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BC Conservation Data Centre: Conservation Status Report

Myotis ciliolabrum
Western Small-footed Myotis

 
Scientific Name: Myotis ciliolabrum
Scientific Name Synonyms: Myotis melanorhinus
English Name: Western Small-footed Myotis
English Name Synonyms: Dark-nosed Small-footed Myotis
   
Provincial Status Summary
Status: S3S4
Date Status Assigned: March 23, 2022
Date Last Reviewed: March 23, 2022
Reasons: Western Small-footed Myotis is found in small numbers and is restricted (both overwintering and summer) to valleys of the dry interior where it ranges as far north as Williams Lake and the Chilcotin River and potentially east along the Columbia Valley.
 
Range
Range Extent: F = 20,000-200,000 square km
Range Extent Estimate (km2): 60,403
Range Extent Comments:

The Range Extent is based on vouchers, observations and acoustic recordings of M. ciliolabrum and was calculated by the B.C. Conservation Data Centre. Acoustic recordings used were vetted by experts as they are difficult to distinguish from several other Myotis spp.

This species occurs in the Okanagan and Similkameen valleys as far north as Oyama and Keremeos. They also occur throughout the lower-elevation grassland valley bottoms of the Thompson and Fraser River valleys and north to at least just east of Williams Lake. There is also one record along the southern reaches of the Fraser River. Based on suitable habitat, and occurrences in the neighbouring states, it may also occur in the Kootenays. There are acoustic recordings from the Cranbrook, Columbia valley area (Lausen et. al. 2022).
Area of Occupancy (km2): U = Unknown
Area of Occupancy Estimate (km2): 77
Area of Occupancy Comments:

The detections of bats are mainly from acoustic records, an individual caught in a mist net, a found specimen and rarely a roost or hibernacula. Recording an individual or individuals are not a good measure of an Area of Occupancy, therefore this number has not been used in the final rank calculation.
 
Occurrences & Population
Number of Occurrences: CD = 21 - 300
Comments: Based on the 2007 provincial range map (Ministry of Environment 2008) there are at least 30-35 known occurrences with another 15-20 showing on the distribution map in Lausen et. al. (2022) including those identified acoustically.

Firman and Barclay (1993) reported captures in the Skagit Valley and their records were included in the range map of Garcia et al. (1995). However, this species is difficult to distinguish from the Californian Myotis, Myotis californicus (Constantine 1998). Luszcz (2004) and Nagorsen et al. (2010) did not capture M. ciliolabrum in the Skagit and its occurrence there is unconfirmed. An unconfirmed capture at the Queen Mary Mine in the Kootenays (mapped in Ministry of Environment 2008) could be M. californicus (T. Hill pers. comm.).
Number of Occurrences with Good Viability / Ecological Integrity: U = Unknown
Number of Occurrences Appropriately Protected & Managed: U = Unknown
Comments: At least 2 occurrences are in protected areas.
Population Size: U = Unknown
Comments: The largest known winter hibernacula is over 40 in a mine between Greenwood and Grand Forks. Summer roosts are largely single bats scattered in rock crevices or up to five females in a natal roost (Lausen et. al. 2022). Total population size is unknown.
 
Threats (to population, occurrences, or area affected)
Degree of Threat: BC = High - medium
Comments: Greatest known threat is disturbance to hibernating populations in caves or mine adits. Hibernacula may also be lost when the entrances are closed or gated with inappropriate gates that prevent access. Recreational cavers are little threat because most known hibernacula in BC are situated in old mine adits or shallow caves.

Human disturbance of summer roosts (found in cliffs, boulders, vertical banks and talus slopes) can result from recreational activities such as hiking or rock climbing. Other threats include pesticide use and reduction of hedgerows and riparian areas causing declines in insect and arthropod prey. Segars et. al. (2021) have recorded a number of anthropogenic causes of fatalities including cat predation, glue traps and mouse traps, however these would be isolated and localized.

