Bats of the United States and Canada

Brazilian Free-tailed Bat, Tadarida brasiliensis

116 bats of the united states and canada BRAZILIAN FREE-TAILED BAT Tadarida brasiliensis Weight is 11–15 grams (0.4–0.5 ounce); wingspan is 29–35 centimeters (11–14 inches); distribution is in the southern United States and southward through Mexico and Central America into northern South America. It also occurs on islands of the Caribbean. Habitat of Brazilian free-tailed bats differs in various parts of the United States. In the Southwest, they are primarily cave bats that migrate long distances into Mexico or beyond to overwinter. During summer , about 20 million bats of this species occupy Bracken Cave near San Antonio, Texas; this is the largest concentration of mammals in the world. In the Southeast, this species does not occur in caves; it is present only in man-made structures. In addition, populations in the southeastern United States do not migrate great distances (if at all), and few colonies larger than several hundred individuals are known. Brazilian free-tailed bats often select hot attics and caves as roosts; the babies seem to be able to tolerate higher temperatures than adults. High temperatures in roosts are essential for rapid growth of young bats; apparently, the larger the colony, the less expenditure of energy per bat to maintain a given temperature. This species usually feeds on small moths and beetles. One baby is born in late spring or early summer. Birth occurs with the mother hanging head downward. Passage of the baby through the birth canal requires about 90 seconds. Newborn are hairless but have all their milk teeth. A mother can locate her own baby among the thousands of babies in a colony. The subspecies inhabiting the southwestern United States in summer, the Mexican free-tailed bat (T. b. mexicana), is present in very large numbers. It has been estimated that more than 100 million are present in Texas alone during summer . The subspecies that occurs in the southeastern United States, LeConte’s free-tailed bat (T. b. cynocephala), is only locally common. recto runninghead 117 ...