Plants and Animals

Myotis lucifugus Little brown bat

Key Characteristics

Coloring of little brown bats ranges from sandy brown to olive brown and they are lighter on the underside. Their ear membranes are hairless and black. Adult body mass ranges from between 5.5 to 11.0 grams and these bats are lightest in the spring when they emerge from hibernation. Forearm length ranges from 3.5 to 4.1 cm with a total wingspan ranging from 22.9 to 26.7 cm.

Status and Rank

US Status: No Status/Not Listed
State Status: T - Threatened (legally protected)
Global Rank: G3G4 - Rank is uncertain, ranging from vulnerable to apparently secure
State Rank: S1 - Critically imperiled


CountyNumber of OccurrencesYear Last Observed
Alpena 2 2012
Antrim 3 1999
Arenac 1 1910
Baraga 3 2010
Berrien 2 2005
Branch 1 1979
Cass 1 2005
Charlevoix 5 1987
Cheboygan 5 1993
Chippewa 5 1980
Clare 1 1986
Clinton 1 1958
Crawford 1 1947
Delta 2 1967
Dickinson 1 2010
Eaton 2 1978
Emmet 4 1993
Gogebic 5 2011
Grand Traverse 1 1977
Hillsdale 1 1980
Houghton 5 2011
Ingham 1 1958
Iosco 2 1986
Iron 4 1994
Isabella 1 1996
Jackson 2 1980
Kalkaska 3 1999
Keweenaw 4 2012
Leelanau 2 1977
Livingston 2 1936
Luce 2 1977
Mackinac 4 2010
Manistee 2 2012
Marquette 6 2012
Mason 2 1980
Mecosta 1 1998
Menominee 3 1940
Montmorency 1 1963
Newaygo 1 1974
Oakland 1 1928
Oceana 1 1903
Ogemaw 2 1986
Ontonagon 8 2012
Osceola 1 1986
Otsego 3 1982
Roscommon 2 1977
Schoolcraft 1 1975
St. Joseph 1 1979
Washtenaw 3 1992
Wayne 1 1928
Wexford 4 2014

Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


Before white-nosed syndrome devastated bat populations, little brown bats were the most common bat species in the northern half of the Lower Peninsula in Michigan accounting for roughly 60 percent of all mist net captures. They occur in a variety of habitats and their abundance is linked closely to availability mines and caves suitable for hibernation. Upon emergence from hibernation they travel throughout the state and will set up maternity roosts in man-made structures, utilizing barns, houses, large buildings, and the underside of bridges. They also roost in tree hollows and under loose bark. Little brown bats often forage over streams and ponds.

Natural Community Types

  • Unknown

For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Management Recommendations

Little brown bat are generalists. Maintaining forest for roosting in and around open water for foraging would benefit this species. Protecting hibernacula from vandalism during winter is critical.

Active Period

Active from second week of April to second week of October

Breeding from first week of September to fourth week of September

Parturition from first week of June to first week of July

Survey Methods

Mist nets should be set perpendicular to travel corridors such as streams, rivers, and logging trails. A typical net setup is 7 to 9 meters (23-30 ft) high and up to 20 meters (66 ft) wide. Surveys should consist of a minimum of 1 net site per kilometer of habitat corridor and 2 sites per square kilometer of habitat. Mist netting at a site should be conducted for four nights and in at least two different locations within a site. Nets should be checked every 20 minutes from sunset to sunrise. The species is most active 25 minutes after sundown to 4 hours after sundown.

Mist netting

Survey Period: From third week of May to fourth week of July

Time of Day: Night
Air Temperature: Above 60 degrees


Survey References

  • Kurta, A. 2008. Bats of Michigan. Indiana State University Center for North American Bat Research and Conservation, Terre Haute, Indiana, 72 pp.
  • U.S. Fish and Wildlife Service. 2018. Range-Wide India Bat Survey Guidelines.
  • Wisconsin Department of Natural Resources. 2013. Wisconsin Little Brown Bat Species Guidance. Bureau of Natural Heritage Conservation, Wisconsin Department of Natural Resources, Madison, Wisconsin. PUB-ER-705