Little Brown Bat (Myotis lucifugus) Al Hicks, NYSDEC

Little Brown Bat (Myotis lucifugus)
Al Hicks, NYSDEC

Class
Mammalia (Mammals)
Family
Vespertilionidae (Evening Bats and Vesper Bats)
State Protection
Not Listed
Not listed or protected by New York State.
Federal Protection
Not Listed
State Conservation Status Rank
S1S2
Critically Imperiled or Imperiled in New York - Especially or very vulnerable to disappearing from New York due to rarity or other factors; typically 20 or fewer populations or locations in New York, very few individuals, very restricted range, few remaining acres (or miles of stream), and/or steep declines. More information is needed to assign either S1 or S2.
Global Conservation Status Rank
G3
Vulnerable globally - At moderate risk of extinction due to rarity or other factors; typically 80 or fewer populations or locations in the world, few individuals, restricted range, few remaining acres (or miles of stream), and/or recent and widespread declines.

Summary

Did you know?

The little brown myotis has been heavily impacted by white-nose syndrome, a disease caused by a fungus that grows on their nose and wing membranes. Prior to 2006, they were the most common bat in the state but became rare throughout most of the state by 2010.

State Ranking Justification

Little brown myotis was very common in New York prior to the appearance of white-nose syndrome in 2006. Only approximately 10% of the statewide numbers remain (NYSDEC 2012).

Short-term Trends

Little brown myotis populations declined approximately 84% in abundance from 2007 to 2015. There was an increase of 900 bats counted in 2012 (totaling 2,400), up from around 1,500 in 2011 during annual hibernacula surveys (NYSDEC 2012). It is not clear whether this represented an actual increase in numbers due to improved survival or fecundity or whether it was caused by movements of bats from other areas. Frick et al. (2010) predicted a 99% chance of extinction of the little brown myotis by 2026.

Long-term Trends

The long-term trends were presumed to be stable or increasing prior to the appearance of white-nose syndrome in 2006 (NYSDEC unpub. data).

Conservation and Management

Conservation Overview

The little brown myotis has suffered significant population declines throughout New York. Although the negative trend in annual survey numbers leveled off between 2011 and 2013, it is too early to say if numbers are stabilizing. White-nose syndrome is a significant and pervasive threat to the persistence of this once common species.

Threats

By far the largest threat to the little brown myotis in New York is white-nose syndrome (WNS) which was first discovered among bats in a cave in Schoharie County, New York in 2006. White-nose syndrome is caused by a fungus Pseudogymnoascus destructans (previously Geomyces destructans) that is often visible on the bats muzzle and wings (Blehert et al. 2009). The fungus may invade hair follicles and cause lesions under the skin (Blehert et al. 2009). Bats wake from hibernation and burn fat reserves that are needed to survive the winter and they become emaciated (Blehert et al. 2009). Extensive damage to their wing membranes and dehydration may also be contributing factors to mortality (U.S. Fish and Wildlife Service 2013). Survival over multiple years after exposure to WNS and healing of wing damage and infection has been documented in some individual little brown myotis at Ft. Drum, New York (Dobony et al. 2011).
Bats may be particularly sensitive to environmental toxins including those found in herbicides and pesticides. Elevated levels of persistent organic pollutants including especially PCBs, DDT, Chlordanes, and PBDEs have been found in little brown bats, in the Hudson River valley in New York (Kannan et al. 2010). The levels found in the bats were only 1 to 3 times less than lethal concentrations reported from previous studies (Kannan et al. 2010). Bats are highly susceptible to DDT residue and this chemical was widely used as a pesticide to control bat infestations in houses in the 1940s (USGS 2013). It was widely used as an agricultural pesticide in the 1950s and 60s until its agricultural use was banned in 1972. Since DDT is highly persistent (soil half-life is 2-15 years, aquatic half-life is about 150 years) (NPIC 1999), it can pose a threat to bats when there is exposure to trace residues remaining in the environment (USGS 2013). Extensive applications of insecticides and some bio control methods, such as Btk, could also pose an indirect risk to bats by reducing availability of insect prey.  Past long-term declines of the little brown myotis may be partly attributed to the use of pesticides (direct and indirect application) and to control measures targeting maternity colonies which may frequently occur in houses (Fenton and Barclay 1980).
If proper precautions are not used, cavers and researchers entering hibernacula may cause disturbance rousing bat colonies or can transport the fungus that causes WNS on their clothing (NatureServe 2013). Other potential threats may include climate change, commercial cave development, flooding and hibernacula collapse; habitat loss and fragmentation from development, hydraulic fracturing, and construction of new wind facilities; and direct mortality from wind facilities (U.S. Fish and Wildlife Service 2013).

