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Montana Animal Field Guide

Montana Field Guides

Spotted Bat - Euderma maculatum

Species of Concern

Global Rank: G4
State Rank: S3

Agency Status


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Copyright Jeff Rice, all rights reserved. Audio file courtesy of the Acoustic Atlas at Montana State University (
General Description
Spotted Bats have huge pink ears (37 to 50 millimeters long), the dorsum is blackish with a large white spot on each shoulder and on the rump, and white patches at the posterior base of each ear. Total length is 107 to 115 millimeters, forearm length is 48 to 51 millimeters, and weight is 16 to 20 grams. The greatest length of the skull is 18.4 to 19.0 millimeters (small sample). The supraorbital region of the skull is sharply ridged, but a median sagittal crest is absent; 34 teeth are present (Watkins 1977). The newborn young lack any indication of having the adult color pattern (Van Zyll de Jong 1985). Four hours after birth, a male weighed 4 grams and measured 59 millimeters in length; tail length was 20 millimeters, hind foot 11 millimeters, ear 12 millimeters, and forearm 21 millimeters.

Diagnostic Characteristics
Spotted Bats differ from other bats in Montana by the unique patterning of the fur and the extremely large ears. Their echolocation calls (an insect-like clicking) are audible to the unaided human ear.

Species Range
Montana Range

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Western Hemisphere Range


Summary of Observations Submitted for Montana
Number of Observations: 143

(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)

Little information is available. The species has not been reported during winter in Montana.

Possibly some Spotted Bats migrate south for the winter, but there is no direct evidence of migratory movements. At least for lower elevation locations, Spotted Bats appear not to migrate (O'Farrell 1981). Possibly they occupy coniferous stands in summer and migrate to lower elevations in late summer/early fall (Barbour and Davis 1969, Berna 1990). There are no winter records for British Columbia (Nagorsen and Brigham 1993), but mid- or late October records from here as well as Wyoming (Priday and Luce 1999) suggest that some individuals may over-winter without making an extensive migratory movement.

Spotted Bats have been encountered or detected most often in open arid habitats dominated by Utah juniper (Juniperus osteosperma) and sagebrush (Artemisia tridentata and A. nova), sometimes intermixed with limber pine or Douglas-fir, or in grassy meadows in ponderosa pine savannah (Fenton et al. 1987, Worthington 1991a, Hendricks and Carlson 2001). Cliffs, rocky outcrops, and water are other attributes of sites where Spotted Bats have been found (Foresman 2012), typical for the global range. Spotted Bats have been captured foraging over an isolated pond within a few kilometers of huge limestone escarpments in the Big Horn Canyon National Recreation Area, Carbon County (Worthington 1991a, 1991b), and the first record for the state was of an individual that flew in an open window at a private residence in Billings, Yellowstone County (Nicholson 1950). Roost habitats and sites have not been documented in Montana.

In other areas, Spotted Bats have been detected at water sources and in meadow openings, often with large cliffs nearby (Leonard and Fenton 1983, Storz 1995, Perry et al. 1997, Rabe et al. 1998, Gitzen et al. 2001).

Spotted Bats roost in caves, and in cracks and crevices in cliffs and canyons, with which this species is consistently associated; it can crawl with ease on both horizontal and vertical surfaces (Snow 1974, Van Zyll de Jong 1985). In British Columbia, individuals used the same roost each night during May through July, but not after early August (Wai-Ping and Fenton 1989). Winter habitat is poorly documented. A possible explanation for the early paucity of collections in natural situations is the Spotted Bat's narrow habitat tolerance (Handley 1959, Snow 1974).
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
This species is insectivorous. Apparently Spotted Bats feed primarily on noctuid moths, and sometimes beetles (Barbour and Davis 1969, Schmidly 1991, Van Zyll de Jong 1985). In Texas, the contents of 15 stomachs combined were 97.1% moths by volume, 2.7% beetles (Scarabidae), and 0.2% other insects (Easterla and Whitaker 1972); volumes in two of the stomachs were 10% and 30% beetles. In British Columbia, foraging took place 5 to 15 meters above ground (Wai-Ping and Fenton 1989). In southeastern Utah, Spotted Bats fed on small insects within 2 meters of the ground. Sometimes insects are captured on the ground (Poche and Bailie 1974), though this has been disputed. In Colorado, individuals foraged at heights above 10 meters (Navo et al. 1992). Timing and routes of foraging may sometimes be quite predictable and consistent (Leonard and Fenton 1983, Van Zyll de Jong 1985, Wai-Ping and Fenton 1989, Rabe et al. 1998). Food habits and foraging ecology in Montana have not been reported or studied.

