailed Frog environmental DNA assessment. Fish and Wildlife Compensation Program: COA-F17-W-1286. Report Prepared for Fish and Wildlife Compensation Program, Coastal. 35 pp.
Matsuda, B.M. and J.S. Richardson. 2005. Movement patterns and relative abundance of coastal tailed frogs in clearcuts and mature forest stands. Can. J. For. Res. 35: 1131-1138.
Nussbaum, R.A., E.D. Brodie Jr., and R.M. Storm. 1983. Amphibians and Reptiles of the Pacific Northwest. Univ. Press of Idaho. 332pp.
Resources Inventory Committee. 2000. Inventory methods for Tailed Frog and Pacific Giant Salamander. Standards for Components of British Columbia's Biodiversity No. 39, Version 2. Prepared by Resources Inventory Branch for the Terrestrial Ecosystems Task Force Resources Inventory Committee. British Columbia Ministry of Environment, Lands and Parks, Victoria, B.C.
Richardson, J.S., and W.E. Neill. 1994. Distribution patterns of two montane stream amphibians and the effects of forest harvest: the Pacific Giant Salamander and Tailed Frog in southwestern British Columbia. Unpubl. rep., Westwater Res. Cent., Univ. B.C. 42pp.
Ritland, K. 1998. Genetic differentiation and gene flow in the tailed frog (Ascaphus truei) of British Columbia. Unpubl. interim rep. Dep. For. Sci., Univ. B.C., Vancouver, BC. 4pp.
True, K. 2010. California-Nevada Fish Health Centre: assists with amphibian disease surveys. The Fish and Wildlife Journal Web site: http://www.fws.gov/arsnew/regmap.cfm?arskey=26845 [acessed November 2010].
Welsh, H. H., Jr. 1990. Relictual amphibians and old-growth forests. Conservation Biology 4:309-19.
Welsh, H.H. Jr., and L.M. Ollivier. 1998. Stream amphibians as indicators of ecosystem stress: a case study from California's redwoods. U.S. For. Serv., Pac. Southwest Res. Stn., Arcata, CA. In press.
 

Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.

Suggested Citation:

B.C. Conservation Data Centre. 2022. Conservation Status Report: Ascaphus truei. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Nov 7, 2024).