Conservation Strategies and Management Practices

Gating mines and caves can prevent human entry allowing the bats unobstructed access.  Following proper specifications and monitoring bat populations before and after gate installation are important, however, as gating can affect the airflow and temperature in the cave, making areas of the cave uninhabitable for certain species (U.S. Fish and Wildlife Service 2013). Buildup of debris at cave entrance gates can also have the same effect (U.S. Fish and Wildlife Service 2013).

Development and Mitigation Considerations

Retaining snags and dying trees can provide summer roosting habitat for the little brown myotis.

Research Needs

Research is needed to document summer roost locations in New York and to determine areas of the state with the highest local abundances. Ongoing winter hibernacula surveys are needed to monitor trends of the remaining populations.

Habitat

Habitat

The little brown myotis uses a variety of forest types and they are somewhat of a habitat generalist. They occur in deciduous, mixed, and coniferous forest stands. At a landscape-scale in New York, they are associated with habitats that have a higher composition of wetlands and shrub cover and lower amounts of agriculture (NYNHP unpub. data). They are known to occur at elevations up to 657 m (2,155 ft) in the Adirondacks during summer (Saunders 1988).

Little brown myotis frequently forage over wetlands and open water (Fenton and Barclay 1980; Broders et al. 2006). One study in Massachusetts found they used a variety of foraging habitats including an open-canopied reservoir, large ponds, and beaver meadows and closed canopy vernal pools; uplands and streams were used less often (Fenton and Barclay 1980).
During summer little brown myotis roosts in trees, buildings, under rocks, in piles of wood, and less frequently in caves (Fenton and Barclay 1980). Maternity roosts occur in hollow trees or in buildings that tend to have southwesterly exposure which creates warmer roost temperatures (Fenton and Barclay 1980).

In winter, little brown myotis hibernate in caves and mines in areas with high humidity and temperatures that are typically above freezing (Fenton and Barclay 1980). Their presence was positively related to mine entrance width and height in West Virginia (Johnson et al. 2006).

