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Montana Animal Field Guide

Montana Field Guides

Little Brown Myotis - Myotis lucifugus
Other Names:  Little Brown Bat

Species of Concern

Global Rank: G3
State Rank: S3

Agency Status


External Links

General Description
The most common bat species in Montana (Foresman 2012). Cinnamon-buff to dark brown above, buffy to pale gray below; hairs on back have long glossy tips; ears, when laid forward, reach approximately to the nostril; tragus about half as high as ear; calcar without keel; length of head and body 41 to 54 mm, ear 11.0 to 15.5 mm, forearm 33 to 41 mm; braincase rises gradually from rostrum; greatest length of skull 14 to 16 mm; length of upper toothrow 5.0 to 6.6 mm (Hall 1981).

Diagnostic Characteristics
Can be distinguished from all but one of the seven Myotis species in Montana by the absence of a fringe of hair around the uropatagium and the absence of a keeled calcar. Can be distinguished from Yuma myotis by the glossy appearance of the dorsal hair and dark brown ear color. (Foresman 2012)

Species Range
Montana Range

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Western Hemisphere Range


Summary of Observations Submitted for Montana
Number of Observations: 1585

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



(Observations spanning multiple months or years are excluded from time charts)

This species is resident year-round in Montana, but may be partially migratory because known winter aggregations are much smaller than the apparent size of summer populations.

Found in a variety of habitats across a large elevation gradient. Commonly forages over water. Summer day roosts include attics, barns, bridges, snags, loose bark, and bat houses. Known maternity roosts in Montana are primarily buildings. Hibernacula include caves and mines.
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
Mostly insects, including gnats, mosquitoes, crane flies, beetles, wasps, and moths. Prey often caught with tip of wing then transferred immediately to mouth.

Males and females mostly segregated during summer, females often in maternity colonies of up to a thousand individuals or more. Can live more than 30 years.

Reproductive Characteristics
Females have one young per year, usually born late June and July.

Maternity colonies are vulnerable to exclusion from buildings; bat boxes attached to the building that formerly housed the colony may provide alternate roosts if properly designed and placed to offer warm temperatures, wide internal temperature gradients, and sufficient width to allow many bats to roost side by side (Brittingham and Williams 2000).

  • Additional ReferencesLegend:   View Online Publication
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    • Adams, R.A. 2003. Bats of the Rocky Mountain West: natural history, ecology and conservation. University Press of Colorado: Boulder, CO. 289 pp.
    • Aldrich, Hugh. 1986. Manoeuverability and ecological segregation in little brown (MYOTIS LUCIFUGUS) and Yuma (M. YUMANENSIS) bats (Chiroptera: Vespertilionidae). Can. J. Zool. 64:1878-1882.
    • Anthony, E. L. P., M. H. Stack, and T. H. Kunz. 1981. Night roosting and the nocturnal time budget of the little brown bat, MYOTIS LUCIFUGUS : effects of reproductive status, prey density, and environmental conditions. Oecologia 51:151-156.
    • Barclay, R. M. R. 1984. Observations on the migration, ecology and behaviour of bats at Delta Marsh, Manitoba. Can. Field-Nat. 98(3): 331-336.
    • Barclay, R. M. R., and K. J. Cash. 1985. A non-commensal maternity roost of the little brown bat (Myotis lucifugus). J. Mammal. 66:783-783.
    • Butts, T. W. 1993. Azure Cave bat surveys, Little Rocky Mountains, Montana, September 1992 and March 1993. Unpublished report for Zortman Mining, Inc. 13 pp.
    • Fenton, M. B. and R. M. Barclay. 1980. MYOTIS LUCIFUGUS . Mamm. Species No. 142. 8 pp.
    • Foresman, K.R. 2001. The wild mammals of Montana. American Society of Mammologists, Special Publication Number 12. Lawrence, KS. 278 pp.
    • Golden Sunlight Mines, Inc., Whitehall, MT., 2000, Golden Sunlight Mines, Inc., Annual Permit Reports.
    • Harris, A. H. 1974. MYOTIS YUMANENSIS in interior southwestern North America with comments on MYOTIS LUCIFUGUS. J. Mammal. 55:589-607.
    • Hendricks, P. 2000. Preliminary bat inventory of caves and abandoned mines on BLM lands, Judith Mountains, Montana. Montana Natural Heritage Program, Helena, Montana. 21 pp.
    • Hendricks, Paul., 1998, Bats surveys of Azure Cave and the Little Rocky Mountains: 1997-1998. November 1998.
    • Herd, R. M. and M. B. Fenton. 1983. An electrophoretic, morphological, and ecological investigation of a putative hybrid zone between MYOTIS LUCIFUGUS and MYOTIS YUMANENSIS (Chiroptera: Vespertilionidae). Can. J. Zool. 61:2029-2050.
    • Humphrey, S. R. and J. B. Cope. 1976. Population ecology of the little brown bat, MYOTIS LUCIFUGUS, in Indiana and north-central Kentucky. Am. Soc. Mamm. Special Publ. (4):1-81.
    • Lunde, Robert E. and A. S. Harestad. 1986. Activity of little brown bats in coastal forests. Northwest Science 60(4):204-207.
    • O'Farrell, M. J. 1999. Blind test for ability to discriminate vocal signatures of the Little Brown Bat Myotis lucifugus and the Indians Bat Myotis sodalis Bat Research News 40:44-48.
    • 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.
    • Parkinson, A. 1979. Morphological variation and hybridization in Myotis yumanensis sociabilis and Myotis lucifugus carrisma. J. Mammal. 60:489-504.
    • Reid, F. 2006. Peterson Field Guide to Mammals of North America, 4th Edition. Houghton Mifflin Company: Boston and New York, 608 pp.
    • Rodhouse, T. J., S. A. Scott, P. C. Ormsbee, and J. A. Zinck. 2008. Field identification of Myotis yumanensis and Myotis lucifugus: a morphological evaluation. Western North American Naturalist 68:437-443.
    • Schowalter, D. B. 1980. Swarming, reproduction, and early hibernation of MYOTIS LUCIFUGUS and M. VOLANS in Alberta, Canada. Journal of Mammalogy 61(2):350-354.
    • Schowalter, D. B. et al. 1979. Life history characteristics of little brown bats (MYOTIS LUCIFUGUS) in Alberta. Canadian Field-Naturalist 93(3):243-251.
    • Waage, Bruce C., 1998, Western Energy Company Rosebud Mine, Colstrip, Montana: 1997 Annual Wildlife Monitoring Report; December 1, 1996 - November 30, 1997 Survey Period. March 23, 1998.
    • Weller, T. J., S. A. Scott, T. J. Rodhouse, P. C. Ormsbee, and J. M. Zinck. 2007. Field identification of the cryptic vespertilionid bats, Myotis lucifugus and M. yumanensis. Acta Chiropterologica 9:133-147.
    • West. E W . and U. Swain 1999. Surface activity and structure of a hydrothermally-heated maternity colony of the Little Brown Bat, Myotic lucifugus, in Alaska Canadian Field-Naturalist 113 425-429.
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Citation for data on this website:
Little Brown Myotis — Myotis lucifugus.  Montana Field Guide.  Montana Natural Heritage Program and Montana Fish, Wildlife and Parks.  Retrieved on May 27, 2016, from