Brazilian free-tailed bat  (Tadarida brasiliensis)

Despite its name, the Brazilian free-tailed bat is actually widespread throughout South, Central and North America. It has fairly complex migratory habits; some populations travel from the extreme north of the range to the extreme south, whilst others remain resident year-round. The largest and most well-known populations are found in Mexico and Texas, USA. There are nine subspecies in total; all occupy different ranges and have different migration routes (3). The population is thought to total between 95 and 105 million individuals, with Bracken Cave in Texas holding between 20 and 40 million individuals alone (2).

In World War II this species was secretly investigated by the U.S. Air Force for its potential to carry tiny bombs into Japan. Bat caves were carefully guarded but the bats refused to cooperate, instead wreaking havoc in Air Force bases (5).

The Brazilian free-tailed bat is found in many different habitats from desert through pinion-juniper woodland to pine-oak forests. It inhabits areas from sea level to 3,000 metres, and roosts in limestone caves, abandoned mines, under bridges, in buildings and in hollow trees (6).