Associated Ecological Communities

  • Allegheny oak forest (guide)
    A hardwood forest that occurs on well-drained sites in the unglaciated portion of southwestern New York. This is a forest of mixed oaks with a diverse canopy and richer ground flora than other oak communities in the state.
  • Appalachian oak-hickory forest (guide)
    A hardwood forest that occurs on well-drained sites, usually on ridgetops, upper slopes, or south- and west-facing slopes. The soils are usually loams or sandy loams. This is a broadly defined forest community with several regional and edaphic variants. The dominant trees include red oak, white oak, and/or black oak. Mixed with the oaks, usually at lower densities, are pignut, shagbark, and/or sweet pignut hickory.
  • Appalachian oak-pine forest (guide)
    A mixed forest that occurs on sandy soils, sandy ravines in pine barrens, or on slopes with rocky soils that are well-drained. The canopy is dominated by a mixture of oaks and pines.
  • Beech-maple mesic forest (guide)
    A hardwood forest with sugar maple and American beech codominant. This is a broadly defined community type with several variants. These forests occur on moist, well-drained, usually acid soils. Common associates are yellow birch, white ash, hop hornbeam, and red maple.
  • Chestnut oak forest (guide)
    A hardwood forest that occurs on well-drained sites in glaciated portions of the Appalachians, and on the coastal plain. This forest is similar to the Allegheny oak forest; it is distinguished by fewer canopy dominants and a less diverse shrublayer and groundlayer flora. Dominant trees are typically chestnut oak and red oak.
  • Hemlock-northern hardwood forest (guide)
    A mixed forest that typically occurs on middle to lower slopes of ravines, on cool, mid-elevation slopes, and on moist, well-drained sites at the margins of swamps. Eastern hemlock is present and is often the most abundant tree in the forest.
  • Limestone woodland (guide)
    A woodland that occurs on shallow soils over limestone bedrock in non-alvar settings, and usually includes numerous rock outcrops. There are usually several codominant trees, although one species may become dominant in any one stand.
  • Maple-basswood rich mesic forest (guide)
    A species rich hardwood forest that typically occurs on well-drained, moist soils of circumneutral pH. Rich herbs are predominant in the ground layer and are usually correlated with calcareous bedrock, although bedrock does not have to be exposed. The dominant trees are sugar maple, basswood, and white ash.
  • Mine/artificial cave community
    The biota of an abandoned mine or artificial underground excavation. Abandoned mines that are deep enough to maintain stable winter temperatures are important bat hibernacula. Mines, like natural caves, may be terrestrial or aquatic. Wells are also included here.
  • Oak openings (guide)
    A grass-savanna community that occurs on well-drained soils. In New York, these savannas originally occurred as openings within extensive oak-hickory forests. The best remnants occur on dolomite knobs.
  • Oak-tulip tree forest (guide)
    A hardwood forest that occurs on moist, well-drained sites in southeastern New York. The dominant trees include a mixture of five or more of the following: red oak, tulip tree, American beech, black birch, red maple, scarlet oak, black oak, and white oak.
  • Pine-northern hardwood forest (guide)
    A mixed forest that occurs on gravelly outwash plains, delta sands, eskers, and dry lake sands in the Adirondacks. The dominant trees are white pine and red pine.
  • Pitch pine-oak forest (guide)
    A mixed forest that typically occurs on well-drained, sandy soils of glacial outwash plains or moraines; it also occurs on thin, rocky soils of ridgetops. The dominant trees are pitch pine mixed with one or more of the following oaks: scarlet oak, white oak, red oak, or black oak.
  • Rich mesophytic forest (guide)
    A hardwood or mixed forest that resembles the mixed mesophytic forests of the Allegheny Plateau south of New York but is less diverse. It occurs on rich, fine-textured, well-drained soils that are favorable for the dominance of a wide variety of tree species. A canopy with a relatively large number of codominant trees characterizes this forest. Canopy codominants include five or more of the following species: red oak, red maple, white ash, American beech, sugar maple, black cherry, cucumber tree, and black birch.
  • Shallow emergent marsh (guide)
    A marsh meadow community that occurs on soils that are permanently saturated and seasonally flooded. This marsh is better drained than a deep emergent marsh; water depths may range from 6 in to 3.3 ft (15 cm to 1 m) during flood stages, but the water level usually drops by mid to late summer and the soil is exposed during an average year.
  • Spruce-northern hardwood forest (guide)
    A mixed forest that occurs on lower mountain slopes and upper margins of flats on glacial till. This is a broadly defined community with several variants; it is one of the most common forest types in the Adirondacks. Codominant trees are red spruce, sugar maple, American beech, yellow birch, and red maple, with scattered balsam fir.
  • Terrestrial cave community
    The terrestrial community of a cave with bedrock walls, including the biota of both solution caves (in limestone) and tectonic caves. Temperatures are stable in deep caves. Small or shallow caves may have a temperature gradient ranging from cold (below freezing) to cool (up to 50 degrees F). Although many caves have ice on the cave floor in winter, the ceiling is warm enough for a bat hibernaculum.
  • Vernal pool (guide)
    An aquatic community of one or more intermittently ponded, small, shallow depressions typically within an upland forest. Vernal pools are typically flooded in spring or after a heavy rainfall, but are usually dry during summer. Substrate is typically dense leaf litter over hydric soils. Vernal pools typically occupy a confined basin (i.e., a standing waterbody without a flowing outlet), but may have an intermittent stream flowing out of it during high water. This community includes a diverse group of invertebrates and amphibians that depend upon temporary pools as breeding habitat. These include amphibians, reptiles, crustaceans, mollusks, annelids, and insects.

