Brazilian Free-tailed Bat

Scientific Name: Tadarida brasiliensis

Weight: 11-15 grams

Wingspan: 29-35 centimeters

Distribution: The southern United States and southward through Mexico and Central America into northern South America.

Ecology and Behavior: Habitat of Brazilian free-tailed bats differs in various parts of the United States. In the southwestern United States, they primarily are cave bats migrating to Mexico to winter. About 20,000,000 bats of this species occur in one cave near San Antonio, Texas; this is the largest concentration of mammals in the world. In the eastern United States, this species does not occur in caves, it is present in only man-made structures, it does not migrate long distances, and few colonies larger than a few hundred individuals are known. These bats often select hot attics as roosts, and young seem to be able to tolerate higher temperatures than adults. High temperatures in roosts are essential for the rapid growth of young bats; apparently, the larger the colony, the less energy expenditure per bat to maintain a given temperature.

Food Habits: This species feeds almost exclusively on small moths.

Reproduction: One young is born in late spring or early summer. Birth occurs with the mother hanging head downwards. Passage of the young through the birth canal requires about 90 seconds. Newborns are hairless, but have all their milk teeth. Mothers usually are able to locate their own young among the thousands of other babies in a cave.

Status of Populations: Common throughout most of its range, but only locally common in much of the southeastern United States.