One of the world's most abundant bats — a single Texas cave (Bracken Cave) hosts an estimated 15 million individuals. Their nightly emergence is one of the great wildlife spectacles of North America.

Also called: Mexican Free-tailed Bat, Brazilian Free-tailed Bat

Native status: Native to southern US into Latin America

§ Quick facts

SizeBody 9–11 cm; wingspan 24–30 cm
Weight10–14 g
LifespanWild 8–18 years
OrderChiroptera
FamilyMolossidae

§ Encyclopedia

The Mexican free-tailed bat or Brazilian free-tailed bat is a medium-sized bat native to North, Central, and South America and the Caribbean, so named because its tail can be almost half its total length and is not attached to its uropatagium. It has been claimed to have the fastest horizontal speed of any animal, reaching top ground speeds over 99 mph (160 km/h). It also flies the highest among bats, at altitudes around 3,300 m (10,800 ft).

Source: Wikipedia — Mexican free-tailed bat Licensed under CC BY-SA 4.0

§ Identification

Field marks. Medium dark brown bat with crinkly ears; long narrow wings; "free" tail extending beyond tail membrane.

Similar species. Other Molossidae species. Big Brown Bat (different shape).

Voice. Ultrasonic echolocation; audible chirps near roosts.

§ Diet & behavior

Diet. Flying insects (moths, beetles, agricultural pests).

Behavior. Forms massive cave colonies; some single colonies contain 10+ million individuals (the largest mammal aggregations in the world). Carlsbad Caverns, Bracken Cave Reserve are famous gathering sites.

§ Range

Southern US to South America; massive colonies in Texas, New Mexico, Arizona

§ Habitat

Caves, abandoned mines, bridges (especially the Congress Avenue Bridge in Austin)

§ Threats

Wind turbine strikes (a major cause of bat mortality), pesticides reducing insect prey, roost disturbance.

§ Conservation status

According to the IUCN Red List, the mexican free-tailed bat is currently classified as Least Concern.

§ What helps

Support pollinator-friendly farming. Visit emergence events with respectful operators. Avoid disturbing roost sites.

Support our work More ways to help

§ Further reading

§ Sources cited

  • Bat Conservation International
  • Carlsbad Caverns National Park
  • IUCN Red List 2018