Associated Species

  • Big Brown Bat (Eptesicus fuscus)
  • Eastern Small-footed Myotis (Myotis leibii) (guide)
  • Northern Long-eared Bat (Myotis septentrionalis) (guide)
  • Indiana Bat (Myotis sodalis) (guide)
  • Tri-colored Bat (Perimyotis subflavus) (guide)

Range

New York State Distribution

The little brown myotis appears to still occur throughout most of New York as of 2013 (NYSDEC unpublished data). However, it is unclear whether die-offs associated with white-nose syndrome may have reduced the summer distribution in some areas of the state.

Global Distribution

The distribution of the little brown myotis is widespread in North America spanning from southern Alaska and Canada through most of the contiguous United States, though the species is generally absent from the southern Great Plains region (NatureServe 2013). Southwestern populations formerly assigned to this species have now been assigned to M. occultus (Piaggio et al. 2002; NatureServe 2013). The southwestern range boundary includes southern California (except extreme southeast), Nevada, northern Utah, northern Colorado, and perhaps northeastern New Mexico (Piaggio et al. 2002). The high density of caves in the Appalachian Mountain range and eastern Midwest (Culver et al. 1999) likely support much larger populations of this species than in other parts in the species' range (NatureServe 2013). The largest known colonies of little brown myotis are in the northeastern and mid-western United States, with the northeastern population considered the core range of the species (Kunz and Reichard 2010). Smaller populations occur in the southern and western United States (Davis and Hitchcock 1965; NatureServe 2013).

Identification Comments

General Description

The little brown myotis has glossy fur that may range from golden brown to cinnamon brown in color and buffy to pale gray below (Fenton and Barclay 1980; Hall 1981). When pressed forward, their ears reach approximately to their nostrils and their tragus, the fleshy protuberance in the outer ear, is approximately half the height of their ear (Fenton and Barclay 1980; Hall 1981). They typically weigh 7-14 grams, with females slightly larger than males (Harvey et al. 2011).

Identifying Characteristics

The little brown myotis appears very similar to the Indiana bat (Myotis sodalis) but they have longer hairs on their feet that extend beyond their toes and they lack a keeled calcar, the spur of cartilage that occurs on the ankle joint (Fenton and Barclay 1980; Hall 1981:198). Northern bats (Myotis septentrionalis) have longer ears that extend beyond the nose when pressed forward, and a sharply pointed tragus, (Fenton and Barclay 1980). Little brown myotis are difficult to distinguish from other Myotis species in flight.

Best Life Stage for Proper Identification

Adults may be easiest to identify.

Behavior

The little brown myotis, like most bats, breed in the late summer to early fall; they swarm and mate near the cave or mine entrance. Breeding during swarming may result in mixture of genetics among groups from different areas since bats may travel to swarm near a cave or mine that they do not select to hibernate in over the winter (Carmody et al. 1971; Fenton and Barclay 1980). Ovulation occurs in the spring which coincides with emergence from winter hibernacula. Females give birth to one young approximately 50-60 days later (Wimsatt 1945; Fenton and Barclay 1980). Young are weaned and can fly after 21-28 days (Saunders 1988).

Little brown myotis are nocturnal with periods of heightened activity at pre-dawn and dusk. They maintain large home ranges to meet their daily energy and resting needs. Mean foraging ranges were 515 ha in Mississippi (Bergeson et al. 2013). During summer, females form large maternity colonies, while males and non-reproductive females may roost individually or in small groups and may use torpor to balance energy needs (Fenton and Barclay 1980). During winter, both genders roost together in large groups.

Communications for the little brown myotis are known to include echolocations (high frequency sounds used to communicate, navigate, and locate prey), vocalizations termed "honking" that are produced prior to an aerial-collision, isolation calls by young that aid in mother-young recognition, and chemical signals produced in the nasal glands that play a primary role in communication (Saunders 1988).

Little brown myotis are short-distance migrants but they may travel several hundred kilometers between hibernacula and summer colonies (Davis and Hitchcock 1965; Griffin 1970) which is farther than for some other myotis species. In Manitoba and northwestern Ontario, migration distances ranged from 10 to 647 km (Norquay et al. 2013) and in New York and New England up to 277 km (Davis and Hitchcock 1965). Site fidelity to summer colonies and winter hibernacula is common (Norquay et al. 2013). However for individuals that do relocate between hibernacula, females may be more likely to switch sites than males (Norquay et al. 2013).

