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BC Conservation Data Centre: Conservation Status Report

Ascaphus montanus
Rocky Mountain Tailed Frog

 
Scientific Name: Ascaphus montanus
English Name: Rocky Mountain Tailed Frog
   
Provincial Status Summary
Status: S2S3
Date Status Assigned: April 15, 2016
Date Last Reviewed: November 25, 2021
Reasons: This species is restricted to two major drainages in the extreme southeast portion of the province. It is most threatened by sedimentation from roads, logging, and fires, and loss of terrestrial dispersal habitat from logging and wood harvesting. Some threats have been potentially reduced due to the protection of breeding habitat and non-breeding reaches below natal areas afforded by the establishment of 19 Wildlife Habitat Areas. Although these cover all known occurrences, monitoring is needed before we can determine whether the WHAs provide adequate protection.
 
Range
Range Extent: DE = 1,000-20,000 square km
Range Extent Estimate (km2): 4435.2
Range Extent Comments: The estimated range extent is 4,435.2 km2. This estimate uses detections that were made using eDNA as well as detections by physical searches (Hobbs et. al. 2020). A. montanus is at its northern range limit in BC and is found in five major watersheds, Flathead, Yahk, Moyie, Wigwam and Tepee. Elder Creek is the eastern most known record, Elmer Creek, a tributary of the Moyie River is the furthest to the west and Ram Creek to the north.

It is possible that the range will be expanded further with more search effort.

The total range encompassing all confirmed occurrences was previously estimated as 3,300 km2 (COSEWIC 2013j). The increase observed in this report is due to increased search effort.
Area of Occupancy (km2): EF = 26-500
Area of Occupancy Estimate (km2): 118
Area of Occupancy Comments: The AOO is estimated at 472 km2, based on CDC mapped occurrences as of 2021. It is very likely that there are more places where the frogs are found within the range extent and potentially outside of the currently known range extent.

2016 assessment: the calculated AOO, based on a 2 km x 2 km grid mapped onto inhabited streams was 296 km2 (COSEWIC 2013j). The increase indicated here is due to increased search effort since this time, particularly via eDNA work and not a true increase in area or numbers.
 
Occurrences & Population
Number of Occurrences: C = 21 - 80
Comments: Within the five known watersheds (Yahk, Moyie, Flathead, Wigwam and Tepee) there are multiple drainages and tributaries where the frogs occur, to a total known 31 occurrences.

Tailed frogs found in the Flathead watershed occur in the Macdonald Range and are found east of Inverted Ridge, west of Flathead River, and south of the Leslie/Twentynine-Mile Creek divide. This range occupies an area of about 300 km2, extending 21 km north from the international border and is a continuation of the distribution of tailed frogs in the Whitefish Ranges, Montana. The Yahk watershed is approximately half (150 km squared) of that in the Flathead watershed and includes the Screw, Boyd, Sprucetree, Malpass, Norge and Upper Yahk drainages.

