Brazilian Free-tailed Bat

Similar Species:
Except for Little Free-tallied, which occurs only in Florida Keys and has ears joined at the base, all other free-tailed bats are considerably larger.

Breeding:
Mates February-March; ovulates in March. Females form very large maternity colonies usually in caves or man-made structures. 1-3 (usually 1) young born in June. Female hangs head downward during birth, but flight membrane I not use to receive young.

Habitat:
Deserts, canyons, farmlands, and other habitats. Roosts in buildings on West Coast and in Southeast, and in caves from Texas to Arizona.

Range:
Throughout s. U.S.; in West, south from s Oregon and s Nebraska; in East, south from n Louisiana, Alabama, and South Carolina. A few are scattered farther north.

The Brazilian Free-tailed Bat is by far the most common bat in the Southwest; with a U.S. population previously estimated at a minimum of 100 million, mammals in the country. In the East and on the West Coast, it hibernates in winter rather than migrate. From Texas though the Southwest, it lives in huge colonies in caves, packed 250 per square foot, a few of the Southwest bats hibernate, but more migrate to México for the winter, usually toward the end of October, returning northward in March to mate. The young hang, sometime amoung million of other, in a nursery, yet pup and mothers are capable of fining one another by their calls and probably odor. Mother make n o attempt to save young that lose their grip on the ceiling, however; such pups perish on the cave floor, where they are consumed by tenebrionied beetles. The Carlsbad Cavers in New México were discover when these bats were seen emerging from them. Although the cavern population has declined from an estimated  8- 9 million in the 1930s to several hundred thousand, the bats’ daily emergence is still a major tourist attraction. At sunset, bats begin flitting about inside the cave, causing a slight rise in temperature and humidity. After circling for several minutes, they begin to emerge from the depths of the caverns in a counterclockwise spiral, ascending 150 to  180 feet into the night air. They emerge in various ways; as one continuous wave; split into tow groups with an interval of half an hour in between; or in bursts of sever hundred to sevral thousand bats that give way after 150 to 20 minutes to a  continuous steam. They make a great roar and form a dark cloud visible miles away when the egression is at it heaviest, 5,000 to 10,000 bats emerge each minute. While they may roam up to  150 miles, most Carlsbad bats feed within a 50-mile radius. Generally they fly throughout the night, at 10 to 15 mph, feeding on a variety of small insects, especially moths, ants, beetles and leafhopper captured in the tail membrane.  Each night, a bat eats up to one-third its own weight; 250, 000 bats can consume half a ton of insects. The return to the caves, at sunrise, is more spectacular then the emergence, the bats plummet strait down from heights of 600 to 1,000 feet at speeds of more than 25 mph to a reported maximum speed of  60 mph. Bat dropping in Carlsbad Caverns over the past 17,000 years have formed guano deposits covering several thousand square feet to a depth of almost 50 feet. Guans was used during the Civil War as a source of sodium nitrate for gunpowder and mined as fertilizer from the turn of the century thought the 1940s. A few small-scale guano mines are still in operation. These bats may have a life span of up to  18 years. Hawks and owls sometimes sit at cave entrances and pry on them as they emerge. Black snakes, Common Raccoons, house cats, and other predator sometimes mange to access to their roosts. A hazard of  entering free-tailed bat caves in the Southwest is the possibility of transmitted by a bat bite or by the airborne virus. People have also contracted histoplasmosis, a fungal infection of the respiratory tract, from bat caves of the Southwest.