Texas Flying Mammal

Mexican Free-tailed Bat

(Tadarida brasiliensis)

Adopted on May 25, 1995.

The Mexican free-tailed bat, Tadarida brasiliensis, is Texas's Flying Mammal, adopted on May 25, 1995.  A medium sized bat. Their bodies are about 9 centimeters in length, and they weigh about 15 grams. Their ears are wide and set apart to help them find prey with echolocation. Its fur color varies from dark brown to gray.
 

Mexican free-tailed bats occupy a wide variety of habitats, ranging from desert communities through pinion-juniper woodland and pine-oak forests at elevations from sea level to 9,000 feet or more. The largest US populations of free-tailed bats live in the West, with the densest concentrations found in Texas where they form maternity colonies numbering in the millions. They are found throughout Mexico and most of the western and southern US The largest colony is found at Bracken Cave, north of San Antonio, Texas, with nearly 20 million bats.

The largest maternity colonies are formed in limestone caves, abandoned mines, under bridges, and in buildings, but smaller colonies also have been found in hollow trees. It is estimated that 100-million Mexican free-tailed bats come to Central Texas each year to raise their young. Nursing females require large quantities of insects that are high in fat, which they obtain by consuming egg-laden moths. The 100 million free-tailed bats living in Central Texas caves consume approximately 1,000 tons of insects nightly, a large proportion of which are agricultural pests. Researchers using Doppler weather radar watch emerging bats ascend to altitudes of 1,000-10,000 feet to feed on migrating cotton boll worm moths, army cut-worm moths, and other costly agricultural pests that migrate north from Mexico. The bats of Bracken Cave can eat up to 250 tons of insects per night!

This species is very important for the control of pest-insect populations. But its populations have fallen because of the use of pesticides and the destruction of their roosting caves.

When baby free-tail bats are born, their mothers leave them behind in the cave while they go out to hunt insects. You would expect that a bat-mother would have trouble locating her own baby (called a pup) among millions of other noisy pups. But it only takes her a few minutes to do so. She remembers where she left her pup, and recognizes its "cry" and smell.