Tadarida brasiliensis
(Geoffroy Saint-Hilaire, 1824)

ta-dAr-i-de bre-zil-E-en-sis

Photo by Stan Roth.
Image © by Greg Sievert.

Tadarida brasiliensis is a relatively small bat in which the distal half of the tail extends freely beyond the tail membrane, or uropatagium. Its calcar (which helps support the uropatagium) does not have a keel. Long hairs extend from the feet. Large, rounded ears have bumps (papillae) on their leading edge. The upper lip has vertical wrinkles. The pelage is short and dense. It ranges from dark brown to grayish brown to very pale, the last resulting from bleaching from the ammonia buildup in roosts. The Brazilian Free-tailed Bat can be distinguished from all other bat species except one in Kansas by its tail that projects well beyond the posterior border of the uropatagium. The one exception is the big free-tailed bat, which is considerably larger. Also, unlike the Brazilian free-tailed bat, the big free-tailed bat has ears that are joined at the base, and has 3 lower incisors on each side rather than 2.

Adults may attain the following dimensions: total length 90-108 mm; length of tail 30-40 mm; length of hind foot 8-12 mm; length of ear 13-19 mm; weight 8-14 grams. Adult measurements of big free-tailed bats are total length 120-160 mm, length of tail 40-57 mm; length of hind foot 7-11 mm; length of ear 25-32 mm; weight 22-30 g. 

The dental formula in the Brazilian free-tailed bat is incisors 1/2, canine 1/1, premolars 2/2, molars 3/3.

The overall distribution of the Brazilian Free-tailed Bat extends from the southern half of Kansas southward through Mexico and Central America and well into South America. Additionally, the species occurs throughout the West Indies. Kansas is at the northern edge of the breeding range of this species. The only documented maternity colonies in the state were in buildings in Medicine Lodge. These colonies evidently were abandoned or destroyed sometime between 1980 and 1993. Females of the species found in Kansas today typically are residents of Merrihew Cave, which is just a short distance south of Barber County, Kansas, in Oklahoma. Widely scattered, all-male bachelor colonies can be found almost anywhere in Kansas during summer. Additionally, individual males or small groups of males occasionally are found far to the north of the breeding range of the species. These have been interpretted as "wanderers," "disoriented migrants," or "pioneers" seeking new roosts. The ability to fly long distances facilitates extensive seasonal movements by this species. This cave-dwelling bat has benefited from man's activities in that settlement of Kansas resulted in man-made structures in which the species sometimes roosts.
The Brazilian free-tailed bat is not common in fossil deposits. The only fossils of this species known from outside its current range are from a 38,000 year old deposit in Kentucky. Other Pleistocene deposits containing this bat have are in Florida, Arizona, New Mexico, Texas, Puerto Rico, and Cuba. Holocene fossils have been found in the Lesser Antilles. 

(, Museum Voucher) (, Observation) (, Literature Record)
Open icons are questionable records; Click on a marker to view details.
  • Occurrence Summary:  
  • 87 Total Records 
  • 80 Museum Vouchers 
  • 7 Other Observations 
Some county occurrences indicated below may be too imprecise to map above.
County Breakdown: County Name (# occurrences):
Barber (40); Cherokee (1); Cheyenne (1); Clark (1); Comanche (11); Douglas (1); Ellis (6); Finney (4); Ford (1); Gove (1); Grant (1); Gray (2); Harper (1); Kiowa (1); Lane (1); Logan (1); Lyon (1); Marion (1); Meade (3); Morton (1); Pratt (1); Rawlins (1); Riley (1); Shawnee (1); Sherman (1); Stafford (1); Sumner (1);

Natural History:
Tadarida brasiliensis is the most gregarious of all mammals. The immense colonies (up to 20 million animals) are one of the wonders of nature. Emergence from large colonies begins about 15 minutes after sunset. How long emergence lasts depends on the size of the colony. The bats may fly considerable distances to their feeding areas because areas near the roost cannot support enough insects to feed them. Rapid, long distance flights are made possible by long, narrow wings. These wings are adapted for speed, but they do not provide enough lift for bats to fly up from the ground without climbing high enough to drop and gain speed. Once at the feeding areas, the bats drink, feed, and rest before returning to their roost. The return of the bats is almost as exciting to watch as the emergence, and it lasts as long or longer. At all but the largest colonies, the bats return by sunrise. Northern populations of the Brazilian free-tailed bat migrate southward to warmer climates for winter; the bats in Kansas migrate to southern Texas or northern Mexico beginning in September. They begin to return to Kansas in late April. Maximum reported lifespan in the wild is 8 years. Maximum potential lifespan is about 15 years. 
Moths are the primary food of this bat, although other kinds of insects also are eaten. The quantity of moths eaten in one night by a large colony of these bats is enormous, thus punctuating the ecological importance of this species and its benefit to agricultural interests.
The Brazilian free-tailed bat is regarded as a "big city bat" because of the large colonies in which it lives. And, as in many large cities, there are perils to avoid. For example, solid waste pollution resulting from guano produced by millions of bats literally can fill up a cave. If a pup loses its grip and falls onto the surface of the guano, it literally is eaten alive by the dermestid beetle larvae that live in the guano. Air pollution resulting from the urine produced by all the bats is another problem. The ammonia literally can bleach the bats blonde. Crime in the streets is represented by all the predators that arrive each evening at the cave entrance just before the exodus. These may include snakes, coyotes, raccoons, opossums, and armadillos, while circling overhead are owls. When the column of bats emerges, they are flying in such close formation that they beat one another with their wings. Those that fall to the ground are immediately grabbed by a predator while the owls above repeatedly fly through the column picking off bats. Other sources of mortality include pesticide poisoning, rabies, accidents, and destruction of bats in their roosts by humans.

Occurrence Activity:
Brazilian Free-tailed Bats in Kansas are referred to the subspecies Tadarida brasiliensis mexicanus.

1952 Cockrum, E. L. Mammals of Kansas. Univ. Kansas Publ. Mus. Nat. Hist. 7:1-303. ():
1967 Jones, J. K. Jr., E. D. Fleharty, and P. B. Dunnigan The distributional status of bats in Kansas. Univ. Kansas Mus. Nat. Hist. Misc. Publ., 46:1-33. ():
1989 Wilkins, K. T. Tadarida brasiliensis Mammalian Species 331():1-10
1996 Sparks, D.W. and J.R. Choate New distributional records for mammals in Kansas Prairie Naturalist 27(4):185-192
1999 Wilson, D. E., and S. Ruff Smithsonian Institution Press, Washsington, DC. 1-750pp.
2008 Timm, R. M., G. R. Pisani, J. R. Choate, N. A. Slade, G. A. Kaufman, and D. W. Kaufman, . pp.
Account Last Updated:
8/21/2018 7:52:50 PM

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