Diet

The little brown myotis is an insectivore that consumes a wide variety of insect orders. There are no known studies on their specific diet in New York, however, there are several from the eastern U.S. and they suggest regional differences in the variety and types of prey consumed. Coleoptera, Lepidoptera, and Diptera are important in the diets of little brown myotis across New England, with other groups consumed opportunistically (Moosman Jr et al. 2012). They are also known to prey heavily on the adult stages of aquatic invertebrates such as chironomids in northern parts of their range (Belwood and Fenton 1976; Anthony and Kunz 1977; Fenton and Barclay 1980). In WV, little brown bats consumed 10-22% each in descending order of importance of Lepidoptera, Diptera, Tricoptera, Coleoptera, Hymenoptera, Homoptera, and lesser amounts of Hemiptera (Carter et al. 2003). In Illinois, little browns consumed similar families, however Hymenoptera and Hemiptera were absent from their diet, and Aranea was added (Feldhamer et al. 2009).

Best Time to See

The best time to see this species is from May through August in the early evening; however, it may be difficult to distinguish it from other Myotis species.

  • Present
  • Active
  • Reproducing

The time of year you would expect to find Little Brown Bat present, active, and reproducing in New York.

Similar Species

  • Northern Long-eared Bat (Myotis septentrionalis) (guide)
  • Indiana Bat (Myotis sodalis) (guide)
  • Tri-colored Bat (Perimyotis subflavus) (guide)

Little Brown Bat Images

Taxonomy

Little Brown Bat
Myotis lucifugus (Le Conte, 1831)

  • Kingdom Animalia
    • Phylum Craniata
      • Class Mammalia (Mammals)
        • Order Chiroptera (Bats)
          • Family Vespertilionidae (Evening Bats and Vesper Bats)

Additional Resources

References

Anthony, E. L. and T. H. Kunz. 1977. Feeding strategies of the little brown bat, Myotis lucifugus, in southern New Hampshire. Ecology 58:775-786.

Belwood, J. J. and M. B. Fenton. 1976. Variation in the diet of Myotis lucifugus (Chiroptera: Vespertilionidae). Canadian Journal of Zoology 54:1674-1678.

Bergeson, S. M., T. C. Carter and M. D. Whitby. 2013. Partitioning of foraging resources between sympatric Indiana and little brown bats. Journal of Mammalogy 94:1311-1320.

Blehert, D. S., A. C. Hicks, M. Behr, C. U. Meteyer, B. M. Berlowski-Zier, E. L. Buckles, et al. 2009. Bat white-nose syndrome: an emerging fungal pathogen? Science 323:227.

Broders, H. G., G. J. Forbes, S. Woodley and I. D. Thompson. 2006. Range Extent and Stand Selection for Roosting and Foraging in Forest-Dwelling Northern Long-Eared Bats and Little Brown Bats in the Greater Fundy Ecosystem, New Brunswick. Journal of Wildlife Management 70:1174-1184.

Carmody, G. R., M. B. Fenton and D. S. K. Lee. 1971. Variation of body weight and proteins in three Ontario populations of hibernating Myotis lucifugus lucifugus (LeConte)(Chiroptera: Vespertilionidae). Canadian Journal of Zoology 49:1535-1540.

Carter, T. C., M. A. Menzel, S. F. Owen, J. W. Edwards, J. M. Menzel and W. M. Ford. 2003. Food habits of seven species of bats in the Allegheny Plateau and ridge and valley of West Virginia. Northeastern Naturalist 10:83-88.

Culver, D. C., H. H. Hobbs III, M. C. Christman and L. L. Master. 1999. Distribution map of caves and cave animals in the United States. Journal of Cave and Karst Studies 61:139-140.

Davis, W. H. and H. B. Hitchcock. 1965. Biology and Migration of the Bat, Myotis lucifugus, in New England. Journal of Mammalogy 46:296-313.