The analysis of eDNA in 2015 and 2016 provide evidence that Rocky Mountain Tailed frogs occur in previously undocumented drainages (Elder Creek and upper Wigwam River) (Adams and Hobbs 2015) and (Tepee Creek and Elmer Creek) (Adams and Hobbs 2016).
Number of Occurrences with Good Viability / Ecological Integrity: Rank Factor not assessed
Number of Occurrences Appropriately Protected & Managed: CD = 4 - 40
Comments: Nineteen Wildlife Habitat Areas (a total of 1239 ha) have been established in the smaller streams. These WHAs protect the known breeding and adjacent foraging stream habitats by the 30-m reserve zone within the WHA. The WHA boundaries were created to extend to the top of main perennial headwaters above the natal areas because juveniles and adults congregate in these locations. If all of the non-harvestable land base (NHLB) is considered (tailed frog WHA reserve zones, riparian reserve zones, old growth and mature management areas, Wildlife Tree Patches and Ungulate winter ranges) then 68% and 63% of tailed frog habitat is protected in the Yahk and Flathead River watersheds, respectively. Integrated Management areas (WHA management zones, riparian management zones and Ungulate winter ranges) provide partial protection for an additional 10% and 4% of tailed frog non-breeding habitat in the Yahk and Flathead River watersheds, respectively. Overall the NHLB protects all aquatic breeding reaches; all potential valley bottom movement corridors and a quarter to a third of small headwater tributaries above natal zones within these two watersheds (Dupuis and Friele 2005).
Population Size: EF = 2,500 - 100,000 individuals
Comments: "There are approximately 3,000 adult Rocky Mountain Tailed Frogs in Canada, clustered into isolated breeding areas within the Yahk River and Flathead River watersheds. This is a ballpark estimate derived from the estimated total length of habitable streams where breeding may occur, coupled with estimates of the density of tadpoles in such streams and estimates of the relative numbers of tadpoles vs. juvenile frogs vs. adult frogs." (COSEWIC 2013j). New locations are being discovered as a result of Edna analysis (Adams and Hobbs 2016).
 
Threats (to population, occurrences, or area affected)
Degree of Threat: AB = Very high - high
Comments: There has not been a formal threat assessment completed since 2014. Since this time, threats are suspected to have increased, including forest harvesting and wildfire (L. Isaac, pers. comm. 2022).

In 2014, the overall province-wide Threat Impact was assessed be species experts as "High". The greatest threats were agricultural & forestry effluents and sedimentation of stream habitats (B.C. Ministry of Environment 2014r).

Threats to breeding habitat and non-breeding reaches below natal areas have been potentially reduced due to the protection afforded by the establishment of 19 Wildlife Habitat Areas (WHAs). Monitoring is required to determine their effectiveness. Threats of habitat loss along and above ephemeral reaches still exist and the affects that habitat fragmentation may have on tailed frog dispersal is unknown. This is especially important in the Flathead River watershed where inter-drainage dispersal occurs primarily at the height of the land (Dupuis and Friele 2005). Logging and other activities such as road building in these areas remain a threat. The potential for mining in the Flathead Valley and the affects it may have on surrounding streams is also a threat. Drought is considered a threat especially with potential global climate changes.

Research on specific populations of A. montanus in the interior of the Pacific Northwest has shown that at least short-term losses of tadpoles can occur following logging (Bull 1994). In the Yahk River range area, adult abundance was highest in areas with the greatest percentage of older forest (Ascaphus Consulting 2002). Most of the Yahk watershed is heavily impacted by fire and forest development, and road densities are high (Ascaphus Consulting 2002). In a number of studies of Ascaphus truei populations in coastal regions, fewer larvae are found in creeks with higher sediment loads and higher water temperatures. Thus logging practices that increase siltation and water temperatures may adversely affect tailed frog populations (Nussbaum et al. 1983; Dupuis and Bunnell 1997). A. truei larval numbers have been found to decline after clearcut logging (Welsh 1990; Bury et al.1991; Dupuis and Friele 1995). 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 (L. Dupuis, pers. comm.). J. Richardson (pers. comm.) found lowest densities and biomass of tadpoles in streams flowing through dense, second-growth forests; he ascribes this finding to low food levels within these creeks.
 
Trend (in population, range, area occupied, and/or condition of occurrences)
Short-Term Trend: U = Unknown
Comments: The increase in range extent and number of occurrences is a result of search effort and using eDNA as a survey aid--not an increasing trend. There has not been long-term monitoring of occurrences to determine a trend.

"Few data are available on which to ascertain population trends in Rocky Mountain Tailed Frogs." (COSEWIC 2013j)
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), with females breeding every other year. These and their relatively low dispersal rate makes them 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: A. montanus is at its northern range limit in BC, and has a narrow set of environmental tolerances (Dupuis and Friele 2005). Primary breeding habitats are step-pools of permanent, cool mountain streams and headwaters (Dupuis 1999). 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). Adult A. montanus are also riparian obligate because of the extreme temperature and moisture regimes associated with a continental climate (Dupuis and Friele 2005).
Other Rank Considerations: Landscape connectivity for this species is limited due to xeric conditions in valley floors and the cold in high mountains which are barriers to dispersal and has resulted in this species isolation.
 
