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Tadarida brasiliensis (I. Geoffroy, 1824)

Brazilian Free-tailed Bat

Federal Protection: No US federal protection

State Protection: No Georgia state protection

Global Rank: G5

State Rank: S4

SWAP High Priority Species (SGCN): No

Element Occurrences (EOs) in Georgia: 0

Habitat Summary for element in Georgia: Georgia habitat information not available


Description

Brazilian Free-tailed bats weigh 11-15 g (0.4-0.5 oz) and have a wingspan of 29-35 cm (11-14 inches). Adults range in size from 79 to 98 mm (7.9-9.8 in) in length and have tails almost half their size at 31 to 41 mm (3.1-4.1 in). This species gets its name because the tail protrudes noticeably beyond the tail membrane. The Brazilian Free-tailed bat is the only bat in Georgia that has this physical trait. These bats are medium to dark brown in color and can be slightly lighter on the belly. Their ears are broad and rounded.

Similar Species

Habitat

Habitat differs in various parts of the United States. Brazilian Free-tailed bats can occupy caves, mine tunnels, old wells, hollow trees, human habitations, bridges, and other buildings as daytime retreats. In the Southwest, they are primarily cave bats that migrate long distances to Mexico or beyond to winter. In Georgia, they are year-round residents.

Diet

The Brazillian Free-tailed bat is insectivorous. Their diet consists of a variety of flying insects, especially small moths and beetles. At dusk, Brazilian Free-tailed Bats emerge from their roosts to feed. Due to their long, angular, narrow wings, their flight is rapid and forceful.

Life History

The Brazilian free-tailed bat is a highly colonial cave bat that has adapted to human structures. Many have been documented using roof underhangs, attics, and narrow spaces between signs and buildings. Brazillian Free-tailed bats are often called “house bats'' for this reason. In the western part of the range, this species migrates to Mexico, Central America, and possibly South America for the coldest winter months.

Mating occurs in early spring before leaving winter roosts and shortly after arriving at maternity colonies. Each female gives birth to only one pup per year. Remarkably, female Brazilian Free-tailed bats, can recognize and locate their own young among the swarms of millions of bats and their offspring. Males mature at about two years, while females mature at nine months. Because the offspring grow up so quickly, the maternity colonies become extremely crowded in a very short period of time. Brazilian Free-tailed Bats can live up to 11 years in the wild.

Survey Recommendations

Since Brazilian Free-tailed bats are high flyers, mist-nets are rarely used to survey this species. Most of the work that has been done to survey and study these bats have been in caves and the areas surrounding maternity colonies. Ultrasonic detectors can also be deployed in riparian, forested, and urban locations to monitor bat activity at selected roost sites. Cave surveys (especially during winter months) should be done with care as to prevent the spread of the Pseudogymnoascus destructans, the causative fungus of white-nose syndrome (https://www.whitenosesyndrome.org/static-page/decontamination-information).

Range

This bat is one of the most widely distributed mammalian species in the Western Hemisphere. The Brazilian Free-tailed bat occurs across Central and South America, extending north into the United States from southern Oregon, northern Utah, southeastern Nebraska, central Arkansas, northern Alabama, and South Carolina. This species is most commonly associated with dry, lower elevation habitats, yet it also occurs in a variety of other habitats, and is found up to at least 10,000 feet in some of the western mountain ranges.

Threats

Human disturbance and vandalism of key roosting sites are likely the single most serious causes of decline. Besides human disturbance and habitat destruction, or alteration of suitable caves, mines, bridges, and old buildings, this bat is also susceptible to pesticides.

Georgia Conservation Status

There are no state-level protections for this species.

Conservation Management Recommendations

Protection of occupied roosts from human disturbance, as well as suitable management of the surrounding forest and nearby aquatic foraging sites, will be necessary to maintain and conserve Brazilian Free-tailed bat populations. Caves can be gated or fenced to prevent human entry but the gate must be properly designed such that bat movement and cave microclimate are not affected. Protection of vital roosts by government agencies and conservation organizations will greatly benefit the species. A continuing educational effort must be aimed at the general public, but efforts should especially be focused towards cave owners and explorers.

References

Arita, H. 1993. Conservation of Biology of Cave Bats of Mexico. Journal of Mammalogy, 73/3:693-702.

Barbour, R. W., and W. H. Davis. 1969. Bats of America. University Press of Kentucky, Lexington. 286pp

Barquez, R., Diaz, M., Gonzalez, E., Rodriguez, A., Incháustegui, S. & Arroyo-Cabrales, J. 2015. Tadarida brasiliensis. The IUCN Red List of Threatened Species 2015: e.T21314A22121621. https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T21314A22121621.en.

“Brazilian Free-Tailed Bat.” Kentucky Department of Fish & Wildlife Brazilian Free-Tailed Bat, fw.ky.gov/Wildlife/Pages/Brazilian-Free-Tailed-Bat.aspx.’’

Genoways, Hugh, et al. “Innovations That Changed Mammalogy: the Cyclone Trap.” Journal of Mammalogy, Oxford University Press, 25 Mar. 2020, academic.oup.com/jmammal/advance-article-abstract/doi/10.1093/jmammal/gyaa017/5811460?redirectedFrom=fulltext.

Sosnicki, Jessica. “Tadarida Brasiliensis (Brazilian Free-Tailed Bat).” Animal Diversity Web, animaldiversity.org/accounts/Tadarida_brasiliensis/.

Authors of Account

Sarah Krueger

Date Compiled or Updated

S. Krueger, March 2020

Photo by: Emily Ferrall (GA DNR)