The Spotted Bat hunts alone, and at least sometimes appears to maintain exclusive foraging areas (Leonard and Fenton 1983), although in other cases individual foraging areas overlap (Wai-Ping and Fenton 1989). Neighboring bats show evidence of mutual avoidance and have been observed to turn away when encountering one another near the boundaries of their hunting areas.

The Spotted Bat has been reported active from early April to late October in British Columbia (Nagorsen and Brigham 1993), early June to mid-October in Wyoming (Priday and Luce 1999), and late March to late October in Nevada (Geluso 2000). The full extent of the active period in Montana is not known; records extend from late June to early August (Nicholson 1950, Worthington 1991a, Hendricks and Carlson 2001, Hendricks and Carlson personal observation).

Apparently Spotted Bats are relatively solitary but may hibernate in small clusters (Easterla 1973); roosts and hibernacula are usually located in cliffs, and to some degree caves. Individuals in British Columbia roost solitarily during the active season (Leonard and Fenton 1983). Home ranges may be relatively large. Foraging 6 to 10 kilometers from the day roost each night was documented in British Columbia (Wai-Ping and Fenton 1989); a lactating female in northern Arizona moved 38.5 kilometers between the day and night roosts, and a male flew 32 kilometers to a day roost (Rabe et al. 1998).

The echolocation call is loud and high-pitched; the fundamental frequency sweeps from 12 to 6 kHz and is a double or single steep frequency modulated pulse. The call is repeated at a rate of 2 to 6 per second and can clearly be heard by the unaided human ear at distances up to 250 meters (Van Zyll de Jong 1985), a very useful feature for determining the presence of these bats during inventory work.

Normal predators have not been reported, but recently released individuals in early morning have been attacked by American Kestrel, Peregrine Falcon, and Red-tailed Hawk (Easterla 1973, Watkins 1977). Sources of mortality in Montana, other than human collection, have not been reported or studied.

Reproductive Characteristics
Little information is available on Spotted Bat reproduction. A lactating female and a juvenile female were captured in mid-July 1990 at the same pond in Carbon County (Worthington 1991a).

In the southwestern states, young are born in late May or early June (Easterla 1973, Watkins 1977); time of birth in the north may be somewhat later (Van Zyll de Jong 1985). A female in southwestern Texas gave birth to a single young on June 11 (Easterla 1973). A pregnant Spotted Bat was collected in British Columbia on June 16. Lactating females have been captured from late June to early July in New Mexico (Findley and Jones 1965, Perry et al. 1997), from mid- to late July in Nevada (Geluso 2000), and mid-August in Utah (Barbour and Davis 1969). Post-lactating females were captured on August 28 and 29 in extreme northern Wyoming (Priday and Luce 1999). All evidence points to the birth of a single young (Easterla 1973, Watkins 1977), which remains with the mother the first few days even during flight. In Texas, testis size was greatest (10 x 3 millimeters, 11 x 3 millimeters) from late June through mid-July (Easterla 1973). Mating may take place in late summer in the south, and later in the north (Nagorsen and Brigham 1993), but reproductive data from across the range are limited.

Typical population age structure and longevity are unknown, but recruitment is expected to be low, given the low birth rate. Age at maturity is also not known, but females probably give birth in their second year.

Spotted Bats have persisted for over 50 years in the general area of the state where they were first discovered (Nicholson 1950, Hendricks and Carlson 2001). This is encouraging, given that essentially nothing is known of abundance, reproductive biology, habitat requirements, movements, and roost site selection in Montana, nor have the potential threats to this bat been identified. The lack of information on this species makes development and implementation of any effective management activity tenuous. Fortunately, the roosting habitat most favored by this bat (cliffs) provides it protection from many kinds of disturbance. Nevertheless, any roosts that are discovered should be protected and monitored. Studies to fill the gaps in our knowledge about this bat in Montana are needed, especially surveys throughout the state in appropriate habitats and landscapes to determine the full extent of its distribution. The audible calls make a survey much easier to conduct (Pierson and Rainey 1998), as no special skill is needed, other than familiarity with the calls and knowledge of the habitats likely to support Spotted Bats. The most immediate management action that can benefit this species (and other bat species as well) is protection of water sources in arid regions where this bat is present and water sources are limited. Open waste sumps, and similar hazardous standing water bodies associated with oil and gas fields, could present a significant hazard to Spotted Bats and other bat species as these energy resources are exploited.