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: This species is listed in the Identified Wildlife Management Strategy under the Forest Practices Code of British Columbia Act. Under this Act, 19 Wildlife Habitat Areas have been established in smaller streams and currently protect all known breeding and adjacent foraging stream habitats. If additional occurrences of this species are found they should also be protected. Habitat fragmentation and tailed frog dispersal should be taken into account when designing harvesting pattens as there is no safeguard against habitat loss along and above ephemeral reaches (Dupuis and Friele 2005). It is also recommended that there be retention of some mature or old forest in the Norge Creek drainage within the Yahk River watershed to allow/promote colonization between drainages (Dupuis and Friele 2005).
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 course. 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: Ramsay, L, S. Cannings, L. Westereng and L. Gelling
Date: November 25, 2021
 
References
Ascapus Consulting. 2002. Distribution of Ascaphus montanus in the Yahk River and neighbouring watersheds. Unpublished report submitted to Tembec Industries, Cranbrook , B.C., and Columbia Basin Fish and Wildlife Compensation Program, Nelson, B.C. 36 pp.
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.
B.C. Ministry of Environment. 2014r. Recovery plan for the Rocky Mountain Tailed Frog (Ascaphus montanus) in British Columbia. Prepared for the B.C. Ministry of Environment, Victoria, BC. 37 pp.
BC Conservation Data Centre: Conservation Data Centre Mapping Service [web application]. 2006. Victoria, British Columbia, Canada. Available: http://maps.gov.bc.ca/imf50/imf.jsp?site=cdc.
Brown, H.A. 1975. Temperature and development of the tailed frog, Ascaphus truei. Comp. Biochem. Physiol. 50A:397-405.
Bull, E. 1994. Tailed frogs in the Blue Mountains. Northwest Science. 63:23.
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. 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. 2013j. COSEWIC assessment and status report on the Rocky Mountain Tailed Frog Ascaphus montanus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xii + 46 pp.
Dupuis, L. 2002. Inland Tailed Frog, ASCAPHUS MONTANUS. Pages 67-79 IN K. Paige (technical editor), Standards for managing identified wildlife, Version 2. Draft for technical review. Ministry of Water, Land and Air Protection, Biodiversity Branch, Victoria, BC. 492pp.
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. 2005. Rocky Mountain Tailed frog - Conservation Analysis. Prepared for Ministry of Forests, Forests Practices Branch, Victoria, BC.
Dupuis, L., and K. Wilson. 1999. Status, distribution and management needs of the tailed frog in the East Kootenays. Report to Forestry Renewal British Columbia. British Columbia Ministry of Environment Lands and Parks, Wildlife Program, Kootenay Region, Nelson, B.C.
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.
Green, D.M. 1999. British Columbia Amphibians: A taxonomic catalogue. B.C. Minist. Environ., Lands and Parks, Victoria. Wildl. Bull. No. B-87. 22pp.
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, Adams, IT, Round, JM, et al. 2020. Revising the range of Rocky Mountain tailed frog, Ascaphus montanus, in British Columbia, Canada, using environmental DNA methods. Environmental DNA. 2:350?361
Nussbaum, R.A., E.D. Brodie Jr., and R.M. Storm. 1983. Amphibians and Reptiles of the Pacific Northwest. Univ. Press of Idaho. 332pp.
Paige, K. (technical editor). 2002. Standards for managing identified wildlife, Version 2. Draft for technical review. Ministry of Water, Land and Air Protection, Biodiversity Branch, Victoria, BC.
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.
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. 2021. Conservation Status Report: Ascaphus montanus. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 6, 2026).