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Montana Field Guides

Fringed Myotis - Myotis thysanodes

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Species of Concern

Global Rank: G4
State Rank: S3

Agency Status
FWP Conservation Tier: 2

External Links

General Description
The Fringed Myotis is a member of the long-eared myotis group. Although similar to Western Long-eared Myotis (Myotis evotis), it is the only species with a well-developed fringe of hairs on the posterior margin of the uropatagium, and is larger than most other Myotis, except in ear size. The robust calcar is not distinctly keeled. The skull is relatively large, with a well-developed sagittal crest, and 38 teeth (dental formula: I 2/3, C 1/1, P 3/3, M 3/3). Color of the pelage varies from yellowish-brown to darker olivaceous tones; color tends to be darker in northern populations. The ears and membranes are blackish-brown and tend to contrast with the pelage. Length of the head and body is 43 to 59 millimeters, length of the tail is 34 to 45 millimeters, length of the ear is 16 to 20 millimeters, length of the forearm is 40 to 47 millimeters, and weight is 5.4 to 10.0 grams. Females are significantly larger in head, body and forearm size (O'Farrell and Studier 1980, Nagorsen and Brigham 1993, Foresman 2012).

Diagnostic Characteristics
The presence of a well-developed fringe of hairs along the posterior edge of the uropatagium is unique among the Myotis found in Montana, including the other long-eared species. The forearm is longer (usually more than 40 millimeters) than all other species of Myotis except some individuals of M. evotis (a long-eared species) and M. volans (a short-eared species with a keeled calcar). The skull is broader than other Myotis species, with a distance across the upper molars more than 6.2 millimeters.

General Distribution
Montana Range

Western Hemisphere Range


Summary of Observations Submitted for Montana
Number of Observations: 86

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Records associated with a range of dates are excluded from time charts)

No information on movements in Montana is available (Foresman 2012). The Fringed Myotis has been observed in Montana only during June to September, indicating it may migrate out of the state for winter.

The few Montana records indicate that the habitats in Montana that are used by the Fringed Myotis are similar to other regions in the interior West (Foresman 2012). It has been captured in ponderosa pine and Douglas-fir forest while foraging over willow/cottonwood areas along creeks and over pools, and taken in caves (Lewis and Clark Caverns); one individual was captured in an urban setting in Missoula (Hoffmann et al. 1969, Butts 1993, Dubois 1999).

Habitat information gathered from range-wide studies state the Fringed Myotis is found primarily in desert shrublands, sagebrush-grassland, and woodland habitats (ponderosa pine forest, oak and pine habitats, Douglas-fir), although it has been recorded in spruce-fir habitat in New Mexico. It also occurs at low elevations along the Pacific Coast, and in badlands in the northern Great Plains (Jones et al. 1983, Humes et al. 1999). It roosts in caves, mines, rock crevices, buildings, and other protected sites. Nursery colonies occur in caves, mines, and sometimes buildings (Easterla 1973, O'Farrell and Studier 1980, Jones et al. 1983). Fringed Myotis in riparian areas tend to be more active over intermittent streams with wider channels (5.5 to 10.5 meters) than ones with channels less than 2.0 meters wide (Seidman and Zabel 2001).

Ecological Systems Associated with this Species
  • Details on Creation and Suggested Uses and Limitations
    How Associations Were Made
    We associated the use and habitat quality (high, medium, or low) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2001, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species’ range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point database associated with each ecological system;
    4. Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of “observations versus availability of habitat”.
    Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.  In general, species were associated as using an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.  However, species were not associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if point observations were associated with that system.  High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the literature.  The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignments of habitat quality.  If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at or (406) 444-3655.

    Suggested Uses and Limitations
    Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.  These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.  Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.  Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.  Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).  Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species’ known geographic range.

    Literature Cited
    • Adams, R.A.  2003.  Bats of the Rocky Mountain West; natural history, ecology, and conservation.  Boulder, CO: University Press of Colorado.  289 p.
    • Dobkin, D. S.  1992.  Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34.  Missoula, MT.
    • Foresman, K.R.  2001.  The wild mammals of Montana.  Special Publication No. 12.  Lawrence, KS: The American Society of Mammalogists.  278 p.
    • Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998.  Montana atlas of terrestrial vertebrates.  Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT.  1302 p.
    • Hutto, R.L. and J.S. Young.  1999.  Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32.  72 p.
    • Maxell, B.A.  2000.  Management of Montana’s amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species.  Report to U.S. Forest Service Region 1.  Missoula, MT: Wildlife Biology Program, University of Montana.  161 p.
    • Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath.  2004.  Amphibians and reptiles of Montana.  Missoula, MT: Mountain Press Publishing Company. 262 p.

Food Habits
Food habits have not been studied in the state. Range-wide information state that Fringed Myotis are insectivorous; beetles occurred in 73% and moths in 36% of fecal pellets in New Mexico (Black 1974). The diet in Oregon included over 40% moths, with lesser amounts of five other insect orders and spiders (Verts and Carraway 1998); moths and beetles have been reported in the diet in South Dakota (Turner and Jones 1968).

