Plants and Animals

Myotis septentrionalis Northern long-eared bat

Key Characteristics

Northern long-eared bat fur ranges from medium to dark brown dorsally and tawny to pale brown ventrally. As its name implies, the key distinguishing feature of the northern long-eared bat is the presence of a long outer ear that tapers to a rounded or pointed tip. When laid forward, the pinna extends 1/3 cm or more beyond the nose. The bat also has a long, slender tragus that is more than half the length of the pinna. Northern long-eared bats are a medium-sized bat with body length of 7.6 to 9.4 cm and a wingspan of 22.9 to 26.7 cm. Forearm length ranges from 3.3 to 3.5 cm and body mass ranges between 4.9 to 7.9 grams.

Status and Rank

US Status: LT - Listed Threatened
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G2G3 - Rank is uncertain, ranging from imperiled to vulnerable
State Rank: S1 - Critically imperiled

Occurrences

CountyNumber of OccurrencesYear Last Observed
Alcona 1 2009
Alger 1 2008
Allegan 1 2000
Alpena 2 2013
Antrim 1 1976
Baraga 2 2012
Berrien 1 2013
Calhoun 1
Charlevoix 1 1923
Cheboygan 2 2012
Chippewa 4 2012
Delta 5 2012
Dickinson 2 2013
Eaton 2 1994
Gogebic 4 2012
Grand Traverse 1 1967
Gratiot 1
Hillsdale 2 2001
Houghton 3 2011
Ionia 1 2011
Iosco 1 1976
Iron 1 Historical
Jackson 2 1998
Kalkaska 1 1967
Kent 1 1975
Keweenaw 3 2012
Lake 3 1999
Leelanau 1 1967
Lenawee 1 2011
Livingston 2 2001
Mackinac 3 2012
Manistee 2 2012
Marquette 4 2012
Mason 3 2009
Ontonagon 7 2013
Presque Isle 1 2013
Roscommon 1 1986
Washtenaw 2 2003
Wexford 3 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.

Habitat

Northern long-eared bats live in areas dominated by deciduous or mixed hardwood-coniferous forest. Forests with low understory cover appear to be preferred by this species. In Michigan, northern long-eared bats are associated with karst topography where they utilize small caves and crevices in limestone cliffs as hibernacula. After emerging from hibernation, northern long-eared bats will readily roost in trees, tree hollows, or bark crevices. During the summer, northern long-eared bats are not tied to a specific natural community type and will inhabit any forest with large trees that offer bark that is loose or has deep enough crevices to roost in. Northern long-eared bats do not appear to show preference for dead trees (as some bat species do) and readily roost in living trees. This species rarely roosts in human-made structures.

Natural Community Types

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

A primary limiting factor in their summer range has been the deforestation of mature forested habitats and the elimination of roost trees, which can be attributed to the cutting of large, dead trees for firewood. Forested habitat can be maintained by protecting mature, wooded areas, leaving large, dead trees standing, and maintaining wide vegetation buffer strips. Cutting of snags, canopy removal, and general land clearing activities for development, agriculture, and utility corridors should be avoided. All stone quarry activity around limestone cliffs pose a threat to this species and should be avoided.

White-nose syndrome has had a staggering impact on northern long-eared bat populations. As a result, this species was listed as threatened under the Endangered Species Act in April, 2015.

Active Period

Breeding from second week of September to second week of October

Migration from second week of August to second week of September

Parturition from second week of June to second 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. Due to the continued spread of white-nose syndrome any mist netting for bats must take precautions to disinfect equipment being used.

Mist netting

Survey Period: From first week of June to fourth week of July

Time of Day: Night

References

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