font settings and languages

Font Size: Large | Normal | Small
Font Face: Verdana | Geneva | Georgia
Languages:

Myotis sodalis

(Mouse-Eared Bats)

Overview

[ Back to top ]

Indiana bats are subject to both natural and human threats . Periodic flooding of winter caves and the collapse of cave or mine ceilings both pose threats. However, the most serious threat to Indiana bats is the disturbance of hibernating colonies by spelunkers or vandals. Pesticides, the commercialization of roosting caves, and the channelization of streams also pose threats to the species.

This small bat has fur that ranges from nearly black to chestnut on its back with lighter gray or cinnamon fur on the belly. Individual hairs have dark bases with lighter tips . Its wingspread is about 9.5 to 10.5 inches. Indiana bats hibernate in caves and mines during the winter. They disperse from their hibernation caves in the spring and form separate male, female, and juvenile colonies. Females form maternal colonies which roost under the loose bark of trees , usually near water. Little is known about where males spend the summers.

Endangered

Threat status

Interesting Facts

[ Back to top ]
 

Common Names

[ Back to top ]

Common Names in English:

indiana bat, Indiana Myotis, Mouse-Eared Bats, Social bat

Description

[ Back to top ]

Physical Description

Species Myotis sodalis

The tragus, a projection which extends from the base of the inside of the external ear , is long and pointed rather than blunt and rounded . All of the Mouse-eared Bats have simple unmodified snouts, and a tail that reaches the end of the membrane from the hind legs . This membrane is never thickly furred. Many of the Mouse-eared Bat species are difficult to tell apart from one another, even in a museum.

Color:

Dark yellowish or grayish brown to gray, depending on species.

Size/Age/Growth

This group of small to medium-sized bats ranges from 8 - 9.5 cm (3.1 - 3.7 in) in total length.

Habitat

For hibernation, Indiana bats need limestone caves with stable temperatures of 39° to 46°F (4-8°C) and 66 to 95 percent humidity. Low cave temperatures allow the bats to maintain a low metabolic rate throughout hibernation. Only a small percentage of caves meets the specific conditions required by Indiana bats. During the summer, they can be found under bridges , in old buildings, under tree bark , or in hollow trees. Indiana bats forage above small- to medium-sized streams . Streams lined with large, overhanging trees are preferred.

Biome: Terrestrial [1].

Ecology: This species is represented by many maternity occurrences and hibernacula, but the majority of the population hibernates at relatively few sites, including several caves and one mine in Missouri, southern Indiana, and Kentucky (Brady et al. 1983, USFWS 1999). About 85% of the total population hibernates in nine Priority 1 caves, which contain at least 30,000 bats; the remaining 15 percent of the population have been or currently are distributed among 50+ Priority II and III hibernacula (Menzel et al. 2001). About ninety wintering sites are known.

Maternity colonies consist of small, widely scattered colonies of females (rarely more than 100) and their young. These are more widely distributed and numerous than are major hibernacula. For example, individuals from one hibernaculum in New York used many roost trees (Britzke et al. 2006). Captures of reproductively active females or juveniles at 24 sites in 16 counties in Illinois indicate that maternity colonies of this species occur throughout the range of this species in that state (Gardner et al. 1996). Maternity sites have been found in 13 counties in Kentucky (Kentucky Bat Working Group; http://www.biology.eku.edu/bats/indianabat.htm).

Myotis sodalis hibernates in caves; maternity sites generally are behind loose bark of dead or dying trees or in tree cavities (Menzel et al. 2001). Foraging habitats riparian areas, upland forests , ponds , and fields (Menzel et al. 2001), but forested landscapes are the most important habitat in agricultural landscapes (Menzel et al. 2005).