This species has been found to be infected with Pseudogymnoascus destructans, the fungus that causes white-nose syndrome (WNS), but has not been found with WNS (White-nose Syndrome Response Team: https://www.whitenosesyndrome.org/ . Accessed 6 February 2022)
 
Trend (in population, range, area occupied, and/or condition of occurrences)
Short-Term Trend: U = Unknown
Comments: A lack of monitoring data makes it impossible at present to determine population trends.
Long-Term Trend: U = Unknown
 
Other Factors
Intrinsic Vulnerability: B=Moderately vulnerable
Comments: Typical of Vespertilionid bats, this species has a low reproductive rate with females producing a single young and one litter per year.
Environmental Specificity: C=Moderate. Generalist or community with some key requirements scarce.
Comments: All known maternity roosts in BC are associated with rock crevices and talus. There is no evidence for tree roosting in BC. In the western US M. ciliolabrum has been found roosting occasionally in buildings (Holloway and Barclay 2001) but no building roosts are known in BC. Crevice roosts are in warm microclimates (Tuttle and Heaney 1974) with temperatures in maternity roosts 26-29 deg C. This species overwinters near the northern limits of its range in the province with it selecting temperature regimes -3-+9 deg C for hibernation (Nagorsen et al. 1993).
Other Rank Considerations: Minimal data and a lack of any data on population trends are obstacles to an assessment. The taxonomy-nomenclature of the BC population needs to be addressed. Wilson and Reeder (2005) and Harvey et al (2011) treated the 2 subspecies of M. ciliolabrum (M. c. ciliolabrum, M. c. melanorhinus) as full species. According to their classification, BC populations would be classified as Myotis melanorhinus. This name change is unlikely to affect the BC ranking other than its global range and possibly the CF ranking. Evidence to support this taxonomic change was based on a misinterpretation of the results in van Zyll de Jong (1984).
 
Information Gaps
Research Needs: Highest priority is for a study of seasonal movements and winter biology in BC. More research is needed to to establish reliable identification criteria (morphology, acoustic files, DNA markers) to distinguish M. ciliolabrum from M. californicus. The two species are morphologically similar and not distinguished by mitochondrial DNA markers (Rodriguez and Ammerman (2004).
Inventory Needs: The known occurrences suggest several widely disjunct metapopulations. However, these disjunctions may be the result of sampling. Inventory across southern BC especially valleys east of the Okanagan and the Fraser River valley are needed to determine if the highly disjunct metapopulations are real or a sampling bias. More surveys are required to locate hibernacula. Monitoring should be done at selected hibernacula to establish long term trends.
 
Stewardship
Protection: The highest priority is protecting hibernacula from human disturbance in winter. Few of the known hibernacula are gated to prevent human access and disturbance.
Management: With so little known about its basic biology in BC it is difficult to prescribe specific management guidleines other than generic guidelines for general bat management (Nagorsen pers.comm). Key cliff roosts should be protected to prevent inadvertent disturbance by rock climbers. Use of insecticides within the foraging vicinity of roosting sites should be avoided. Education concerning the relative rarity of this species, and its sensitivity to disturbance should be implemented. Extremely little is known of the specific habitat requirements and basic biology of the Western Small-footed Myotis. The use of wildlife trees and roost sites (particularly maternal roosts) needs to be identified and better characterized (Garcia et al. 1995).
 