The diet in Montana has not been reported or studied. The wings of the Fringed Myotis have a high puncture strength, which is characteristic of bats that forage by gleaning from the ground or near thick or thorny vegetation (O'Farrell and Studier 1980); when in flight, Fringed Myotis often forages close to the vegetative canopy.

No ecological information is available for the Fringed Myotis in Montana. Across its range, including the Black Hills region, the known activity period of the Fringed Myotis extends from April through September (O'Farrell and Studier 1980, Jones et al. 1983), with hibernation extending from September to April or early May; activity is greatest during the first two hours after sunset. All Montana records to date (n = 13) have occurred from mid-June to early September. Predators of Fringed Myotis are largely unknown; a domestic cat captured a juvenile in Montana (Hoffmann et al. 1969).

Females generally are found at lower elevations than males (Cryan et al. 2000), perhaps because reproductive individuals need warmer roosts in which to raise young. Males and females form separate colonies in summer, although an occasional male may be found in a maternity colony. Sex ratios in trapping samples may be biased because of sex-related differences in habitat use (Bogan et al. 1996). Individuals in an attic complex maternity colony tended to roost in the open in tightly packed clusters. The Fringed Myotis is found with many other bat species (O'Farrell and Studier 1980, Butts 1993, Choate and Anderson 1997, Dubois 1999), including Townsend's Big-eared Bat (Corynorhinus townsendii), Western Long-eared Myotis (M. evotis), Long-legged Myotis (M. volans), Little Brown Myotis (M. lucifugus), Yuma Myotis (M. yumanensis), Western Small-footed Myotis (M. ciliolabrum), and California Myotis (M. californicus), each of which is present in Montana. However, the ecology of the Fringed Myotis in Montana is largely unknown and has not been studied.

Reproductive Characteristics
There is almost no information on reproduction of the Fringed Myotis in Montana, and no published studies. A juvenile was collected in Missoula County in early September, and an adult female in mid-June in Ravalli County, indicating that reproduction occurs in Montana (Hoffmann et al. 1969).

Information gathered from studies in other areas of the species' range indicate apparently little variation in the timing of reproduction throughout the range. In northeastern New Mexico, mating occurs in fall, ovulation, fertilization, and implantation occur from late April to mid-May, gestation lasts 50 to 60 days, and young are born in late June to mid-July. In South Dakota, pregnant females have been captured in mid-June, lactating females in late July through August, and flying young-of-the-year as early as late July or early August (O'Farrell and Studier 1980, Jones et al. 1983, Bogan et al. 1996). The litter size is 1. Young can fly at 16 to 17 days. Maternity colony sizes range up to several hundred individuals. Individuals may live 11 years or more (Paradiso and Greenhall 1967); the record is 18.3 years (Verts and Carraway 1998).

Although no management measures have been enacted specifically for the protection of Fringed Myotis in Montana, protection of bat roosting habitat through gating of caves and abandoned mines should be beneficial for this species. Protection guidelines and management protocols designated for Townsend's Big-eared Bat (Corynorhinus townsendii) (Pierson et al. 1999) are also appropriate for Fringed Myotis (the two species coexist over much of their ranges) and are recommended as default measures until specific conservation protocols for this species are developed. So little is known about Fringed Myotis in Montana, including its distribution and relative abundance, that standardized surveys of potential roosts and foraging habitats are desirable as the first step to identifying the spatial and temporal context in which this species is present in the state. This basic information will make it easier to design and implement appropriate and effective conservation guidelines to protect important habitats and roosts.