Dobony, C. A., A. C. Hicks, K. E. Langwig, R. I. von Linden, J. C. Okoniewski and R. E. Rainbolt. 2011. Little brown myotis persist despite exposure to white-nose syndrome. Journal of Fish and Wildlife Management 2:190-195.

Feldhamer, G. A., T. C. Carter and J. O. Whitaker. 2009. Prey Consumed by Eight Species of Insectivorous Bats from Southern Illinois. The American Midland Naturalist 162:43-51.

Fenton, M. B. and R. M. Barclay. 1980. Myotis lucifugus. Mammalian species:1-8.

Frick, W. F., J. F. Pollock, A. C. Hicks, K. E. Langwig, D. S. Reynolds, G. G. Turner, et al. 2010. An Emerging Disease Causes Regional Population Collapse of a Common North American Bat Species. Science 329:679-682.

Griffin, D. R. 1970. Migrations and homing in bats. Pp. 233-264 in. Academic Press, New York.

Hall, E. R. 1981. The Mammals of North America. John Willey & Sons, New York.

Harvey, M. J., J. S. Altenbach and T. L. Best. 2011. Bats of the United States and Canada. JHU Press.

Johnson, J. B., P. B. Wood, J. W. Edwards and McCleery. 2006. Are External Mine Entrance Characteristics Related to Bat Use? Wildlife Society Bulletin 34:1368-1375.

Kannan, K., S. H. Yun, R. J. Rudd and M. Behr. 2010. High concentrations of persistent organic pollutants including PCBs, DDT, PBDEs and PFOS in little brown bats with white-nose syndrome in New York, USA. Chemosphere 80:613-618.

Kunz, T. H. and J. D. Reichard. 2010. Status review of the little brown myotis (Myotis lucifugus) and determination that immediate listing under the Endangered Species Act is scientifically and legally warranted. Boston Univ., Boston, MA:31.

Moosman Jr, P. R., H. H. Thomas and J. P. Veilleux. 2012. Diet of the widespread insectivorous bats Eptesicus fuscus and Myotis lucifugus relative to climate and richness of bat communities. Journal of Mammalogy 93:491-496.

NPIC [online]. 1999. National Pesticide Information Center DDT general fact sheet. <http://npic.orst.edu/factsheets/ddtgen.pdf> (19 December 2013).

NYSDEC [online]. 2012. DEC Reports: 2012 Winter Bat Survey Results. NY Department of Environmental Conservation. <http://www.dec.ny.gov/press/81767.html> (3 February 2014).

NatureServe [online]. 2013. NatureServe Explorer: an online encyclopedia of life [web application] Version 7.1. .

New York Natural Heritage Program. 2019. New York Natural Heritage Program Databases. Albany, NY.

Norquay, K. J. O., F. Martinez-Nuñez, J. E. Dubois, K. M. Monson and C. K. R. Willis. 2013. Long-distance movements of little brown bats (Myotis lucifugus). Journal of Mammalogy 94:506-515.

Piaggio, A. J., E. W. Valdez, M. A. Bogan and G. S. Spicer. 2002. Systematics of Myotis occultus (Chiroptera: Vespertilionidae) inferred from sequences of two mitochondrial genes. Journal of Mammalogy 83:386-395.

Saunders, D. A. [online]. 1988. Little Brown Bat (Myotis lucifugus). P. 216 in Adirondack Mammals. State University of New York, College of Environmental Science and Forestry.

U.S. Fish and Wildlife Service. 2013. 12-Month finding on a petition to list the eastern small-footed bat and the northern long-eared bat as threatened or endangered; Listing the northern long-eared bat as an endangered species; Proposed rule. Vol. 78 No. 191, Department of the Interior.

USGS [online]. 2013. House Bat Management: Bat Toxicants. <http://www.npwrc.usgs.gov/resource/mammals/housebat/battox.htm> (19 December 2013).

Wimsatt, W. A. 1945. Notes on breeding behavior, pregnancy, and parturition in some vespertilionid bats of the eastern United States. Journal of Mammalogy:23-33.

About This Guide

This guide was authored by: Kelly A. Perkins

Information for this guide was last updated on: March 25, 2014

Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Myotis lucifugus. Available from: https://guides.nynhp.org/little-brown-bat/. Accessed September 23, 2019.

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