Version
Author: L. Ramsay and D. Nagorsen
Date: February 07, 2022
 
References
Constantine, D. G. (1998). An overlooked external character to differentiate Myotis californicus and Myotis ciliolabrum (Vespertilionidae). Journal of Mammalogy 79: 624-630.
Fenton, M.B., C.G. van Zyll de Jong, G.P. Bell, D.B. Campbell, and M.Laplante. 1980. Distribution, parturition dates, and feeding of bats in south - central British Columbia. Can. Field-Nat. 94:416-420.
Firman, M. C. and R. M. R. Barclay. 1994. Bat survey of the Skagit River Watershed in British Columbia. IN Harcombe, A. P. Skagit River rare elements study: Final report. Rep. submitted to Skagit Environmental Endowment Commission. 17pp.
Gannon, W. L., R. E. Sherwin, T. N. DeCarvalho and M. J. O'Farrell (2001). Pinnae and echolocation call differences between Myotis californicus and M. ciliolabrum (Chiroptera: Vespertilionidae). Acta Chiropterologica. 3(1): 77-91.
Garcia, P.F.J., S.A. Rasheed, and S.L. Holroyd. 1995. Status of the Western Small-footed Myotis in British Columbia. B.C. Minist. Environ., Lands and Parks, Wildl. Branch. Working Rep. WR-74. 24pp.
Harvey, M. J., J. S. Altenbach and T. L. Best (2011). Bats of the United States and Canada. Baltimore, MD, Johns Hopkins University Press.
Herd, R. M. 1987. Electrophoretic divergence of Myotis leibii and Myotis ciliolabrum (Chiroptera: Vespertilionidae). Can. J. Zool. 65:1857-1860.
Holloway, G.L., and R.M.R. Barclay. 2001. Myotis ciliolabrum. Mammalian Species 670:1-5.
Lausen, C, D.W. Nagorsen, R. M. Brigham and J. Hobbs. 2022. Royal Museum Handbook. Bats of British Columiba. Second Edition. Royal BC Museum. Victoria, Canada. 375 pp.
Luszcz, T. 2004. Community structure and habitat use by forest-dwelling bats in southwestern British Columbia. MSc Thesis, University of Calgary.156 pp.
Ministry of Environment. 2008. Map-Western Small-footed Myotis (Myotis ciliolabrm). Bat distribution. mapping project. Victoria, BC.
Nagorsen D, C. Lausen, D. Burles, and P. Govindarajulu. 2010. Identification of long-eared Myotis bat species in British Columbia: An essential tool for developing management recommendations for bat species at risk. Forest Sciences Program Project Y092135. Final Report. 26 pp.
Nagorsen, D. 1990. The mammals of British Columbia: a taxonomic catalogue. Mem. No. 4. Royal B.C. Mus., Victoria. 140pp.
Nagorsen, D.W., et al. 1993. Winter bat records for British Columbia. Northwest. Nat. 74:61-66.
Nagorsen, D.W., and R.M. Brigham. 1993. The bats of British Columbia. Royal B.C. Mus. Handb. Victoria, BC. 164pp.
Rodriguez, R. M., and L. K. Ammerman. 2004. Mitochondrial DNA divergence does not reflect morphological difference between Myotis californicus and Myotis ciliolabrum. Journal of Mammalogy 85:842-851.
Schmidly, D. J. 1991. The bats of Texas. Texas A & M University Press, College Station, Texas. 188 pp.
Segars, J., S. McBurney, M. Jones, et al. 2021. The Canadian Wildlife Health Cooperative National Bat Health Report ? 2021
Tuttle, M.D. and L.R. Heaney. 1974. Maternity habits of Myotis leibii in South Dakota. Southern California Acad., Sci., Bull., 73(2):80-83.
US Fish and Wildlife Service. 2022. White-nose Syndrome Response Team. Website accessed January 2022. https://www.whitenosesyndrome.org/
van Zyll de Jong, C. G. 1984. Taxonomic relationships of Nearctic small-footed bats of the Myotis leibii group (Chiroptera: Vespertilionidae). Can. J. Zool. 62:2519-2526.
van Zyll de Jong, C.G. 1985. Handbook of Canadian Mammals. Vol. II, Bats. National Museum of Natural Sciences, National Museums of Canada, Ottawa, Canada. 212 pp.
Wilson, D. E., and D. M. Reeder (editors). 2005. Mammal species of the world: a taxonomic and geographic reference. Third edition. The Johns Hopkins University Press, Baltimore. Two volumes. 2,142 pp. [As modified by ASM the Mammal Diversity Database (MDD) at https://www.mammaldiversity.org/index.html]
Woodsworth, G. 1981. Spatial partitioning by two species of sympatric bats, Myotis californicus and Myotis leibii. MS thesis, Carleton University.68 pp.
 

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: Myotis ciliolabrum. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 5, 2026).