  • Literature Cited AboveLegend:   View WorldCat Record   View Online Publication
    • Black, H.L. 1974. A north temperate bat community: structure and prey populations. Journal of Mammalogy 55:138-157.
    • Bogan, M. A., J. G. Osborne, and J. A. Clarke. 1996. Observations on bats at Badlands National Park, South Dakota. Prairie Naturalist 28:115-123.
    • Butts, T. W. 1993. A survey of the bats of the Townsend Ranger District, Helena National Forest, Montana. Montana Natural Heritage Program. Helena, Montana. 16 p.
    • Choate, J. R. and J. M. Anderson. 1997. Bats of Jewel Cave National Monument, South Dakota. Prairie Naturalist 29:39-47.
    • Cryan, P. M., M. A. Bogan, and J. S. Altenbach. 2000. Effect of elevation on distribution of female bats in the Black Hills, South Dakota. Journal of Mammalogy 81:719-725.
    • Dubois, K. 1999. Region 4 bat surveys: 1998 progress report. Unpublished report, Montana Fish, Wildlife & Parks Region 4 Headquarters, Great Falls, Montana. 20 p.
    • Easterla, D. A. 1973. Ecology of the 18 species of Chiroptera at Big Bend National Park, Texas. Part I and II. Northwest Missouri State University Studies 34:1-165.
    • Foresman, K. R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 p.
    • Hoffmann, R. S., D. L. Pattie and J. F. Bell. 1969. The distribution of some mammals in Montana. II. Bats. Journal of Mammalogy 50(4): 737-741.
    • Humes, M. L., J. P. Hayes, and M. W. Collopy. 1999. Bat activity in thinned, unthinned, and old-growth forests in western Oregon. Journal of Wildlife Management 63:553-561.
    • Jones, J. K., D. M. Armstrong, R. S. Hoffmann and C. Jones. 1983. Mammals of the northern Great Plains. University of Nebraska Press, Lincoln. 379 p.
    • Nagorsen, D. W. and R. M. Brigham. 1993. Bats of British Columbia. Volume I. The Mammals of British Columbia. UBC Press, Vancouver. 164 p.
    • O'Farrell, M.J. and E.H. Studier. 1980. Myotis thysanodes. Mammalian Species 137:1-5.
    • Paradiso, J. L. and A. M. Greenhall. 1967. Longevity records for American bats. American Midland Naturalist 78:251-252.
    • Pierson, E. D., and 14 others. 1999. Species conservation assessment and strategy for Townsend's big-eared bat (Corynorhinus townsendii townsendii and Corynorhinus townsendii pallescens). Idaho Conservation Effort, Idaho Department of Fish and Game, Boise, Idaho. 68 p.
    • Seidman, V. M. and C. J. Zabel. 2001. Bat activity along intermittent streams in northwestern California. Journal of Mammalogy 82:738-747.
    • Turner, R. W. and J. K. Jones, Jr. 1968. Additional notes on bats from western South Dakota. Southwestern Naturalist 13:444-447.
    • Verts, B. J. and L. N. Carraway. 1998. Land mammals of Oregon. University of California Press, Berkeley. xvi + 668 p.
  • Additional ReferencesLegend:   View WorldCat Record   View Online Publication
    Do you know of a citation we're missing?
    • Adams, R. A. 2003. Bats of the Rocky Mountain West: natural history, ecology and conservation. University Press of Colorado: Boulder, CO. 289 p.
    • Boyce, Mark S. October 8, 1968. First Record Of The Fringe-Tailed Bat, Myotis thysanodes, From Southeastern Wyoming. Southwest. Nat. 25:114-115.
    • Flath, D. L. 1984. Vertebrate species of special interest or concern. Mammals, birds, reptiles, amphibians, fishes. Spec. Publ. Montana Department of Fish, Wildlife, and Parks, Helena. 76 pp.
    • Flath, Dennis L., 1979, Nongame species of special interest or concern: Mammals, birds, reptiles, amphibians, fishes. January 1979.
    • Foresman, K. R. 2001. The wild mammals of Montana. American Society of Mammologists, Special Publication Number 12. Lawrence, KS. 278 p.
    • Hall, E. R. 1981. The mammals of North America, volumes I and II. John Wiley & Sons, New York, NY. 1181 p.
    • Hendricks, P., K. Jurist, D. L. Genter, and J. D. Reichel. 1995. Bat survey of the Sioux District, Custer National Forest: 1994. Montana Natural Heritage Program. Helena, Montana. 41 pp.
    • Jones, J.K. Jr. and Goneways, H.H. 1967. A new subspecies of the fringe-tailed bat, Myotis thysanedes, from the Black Hills of South Dakota and Wyoming. J. Mammal. 48(2):231-235.
    • Manning, R. W. and J. K. Jones, Jr. 1988. A new subspecies of fringed myotis, MYOTIS THYSANODES, from the northwestern coast of the United States. Occas. Pap. Mus. Texas Tech Univ. No. 123:1-6.
    • O'Farrell, M.J., and E.H. Studier. 1973. Reproduction, growth, and development in MYOTIS THYSANODES and M. LUCIFUGUS (Chiroptera: Vespertilionidae). Ecology 54:18-30.
    • Perkins, J. M., J. M. Barss, and J. Peterson. 1990. Winter records of bats in Oregon and Washington. Northwestern Naturalist 71:59-62.
    • Priday, J., and B. Luce. 1997. Inventory of bats and bat habitat associated with caves and mines in Wyoming: completion report. Pp. 50-109 in Endangered and nongame bird and mammal investigations annual completion report. Nongame Program, Biological Services Section, Wyoming Game and Fish Department, Cheyenne, Wyoming.
    • Reid, F. 2006. Peterson Field Guide to Mammals of North America, 4th Edition. Houghton Mifflin Company: Boston and New York, 608 pp.
    • Schmidly, D. J. 1991. The bats of Texas. Texas A and M University Press, College Station. 188 p.
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Citation for data on this website:
Fringed Myotis — Myotis thysanodes.  Montana Field Guide.  Montana Natural Heritage Program and Montana Fish, Wildlife and Parks.  Retrieved on April 17, 2014, from
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