  • Literature Cited AboveLegend:   View Online Publication
    • Barbour, R. W. and W. H. Davis. 1969. Bats of America. The University of Kentucky Press, Lexington, Kentucky. 286 pp.
    • Berna, H. J. 1990. Seven bat species from the Kaibab Plateau, Arizona, with a new record of Euderma maculatum. Southwestern Naturalist 35:354-356.
    • 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.
    • Easterla, D. A. and J. O. Whitaker, Jr. 1972. Food habits of some bats from Big Bend National Park, Texas. Journal of Mammalogy 53:887-890.
    • Fenton, M. B., D. C. Tennant, and J. Wyszeck. 1987. Using echolocation calls to measure distribution of bats: the case of Euderma maculatum. Journal of Mammalogy 68:142-144.
    • Findley, J. S. and C. Jones. 1965. Comments on spotted bats. Journal of Mammalogy 46:679-680.
    • Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
    • Geluso, K. 2000. Distribution of the spotted bat (Euderma maculatum) in Nevada, including notes on reproduction. Southwestern Naturalist 45:347-352.
    • Gitzen, R. A., S. D. West, and J. A. Baumgardt. 2001. A record of the spotted bat (Euderma maculatum) from Crescent Bar, Washington. Northwestern Naturalist 82:28-30.
    • Handley, C. O., Jr. 1959. A revision of American bats of the genera Euderma and Plecotus. Proceedings of the U.S. National Museum 110:95-246.
    • Hendricks, P. and J. C. Carlson. 2001. Bat use of abandoned mines in the Pryor Mountains. Report to the Montana Department of Environmental Quality, Mine Waste Cleanup Bureau. Montana Natural Heritage Program. Helena, Montana. 8 pp.
    • Leonard, M. L. and M. B. Fenton. 1983. Habitat use by spotted bats (Euderma maculatum, Chiroptera: Vespertilionidae): roosting and foraging behavior. Canadian Journal of Zoology 61:1487-1491.
    • Nagorsen, D. W. and R. M. Brigham. 1993. Bats of British Columbia. Volume I. The Mammals of British Columbia. UBC Press, Vancouver. 164 pp.
    • Navo, K. W., J. A. Gore, and G. T. Skiba. 1992. Observations on the spotted bat, Euderma maculatum, in northwestern Colorado. Journal of Mammalogy 73:547-551.
    • Nicholson, A. J. 1950. A record of the spotted bat (Euderma maculatum) for Montana. Journal of Mammalogy 31(2):197.
    • O'Farrell, M. J. 1981. Status report on the spotted bat, Euderma maculatum. Westech Services, Inc., Las Vegas, NV. U.S. Fish and Wildlife Service Report Number 810400.
    • Perry, T. W., P. M. Cryan, S. R. Davenport, and M. A. Bogan. 1997. New locality for Euderma maculatum (Chiroptera: Vespertilionidae) in New Mexico. Southwestern Naturalist 42:99-101.
    • Pierson, E. D. and W. E. Rainey. 1998. Distribution of the spotted bat, Euderma maculatum, in California. Journal of Mammalogy 79:1296-1305.
    • Poche, R. M. and G. L. Bailie. 1974. Notes on the spotted bat (Euderma maculatum) from southwest Utah. Great Basin Naturalist 34:254-256.
    • Priday, J. and B. Luce. 1999. New distributional records for spotted bat (Euderma maculatum) in Wyoming. Great Basin Naturalist 59:97-101.
    • Rabe, M. J., M. S. Siders, C. R. Miller, and T. K. Snow. 1998. Long foraging distance for a spotted bat (Euderma maculatum) in northern Arizona. Southwestern Naturalist 43:266-269.
    • Schmidly, D. J. 1991. The bats of Texas. Texas A and M University Press, College Station. 188 pp.
    • Snow, C. 1974. Spotted bat, Euderma maculatum. Habitat management services for endangered species: report number 4. Bureau of Land Management, U.S. Department of the Interior, and Denver Service Center, Denver, CO.
    • Storz, J. F. 1995. Local distribution and foraging behavior of the spotted bat (Euderma maculatum) in northwestern Colorado and adjacent Utah. Great Basin Naturalist 55:78-83.
