Carlsbad Caverns National Park

Carlsbad Caverns National Park

Species Spotlight: Brazilian free-tail bat

October 16, 2009, 10:19 am

Go batty over the Brazilian free-tail bat!

Brazilian free-tail bat (Tadarida brasiliensis Mexicana): Also called Mexican free-tail bats and guano bats, these creepy critters have made their home in Carlsbad Caverns for a long time, thanks to their roosts conveniently located above the caverns’ massive guano mounds. In 1930, early explorers found a second active bat roost deep within the cave. Today, 400,000 hungry Brazilian free-tail bats emerge from the depths of Carlsbad Cavern every night to dine on tasty, unsuspecting insects.
 
Belonging to the family Molossidae, the species contains nine recognized subspecies. Carlsbad Caverns’ regional subspecies is Tadarida brasiliensis Mexicana.
 
Description: The Brazilian free-tail bat can be distinguished from other regional bats by its distinctive "free-tail" which extends beyond the tail membrane and from the uncommon Big free-tail bat (Nyctinomops macrotis) by its smaller size and ears that are not joined across the forehead.
 
Total length: 85-109 mm; Tail: 31-41 mm; Hind foot: 8-12 mm; Ear: 14- 20 mm; Forearm: 36-46 mm; Weight: 10-15 g.
 
Distribution: North America:  Southern US, from California to Kansas, eastward along the Gulf and lower Atlantic coasts, and south throughout Mexico into Central America.
 
Ecology and diet: Free-tail bats undergo seasonal migrations, moving north during spring and summer to form large colonies. Their diet consists primarily of moths and other flying insects that they catch while foraging in open habitat, often at high altitudes.
 
Life History: Females bear single offspring between late spring and early summer. Females and dependent young form large maternity colonies. Young are weaned in about 6 weeks. Life span may exceed 10 years.
 
References:   Wilkins 1989; Ports & Bradley 1996;  McCracken 1999; Rickart & Robson 2005.