In hibernation, limestone caves with pools are preferred. Hall (1962) noted that preferred caves are of medium size with large, shallow passageways. Roosts usually are in the coldest part of the cave. Preferred sites have a mean midwinter air temperature of 4-8 C (tolerates much broader range) (Hall 1962, Henshaw and Folk 1966), well below that of caves that are not chosen (Clawson et al. 1980). Roost sites within caves may shift such that bats remain in the coldest area (Clawson et al. 1980); individuals may move from a location deeper in the cave to a site nearer the entrance as the cold season progresses; they may move away from areas that go below freezing. Hibernation in the coldest parts of the cave ensures a sufficiently low metabolic rate so that the fat reserves last through the six-month hibernation period (Henshaw and Folk 1966, Humphrey 1978). Relative humidity in occupied caves ranges from 66 to 95% and averages 87% throughout the year (Barbour and Davis 1969, Clawson et al. 1980). Because of these requirements, M. sodalis is highly selective of hibernacula.

During the fall , when these bats swarm and mate at their hibernacula, males roost in trees nearby during the day and fly to the cave during the night. In Kentucky, Kiser and Elliott (1996) found males roosting primarily in dead trees on upper slopes and ridgetops within 2.4 km of their hibernaculum. During September in West Virginia, males roosted within 5.6 km in trees near ridgetops, and often switched roost trees from day to day (C. Stihler, West Virginia Division of Natural Resources , pers. observ., October 1996, cited in USFWS 1999). Fall roost trees tend to be in sunnier areas rather than being shaded (J. MacGregor, pers. observ., October 1996, cited in USFWS 1999). In summer, habitat consists of wooded or semiwooded areas, often but not always along streams . Solitary females or small maternity colonies bear their offspring in hollow trees or under loose bark of living or dead trees (Humphrey et al. 1977, Garner and Gardner 1992). Humphrey et al. (1977) determined that dead trees are preferred roost sites and that trees standing in sunny openings are attractive because the air spaces and crevices under the bark are warmer. In Illinois, Garner and Gardner (1992) found that typical roosts were beneath the exfoliating bark of dead trees; other roost sites were beneath the bark of living trees and in cavities of dead trees. Kurta et al. (1993) found a large maternity colony in a dead, hollow, barkless, unshaded sycamore tree in a pasture in Illinois. In Michigan, a reproductively active colony occupied eight different roost trees (all green ash), all of which were exposed to direct sunlight throughout the day; bats roosted beneath loose bark of dead trees (Kurta et al. 1993). In western Virginia, a male used a mature , live, shagbark hickry tree as a diurnal roost; the bat foraged primarily among tree canopies of an 80-year-old oak-hickory forest (Hobson and Holland 1995). In Missouri, primary maternity roosts were in standing dead trees exposed to direct sunlight; there were 1-3 primary roosts per colony; alternate roosts were in living and dead trees that typically were within the shaded forest interior (Callahan et al. 1997). See Garner and Garner (1992) for detailed information on summer habitat in Illinois. Though maternity sites have been reported as occurring mainly in riparian and floodplain forests (Humphrey et al. 1977, Garner and Gardner 1992), recent studies indicate that upland habitats are used by maternity colonies much more extensively than previously reported. Garner and Gardner (1992) reported that 38 of 51 roost trees in Illinois occurred in uplands and 13 trees were in floodplains. Of the 47 trees in forested habitat, 27 were in areas having a closed (80-100%) canopy , and 15 were in areas having an intermediate (30-80%) canopy. A single roost tree was found in the following types of habitat: a heavily grazed ridgetop pasture with a few scattered dead trees, a partially wooded swine feedlot, a palustrine wetland with emergent vegetation , a forested island in the Mississippi river , and a clearcut around a segment of an intermittent stream where dead trees were retained for wildlife. Roosts were not found in forests with open canopies (10-30%) or in old fields with less than or equal to 10% canopy cover. In eastern Tennessee and western North Carolina, several maternity colonies were in sun-exposed conifer snags (roost sites were above the surrounding canopy); some of these snags fell and were not used in subsequent years (Britzke et al. 2003). Rarely maternity colonies have been found in crevices in utility poles or in bat boxes (e.g. , Ritzi et al. 2005). See Menzel et al. (2001) for a review of forest habitat relationships . Known roost tree species include elm, oak, beech, hickory, maple, ash, sassafras, birch, sycamore, locust, aspen, cottonwood, pine, and hemlock (Cope et al. 1974, Humphrey et al. 1977, Garner and Gardner 1992, Britzke et al. 2003, Britzke et al. 2006), especially trees with exfoliating bark.