    • Van Zyll de Jong, C.G. 1985. Handbook of Canadian mammals. Volume 2. Bats. National Museums of Canada, Ottawa. 212 pp.
    • Wai-Ping, V. and M. B. Fenton. 1989. Ecology of spotted bat (Euderma maculatum) roosting and foraging. Journal of Mammalogy 70:617-622.
    • Watkins, L.C. 1977. Euderma maculatum. Mammalian Species 77:1-4.
    • Worthington, D. J. 1991. Abundance, distribution, and sexual segregation of bats in the Pryor Mountains of south central Montana. M.A. Thesis. University of Montana, Missoula, Montana. 41 pp.
    • Worthington, D. J. 1991. Abundance and distribution of bats in the Pryor Mountains of south central Montana and north eastern Wyoming. Montana Natural Heritage Program, Helena, MT.
  • 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.
    • Bogdanowicz, W., S. Kasper, and R. D. Owen. 1998. Phylogeny of plecotine bats: reevaluation of morphological and chromosomal data. Journal of Mammalogy 79:78-90.
    • Fenton, M.B., C.C. Tennant, and J. Wyszecki. 1983. A survey of the distribution of Euderma maculatum throughout its known range in the United States and Canada by monitoring its audible echolocation calls. U.S. Fish and Wildlife Service, Albuquerque. 20pp.
    • Fenton, M.B., D.C. Tennant, and J. Wyszecki. 1987. Using Echolocation Calls to Measure the Distribution of Bats: The Case of Euderma maculatum. Journal of Mammalogy. 68 (1): 142-144.
    • 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 pp.
    • Frost, D. R., and R. M. Timm. 1992. Phylogeny of plecotine bats (Chiroptera: "Vespertilionidae"): proposal of a logically consistent taxonomy. Am. Mus. Novitates 3034:1-16.
    • Genter, D. L. 1988. Status and distribution of the spotted bat (EUDERMA MACULATUM) and western big-eared bat (PLECOTUS TOWNSENDII) in the Custer National Forest, MT. Unpublished report to the U.S.D.A. Forest Service. Montana Natural Heritage Program, Helena, MT.
    • Hoofer, S. R., and R. A. Van Den Bussche. 2001. Phylogenetic relationships of plecotine bats and allies based on mitochondrial ribosomal sequences. Journal of Mammalogy 82:131-137.
    • Mickey, A. B. 1961. Record of the spotted bat from Wyoming. Journal of Mammalogy 42(3):401-402.
    • Qumsiyeh, M. B., and J. W. Bickham. 1993. Chromosomes and relationships of long-eared bats of the genera PLECOTUS and OTONYCTERIS. J. Mamm. 74:376-382.
    • Reid, F. 2006. Peterson Field Guide to Mammals of North America, 4th Edition. Houghton Mifflin Company: Boston and New York, 608 pp.
    • Reynolds, R. P. 1981. Elevational record for EUDERMA MACULATUM (Chiroptera: Vespertilionidae). The Southwestern Naturalist 26(1):91-92.
    • Thompson, L.S. 1982. Distribution of Montana amphibians, reptiles, and mammals. Bozeman: Montana Audubon Council. 24 pp.
    • Tumlison, R., and M. E. Douglas. 1992. Parsimony analysis and the phylogeny of the plecotine bats (Chiroptera: Vespertilionidae). J. Mamm. 73:276-285.
    • Verts, B. J. and L. N. Carraway. 1998. Land mammals of Oregon. University of California Press, Berkeley. xvi + 668 pp.
    • Woodsworth, G. C., G. P. Bell, and M. B. Fenton. 1981. Observations of the echolocation, feeding behaviour, and habitat use of EUDERMA MACULATUM (Chiroptera: Vespertilionidae) in southcentral British Columbia. Canadian J. Zool. 59:1099-1102.
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Citation for data on this website:
Spotted Bat — Euderma maculatum.  Montana Field Guide.  Montana Natural Heritage Program and Montana Fish, Wildlife and Parks.  Retrieved on May 31, 2016, from