In Illinois, Indiana bats used the same, evidently traditional, roost sites in successive summers. Recapture of the same individuals within traditional roost sites during subsequent summers suggests site fidelity (Garner and Gardner 1992, Gardner et al. 1996). Relatively few individuals roost in caves at the mouths of which late summer swarming occurs (Cope and Humphrey 1977, Barbour and Davis 1969).[1].

List of Habitats:

Biology

[ Back to top ]

Diet

Members of the genus usually feed over water or forests adjacent to water. Some species may travel as far as 24.1 km (15 mi ) on foraging flights. Their diet is composed mostly of mayflies, midges, flies, moths, beetles, and mosquitos.

Reproduction

Indiana bats are migratory. Approximately 85 percent of the known population hibernates in just seven caves. Indiana bats mate in the fall and begin to enter hibernation in October. Males tend to be active longer into the fall, but are in hibernation by late November. Sperm is stored during the winter and females become pregnant soon after emergence in late March and early April. Young are born in June and July. Females and their young roost in small colonies (50 to 100 individuals) under tree bark during the summer months. Colonies are usually located along streams where the bats forage for flying insects. Not much is known about male roosting behavior. Young bats are able to fly approximately a month after birth.

Breeding generally takes place in late autumn, and 1 - 2 young (depending on the species) are born in May or June of the following spring . In some species, females gather together to form a "maternity colony" of up to several hundred individuals, and remain together until August or September when the young are able to fend for themselves. The young are able to fly within 3 - 5 weeks after birth. Sexual maturity is reached in 1 - 2 years, depending on species.

Behavior

The Little Brown Myotis can live for 30 years. This is the longest life span known for a bat. As in all bats, members of this genus use echolocation to find food and to avoid collisions with obstacles.

Taxonomy

[ Back to top ]

Synonyms

Myotis sodalis (Miller & Allen 1928)

Notes

Name Status: Accepted Name .

Last scrutiny: 08-Jun-2004

Similar Species

[ Back to top ]

The Big Brown Bat is noticably larger and the Evening Bat has a blunt, forward-curved tragus.

Members of the genus Myotis

ZipcodeZoo has pages for 134 species and subspecies in this genus. Here are just 100 of them:

M. abei (Sakhalin Myotis) · M. adversus (Large-Footed Myotis) · M. aelleni (Southern Myotis) · M. albescens (Silver-Tipped Myotis) · M. alcathoe (ALCATHOE WHISKERED BAT) · M. altarium (South-Western Mouse-Eared Bat) · M. anjouanensis (Anjouan Myotis) · M. annamiticus (Annamit Myotis) · M. annectans (Hairy Faced Bat) · M. atacamensis (Atacaman Myotis) · M. ater (Peters's Myotis) · M. atra (Peters's Myotis) · M. aurascens (Steppe Whiskered Bat) · M. auriculus (Southwestern Myotis) · M. australis (Ustrailian Myotis) · M. austroriparius (Mouse-Eared Bats) · M. austroriparius austroriparius (Southeastern Myotis) · M. bechsteini (Bechstein's Bat) · M. bechsteinii (Bechstein's Myotis) · M. blythii (Lesser Mouse-Eared Myotis) · M. bocagei (Rufous Mouse-Eared Bat) · M. bocagei bocagei (Rufous Mouse-Eared Bat) · M. bocagii (Rufous Mouse-Eared Bat) · M. bombinus (Far Eastern Myotis) · M. brandti (Brandt's Bat) · M. brandtii (Brandt's Myotis) · M. bucharensis (Bokhara Whiskered Bat) · M. californicus (Californian Myotis) · M. californicus californicus (Californis Myotis) · M. capaccinii (Long-Fingered Bat) · M. capaccinii capaccinii (Long-Fingered Bat) · M. chiloensis (Chilean Myotis) · M. chinensis (Large Myotis) · M. ciliolabrum (Western Small-Footed Myotis) · M. ciliolabrum ciliolabrum (Western Small-Footed Myotis) · M. cobanensis (Guatemalan Myotis) · M. csorbai (Csorbas Mouse-Eared Myotis.) · M. dasycneme (Pond Myotis) · M. daubentoni (Daubenton's Bat) · M. daubentonii (Daubenton's Myotis) · M. davidii (David's Myotis) · M. dominicensis (Dominican Myotis) · M. elegans (Elegant Myotis) · M. emarginatus (GEOFFROY'S MYOTIS) · M. emarginatus emarginatus (Geoffroy's Bat) · M. evotis (Long-Eared Myotis) · M. evotis evotis (Long-Eared Myotis) · M. fimbriatus (Fringed Long-Footed Myotis) · M. findleyi (Findley's Myotis) · M. formosus (Hodgson's Myotis) · M. formosus formosus (Hodgson's Bat) · M. fortidens (Cinnamon Myotis) · M. fortidens fortidens (Cinnamon Myotis) · M. frater (Long-Tailed Whiskered Bat) · M. gomantongensis (Gomantong Myotis) · M. goudoti (Malagasy Mouse-Eared Bat) · M. grisescens (Mouse-Eared Bats) · M. hajastanicus (Armenian Myotis) · M. hasseltii (Lesser Large-Footed Myotis) · M. hermani (Herman's Myotis) · M. horsfieldii (Horsfield's Myotis) · M. hosonoi (Hosono's Myotis) · M. ikonnikovi (Ikonnikov's Whiskered Bat) · M. insularum (Insular Myotis) · M. keaysi (Hairy-Legged Myotis) · M. keenii (Northern Long-Eared Bat) · M. laniger (Chinese Water Myotis) · M. leibii (Western Small-Footed Myotis) · M. leibii leibii (Eastern Small-Footed Myotis) · M. lesueuri (Lesueur's Hairy Bat) · M. levis (Yellowish Myotis) · M. levis levis (Yellowish Myotis) · M. longipes (Kashmir Cave Bat) · M. lucifugus (Little Brown Myotis) · M. lucifugus lucifugus (Little Brown Myotis) · M. macrodactylus (Big-Footed Myotis) · M. macropus (Large-Footed Myotis) · M. macrotarsus (Philippine Large-Footed Myotis) · M. martiniquensis (Schwartz's Myotis) · M. melanorhinus (Dark-Nosed Small-Footed Myotis) · M. milleri (Miller's Myotis) · M. moluccarum (Maluku Myotis) · M. montivagus (Burmese Whiskered Myotis) · M. morrisi (Morris's Bat) · M. muricola (Nepalese Whiskered Bat) · M. myotis (Greater Mouse-Eared Bat) · M. mystacinus (WHISKERED MYOTIS) · M. nattereri (Natterer's Bat) · M. nesopolus (Curacao Myotis) · M. nigricans (Black Myotis) · M. nipalensis (Nepal Myotis) · M. occultus (Arizona Myotis) · M. oreias (Singaporese Whiskered Myotis) · M. oxyotus (Montane Myotis) · M. ozensis (Honshu Myotis) · M. peninsularis (Peninsular Myotis) · M. pequinius (Peking Myotis) · M. pilosus (Rickett's Big-Footed Myotis) · M. planiceps (Flat-Headed Myotis) · M. pruinosus (Blackish Whiskered Bat)

More Info

[ Back to top ]

Further Reading

[ Back to top ]

Notes

[ Back to top ]

Contributors

Data Sources

Accessed through GBIF Data Portal March 12, 2008:

Identifiers

Footnotes

  1. Arroyo-Cabrales, J. & Ticul Alvarez Castaneda, S. 2008. Myotis sodalis. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 02 February 2012. [back]
Last Revised: 2012-05-03